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1
BOILERS AND EFFICIENCY
Gary Archer
Vice President of Sales
JW Stevens Co.
2
BOILERS AND EFFICIENCY
TYPES OF BOILERS – STEAM
Water tube, Fire tube, Cast Iron Fuels – gas, oil, combination Typical Efficiencies – 78-84%
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HOW DO YOU INCREASE EFFICIENCY ON STEAM BOILERS?
Burner/controls upgrades as discussed earlier
ECONOMIZERS!!!!
ECONOMIZERS
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ECONOMIZERS
Take flue gases from the boiler to pre-heat water that can be used for potable use if you have a large need for domestic hot water. (i.e. Hospital, Food Processing )
OR Use the hot water (260 degrees) to be used as boiler feed water. (Typical feed water temperatures
are 160-225) Increases boiler efficiency by 3% or more and
usually have less than an 18 months payback
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BOILERS AND EFFICIENCY
TYPES OF BOILERS - HOTWATER Water tube, Fire tube, Cast Iron Fuels – gas, oil, combination Typical Efficiencies – 78-84%
MODULAR BOILERS!!!!
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MODULAR BOILERS
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MODULAR BOILERS
Gas Only – Natural or Propane Small Footprint Low mass/light weight design Non-Condensing and Condensing
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\
What is a Non Condensing -vs- a Condensing Boiler?
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Non – Condensing BoilersThese style boilers run in the 85-86% efficiency range
regardless of return water temperatures.
Vessel design must allow for continuous operation @ >130 F return water temperature.
Heat transfer (fireside) surfaces do not consist of materials resistant to acidic condensate and corrosive elements. They are typically made of copper
Less expensive than condensing boilers
Typical Applications are Standard building heat and/or indirect DHW.
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Condensing BoilersTo achieve maximum efficiency a hydronic boiler must fully
condense. This means the return water temperature back to the boiler
must be below 130F. This allows for the flue gas temperature to drop below its dew point. This causes the water vapor in the flue gases to condense or change phase from a gas to liquid therefore giving off more energy
Vessel design must be such that the flue gases are cooled down as low as possible.
Heat transfer surfaces [fireside] must consist of materials resistant to acidic condensate and corrosive elements, typically stainless steel.
Condensing boiler efficiencies can run as high as 99%.
Typical Applications are radiant floor heating, snow melt, heat pump, hybrid heating systems
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6820
80630
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140 16058
Return flow temperature °F
Boi
ler
Eff
icie
ncy
%
20%
50%75%
100%
RelativeBoiler Load
Condensing
Non condensing
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Modular Boilers – Hybrid System
What Is a Hybrid System???
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Hydronic Boilers – Hybrid System
Hybrid Systems Utilize Both Non-Condensing And Fully
Condensing Boilers.
The Condensing Boilers Run In The Warmer Or “Shoulder”
Months (i.e. October, November, March, April) while the Non
Condensing Boilers Run In The Coldest Of Months.
Building management systems can control the enabling or
disabling of the two different type of boilers or most boiler
manufacturer’s have their own stand alone controls that can
achieve the same results.
16
84
86
88
90
92
94
96
98
99
6820
80630
1004
1202
140 16058
Return flow temperature °F
Boi
ler
Eff
icie
ncy
%
20%
50%75%
100%
RelativeBoiler Load
Condensing
Non condensing
17
Hydronic Boilers – Hybrid System
In conclusion about Hybrid systems,
Use the boilers that condense and get up to 99%
efficient when the outside air temperature is
milder and supply water temperature to the fin-
tube radiation in the occupied space can be lower
Use the non-condensing boilers in the coldest
months when you need high temperature water to
keep the occupied spaces warm. This will achieve
maximum seasonal efficiency.
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JW Stevens Co
Stop by our booth to see a case study on a DVD loop to see an example of a hybrid system we did last year with Oswego CSD.
They will earn well over $100,000.00 in National Grid Incentive Dollars