Zone Control Valve operating backwards?

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Old 09-13-14, 12:20 PM
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Zone Control Valve operating backwards?

Hello,

I recently moved into a new place with hot water baseboard heating. I was told that the zone control valves had been replaced by the previous owner, but I believe this is the first time they are now being tested in cold weather. The thermostats are new too.

Here is my issue: I noticed my first floor "zone" has the heat on constantly. I feared a stuck valve. However, I took the baseboard apart and removed the motor from the zone control valve (but I did not disconnect the power). I played with the thermostat and noticed the motor would turn when I set the thermostat to max. Conversely, the motor would not move if the thermostat was set below the room temperature.

The puzzling thing about this is that the zone control valve is an "always open" design (at least thats what google tells me).This means that it is turning OFF the heat when I set the thermostat to max, and turning ON the heat when I turn the thermostat down.

I have no experience with these things, but I'm hoping there's just a wire crossed somewhere. Any help is appreciated.

The zone control valve model: Honeywell V8043D1205
The thermostat model: CT30A1005
 
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Old 09-13-14, 12:44 PM
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That's a shame...

First off, it's not a good idea to operate the power head with it not connected to the valve. It's possible for the motor to 'over run' the mechanism and may possibly damage it... it might not, but it's just not a good idea.

Yeah, the " D " model is in fact a 'normally open' model.

I believe that the valve body itself is the same and that all you'll need to do is change the power head to a normally closed model.
 
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Old 09-13-14, 12:51 PM
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I don't have a lot of experience with residential hw heating but it is common in commercial circles to have a valve that is normally open.
This is so that in the event of a failure of the control system the valve will remain open and heat the space.
To control these valves you would actually use an air conditioning thermostat that closes on a drop in temperature which is opposite what a heating stat does.

You could also use an air conditioning thermostat or possibly change the sub-base on the one you have to make them work......your sub-base may already have the right connections.

What is the make and model of your thermostat(s)?
 
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Old 09-13-14, 01:00 PM
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Funny thing is, I can find the " D " valve on-line, but not in the latest Honeywell catalog that I have. It seems that the " B " model is shown as the normally open one.

Maybe they replaced it with some 'new old stock' items that they found somewhere?
 
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Old 09-13-14, 01:03 PM
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I don't think that will work Greg...

Reason being that the Honeywell valves are for 'intemittent' service and in order for the valve to remain closed it would have to be POWERED closed at all times. Motor would burn up pretty quick.

The t'stat is a cheapo heat only CT300
 
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Old 09-13-14, 01:04 PM
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RK, what model valve and thermostat is on the 'other' zone, and does that one work properly?
 
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Old 09-13-14, 01:14 PM
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NJTrooper,the other theromstat is a Honeywell T822L1000. I think we are thinking on the same lines, as I just got back to my computer. While I was away, I switched the upstairs thermostat downstairs. The zone control valve now works properly.

I only have two wires to connect to the thermostats. The only difference between the two was the downstairs thermostat only accepted a 'W' and 'R' cable. The upstairs one was wired as 'R' and 'Y'. I wired it the same way downstairs and that seems to be what fixed the problem.

Guess it's new thermostat time?
 
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Old 09-13-14, 01:40 PM
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Did someone recently change the downstairs thermostat?

The one from upstairs was wired for A/C, so Greg may well be correct...
 
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Old 09-13-14, 02:24 PM
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Yes, I believe the previous owner changed all zone control valves and thermostats during renos before selling the place (to me). This is the first time the system is getting tested out.But yep, looks like Greg is right - wiring for A/C is what I need to do. Cheers, and thanks for the help.
 
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Old 09-13-14, 03:32 PM
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As far as I know normally open valves are becoming the standard because they offer a certain amount of redundancy.

I wonder about valves that were rated for intermittent service.
How would that work for a heating coil that was undersized for the load and the heat stayed on continuously?
Would you have a high failure rate?
 
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Old 09-13-14, 04:47 PM
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Would you have a high failure rate?
I'm sure...

I can tell you that when the standard honey valves are called to open, and the system doesn't fire up, and the thermostat calls and calls, those motors get HOT HOT HOT!
 
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