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Ballastar 01-13-2012 01:20 AM

Raypak boiler pilot light problem
Replaced new thermocouple, but the pilot light still goes off every day, checked the gas outlet pressure 4.80" WC in the 2nd stage, is it right? or the gas valve need replace. Thanks.
Model: H3-0135R

how 01-13-2012 02:11 AM

Boiler pilots go out because of faulty thermocouples, bending of the copper line as it immediately exits the thermocouple body, incorrect thermocouple placement in the pilot assy, partially obstructed pilot orifices, anything that causes the cold junction of the thermocouple to overheat, pilot flames snuffed from concussive ignitions or shut offs, water dripping on the coupler, obstructed heat exchanger, faulty gas valve pilot solinoid, etc.
In the field a thermocouple tester (it's cheap) which allows a closed active measurement of the dcmv output of the thermocouple through a heating cycle is the usual diagnostic tool.

beenthere 01-13-2012 04:33 AM

Gs pressure sounds way too high.

COLDIRON 01-13-2012 06:15 AM

I agree recheck that gas pressure again.

After the main valve opens watch your pressure and adjust lower probably around 3 to 3.5 WC. Look on the heater doors and check the manuals that came with the unit they should instruct you how to adjust gas pressure and what the normal reduced pressure should be when main burners are on.

how 01-13-2012 10:42 AM

All residential natural gas valves that I've seen have output press spec's close to 3.5" WC. The only time I've seen that kind of pressure from a gas valve has been when it's been broken, seriously miss adjusted by someone without a manometer or been hooked up to 2 lb gas. The first & second stage of your gas valve should only effect the gas volume, not the pressure.
If the pressure is that much higher on the second stage than the first, then something is wrong with that gas valve and I'd change it.
Only if the first & second stage are both putting out 4.8" would I consider reg adjustment.
If you are actually getting 4.8"WC, then that's way off base and I'm suprised that your furnace limit and roll out switches are not beating the thermocouple in shutting the furnace down.

The overheating of the cold junction of the thermocouple by an over fired furnace would be the probable reason the thermocouple is shutting down the furnace.

Ballastar 01-13-2012 12:18 PM

The Gas control valve is from Robertshaw 004824F ( Nat. Std 2 stages)? I can not find where to adjust the gas pressure.

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