Problem with Hot Water from Boiler (with pictures)

Old 05-27-05, 01:13 AM
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Problem with Hot Water from Boiler (with pictures)


Before I even begin, please forgive me if some things I say are incorrect. I read through the forum to try to figure out what is wrong but I am an extreme novice when it comes to boilers. I have bled the oil after a delivery when we ran out and have bled the air from the baseboards, that's about it. I believe I have figured out how the boiler is heating the water but I am stumped from there.

I am having a problem with hot water in the house. When the boiler is running, because it is heating the house, the hot water will come out cold for a few seconds, then get warm, go to hot, and finally go back down to cold. All of the temp changes happen in a matter of 20-30 seconds. When the boiler is not running there is absolutely no hot water.

I have attached a few pictures so you can see what I am talking about here.

My first theory and picture one:
Is it possible that the circled valve (which is in the off position) is faulty and allowing cold water into the hot water supply coming form the boiler? I don't know if that's possible but I am thinking that if the valve is allowing the cold supply water to bypass the coil which is not allowing the coil to heat the water. Maybe it is allowing the water out of the coil and because the value is faulty most of the cold supply water is bypassing the coil? However, why isnít the water beating heated when the house is not being heated by the boiler? By the way, where it says 'not connected' in the picture there is no connection to the boiler at this point; it just looks like it in the picture.

Theory two and picture two:

Is something possibly wrong with the thermostat for the water? I find this theory to be unlikely because it is heating the water; it is just not maintaining the heat. I have attached a picture of the inside of the thermostat so you can see what type it is. The outside of the thermostat can be seen in the first picture.

I find it hard to believe that it is the coil. The pressure coming out of the hot water faucets are strong. However, like I said, I don't know much about boiler.

Any help you could give me would be appreciated. Thanks.
Old 05-29-05, 05:59 PM
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Hot water problem

Good pix, thanks. Of your two theories, I would tend to think the second would be more likely. Aquastats like this one are no longer made but may be available as a re-built (I doubt it) & are usually directly inserted into the boiler thus requiring draining to change. I suggest you call a local service company well versed in older boilers & their controls. The aquastat will probably have to be changed.

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