How Do Troubleshoot A Honeywell Zone Valve?

bugdoc@linkny.com

The problem is very little heat coming from the radiators in one apartment. both apartments are controlled with separate Honeywell T87 type stats. One works fine and the other is set at 74 degrees and only makes about 64 room temp. Stat is OK.

How do I go about checking the zone valves complete operation ?
What I mean by "complete" is that it is fully opening when heat is called for via the stat ? I took the cover off and it seems as though that the motor is turning "but not very much" that is why i am wondering about fully opening, ect. Leads me to wonder if the valve works only part of the time? Also, it seems that this is an intermittent problem as it works ok from time to time but currently not so.

I believe that I have eliminated a bad circulating pump due to the other apartments being okay ? And, i can sense it running when the boiler is firing ! Is there one zone valve that takes care of each apartment (there is two mounted on this system), inotherwords, one for one apartment and another for the one that I am concerned about ? Any help would be appreciated. Jim

randomkiller

I can give you a general idea but as for what the valve controls is up to the install. On a basic Honeywell zone valve there are four leads two yellow and two red. The red are an end switch that makes when the valve is fully open, so if you check them with a continuity tester they will only be made when the valve is driven fully open. The two yellow wires operate the motor, if there is voltage there the motor should be in the stalled position of fully open.
Two small screws hold the motor in, it is easy to pull out, there is a small manual handle that you can operate the valve with. If you replace a motor, make sure the handle is in the far left side of the slide (off) and install the motor unwired. When powered up the motor should drive the cam arm to the right side of the slide and make the end switch. Inside the t stat there is a small heater (heat anticipator), it should be set to .4 or toward the longer -> position to keep the valve from closing before the heat is working. Hope this helps.

bugdoc@linkny.com

Randomkiller: thanks for the help, your comments helped alot.... when I checked the zone valve in question I noticed that the cam was not touching the end switch at all -- but was some distance (but not closed position) away from the switch (and the manual lever was free, left and right). I actuated the end switch and just as soon as I did the pipe became hotter and (flow from pump,ect.) and the questionable heaters began to heat also (of course). So then , my guess was /is that the valve was only partially open letting some hotter water through but not adequate enough to perform properly via the stat setting calling for more; cause and effect was that the zone motor was not functioning properly, or strong enough, to move the cam down the total path to and actuating the end switch; hence the pump comes on and hotter water from the boiler is sent downstream to the radiators via the fully open valve position ? Make sense to you ? I am going to change out the motor in the morning, but for today I have left the t-stat and the boiler as is , as it is heating for now since my findings so far. I'll let you know ASAP. Would it be a good idea to change out both zone motors while I am at it ? JIM

MechanicalDVR

If they look the same age it couldn't hurt. It is very easy to change out the motors, just make sure you pull the right screws or you could get blasted in the face with hotwater. Like random said make sure the valve is in the closed position when you install the new motor.

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bugdoc@linkny.com

Thanks for the reply, I think as long as I have to change out one I might as well do the other as you have mentioned " more likely then not they are the same age " as I assume, so for whats it's worth to have them both in sync it's time/money well spent. Do you know for instance: if the stat (T87) is set to call for heat how long does it take for the zone valves (normally closed)(honeywells also) to respond or begin there slide to the end switch, 2) is there such a position as half way or does the motor start and stop throughout the slide continuously ? Seems to me that when it is powered up the motor's provided voltage keeps it powered up until the t-stat says that heat is made ?

MechanicalDVR

As soon as the t-stat makes it sends voltage to the motor and the motor should start moving until it opens the valve all the way and stops, should take less than a minute. There is no half way position, the motor keeps it open as long as the t-stat is calling, then it closes by spring tension.

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bugdoc@linkny.com

Understood and thanks. Reason I asked was that when i first got into this project the one zone valve cam was not all the way contacted, only part way through (maybe half way) it's slide towards the end switch thus no circulating heated water. This is of coarse with the t-stat turned up calling for heat ! I did not check for voltage then but there must have been otherwise the valve would have returned to the start position with the spring tension(normally closed situation), correct ?

MechanicalDVR

Yup.

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"Injustice anywhere is a threat to justice everywhere" mlk
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bugdoc@linkny.com

Thanks for the pleasant and informative conversation MECHANICALDVR. I'll go at this first thing in the AM.

BigMikeB

pretty good for a spark-o-matic