Honeywell zone valve: replace valve or just power head? How to tell?

onum · February 4

Hello everyone. I have 5 heating zones (hydronic air handlers) in my house with a Triangle Tube Prestige boiler, and one zone (2nd floor) was not getting heat the other day, with the air handler blowing cold air. Here's what I learned from my own investigation so far. (Please excuse any errors in basic terminology and description as I'm just a handy homeowner. I'm happy to clarify. Also, the whole system was installed in mid-2014.)

When the t-stat calls for heat in the problem (2nd Fl) zone, the motor actuator was not moving at all. (The lever that sticks out on the bottom of the Honeywell zone valve did not move.)
Suspecting (and hoping) it was just the motor, I took a working motor from another zone (basement) and replaced the 2nd floor zone motor with it.
The (supposedly) good motor still did not seem to respond to a heat call from the t-stat.
Next, I tested to see if I could open the zone valve manually by pushing the actuator lever to open position (while another zone was getting heat), and immediately hot water was going into the problem zone.

That's as far as I got as of now. So, on cold nights here in New Jersey, I can at least manually heat the 2nd floor (where the bedrooms are).

Now, I would appreciate your guidance as I try to deal with the repair. Please let me know if the plan below makes sense.

Option 1. I want to see if replacing the entire power head (not just the motor, like I've done so far) would make a difference. So I plan to take the working power head off the zone valve piping for the basement zone and install it on the problem zone.

This way, I don't have to deal with shutting off water and potential leaks, etc.
Is there a possibility this will work? Does the fact that I can manually push the zone valve open mean that the actual zone valve (inside the pipe) is not "blocked" or "stuck?"
If the zone valve mechanical is good, why is the motor unable to move it open?

Option2. If replacing the power head doesn't work (or if it's just a bad idea to begin with), I would then need to use the conversion kit to replace the zone valve. Is that correct?

When replacing the zone valve, do I just close the yellow valve on the return side? (after turning power off on the boiler and to be safe all the t-stats)
I don't see a separate valve on the supply pipe. When I close the return side valve and pop open the zone valve, will water gush out? That would be a disaster. I see the orange (darker yellow) valves on either side of the green pump. Should I shut those closed?
Do I need to worry about getting air out of the zone once I'm done installing the conversion kit?

Below are the pictures of my plumbing around the boiler. There are 5 hydronic air zones (some zone valve covers removed during troubleshooting), and 4 radiant floor zones on the left (please ignore those for this discussion).

hot_rod · February 4

Test to see if you have 24V at the motor when that thermostat is turned up. If not the thermostat or relay box that may be powering it is not working.

The green box on the left, is that what the zone valves wire to?

onum · February 4

https://forum.heatinghelp.com/discussion/comment/1840185#Comment_1840185

Thanks hot_rod. I'll check for 24V at the motor when I get home.

The green box with the three wire conduits coming out on the bottom (if you're referring to the green box on the wall on the far left) looks like it's connected to the round green devices (I assume they are some type of pumps to circulate the water?) for the radiant zones. Radiant floor zones have their own Tekmar t-stats.

Air handler zone valve wires are all clumped together in zip ties along the wall. I'll check to see where those wires go when I get home.

EdTheHeaterMan · February 4

You may not need to open up the water side of the system. Those motors are replaceable as is the entire head assembly. But you wan to see if the head is getting power as @hot_rod said. if you don't give power to the new valve actuator/motor, that one won't open either. And you will own a spare actuator.

How old are your zone valves? If you need to open up the water side to remove the actuator, those valves are really old. Honeywell has not sold those for years. If you have the older valves than you need to install the conversion plate.

onum · February 4

https://forum.heatinghelp.com/discussion/comment/1840224#Comment_1840224

Thanks @EdTheHeaterMan — Yes, I will first check to be sure I'm getting 24V power at the motor. And yes, I understand the entire head assembly can be replaced without opening up the water side. I was just thinking that in the worst case, the zone valve ball might be stuck or hard to move, in which case I would need to open it up. (But as I said in my original post, I can manually open the zone valve, so I was confused…)

EdTheHeaterMan · February 4

When you said that you opened the valve with the manual lever and it did not stick…. that proves the ball inside is just fine.

Alan (California Radiant) Forbes · February 5

I’ll bet that mechanical area is nice and warm. All those bare pipes at 180F makes a nice radiator.

onum · February 8

https://forum.heatinghelp.com/discussion/comment/1840224#Comment_1840224

I finally was able to test if the motor head is getting power, and here's what I found.

I first wanted to know what I should be seeing if everything was normal, so tested for power in one of the working zones:

23V when the thermostat is off
27V when the thermostat is turned up

I then checked the problem zone and found it was getting power:

25.35V when the thermostat is off
25.35V when the thermostat is turned up (no difference in power when the thermostat calls for heat)

Any advice on what to check for next?

Thank you.

hot_rod · February 8

Pop the thin cover off the motor, does the motor spin? It will spin for 45 seconds or so then stop, and stall.

Also the thin covers get real hot when the valve is open as it becomes a heater when the motor stalls.

Screenshot 2025-02-08 at 10.57.10 AM.png

HVACNUT · February 8

What exactly are you testing? It should be 0 volts on both zones valve motors with the thermostats off.

onum · February 23

Thanks for all the advice from the community. Just to close this one out, the issue was with the gunk build up (the dark viscous grease) in the gears of the motor, causing the motor to fail to push the valve open. I tried the "tear down, clean and rebuild" method, and it worked (for now). But in the end, I don't think it's a good use of my time (other than learning about the internal mechanism) and decided to order the replacement motor part (Honeywell 802360JA).

@HVACNUT - For some reason, I detect 24v power on the yellow motor wires even when the thermostat is off. I even shut off the emergency shut off switch for the air handler, and I still get 24v at the motor. I don't understand how the motor recognizes when there's a call for heat from the thermostat if it's already getting power, but that is what I see.

https://forum.heatinghelp.com/discussion/comment/1841288#Comment_1841288

Not sure if it spins for that long, but yes I did see it spinning then coming to a twitching stop (spinning with my fingers).

Anyway, even after I cleaned the motor gears (below), there's still a good amount of resistance when I try to spin it. I don't know how a new motor should feel, so I'll check when the new part arrives.

Thank you again.

hot_rod · February 23

The resistance you feel is the gear reduction inside the assembly.

Honeywell zone valve: replace valve or just power head? How to tell?

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