Hot Water BB First Too Much Heat, Now Boiler Overheating?


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Old 12-09-11, 10:37 PM
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Hot Water BB First Too Much Heat, Now Boiler Overheating?

I have a 3 zone system with Taco valves that are not new by any means, but they work, until it is below 0 for days on end. Then, they work and never shut off...

So, we have been (last two days now) manually closing the valve on the one zone as necessary to stop the heat. Thermostat is working, but if it's set to 65 and no longer calling for heat, I'll wake up at 78 and gaining. I have replaced the thermo just in case. Same problem. Tried crossing wires manually... then separating.. same problem.

Now, today, another zone decided to do the same thing.

All day, it ran too hot, but most noticeably, after the sun went down. So, I thought well, maybe another thermo has gone bad (they're not 12 months old yet, but hey). I disassembled it to reset, entirely. Zone kept heating with the thermo brain disconnected from the receptacle. ERgh..

Then, some time tonight, about 9:30 we changed out the third thermo, just in case. Yeah.. I know... and guess what!! No heat.

Relay is good. Transformer is fused - good. Zone valves are receiving current and opening when instructed by thermos. Pump is running. Pressure is good. Temp is 70 - not good. Expansion tank is empty. Pipes on return and out are cold, but the inlet pipe (freshwater), which is the same that feeds the pump, gets insanely hot.

Boiler fires but shuts off way before water temp reaches usual 180 or 170. It acts like it's stuck between the boiler and the pump... and is shutting off because of over heating.

So far, we have tried a thousand combinations and the only thing that has managed to get the pipes to warm and water temp to raise, and cool off the main line that fees the pump, is to allow some fresh water in and bleed the system while operating.. scary yes.

Help. We live in the middle of no where with high temps at maybe 10 at noon.. lows -20. No plumber in sight or that will answer at this time of night on a Friday no less...

This system has been so much fun.
 
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Old 12-10-11, 04:30 AM
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A couple of things...

You said "pressure is good"; what is the pressure? Is the gauge known good?

On the zones that are overheating, are the pipes to each end of the zone (supply and return of that zone) both super hot? Is one hot and one warm? Are there flow checks installed?

On your last symptom of no heat, can you tell if the pump is actually working? It's tough sometimes with newer pumps, they are so quiet.

It almost sounds like you have more than one problem. A picture of your boiler setup would be worth a million words.

I think a good start would be to confirm pressure is good with a known good gauge.
 
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Old 12-10-11, 05:02 AM
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Yes. What is the pressure of the system and at what temperature was the reading made?

To better hear if the pump is running, take a screw driver and touch the tip to the pump casing and put your ear at the end of the handle. It works well.

When you are having this problem with the rooms overheating, is the boiler firing to keep the water hot? Are the zone valves open when this occurs?
 
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Old 12-10-11, 09:48 AM
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My first question is make/model of the boiler.

I'm having trouble after reading your description of deducing the problem area... seems to wander all over...

It almost sounds like you have more than one problem. A picture of your boiler setup would be worth a million words.
That's what I'm thinking too... to post pics, set up a FREE account at Image hosting, free photo sharing & video sharing at Photobucket and upload the pics there. Come back here and place a link to your PUBLIC album.

I think perhaps the most confusing to me is your statement:

Pipes on return and out are cold, but the inlet pipe (freshwater), which is the same that feeds the pump, gets insanely hot.
I don't get this at all...

"return and out are cold" ... which pipes exactly are these?

"but the inlet pipe (freshwater), which is the same that feeds the pump, gets insanely hot."

Freshwater? the only fresh water that enters the boiler should be coming from your "pressure reducing valve" ... and it certainly should not be hot...

We need more info. and pictures.
 
 

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