Replacing gas valve on very old gas boiler

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Old 02-26-13, 07:34 PM
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Replacing gas valve on very old gas boiler

I have a very old (30+ years) Utica gas boiler (model PGB200). The other day the pilot went out and would not stay lit. We replaced the pilot assembly and it was working fine. Last night the pilot went out again, I relit it and the burners fired up and all was well. It went out again tonight, I relit it and it's working again.

I'm pretty sure the gas valve is going bad. I plan on replacing the boiler this spring/summer, but I would like to be able to limp along for the last month or two of this Massachusetts winter.

I know Utica does not make any parts for this model any more, but is there any way to get a replacement gas valve for this unit? I tried to get the model name and # off the assembly, but it was almost all worn off. The only thing I could get off of it was "Type 433". Here is a pic:

http://i1235.photobucket.com/albums/...t/BB574F40.jpg

Any ideas on where to get a replacement part?

Thanks in advance.
 
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Old 02-26-13, 09:10 PM
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What size inlet and outlet? How many btu is the boiler?

Are you sure the pilott flame is engulfed in the power pile? Sometimes its a bad connection on the wiring. The MV systems are sensitive to that.

You can adjust the pilot flame up higher is needed. possibly with its age its too low.

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Old 02-27-13, 07:18 AM
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The inlet supply line is 1/2" and the outlet is 3/4". The input/output BTUs are 200,000/160,000.
 
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Old 02-27-13, 07:27 AM
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Gas valves are readily available (e.g. Honeywell) - don't bother going to Utica. You will find one with the same inlet and outlet threads and width. If this is a milivolt system, you might consider converting to 24-V.
 
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Old 02-27-13, 07:30 AM
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I was able to decipher some more information on the valve. There is a circle with the letters "WR" in it - White Rodgers I assume? It also says "Reg 3.5 WC".
 
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Old 02-27-13, 09:13 AM
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30 years is not normally considered "very old" for a boiler. But, looking at the photo, has yours been flooded in the past?

The markings you found on the valve are generic. There is no reason to search for the same model. Just replace it with a gas valve that has the same dimensions.
 
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Old 02-27-13, 10:08 AM
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There hasn't been any flooding since I've lived there (7 years). I just checked - the house was built in 1971, so if that's the original unit, it's actually over 40 years old.

I think I found the exact replacement here:

36C03U-433 - White Rodgers 36C03U-433 - 3/4" X 3/4" Universal Gas Valve, 750 Mv
 
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Old 02-27-13, 12:03 PM
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I think I found the exact replacement
You previously said the valve was 1/2"x3/4". But 1/2" would be rather small for most reasonably sized boilers.
 
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Old 02-27-13, 12:40 PM
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A 1/2 inch inlet would be acceptable for most residential boilers. The new valve may come with a 3/4 x 1/2 inch face bushing.
 
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Old 02-27-13, 02:29 PM
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It would be this one if you want to keep the WR. About $60 bucks cheaper then the honeywell.


36C03U-333 - White Rodgers 36C03U-333 - 1/2" X 3/4" Universal Gas Valve, 750 Mv
 
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Old 02-27-13, 02:38 PM
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The National Fuel Gas Code (NFPA 54) has tables that prescribe the minimum gas pipe size. It depends upon the length of the line and the gas flow rate. I can see that 1/2" would be acceptable for many residential boilers. But around my area, 1/2" is used for 40-gal gas water heaters and 3/4" for most heating boilers and furnaces. My boiler is supplied by 1" pipe.
 
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Old 02-27-13, 04:21 PM
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We replaced the pilot assembly...
Did replacing the pilot assembly include also replacing the 'POWERPILE' ?

Is your basement very damp? (silly question, I know... it MUST be.)
 
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Old 02-27-13, 04:37 PM
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I just checked - the house was built in 1971, so if that's the original unit, it's actually over 40 years old.
My gas-fired hot-water boiler is 60 years old, and still going strong - and compared to mine, yours seems to be in deplorable condition. I can't imagine what caused yours to look like that unless it has been repeatedly flooded.

Trooper's question is important: was the powerpile replaced?
 
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Old 02-28-13, 04:44 AM
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Yes, the thermopile was replaced. The model of the existing valve is the 433 which is 3/4 by 3/4, but the the existing inlet is definitely 1/2 and the outlet is 3/4. I agree about the water damage. We haven't had any water n the basement since we have lived here (7 years), but there is a ton of corrosion on the boiler so there must have been some water damage at some point.

Here are some more pics.

D87071B9.jpg Photo by markmin1 | Photobucket
Inlet 1/2 Photo by markmin1 | Photobucket
Outlet 3/4 Photo by markmin1 | Photobucket
032AFFCC.jpg Photo by markmin1 | Photobucket
 
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Old 02-28-13, 04:28 PM
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Mark, what are those wires wrapped around the burners for?



The condition of that gas pipe feeding the valve is a bit concering:



I think once one starts 'wrestling' with the pipe, the chance for gas leakage is pretty good.
 
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Old 02-28-13, 04:42 PM
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Trooper I think those wires are the original shipping straps to hold the cast iron burners on.

Those burners just sit on top the arm I remember right. Mine are cast but a little different and part of the arm.
 
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Old 02-28-13, 06:21 PM
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wires are the original shipping straps to hold the cast iron burners on.
I guess that means that the burners haven't been cleaned in 30 years!
 
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Old 02-28-13, 06:54 PM
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"I guess that means that the burners haven't been cleaned in 30 years!"How often do gas fired burners really need to be cleaned? I give mine a lick and a promise every couple of years or so, but not sure it's all that necessary.
 
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Old 02-28-13, 07:17 PM
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How often do gas fired burners really need to be cleaned?
Cast iron burners in that damp environment? Pretty often I would think, along with a brush down of the flue passages. It wouldn't surprise me to find that heat exchanger half plugged with rust flakes.
 
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