Boilersmith Ltd. Hot Water Boiler Operational Guidelines September 13, 2001

1. Frequency of Temperature ChangeAvoid oscillating water temperatures. This may result in weeping boiler tubes, cracked tubeligaments, cracked stays or cracked welds. Damage due to fatigue may take several days or months to become apparent.

2. Thermal ShockAvoid sudden temperature changes between the supply and return water temperatures.. This mayresult in weeping boiler tubes, cracked tube ligaments, cracked stays or cracked welds. A sudden

temperature change may loosentubes immediately, whereas severaloccurrences may be required beforesigns of fatigue become apparent.

Boilersmith Ltd. Hot Water Boiler Operational Guidelines September 13, 2001Page 2 of 2

3. Temperature RiseAvoid a rapid rise in boiler water supply temperature asmay occur after a night setback or boiler shutdown. Thismay result in weeping boiler tubes, cracked tubeligaments, cracked stays or cracked welds. Damage dueto fatigue may not become apparent for weeks, months oryears.

4. TemperatureMaintain a minimum supply temperature of 1600F (650C)Maintain a minimum return temperature of 1300F (550C)These temperatures should minimize the formation ofcondensate in the boiler

The optimum temperature difference between supply andreturn is 200F (100C). However, the boiler may beoperated with a larger temperature difference, not toexceed 360F (200C). Care must be taken to prevent 1.and 2. above from occurring.

5. Variable Speed PumpingVariable Speed Pumping results in a variable water flow rate through the boiler. This variableflow may result in a fluctuating temperature difference between the supply and return, which maylead to 1. or 2. above. Therefore, we do not recommend this practice.

6. Water LossThe volume of make up water should be monitored. Adding fresh water introduces dissolvedoxygen and other gases as well as substantial solids. Solids that deposit onto hot boiler plates, insulate those plates which in conjunction with 1., 2. or 3. above may result in weeping boilertubes, cracked tube ligaments, cracked stays or cracked welds. Damage because of solid depositsmay take several days or months to become apparent.

7. ReportingThe boiler water supply and return temperatures should be monitored continuously. It isparticularly important to review the data regularly in the first few months of operation to ensurethat the control systems are functioning properly. This will aid the operator in makingadjustments to minimize the conditions as outlined in 1., 2. or 3. above.

In addition, the amount of fresh make-up water should be recorded daily. This will insure thatdissolved oxygen and solids are minimized. This will aid the operator in making adjustments towater treatment levels and to find the source of water consumption or loss.