Hi all (again),
I am working on diagnosing a zone valve which appears to be stuck open. Unfortunately for me it is in the house I used to live in and now rent out and although the tenants are good, they have a dog that doesn't like me, so long story short I'm trying to reduce the number of trips over there.
They have reported heat coming in through the baseboards for the last month or so even when the thermostat is set below the temp of the room or just turned off. They stated they swapped the batteries when it started getting too hot in there, and did not notice a change. I checked the thermostat last week which appeared to be working normally. There was 24v between the red and white wires, and I believe 24v showing between white and the screw between the red/white. Red to blank showed 0v. (Pictures attached)
The zone valve in the middle (first floor zone, the one in question) seems to want to stay open if I try to cycle the slider on the bottom to the right (the other two cycle normally back to the left after being pushed to the right).
From what I read here the best troubleshooting method is:
Shut off power to the boiler and see if the valve closes. If it does disconnect yellow zone valve wire and see if it closes, if it does it is likely an issue with the wiring between the t-stat and zone valve. If it does not close it could be the power head has gone bad?
If it seems like it could be the power head can I take the power head off the zone valve to the right (for the basement, which never seems to need to turn on) and swap it, at least for the spring? Is there any reason to try and lube up the connector going into the valve?
How can I tell if the valve itself needs to be replaced?
Anything else worth doing to help troubleshoot?
Valve in the middle, after I tried cycling it. Valve in the middle is the one in question, the one on the right is rarely if ever used as its in the basement which stays warm enough. Tstat Back of Tstat
That valve is sitting in the open position.
You removed the thermostat and it didn't close.
More than likely the motor unit is jammed.
Even is the valve was bad.... the spring would still close the mechanism.
If both of those have the removable heads than you could use the right one in the center position.
You could leave the right valve with no motor right now. It would stay closed.
In order to confirm 100% it's not the wiring.... just open one of the splices in the yellow wire on that valve.
Adam,
If you look at the bottom of the middle ZV you will see the lever is the manual or open position so either the stat is calling for it to be on or the head is the problem.
What I would do is disconnect the RED WIRES at the ZV. Those are the wires that turn the boiler on, on a call for heat. The YELLOW WIRES go the stat. On a call for heat a signal is sent from the stat to the yellow wires to open the ZV. When the ZV opens it makes an end switch and the red wires turn on the boiler.
By disconnecting a RED WIRE you are breaking the connection to the boiler and it should stop. That will tell you the head is bad. This is all done with the stat off.
Depending on your skill level there are replacement parts for this valve. As if they are compatible, you will have to take the covers off and see.
Below is a sight that might help with info and parts.
Pete,
Under different circumstances that would be a good test but the way I'm looking at this is,
According to the pics he has the stat off the wall with just the wires exposed and unless someone put the ZV lever on manual then the valve is acting as if it's on a call for heat so unless there's a shot in the stat wire the yellow wire doesn't come into play.
I'm thinking disconnecting a red wire to see if that stops the boiler from firing. If it did then that tells me the red wires are doing their job but the yellow wires to the motor is the problem.
Pete, to your point though if he did take a yellow wire off and the ZV shut off, that would make the problem either the stat or a short in the stat wire. If he did that with the stat off the wall and the ZV shut off that would even eliminate the stat and put attention on the wire.
That could be a good place to start also. He could try to manually return the lever to normal and see what happens.
Zone valve is mechanical device, electrically activated. Without electric connected valve is closed by spring.
Eliminating electric power on motor, as possible cause, is simple, easy first step.
If still flow, next second step is mechanical.
While Manual Open Lever is moved to Latch position, watch mechanism. Shaft only rotates slightly 20 degrees? With good mechanism lever should move smoothly and latch. If it does not, then valve ball may not fully close port, possibly due to debris, allowing water flow.
Another trouble shooting tip is learning how "normal" working Manual latch feels when moved.
With no zone active, separately open each valve. All should move and feel similar. If valve on problem zone feels different may indicate mechanical problem and not electrical. .
To answer the other part of your question, Yes, you can move a powerhead from another zone to verify it is not the ball fouled and not moving.
You can pull the powerhead off the zone not working and disconnect a yellow wire and reconnect and you should see the valve moving while in your hand. This will verify if the valve is operating or not of if the shaft is seized.
Turn power off, remove powerhead from each zone. Make sure you line up the drive pin with the valve body shaft. Turn power back on and verify the other zone thermostat is demanding heat. The zone should work if it was the powerhead.
Hydronic baseboard heating system in single story house with a basement runs for 4 minutes then off for 8, consistently until getting up to set temp, which literally takes hours, even for only a couple degrees. Runs longer only on the first call for heat in the morning. There is only 1 thermostat so only 1 zone. I've checked all settings on the thermostat.
The aquastat has HI limit set to 180 with 10 differential and no LO limit because it's heating only, not also domestic hot water. I've bled all the baseboards that have a valve and only water comes out, no air. The radiators in the 2 rooms in the basement do not have bleeder valves. All baseboards are warm/hot, no cold spots that we can find.
I do occasionally hear crackling sounds downstairs at the pipes in the unfinished ceiling that's the living room floor, a little way from the boiler and sometimes at the boiler, that I'm guessing may be air that's not working its way to the valves? There are some blue faucets in the pipes running toward the living room, if that makes a difference.
Any ideas why the boiler reaches the HI limit in only 4 minutes and shuts off, then cools down the 10 degree differential before coming back on and repeating? It does seem to run more "normally" once it's reached set temp. I've mentioned it to the service person for several years when he's here for the cleaning/tune-up and he says this is normal. This is the first year I decided to time the on/off cycles and realized it was that short.
When I ask the service company, they want to bleed the entire system to "reset it", instead of checking to see if all components are working properly. Does this make sense? Definitely expensive at $149/hr. I've decided to try to do more research first.
Oil fired Beckett RSA85LN-TB low pressure boiler,
Beckett by Honeywell R7184B Interrupted Ignition Oil Primary Control,
Beckett Electronic Oil Burner ignitor 746001,
Beckett 21805 burner model K37MYBKN-597,
Honeywell L7224U aquastat,
Taco Cartridge Circulator model 007-F5, (by boiler controls),
Bell & Gossett NRF-22 Circulator (higher up on other pipes),
Lux 9100uc programmable thermostat.
03-14-23, 07:27 PM
