strange zone valve issue

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Old 10-10-14, 07:11 AM
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strange zone valve issue

First post for me, I am having problems with two of my Taco 3 wire valves.My system is about 18 years old,hot water baseboard ,Burnham Boiler,Tjorland blower,Becket burner, external hot water plus three zones.I have had some circulation issues for a while but lately I have a programmable T stat on my main zone and it doesn't seem to be controlling. We had a 12 hr power outage last weekend and I thought that maybe that had something to do with things so I reprogrammed the T stat with no luck.I went and checked the system and I am getting power to everything (24vac) but when I initially did my check i was getting 48vac on the bottom connection on the valve head,I got this on all four valves.I shut the system down and checked all the wiring which seemed OK but a few loose connections which I fixed.Turned the power on and rechecked and now I am getting 24 vac on the bottom connection,Good. Still nothing from the main zone however,then I tried exercising the valve manually and when I opened the valve the boiler lit off,temp and pressure weren't up so I let it cycle when it shut off I manually opened the valve again and the same thing happened. I have done this before with out this result. Do I have a bad valve head?

sorry for the long post,Thanks Ron
 
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Old 10-10-14, 05:34 PM
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problems with two of my Taco 3 wire valves
Still nothing from the main zone however
Are you saying that the cleaning up of the connections got one of the two troubled valves working now?

With all thermostats all the way down:

Measure voltage between 1 and 2 on the bad valve.

Should be ZERO when no call for heat

Turn thermostat on bad zone all the way UP.

should be 24 VAC when there is a call for heat and valve should open (takes a couple three minutes for Taco valves to open)

Next, measure voltage between 2 and 3.

Valve should still be open.

Should measure ZERO volts at 2 and 3 and boiler should be firing.

Turn thermostat all the way down.

Takes a minute or two for valve to close...

Should measure 24 VAC with no call for heat at 2 and 3.


If you have 24 VAC at 1 and 2 with thermostat up, and 2 and 3 never goes to zero, it means either the valve isn't opening (bad 'heat motor') or the valve may be opening but the ENDSWITCH is bad.
 
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Old 10-11-14, 12:18 PM
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Thanks Trooper,I found out why I am getting 48 volts to position 3 on the valves and I'm not sure how to fix it. TT is coming out of the box to position 2 and 3 on the hot water tank zone valve. The rest of the (3) valves are connected by wiring from the HW valve(don't know if its series or parallel but it's 2-2-2-2 and 3-3-3-3). I have the T stats wired to the transformer and the 1 position on the valves with the hot wire from the transformer going to position 2 on the main heat zone valve. So...I'm getting 24 vac from TT and the transformer.

It's been like this for 15 years and hasn't seemed to hurt anything...it just doesn't look to me like it's wired correctly...
 
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Old 10-11-14, 04:05 PM
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Did you perform the tests I outlined? What was the result?

It's PARALLEL. All of the 2's together, and all of the 3's together, going to the T T on the boiler control. That's correct.

I terminal of the transformer should go to all of the 2's.

The other terminal of the transformer should go to one wire of all the thermostats.

The other wire from the thermostats goes to the terminal 1 of the respective valve.

You should NEVER SEE 48 volts between 2 and 3 of the valves.

You MAY see 48 volts between terminals ONE and THREE of the valves, but that's not a problem.

If you see 48 volts between 1 and 2 , OR , 2 and 3 , then you've got a wiring error that should be corrected. Just because it's been that way for 15 years doesn't make it right, and I'm very surprised it worked for more than a day or two.

Are you sure you weren't measuring between 1 and 3 ?

This is the wiring for two valves, any more valves would get added to the chain just like the first two

 
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