Zone Valve wont close. Room sweltering


  #1  
Old 10-19-04, 10:41 AM
homebrew1994
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Unhappy Zone Valve wont close. Room sweltering

I have a hot water baseboard system. Age of boiler unknown, maybe 10-15 years.
3 zones with Taco zone valves. Electronic timer thermostats.
Begining last winter, one valve refuses to close when the thermostat cuts off. The valve can only be closed by cutting the main power to the furnace (the emergency off switch).
I had a plumber come out and replace the offending zone valve and power head. This had no effect. He suggested it may be a short in the thermostat wiring. I ran new thermostat wire from the valve to the furnace (basement) to the thermostat (2nd floor), replacing the existing wire.
This had no effect.
I swapped out the thermostat with one from downstairs. No effect.
I swapped the power head off the valve with one of the other valves. The effect on that was to cause the other valve to stick open.

Springtime came and I forgot about it. Now with cool weather setting in, I notice that I am still stuck with this problem.

Any one else ever encounter this?
Any ideas?
 
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Old 10-19-04, 06:54 PM
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First you need to be 100% certain whether the problem is mechanical or electrical. Is the manual operation lever in the auto position? If you remove the wire from the #1 terminal (farthest from the valve body) does the valve close? Lets start there and work outward.

Ken
 
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Old 10-20-04, 04:07 PM
homebrew1994
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OK, tried it

First I turned the heat up, so it would be on and the valve open.

I confirmed the valve was open by moving the override bar/switch/slider thing.

Then I disconnected terminal 1. (It must be the live wire, as it sparked a bit when I took the wire off.

I then listened and could hear the water flow being shut off.

Again, I checked the override thingy. I felt resistance, indicating the valve is closed.

Reattached wire 1 (again, sparks, so its live). and almost immediatly I could hear the valve open.



Does that rule out the mechanical?

Thanks
 
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Old 10-20-04, 07:37 PM
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Yes it does and it confirms the electrical. Your thermostat is calling for heat (your zone valve thinks it is) or the new wire is pinched somewhere.

Ken
 
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Old 10-21-04, 06:16 AM
homebrew1994
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OK, electrical

I donít think the wire it pinched. That was what the plumber that replaced the zone valve suggested and it made sense.
I replaced the entire thermostat wire, from the attic all the way to the basement where it meets the other wires.
The problem is the same as before I replaced it. It seems unlikely to me that the replacement wire would also be pinched/shorted.
Also, I suspect that a short would always be on. Remember that the zone valve resets and stays normal if I cycle the furnace power off then on.

I have two possible areas of suspicion here.

First: Is there some sort of control in the furnace/boiler itself? I know it is in the wiring equation, but not exactly how it is involved in the circuit. I suspect it is not the cause, since only one valve is acting up.

Second: The wiring for all 3 zones converge in a work box in the basement ceiling. The schematic is written on the rafters in magic marker. All the wires are numbered and identified (i.e. #1- 1st floor thermo. #2- 1st floor zone valve, etc). A bunch of these wires are crossed, that is the ones that lead from the valves all converge and connect to the furnace. I am guessing these wires are the ones that signal the furnace to go on. When I get home tonight Iíll post the exact wiring config.

Could some unintended short in this box be causing the intermittent and unintended firing of the furnace and opening of the zone valve? Might there be some alternate way of wiring them?


Oh Yeah, Thanks for tanking the time to read this and help.
 
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Old 10-21-04, 06:33 AM
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The boiler has no control over the zone valve. When you cycle the boiler power, you cycle the power to the zone valve. It is normally closed so with power off, all of them will be closed.

I wasn't implying that you pinched the new wire but the thermostat wire is just a switch and your zone valve thinks that switch is closed. I have seen nightmare spaghetti junctions like you have in the ceiling and what I do is trace all the wires and mark them with tape markers and rewire the whole thing. You may be able to trace the problem back but it is probably in a place like that. The tech you had in to replace the zone valve should have spent his time helping fix the problem instead of replacing a perfectly good zone valve that was only doing what it was told to do. If you want to work from one end of this to the other, find the end of the new thermostat wire that you ran in the junction box. disconnect it and see if the valve closes. If it does, the problem is from there toward the thermostat. If the valve does not close, trace the #1 wire back from the zone valve to the junction box. It should only go up to the thermostat, so it should be one of the open wires you disconnected earlier. I think by that time you will have found the problem, or at least be much closer to it. I don't know what thermostat you are using byt sometimes it can be close quarters on the terminal strip back behind the stat. Make sure that when you put it back on the wall, the wires don't touch together. Keep us posted.

Ken
 
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Old 10-21-04, 09:58 AM
homebrew1994
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in fairness to the plumber

I called him and asked him to replace the valve, based on the opinion of my brother, who had encountered the same problem and told me "just replace that valve there".

He also offered to trace the wiring, once he replaced the vavle and realized it was a waste of time. But, he acknowledged that I had already spent a good chunk of change with him to not fix it, he suggested that I could trace it back myself for free as opposed to his hourly fee. I then replaced the wires to the thermostat.

I think this weekend I will tackle the birds nest of wires in the rafters.
 
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Old 11-25-04, 06:17 AM
chargeitup
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Check for continuity

Hi!! Just browsing around looking for answers to another problem I'm having. If you simply check for continuity at the wires going up to the thermostat in question, you could rule out the damaged wiring problem. With the thermosat not calling for heat, you should not have continuity between both leads. With the thermostat at full open, the circuit will be complete and you would have continiuty. If the thermostat should be off and you still have continuity, you have a short somewhere. You just need a multimeter to check...
 
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Old 11-25-04, 06:39 AM
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If you try that test, just be sure to remove the thermostat wires from the valve before testing. If you tested them from the thermostat location you could damage your meter because there is voltage there. If you check from the basement with wires disconnected, follow chargeitup's suggestion.

Ken
 
 

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