00 Astounding Customer Service - · PDF fileFunction of fuel units: ... Return To Inlet Inlet Port Cone Valve Nozzle Port ... the shutoff pressure will be about 80 PSI

00 Astounding Customer Service

Fuel Units and Oil ValvesChapter 4

Chapter 4—Fuel Units and Oil Valves 4-3

IntroductionFunction of fuel units: These componentslift the oil from the tank to the burner,deliver oil at a constant and regulatedpressure to the nozzle, and provide cleancutoff of fuel.

Component partsof the fuel unit

• The fuel unit contains a set ofmachined gears, which provide bothvacuum and pressure. The single stage fuel

unit, Figure 4-1, contains oneset of fuel pump gears.

• The pressure-regulatingvalve controls the pressure ofthe oil discharged to thenozzle. A cutaway of thisvalve is shown in Figure 4-2.This assembly consists of avalve body and matchingpiston. In the closed position,the piston is held against thenozzle discharge port by a

Figure 4-1: Singlestage fuel unit

Figure 4-2:Cutaway of oilvalve

Chapter 4Fuel Units and Oil Valves

No. Description1 Vacuum Gauge Connection Port2 Pressure Regulator Adjustment Screw3 Pressure Gauge Connection Port and Bleeder4 Pump Cover Screws5 Return Fuel Line Port

6 By-pass Plug7 Supply Fuel Line Port8 Capillary Tube Connection Port9 Oil Delivery Port

10 Pump Cover O-ring11 Pump Cover

To Nozzle

Easy Flow AirBleed Valve andGauge Port

Check ValveAssy. Special

Piston Assy. SpecialRemoveable SleeveStandard

Pressure AdjustingSpring Special

4-4 Fuel Units and Oil Valves

spring located behind the piston. When thefuel pump gears develop sufficient pressureto overcome the spring tension, the pistonis forced back, allowing oil to flow throughthe nozzle discharge port. The pressureadjusting screw regulates the spring tensioncontrolling the pressure of the oil dis-charged to the nozzle.

• The strainer screen, see Figure 4-3,within the fuel unit reservoir,filters the incoming oil andhelps to prevent any contami-nation from entering thenozzle.

• A solid shaft extendingthrough the pump housing sealdrives the gear pump. The endof this shaft is connected to theburner motor by a flexiblecoupling. (Note that the

R.P.M. rating of the gear pump must be thesame as the burner motor.)

• A shaft seal is provided to prevent oilfrom leaking out of the fuel pump housingaround the rotating shaft. Lubrication isprovided to this seal through internalporting.

Operation of the singlestage fuel unit

The single stage fuel pump, Figure 4-4,produces both pressure and vacuum.Pressure is the force created by the meshingof the pump gears, and is expressed inpounds per square inch (PSI). Pressuremoves the oil away from the pump.Vacuum is expressed in inches of mercury,and is abbreviated as in. Hg. Normally wesimply show the numerical value of the

Figure 4-3:Strainer screenand gasket.

Figure 4-4:Suntec Industries;Cutaway examplesingle stagefuel unit

Diaphragm Valve

Optional Return

To Seal Chamber

From Seal Chamber

Easy FlowBleed Valve

Return PortReturn To Inlet

Inlet Port

Cone Valve

Nozzle Port

Pressure Gauge Port


Caution: This valve must beset at the factory or authorizedservice station. Do not tamper

with this in the field.

Note: Do not try to adjustnozzle pressure with gaugein this port.


vacuum with an inch (") mark. Example:10" of vacuum. Vacuum brings oil to thepump. We need about .75" to 1" Hg ofvacuum for each foot we lift the oil, 1" ofvacuum for each 10 feet of horizontal run,and ½" for a clean oil filter. For example, ifwe have 4 feet of lift from an undergroundtank, plus 10 feet of oil line run to theburner, and add the oil filter, the calculatedvacuum reading should be 5.5". A vacuumgauge reading of from 5" to 6" is accept-able.

When the motor turns the pump shaft, oilenters the strainer chamber through theintake port, either by gravity or by thevacuum developed on the intake side of thegear pump. As the gears rotate, the teethsqueeze the oil and discharge it on thepressure side to the pressure regulatingvalve. The pressure adjusting screw on theregulating valve controls spring tension,which determines the pressure at which theoil will force the piston open and bedischarged through the nozzle port. Thispressure is about 80% to 95% of theoperating pressure. The minimum factoryset operating pressure is 100 PSI.

The pump can deliver 5 to 20 times theamount of oil required by the nozzle. Thisexcess oil is bypassed by the pressureregulating system and returned to thestrainer chamber. The total oil capacity of agearset is referred to as TGSC or Total GearSet Capacity. The bypassed oil returnsthrough internal porting in the pressureregulating valve and pump body. As theexcess return oil is no longer at pressure,some of this oil is used for the lubricationof the shaft pump seal.

In order for the excess oil to return tothe strainer chamber, the bypass pluglocated between the pump and the strainerchamber must not be installed. If this plugwere in place, the excess oil could not

return to the strainerchamber and wouldrequire a return line fromthe pump back to the tank.If there were no returnline, the high-pressure oilwould be forced into thefront seal chamber, whichwould rupture this seal. Inmost pressure fuel units, thisseal can only withstand 10PSI of pressure. You shouldalways check to be sure thatthe bypass plug has not beeninstalled when using the uniton a one pipe installation. The bypass plugis only installed when using a two pipesystem.

Pressure regulatingvalve operation

The discharge oil pressure of the fuelunit can be adjusted between 100 and 200PSI. Normal pressure setting on a high-pressure burner is 100 PSI, but someburners are designed for higher oil pres-sure. For variations in this pressure settingand its resulting effect on nozzle perfor-mance, see the Nozzle Chapter # 5, of thismanual. Also refer to manufacturers’specifications for recommended pumppressure on flame retention burners.

On burner shutdown, spring tensionagainst the pressure regulating piston willcause the piston to close, shutting off oildischarge to the nozzle at a pressureapproximately 20 percent below operatingpressure. Therefore, if the pump pressure isadjusted to its normal operating 100 PSI,the shutoff pressure will be about 80 PSI.For pumps with high-speed cut off, the cutoff pressure may be different than 20percent. What is important is that thepressure should drop and hold.

For acceptablevacuum, figure

1" Hg per foot oflift plus

1" per ten feethorizontal run

and add 1/2" forthe oil filter



One pipe systemMost of today’s Oilheat systems require

only a suction line to bring the oil from thetank to the burner. We call these one pipesystems. Older single stage fuel units shouldbe piped only as one pipe where oil canflow to the unit under gravity conditions;that is, the burner is located level with orlower than the bottom of the oil tank.

Newer single stage pumps operate at amaximum of 6" of vacuum on a one pipesystem. They can create much more, butthe oil will begin to give us trouble over6". If your calculated vacuum is less than6" and you are using a new fuel unit, itshould be installed one pipe.

Two pipe systemIf more than 6" of vacuum is required, a

single stage fuel unit should be piped witha return line to the tank or fuel de-aerator.This is called a two pipe system. Anexample of such an installation would be anabnormally long run from the oil tank tothe unit. If a single stage fuel unit two pipesystem has an operating intake vacuumover 10", unstable flame conditions,carboned-up firing assembly, after fire, andnoisy flame may result. High vacuum mayalso shorten the life of the fuel unit.

Two stage fuel unit,two pipe system

If more than 10" of vacuum is required,you should install a two stage pump orbooster pump. The two-stage fuel unit hastwo sets of fuel pump gears. The first setpurges the pump of air and supplies an

PistonAssembly

PressureGaugePort

OptionalReturn

PressureAdjustingScrew

High Speed Modelsto Strainer

Low Speed Modelsto Seal Chamber

Lip Seal

Input Shaft

Return to Tank

By-pass Plug

To Strainer

First StageGearset

Second StageGearset

IntakeFrom Tank

PositiveStrainer

Cone Valve

Nozzle Port

DiaphragmValve


Figure 4-5:Suntec Industries;cutaway exampletwo-stagefuel unit

SuctionGear Set PressureReturnNozzle Pressure

Legend


uninterrupted flow of oil to the secondstage that pressurizes the oil to the nozzle.Figure 4-5 shows the oil flow in a twostage pump. The first gear set provides thevacuum to fill the strainer chamber as wellas the low pressure oil supply to lubricatethe shaft seal. From the shaft seal chamber,the oil flows to the low-pressure side of thepressure regulating valve and then back tothe tank. The second set of gears providesthe pressure for the oil taken from thestrainer chamber, with the surplus oil beingbypassed through the porting in thepressure regulating valve and back to thestrainer chamber.

Note that the bypass plug is installed inthis unit because two stage pumps mustalways be two pipe. If a two-stage pump isconnected to one pipe, it becomes a singlestage pump. The first stage will only takeoil from the cover and return it to thecover. Installing two stage pumps on one-line systems is a waste of money. Not onlydoes the pump cost more, it also uses moreelectricity to turn the second set of gears.

Even though single stage pumps arecapable of creating 20" of vacuum, weneed two stage pumps because fuel oilstarts to break up or “vaporize” at vacuumlevels as low as 6.7" (Figure 4-6). Whenthis happens, foamy oil collects in thepump and the pump begins to cavitate. Thepump sends this foam directly to thenozzle, causing unstable atomization,smoke, and soot. Also when the burnershuts down, the air bubbles in the nozzleexpand, pushing oil out of the orifice,creating after drip. The two stage pumpmay correct the foaming oil problem. Thefirst set of gears brings the oil into thepump, and returns any foam back to thetank via the return line. It is important touse the lower intake port so even at 17" of

vacuum, only foam free oil is picked upand delivered to the nozzle. It is recom-mended that all two-stage pumps bemounted right side up so the air will collectin the top of the pump and can be sent backto the tank.

In a two pipe system with a two stagefuel unit, it is not advisable to exceed 17"of intake vacuum. Figure 4-7 shows theeffect that 20" of vacuum has on a pump.With long oil line runs where excessvacuum is required, or for overhead

Figure 4-6

Figure 4-7



Figure 4-8:Boosterpump

Figure 4-9: Fuel de-aerator


Most fuel pump manufacturers say thatthe maximum vacuum for a one pipesystem is 6"; therefore to convert from twopipe to one pipe, your calculated vacuummust be less than 6". If you need over 6",consider installing a de-aerator in the oilline, especially if the line comes out of thetop of the tank, so the pump will not get airbound.

Fuel de-aeratorsFuel de-aerators shown in Figure 4-9

have been developed to eliminate airproblems caused by excessive vacuum.Here is how the system works:

1. Oil is drawn from the tank to the de-aerators through a single pipe. A dual-pipesystem, operating between the unit and theoil pump allows the device to remove theair. Only the amount of oil that is burned isreplaced from the oil tank. The single pipesystem eliminates the need to circulateunnecessary oil andits impuritiesthroughout thesystem.

2. The surplusoil is pumpedback to the de-aerator, insteadof back to thetank.

3. De-aerationincreases thepump’s suctioncapacity whilereducing its sensitivityto minor leaks in thesuction line.

4. As surplus oil cyclesthrough the de-aerator loop, itabsorbs heat from the ambientair and the pump gears’ friction,reducing cold oil problems.

burners, the use of abooster pump is required,Figure 4-8. The installationand associated piping of asystem using a booster fuelpump is fully describedlater in this section.

Avoid two pipe systemsTwo pipe oil systems should be avoided if

possible. With a two-pipe system you arefiltering way too much oil. The average oilpump, pumps over 15 gallons of oil an hour.The average burner fires at 1 gallon perhour. This means you are filtering over 15gallons of oil for every one burned. You areusing up the filter 15 times faster thanneeded. You are cleaning the oil tank throughthe filter. This is very expensive and incon-venient.

The second problem is that the averagereturn line is under about two pounds ofpressure. A lot of oil can leak out of a smallpinhole under two pounds pressure in thehundreds of hours a year a burner runs. Theburner will not be affected by a return lineleak. The only way you know you have aleak is when the customer runs out of oil orthe oil shows up in the sump pump pit. Thisis way too late!

If these were not reasons enough, itappears that two pipe systems are sludgemachines. Copper is a catalyst that can affecthydrocarbons. Prolonged exposure to coppercauses little hydrocarbon molecules to clumptogether into big, long hydrocarbon strings.They can plug up nozzles, strainers, andfilters. Since we pump over 15 gallons anhour and burn only one, think of how manytimes each little hydrocarbon molecule has totravel back and forth to the burner throughall that copper pipe before it is finallyburned. On each trip the fuel gets a bit lessstable and a few more hydrocarbon stringsshow up in the tank.


Figure 4-10:Booster fuelunit

Aux.Tank

Tank

Tank


1/2 in. O.D. Tubing—Inlet Line Suntec Boost Pumpand Motorset

1/2 in. O.D. Tubing—Return Line

Approx. 3 inches

Figure 4-11:Booster fuelunit; lowpressure sideinstallation

Filter

H(15 Ft.Max.)

Figure 4-12: Boosterfuel unit; auxiliary tankinstallation formultiple furnaces

Vent

2 Ft. Min.

FeederLines

Suspended Furnaces

1-1/4 In. Pipe

SuntecBoost Pump &Motorset

Approx. 3 Inches

15 Ft.Max. Lift

1/2 In. O.D. Tubing—Return Line

Auxiliary Filter

Shut Off Valve1/2 In. O.D. Tubing—Inlet Line

35 Ft.Max.

Booster fuel unitsBooster fuel units are normally used to

assure an adequate supply of oil to one ormore overhead furnaces. They are usuallycapable of lifting oil 15 feet and supplyingthe oil up to 35 feet above the pump. Theycan be used as continuous or intermittentduty transfer units for filling a smalloverhead feeder tank or for other similarpurposes. Booster pumps are a fuel unit andmotor. Figure 4-10 shows a Booster FuelUnit.

The pressure regulating valve assemblyfunctions as a relief valve. A vacuumbreaker is recommended as a protection toinsure an instantaneous supply of oil whenmore than one burner is being supplied.

Piping: Suction and return lines shouldbe sized to the specific model boost pumpand lift location. Follow manufacturers’instructions. All fittings should be of theflare type. A return line from the fuelpump bypass connection to the tank isrequired in all installations. Extend thereturn line to the same depth in the tank asthe suction line. Also check local codebefore making the installation. Figure 4-11shows the input or low pressure side of theinstallation. The Auxiliary Tank Installa-tion shown in Figure 4-12 is another wayof hooking up multiple suspended furnaces.

Figure 4-13 on following page shows aPressurized System installation.

R


Figure 4-13:Booster fuel unit;pressurizedsysteminstallation

# 1 # 2 # 3

Tank


Manifold Air Bleed—Highest Point in Line

1/2 In. O.D. Tubing—Manifold Line

Max. Intake Pressureat Burner 10 PSI

0-30 PSIPressure Gauge

SolenoidValves

35 Ft.Max.

AuxiliaryFilter

Suspended Furnaces

1/2 In. O.D. Tubing—Return Line

Approx. 3 Inches

H15 Ft.Max.

1/2 In. O.D. Tubing—Inlet Line

Fuel unit limitations1. NFPA31, the National oilburner

code, limits the shaft seal pressure to 3 PSI,although most pumps can take up to 10PSI.

2. Single-stage pumps should not beoperated beyond 6" of vacuum whenhooked up one pipe. Single stage, two pipeinstallations should not be operated above10" of vacuum.

3. Two-stage pumps should generallyoperate below 12" of vacuum because atvery high vacuums, oil foams within thepump.

Pumps with integralsolenoid valves

There are two types of pumps with builtin electronic shut off valves called integralsolenoid valves. One is the blocking valvepump and the other is the by-pass valvepump.

The blocking valve stops the flow of oilto the nozzle just like an externally mountedsolenoid valve does. With this pump, the oilis shut off two ways: with the electric valve,and the pressure regulating valve.

The by-pass valve pump has a valve thatcontrols the flow of oil to the nozzleindirectly by diverting oil flow inside thepump. When it is time to shut off the oilflow the dumping valve opens, causing thepressure to drop quickly and the pressureregulating valve to close sooner. This isopposite the blocking valve operation.When the blocking valve opens, oil flows;when the dumping valve opens, oil stops.

Either type of valve will give you quickcutoff, but to get delayed cut-in, andcleaner starts, you need either a valve-ondelay primary control, a hydro-mechanicalpump delay, or an electric delay device.

Servicing and testingthe fuel unitPrimary venting and bleedingIn a one pipe system, when a pump runs outof oil or picks up air due to high vacuum ora leak or break in the oil supply line, the airmust be bled from the fuel unit and lineafter the tank is filled or the supply line isrepaired. Failure to do this properly cancause pulsation, changes in flame condi-tion, or excessive dripping at the nozzleafter the burner shuts off. There are twomethods for air elimination in a one pipesystem. If the system is a gravity feed and

R

Pipe Cap

Suntec Boost Pump& Motorset

Filter

Shut OffValve


Figure 4-14:Bleed valve

Figure 4-15:Bleederwrench


the unit is mounted so that the oil supplyline enters at the bottom of the unit, theinlet port plug in the cover may be loos-ened and removed. This will allow the oil toflow by gravity into the unit and fill thestrainer chamber. Then the intake port plugshould be replaced and the burner fired.

If it is not possible to fill the strainerchamber in this manner, then the bleederplug on the side of the regulating valvechamber should be loosened, the burneroperated, and sufficient oil allowed to flowfrom this plug to purge the entire system ofair until there is a steady stream of oil. Ifthe pump has been completely drained ofoil it may be necessary to remove thesupply line and fill the unit with oil beforeadequate suction can be obtained. In thenewer units, an Allen screw, or easy bleedplug, Figure 4-14, has been provided inthis port to allow for bleeding. Continue tobleed the pump for 15 seconds after the lastair bubble can be detected. After bleedingthe unit, always check the flame forstability and burner shutdown to be sure all

air has been purged from the system.Venting of air is normally not necessary ina two pipe system with a two stage pump,

but may be done faster if the bleeder plugis opened to expel air.

Vacuum power bleedIf the oil lines run above the oil tank and

back down to the burner (a siphon system)proper bleeding of the pump is crucial. Tobleed a pump line and everything else allthe way back to the tank, do the following:First fill the pump with oil. Place a hoseover the bleeder. A device like the oneshown in Figure 4-15 works well for thispurpose. Open the bleeder one-half turn.Make sure that the open end of the bleedhose is immersed in oil in your pail or

bucket. Close the inlet valve at the tank andstart the burner. Wait until the pump startsto whine. If you have a vacuum gaugeinserted, it will show 20" to 25" ofvacuum. (If white smoke starts coming outof the hose, you didn’t fill the pump andthe oil is burning.) Open the inlet valve andbleed for several minutes. After a tune-up,you would see some oil, then lots ofbubbles and then air free oil. Once it’s bledout, close the bleeder with the pumprunning.

Field pressure and cutoff checksTwo of the most important service

checks for a fuel unit are the outputpressure check and the cutoff pressure


Figure 4-17: Pressure test

Figure 4-16:Pressuretester


If a fuel unit operating pressure of atleast 100 PSI cannot be obtained, theproblem may be, in addition to the aboveitems, one of the following:

1. Worn pump gears.

2. Nozzle capacity beyond pumpcapacity.

3. Motor not up to speed.

4. Loose shaft coupling.

5. Defective pressure regulating valve.

Pressure check at cutoffOnce you are finished with the operating

pressure check, shut off the burner. Insert apressure gauge directly into the pumppressure port, Figure 4-17, and run theburner until the pump reaches its pressuresetting and then shut the burner off.

(Note that cutoff pressure cannot bemeasured at the bleeder port as the pres-sure-regulating valve has an internal bypasssystem which does not hold pressure at thebleeder port on shutdown.) As soon as theburner shuts off, the pressure should dropvery quickly about 10 to 25%, and thenhold that pressure. The pressure cutoffreading should hold for at least fiveminutes without change.

check. These checks can be made on somepumps by inserting a pressure gauge into anozzle port, with others a tester may have

to be used, Figure 4-16. You will need apressure gauge capable of reading at

least 300 PSI.

First operate the burner todetermine fuel unit pressure, whichshould normally be adjusted to100 PSI or more depending onthe burner manufacturer’s recom-mendations. Turn the pressureregulator adjusting screw (nor-mally clockwise) until the pressureincreases 40 to 50 pounds (but notabove 200). If the pump cannot

achieve at least 150 pounds, the pump gearsor regulating valve are worn out and youshould replace the pump. Then back off thepressure adjusting screw (counterclockwise)to the desired operating pressure.

Uneven or fluctuating pressure can causesevere flame pulsation. A pulsating pres-sure reading (gauge needle jumps aboutfrom high to low) may indicate:

1. A partially clogged filter orpump strainer.

2. Air may be present in thepump caused by:

a. Loose strainer chambercover or defective strainerchamber gasket.

b. Air leak in the suction line.

c. Excessive intake vacuum.

3. Slipping pump coupling.

Note: Slight regular vibrations of theneedle are considered normal as theresonance frequency of gauges is very closeto gearset frequency. Liquid filled gaugescan help dampen or eliminate frequencyvibrations and are preferred.



Any decrease from the cutoff pressureindicates a defective or dirty pressureregulating valve (piston or piston seat) thatwill result in oil dribbling from the nozzleand an after fire. The fuel pump should bereplaced in this case.

Field vacuum checkWhile there are many reasons for the

following problems, one of the leadingpossibilities is a leaking suction line,fittings or gaskets. If there is no otherobvious cause for these problems, youshould take an operating vacuum test todetermine if you have a leak.

1. Pulsating pump pressure

2. Oil pump noise

3. Hard starting (ignition)

4. Poor flame retention

5. Noisy fire

6. Loss of flame during running cycle

7. Burner flame will not establish afterlong shutdown

8. After fire

Checking system vacuumThe first step is calculate what the

vacuum should be, then test to see what itactually is and compare the two.

To calculate the vacuum, figure about 1"of vacuum for each foot of oil lift, 1" ofvacuum for each 10 feet of horizontal run,and ½" for a clean oil filter. If the actualoperating vacuum is significantly less thanthe calculated vacuum, you probably have aleak either in the pump or somewhere inthe line.

To do this test, a vacuum gauge capableof reading 30" of vacuum should be

screwed into the unused intake port. It isimportant that the vacuum gauge besecurely tightened so that vacuum leakswill not develop around the threadedfittings.

If the unit to be tested is set up for aone-pipe system, a return oil line from theunit nozzle port should be provided tocatch the oil removed from the strainerchamber during the vacuum check. Thenrun the burner, bleed the pump, and readthe vacuum. The vacuum reading shouldapproximate the calculated vacuum.

If the gauge reading is substantiallyabove the calculated vacuum, there is arestriction in the oil supply that may becaused by of one of the following:

1. Plugged fuel filter

2. Kinked oil supply line

3. Partially closed oil supply valve

4. Check or foot valve inoperative orsticking

Note: The excess vacuum caused by apartially clogged pump strainercannot be read on the gauge. Be sureto look at the strainer through theinlet port before installing the gauge.If it appears dirty, remove the strainerand clean or replace it.

If vacuum reading is below the calcu-lated operating vacuum, the probablecauses are:

1. Clogged pump strainer

2. Air leak in the suction line or suctionline fittings

3. A suction leak around strainerchamber cover plate and gasket

4. Worn pump gears


Figure 4-18:Hand pump


chamber bolts, pump seal leak, or the pumpleaking at ports, or it could be the fittingsup to the shut off valve. Recheck thegasket, plugs and fittings and try again. Ifyou are sure everything is tight, the leakmay be in the unit itself, and you will haveto replace it.

10. If the vacuum holds, you know thatthe fuel unit and all the piping up to theshut off valve are OK. Now it is time toopen the shut off valve near the pump, andif there is one, shut off the valve at thetank, or at the wall where the suction lineenters the building. Do the test again. If thevacuum holds, you know the leak isbetween the valve and the tank.

Warning: We used to check forleaks using the pressure testmethod. The problem withpressurizing oil lines is it usuallycreates more leaks than it finds.We strongly urge you to neverpressurize oil lines or tanks. Thisincludes blowing out the lineswith a CO2 cartridge; instead usea hand pump to suck the lineclear, Figure 4-18.

Visual test or sight glass testfor air in oil lines

When you detect air in oil lines, youmust find the source of the leak. The firststep is to tighten all fittings in the suctionline and tighten unused inlet port plugs inthe pump. Be sure there are no compressionfittings in the oil lines. Then check thefilter cover and gaskets, making sure thereis a good gasket on the pump cover. If noneof this eliminates the air, you must startsearching for the source of the leak. Toconfirm that there is a leak and to pinpointthe source, use the Visual Test or SightGlass Method.

Vacuum testIf the operating vacuum is less than the

calculated figure, you have a leak to find.First determine if the pump or fittings upto the pump shut off valve are leaking byperforming a Vacuum Test.

1. Fill the fuel unit with oil.

2. Shut off the valve closest to thepump. If there is no valve, disconnect thesupply line at the fuel unit.

3. On a two pipe system, disconnect thereturn line and place an open containerbelow the return port of the fuel unit.

4. If the system is single pipe, connect ableed hose to the bleeder port and theopposite end in an open container.

5. Install your vacuum gauge in thealternate inlet port on the pump. (If therewas no shut off and you have disconnectedthe suction line, install the gauge in theinlet port.)

6. Start the burner and open the bleedport. Run it until a vacuum of 15" isreached. On a single pipe system you mustopen the bleed port while the burner isrunning to raise the vacuum.

7. Once the vacuum is reached, close thebleed port. (You may need to jumper the F-F terminals on the primary control afterburner start up to get the burner runninglong enough to reach the vacuum reading.)

8. While the burner is running and youhave reached the required vacuum, on thetwo pipe system, plug the return port andturn the burner off. On a single pipe, close

the bleed port and turn the burner off.

9. Check the vacuum reading aftershut down. The vacuum should holdfor at least five minutes. If the vacuumdoes not hold steady, you could have aleak in the pump, a leak in strainerchamber gasket, loosened strainer


Figure 4-19: Oil leak test kit


To do a visual test, use of a vacuumgauge and plastic tubing with fittings suchas the Oil Watcher or Clearview, see Figure4-19. Install the device between the pump,shut off valve and the suction line. Bleedall the air out of the lines, then run the unitand look for bubbles. One at a time,heading toward the tank, coat the fittingswith lithium grease. The grease temporarilyseals the leak. When the leaking fitting iscovered, the air bubbles will disappear.Repair the leaking fittings and clean thegrease off everything you have coated.

An easier way to find leaks is by usingan electronic sight glass. The electronicsight glass is a tool used by many airconditioning technicians. It is a hand heldmeter that has two transducers which youcan easily mount at any point in your

suction line. When operating, one trans-ducer transmits and the other receives anultrasonic signal. The pulse the signalreceives tells the unit if there is air in thepipe. If it detects air, it makes a noise.When using the electronic sight glass,attach the sensors just prior to the firstfitting in the line. If no air is detected,attach the sensors just past the same fitting

and test again. Proceed in this manner untilyou arrive at a fitting with no air cominginto it, but air after the fitting. You knowthat fitting is leaking. Continue on until allthe leaks have been found.

To check for leaks in the return line:More difficult to find is a leak in the

return line. Over time, these can be themost troublesome leaks, because they cango for so long before being detected. Whenthe burner is running, return lines can haveup to five pounds pressure. This can add upto a lot of lost oil in a short time.

The best way to check for a leakingreturn line is to hook the return line up tothe suction side of the fuel unit andperform the operating vacuum test. Theoperating vacuum on the return line, whenit is hooked to the pump as the suction line,should be about the same as the operatingvacuum reading for the original suctionline. If the vacuum is less than the returnline, it is either leaking or the orginalsuction line is partially plugged. Thepotential problem with this method is thatthe installer may not have run the returnline all the way to the bottom of the tank.

If you cannot draw oil up the return lineyou will not know if it is a big leak, or theline terminates at the top of the tank. Eitherway your next tool will be a shovel to digup the top of the tank. (Do not hook upthe suction line as a return, it could plug itup, or if there is a foot valve or other checkvalve in the line, it will blow the pumpseal. Just vent the return oil into a bucket).

If the operating vacuum is much lessthan the calculated vacuum or the operatingvacuum of the suction line, look for air inthe oil. If air is present, there is a goodchance that you have a leak. Check allfittings and joints, as well as the optionalinlet plug on the fuel unit. Be sure all flarefittings are done properly and there are no


Figure 4-20: Dirty strainer


Nozzle discharge port locationFor ease of installation, fuel units are

built with both right and left-hand nozzleor discharge ports. Again, a right or lefthand port location is determined by holdingthe unit with the shaft pointing toward you.

Shaft sizesMost oil pumps have either a 5/16" shaft

or a 7/16" shaft. The smaller shaft may bebushed up for substitute replacement.

Installation requirementsBe sure that the replacement unit is

properly mounted and in line with themotor coupling. The Allen screws or flangemounting bolts, which hold the fuel unit tothe burner housing, must be securelytightened. If the coupling between themotor and the fuel unit has Allen setscrews, these should be securely tightenedagainst the motor shaft, after tighteningunit-mounting bolts. To do otherwise mayresult in a jammed coupling and damage tothe pump or the motor may occur.

Pump strainersIt is necessary to periodically clean the

fuel unit strainer, Figure 4-20. To clean orreplace the strainer, loosen the strainer

compression fittings. Be sure all oil linesthat go through a wall or under concrete aresheathed in plastic tubing. Be sure to usenon-hardening oil pipe dope on threads. Donot use Teflon® tape on fittings; it will voidthe pump warranty.

Selection of replacementfuel units

It is good general practice to replace afuel unit with one of a similar type, unlessyou have determined that there is a mis-match between the fuel unit capacities andthe operating requirements of the burner.Fuel unit manufacturers attach identifica-tion plates to their units. These platescontain serial numbers that identify theunits and their operational characteristics.Reference material for these identifyingserial numbers is available from themanufacturers and should be included inyour burner service data, as it will makeselection of proper replacement units easier.When replacing fuel units, consider thefollowing.

Shaft rotationPumps are designed for either clockwise

(CW) or counterclockwise (CCW) rotationand proper rotational direction is shown onthe unit identification plate. With the unitshaft held toward you, clockwise rotationwill be to the right, often shown by anarrow pointing to the right. Counterclock-wise to the left, with an arrow pointingleft. This rotation must be matched to theburner motor.

Rotational speedThe great majority of older domestic

oilburner motors operate at a speed of 1725RPM, while most flame retention burnersoperate at 3450 RPM. Pump speed shouldbe matched to motor speeds.



chamber cover bolts and remove the coverand slide out the strainer. Whenever youtake the cover off the strainer, be sure toscrape off the old gasket between the coverand unit body and replace it with theproper replacement gasket. Some Websterpumps have no strainers, but they docontain chopper gears that clean the oil andthe cover should be removed on a routinebasis and cleaned out. Make sure you havethe proper gasket before you do this.

Clean the pump strainer screen inheating oil or kerosene and reassemble,making sure to tighten all cover boltsevenly to prevent distortion of the cover.When putting the burner back into service,be sure to bleed the air from the system andcheck for proper flame cutoff. Rememberthat the strainer is a secondary filter andthat a proper installation also has anexternal or primary filter.

Pump gasketsIt is also important that the correct

gasket be used. Using incorrect gaskets candamage the pump.

Noise problems in fuelunits, oil lines or tanks

Noise generated as a result of pumpoperation, or noise transmitted by oil lines,is annoying to the customer and should beeliminated.

Pump noise: In addition to noisecreated by worn internal parts in the pump,misalignment of the fuel unit and motorcoupling shaft or loose installation boltsmay be the source of noise problems. Allfittings and bolts should be tightenedsecurely.

Oil line noise is the result of improperlyfastened oil lines which are allowed to

vibrate against surrounding objects such assheet metal furnace covers, duct work, etc.If oil line noise is a result of noise transmit-ted from the fuel unit, check the anti-humdevice in the pump. The return line on twopipe systems may occasionally provide linenoises. If the suction and return lines toucheach other they can create line noise.

Tank noise: This is not a commonsource of noise complaints. If such acomplaint should develop, the cause cannormally be traced back to transmission ofnoise by the oil lines. Tank noise can also beeliminated in many cases by a hum elimina-tor. A commonly overlooked source of tanknoise is improper installation of the returnline. The end of the return line of a twopipe system should be located approxi-mately 3" above the bottom of the tank.This will permit discharge of return oil tobe at a point beneath the surface of the oil,thereby eliminating the noise of return oilfalling into the tank.

Potential leaksin oil lines

Leaking suction and return lines cancause serious problems. We all must beever vigilant for possible pipe leaks.

• Treat every out of oil/automaticdelivery as a potential leak that should befurther investigated.

• Study oil deliveries; further investi-gate each tank that takes more oil thanprojected.

• Respond quickly to any calls fromcustomers for oil smells and concerns aboutincreased consumption. These can be earlywarning signs of trouble.

• Treat every water-in-the-tank call as apotential tank leak that must be investigated.


Figure 4-21:Delayed oilvalve

Figure 4-22: Construction detail with valve closed


Stem

Coil

FuelFlow

BodyOrifice

Seat

Piston

Spring

FuelFlow

Figure 4-22: Construction detail with valve open

Operation of the delayed actionsolenoid valve

The delayed oil valve may also help inpreventing a puff back as a result of poorignition. During startup, the burner motorrequires a substantial starting current. Thiscurrent requirement may rob voltage fromthe ignition system, resulting in a weakspark at the electrodes. When the motorreaches operating speed, the currentrequirement of the motor drops appreciablyand the full supply voltage is available tothe transformer. This results in maximumignition voltage at the time the delayed oil

• Operating problems with the burnercan signify a leak, and any air in the oilpump call, poor pump cut-off, noisyoperation, and erratic fire calls, loss offlame retention (flame pulsates on the endcone), loss of oil prime, rough starts orshut downs, pump whine and pressurefluctuation, and after drip could all indicatea leak.

In order to check for leaks in the suctionpipe and fittings you must first run anoperating vacuum test, covered earlier inthe chapter.

ValvesSolenoid oil valves

Not allowing oil to flow until the burneris up to full speed and air flow into theheat exchanger has been established canmake for cleaner start up. The use of a

solenoid oil valve can delay fueldelivery to the nozzle for anywherefrom 4 to 15 seconds after burnerstartup. Figure 4-21 shows an oilvalve. To achieve a longer delay. aprimary control with a valve-ondelay feature and a non-delay valveshould be used. On burner shutdown,the oil valve closes immediately,

providing a much more rapid shutdownthan is obtainable with the pressure controlvalve on the fuel unit. Figure 4-22 showshow the valve works.

In operation, this valve can solve manyproblems associated with poor startup andshutdown conditions such as:

1. Pulsating starts

2. Puff back

3. After fire as a result of a malfunc-tioning pressure regulating valve

4. Long term soot buildup in heatexchanger resulting from incompletecombustion on burner startup andshutdown


Figure: 4-23:Delayed oil valveinstallation forinterruptedignition


PrimaryControl

BurnerMotor

DelayedOil Valve

IgnitionTrans.

Do Not Connect DelayedOil Valve To This Line

valve opens and oil is supplied to thenozzle.

On burner shutdown, the delayed oilvalve closes immediately, shutting off thefuel supply and providing a clean cutoff ofthe flame. Without the delayed oil valve,the motor speed must decrease before thepressure regulating valve closes, whichagain causes smoke because of a lack of air.

Note: The delayed oil valve will onlyproduce a clean shutdown if the oil supplysystem is free of entrapped air. Thedelayed oil valve will not control nozzleafter drip that results from air in the oilsupply system between the valve and theoil nozzle. This air is caused by an air leakin the suction line or pump fittings orhigh vacuum.

Installation: The delayed oil valve isinstalled on the output side of the fuel unit.Standard 1/8" (I.D.) black iron pipe can beused to connect the inlet port of the delayedoil valve to the nozzle discharge port on thefuel pump. Use of the 1/8" pipe provides arigid mounting for the valve.

The coil is electrically connected inparallel with the burner motor. See Figure4-23 for a wiring diagram. If the burnerhas interrupted ignition, be sure that thesolenoid valve is connected to the motorleads and not to the ignition leads. If thevalve is inadvertently wired to the inter-rupted ignition circuit, the valve will closewhen ignition is cut off and burner will gooff on safety lockout.

It is code in most jurisdictions, and goodpractice in all cases, to run the electricalleads from the delayed oil valve throughGreenfield tubing to protect electrical leadsfrom the valve to the burner junction box.The oil valve housing cover is threaded toaccept Greenfield connectors or the tubingitself. Use anti-short bushings on the endsof the Greenfield. A handy device to havefor the installation is a double Greenfield(BX) connector that allows two pieces ofGreenfield to be connected to a single hole.This will make the electrical installationmuch easier in cases where the burnerjunction box does not have an extra outlethole.


the two leads of the switch together. As thisfield fix removes the delay feature of thevalve, a new coil should be installed at theearliest possible time.

The delayed oil valve is needed onburners with older pumps. Most of the newburners utilize non-delay instant openingsolenoid valves because of the relativeunreliability of the thermal delay switch.Figure 4-24 shows a solenoid valve.

Manufacturers have gone to micropro-cessor based primary controls with Valve-Delay-On and Motor-Delay-Off, com-monly known as pre- and post purgetechnology. The delay is built into theprimary so the delay timing can be moreprecisely controlled. It is becomingincreasingly popular for manufacturers toattach the solenoid valve, controlled by theprimary, directly to the fuel unit. SeeFigure 4-25.

Anti-siphon valve and oil safety valveIf the oil tank is higher than the burner,

some codes require an overhead suctionline and an automatic valve that will breakthe siphon should an oil line leak develop.Two popular anti-siphon valves are theWebster Oil Safety Valve (OSV), and theSuntec PRV.

Figure 4-26 shows a Suntec PRV. Its jobis to protect against line leaks and tank

A conventional fuel line flared fitting isinstalled in the outlet port of the delayedvalve (in most cases this will be the samefitting you have removed from the nozzledischarge port) and the fuel line to thedrawer assembly fuel pipe should be

reinstalled. With some small amount ofreworking, it should be possible to use thesame fuel line that was on the burnerbefore installation of the delayed valve.

Servicing: The most sensitive part ofthe delayed valvesystem is the thermaldelay switch that istaped to the valvecoil. Should thevalve at any time failto operate due to adefective time delayswitch, it is possibleto temporarilyremove this switchfrom the circuit byremoving the tapebindings and twisting

Figure 4-26: Suntec PRV

Figure: 4-24:Drawing of asolenoid valve


Figure: 4-25: Fuelpump with solenoid


siphoning as well protect the pump fromexcess head pressure. When the burnercomes on the pump creates a vacuum thatpulls the valve stem down and opens thevalve. When the burner shuts off, if thereare no leaks the valve stem will stay downand remain in this position. If there is aleak between the PRV and the burner, thesiphon created by the leak will close thevalve, shutting off the oil supply to the line.If the red stem sticks out of the top of thevalve, you know a loss of vacuum (siphon)has occurred.

If the top of the oil supply source ismore than 8 feet above the fuel unit youneed to install a PRV. The NFPA rating forthe head pressure on a fuel unit is only 3PSI, about 8 feet. If the tank head (heightof oil supply above the unit) is greater than8 feet, the supply oil pressure may exceed 3PSI and thereby shorten shaft seal life. If itis necessary to locate the tank at a greaterheight, a pressure reducing valve or an oilsafety valve should be used in the oilsupply line.

Thermal safety valveA thermal safety shut off (Firomatic)

valve should be installed in the suction lineat the tank. The shut off valve should beUL listed and should be equipped with afusible type handle that melts at 165°F.

Also install a shut off valve before thefilter and at the fuel pump for ease ofservice. If the tank is outside of thebuilding, there should be a shutoff valve atthe wall where the suction line enters thebuilding.

Foot valvesFoot valves are check valves installed

on the end of the suction line in under-ground tanks. They are no longer neededand not recommended; however, they werecommon on older installations and someare still in the field. It is not unusual forthem to get stuck closed and not allow oilto flow.

There are two options in this case:1. Run new oil lines from the tank to the

burner.2. If the return line extends to the

bottom of the oil tank, you can convert thesystem to a one-pipe system by capping thesuction line and using the original returnline as the new suction line. (Remember toremove the bypass plug in the fuel pump).


Suntec has provided a veryhelpful Technical Bulletin and SystemTrouble Shooting Flow Chart whichreviews the service procedures forboth old and new style pumps, shownon pages 4-23 thru 4-25.


Troubleshooting Fuel Units

No Oil Flow at Nozzle Oil level below intake line in supply tank. Fill tank with oil.

Clogged strainer or filter Remove and clean strainer. Replace filter element.

Clogged nozzle Replace nozzle.

Air leak in intake line Tighten all fittings in intake line. Tighten unused intake port plug.Tighten in-line valve stem packing gland. Look for leaks in piping.

Restricted intake line Replace any kinked tubing and check any valves in intake line.

A two-pipe system that becomes air bound Check for bypass plug.

A one-pipe system that becomes air bound Loosen gauge port plug, or open the bleed valve, start theburner, and drain oil until foam is gone. Check for high vacuum(over 6" vacuum). Check for air leaks in pump or oil line.

Slipping or broken coupling Tighten or replace coupling.

Air Leak Loose plugs or fittings. Dope with good quality thread sealer orpipe joint compound.

Leak at pressure adjusting cap nut Fiber washer may have been left out after adjustment of pumppressure. Replace the washer.

Blown seal—One-pipe system Check to see if bypass plug has been left in unit. Replace fuelunit.

Blown seal—Two-pipe system Check for kinked tubing, rust in pump, or other obstructions inreturn line. Replace fuel unit. Check tank for water.

Noisy Operation Bad coupling alignment, loosen fuel unit mounting screwsslightly and shift unit in different positions until noise is elimi-nated. Retighten mounting screws or replace coupling.

Pulsating Pressure Partially clogged strainer or filter. Remove and clean strainer.Replace filter element.

Air leak in intake line Tighten all fittings and valve packing in intake line.

Air leaking around cover Be sure strainer cover screws are tightened securely. Install anew gasket.

Improper Nozzle Cut-Off To determine the cause of improper cut-off, insert a pressuregauge in the nozzle port of the pressure fuel unit. After a minuteof operation, shut the burner down. If the pressure drops approxi-mately 20% from normal operating pressure and holds at thatpressure, the pump is operating properly and air is the cause ofimproper cut-off. If, however, the pressure drops more than 20%in 5 minutes, fuel unit should be replaced.

Air pocket remaining in nozzle line Run burner, bled pump, stopping and starting unit, until smokeafter disassembly and after-fire disappear.

Air leak in intake line Tighten intake fittings and packing nut on shutoff valve. Tightenunused intake port plug.

Partially clogged nozzle strainer Replace nozzle. Clean and flush out oil line and pump.



SystemTroubleshooting—Diagnostic Flow Chart

Follow a logical sequence oftroubleshooting from the no-heatcall through to system operationusing the following chart forsimilar sequence.

Chart courtesy of Suntec





Documents

00 Astounding Customer Service - · PDF fileFunction of fuel units: ... Return To Inlet Inlet Port Cone Valve Nozzle Port ... the shutoff pressure will be about 80 PSI