Constant heat in 1 zone


  #1  
Old 01-03-23, 06:48 AM
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Constant heat in 1 zone

I have a gas hot water boiler with 6 zones for heating a 2.5 story building, plus a 7th one for hot water with a coil inside the boiler. It has individual flow check valves on the supply side and individual circulators on the return. One of the zones has constant heat even when the thermostat is off and not calling for heat. The pipe on the return size for that zone is hot. I already replaced the flo control valve for that zone and the output of the flo control valve is not hot. Any ideas?? It was fine previously. Itís zone 5 (top floor), the one with the green Taco 007, and the shutoff valve partially closed now to control the heat till I figure it out.




 
  #2  
Old 01-03-23, 11:18 AM
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What does boiler pressure gauge read when boiler cold? What is your guess for the height of loop 5 relative to boiler pressure gauge? Where are zone valves relative to circ pumps?
 
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Old 01-03-23, 12:53 PM
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the boiler pressure is about 18. the height is about 2 stories up, so about 14 feet. There are no zone valves.... each zone has a thermostat, which controls a relay, which operates its individual circulator. there is a flo check valve on the supply side of each zone.
 
  #4  
Old 01-03-23, 02:49 PM
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It looks like the light for zone 5 on the Argo board is ON. Is that right? I would think that would only be ON if the thermostat was calling for heat.
 
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Old 01-03-23, 03:04 PM
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actually zone 5 is OFF.... its just the angle that shows that it's on. it's zone 6 that was on
 
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Old 01-03-23, 03:25 PM
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Yea - from that pic it really looks like it's the middle relay light is ON and someone wrote a 5 there. But such is not the case and my eyes lie to me a lot these days. I would try and determine if the pump for 5 is running when it should not be running. Maybe the old screwdriver trick where you put the screwdriver blade on the pump and the handle end at your ear will work.

Supposedly you will be able to hear the pump running. I never tried it, but I think that works. Maybe one of the pros will weigh in on that.

(AH - think I see. The leds are offset from the relays - I think -lol)

Maybe you could disconnect the pump at the Argo board and see what happens. Just a thought.
 
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Old 01-03-23, 04:44 PM
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Also - maybe the relay on the Argo is welded closed. I think that can happen if they start arcing. Pretty sure that can happen especially when the relays are old. That would cause the pump to run continuously.
 
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Old 01-03-23, 04:53 PM
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The boiler pressure is OK for the elevation you stated. The static pressure at the highest point in loop 5 is the lowest. The static pressure is the highest, relative to loop 5, at the highest point at the loop with the least elevation change . My guess is whenever any circulating pump is running (assume all have same head rating), it will force the hot water through the non operating circ pumps and up the return lines. Assuming the check valves in the supply side close, the return lines, not operating, get hot to a height relative to their static pressure. To me, this is the normal condition, so not sure what you meant when you said it was fine previously in post 1.
 
  #9  
Old 01-03-23, 11:39 PM
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This is just a thought. If your pump was on then your Flocheck would be open and hot. You said the pipes were cold on that end which would eliminate the pump being on when stat not calling.
Since it's your return line that is hot I would follow the pipe back to see where it starts to cool. Since it's backfeeding or gravity feeding back it will heat the floor backwards so where the pipe returns would be hot or warm and where the pipe comes up would be cold.
What you could try is to shut all the zones off and turn them on 1 by 1 and see which one if any back feed up zone 5. Open that ball valve all the way and obviously don't turn on that stat.

That zone is the 2nd from the right so my guess would be a pump or pumps to the left of 5 is somehow feeding back up the return. Very strange.

When 5 calls for heat does the zone work normally. Is the pipe hot after the Flocheck.
 
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Old 01-04-23, 06:32 AM
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the problem actually started last week. i had a frozen pipe and in the process of troubleshooting, I replaced the flo control valve and the circulator for this zone. the output of the flo control valve is not hot when the the thermostat isnt calling for heat. not sure if it's something with the taco 007 circulator, when all others are bell and gossett.
 
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Old 01-04-23, 02:58 PM
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Can't really see a circ. problem. One is the same as the other as long as they are going in the right direction.
 
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Old 01-06-23, 01:13 PM
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The Taco 007 is pointing in the right direction and it's not running since the thermostat is not calling for heat. Any chance that having a different circulator in there is causing this "ghost flow"?? The output of the flo control valve on the supply side isnt hot, and the only thing that changed recently is a new flo control valve and this new taco 007
 
  #13  
Old 01-06-23, 02:07 PM
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My only thought at this time would be to double check the Flocontrol and make sure it's fully closed. Why I say that is although the pipe is not hot I'm wondering if the water is flowing up through the return tee along with returning to the boiler from other pumps is overcoming supply water leaking by the Flocontrol due to the added pressure from the other zone pumps.

If that is the case then with all the other zones shut off and just the boiler running it would then allow boiler water to get by and the pipe would heat up after the FC. Tap the FC ane see if the flapper got stuck and didn't fully close.

There is no chance of different brand circulators unless the other circulators have check valves in them and yours does not. I don't see why you would them but this is a strange case. Did you try things from my previous post.
 
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Old 01-07-23, 09:03 AM
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Are the emitters and the space actually getting warm/hot or just the return piping near the boiler? If only the near piping is getting hot it could be by conduction. Unless the flow control at the supply is open, heat by conduction should not be creating a gravity flow in the zone.
 
 

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