Honeywell V8043F10 Zone Valve Getting Stuck Open

iced98lx

Hello HeatingHelp.com folks! I've got 5 zones of hot water baseboard heat. I've replaced the older dial style electronic (but not digital) thermostats with new digital thermostats in all but 1 zone that had a mercury activated thermo. One of the zones (the largest of the zones, if that matters) is heating any time any other thermostat calls for heat. I the valve opens/closes okay if I turn it.

Here is the back of the zone valve:


I had to hook this one back up because it was disconnected when we moved in and forced open (according to the PO "to get longer run times on the boiler vs short cycling") This one and one other have 4 wires but the others have two terminals jumped, like so:



How do I troubleshoot this? Measure voltage across two terminals (?) on the zone controller having the problem when another tstat is commanding heat?

Any suggestions welcome...

iced98lx

Just got everything shut off then activated another zone, that zone appears to stay shut. Perhaps it only stays open if it calls for heat then gets up to temp while another zone is open?

mattmia2

It is probably accidentally wired such that the end switch is energizing the coil when it closes. The thermostat opens the valve then the end switch is used to start the pump and/or boiler once the valve is open. If it isn't wired exactly right it might end up doing that, like swapping wires since it looks like they are using a common wire to power the stat and the end switch.

BTW, those mercury switch t-stats would have probably outlived all of us.

iced98lx

mattmia2 said:

It is probably accidentally wired such that the end switch is energizing the coil when it closes. The thermostat opens the valve then the end switch is used to start the pump and/or boiler once the valve is open. If it isn't wired exactly right it might end up doing that, like swapping wires since it looks like they are using a common wire to power the stat and the end switch.

BTW, those mercury switch t-stats would have probably outlived all of us.

(I left the 1 mercury switch that was here )

So I need to figure out what each terminal should read across each other and verify it I suppose..

I have two brand new Taco 4 zone controllers sitting here but I'm not especially looking forward to installing them... perhaps a good reading of the Honeywell 8103 manual will help me feel more comfortable doing so.

iced98lx

My apologies for calling it an 8103, I guess it's referred to as a V8043F1051 The wiring diagram makes sense if I knew what wire is what...

iced98lx

A little further diagnostics based on my reading.

The end switch is functioning as designed and signaling properly.

When that Tstat calls for heat, I get 27v AC across the two thermostat terminals, the valve opens fully, the end switch activates.

When heat is no longer called I get 0V across the thermostat terminals but the valve does not self close, never de-activates the end switch and the boilers Aquastat keeps it hot obviously, causing constant heating of that zone.

I've disabled the zone for now but it is our main living space so I'll have to fix it.

I suspect this is why it was manually opened, so it only heated when other zones called for heat vs sticking with the end switch on all the time. Probably kept it roughly comfortable most days.

So, appears the valve is "Sticky" ? Any suggestions or is it just pull it and sweat in a new one?

EDIT: I read a few other posts on here about greasing the gears a little, I'll certainly try that.

mattmia2

Try pulling one of the wires off the end switch and see if it closes. If the actuator is sticking you can buy new actuators for those, they are just held on with a couple screws, don't even need to drain the system. You can pull the actuator and see if the shaft in the valve itself is sticking, but i would suspect the actuator.

If you see 0vac across th and tr when the t-stat is satisfied then the problem is mechanical.

iced98lx

mattmia2 said:

Try pulling one of the wires off the end switch and see if it closes.

The end switch opens/closes properly when the arm moves (I can see the arm is still pressing the switch when the "runaway" situation occurs)

mattmia2 said:

If the actuator is sticking you can buy new actuators for those, they are just held on with a couple screws, don't even need to drain the system. You can pull the actuator and see if the shaft in the valve itself is sticking, but i would suspect the actuator.

I'm a little confused by this part, I can take the motor off easily enough, what am I looking for exactly?

mattmia2 said:

If you see 0vac across th and tr when the t-stat is satisfied then the problem is mechanical.

This is the case, and when I manually move the lever from "Auto" towards "manual open" it then runs itself back, albiet slowly. I worked it back and forth a bit to let it get a few cycles in but I wonder if the arm/shaft isn't the problem here since it is showing 0v when it's supposed to be shutting off (the arm just never moves back away to deactivate the end switch and eventually close the valve..). If I give it a manual bump with a screw driver it then goes off as expected. I'm guessing it was working intermittently until recently when it began to stick pretty regularly and we saw 75+ degree temps in that space... Makes me think the valve itself will need to be pulled and replaced.

I'll start with pulling the motor off and inspecting gears for damage, make sure it's greased ok etc tomorrow. I appreciate your responses and help!

mattmia2

The actuator (the "motor and gears") turns a shaft that sticks out of the valve body. If you remove the actuator you can figure out if it is the actuator or the valve that is sticking. i suspect it is the actuator. The actuator should open and close even if it isn't mounted on the valve. If it sticks when it isn't on the valve then you know it is the actuator. It is something similar to this:
https://www.supplyhouse.com/Honeywell-40003916-048-Replacement-Head-for-V8043F-Zone-Valves

iced98lx

Thanks for the clarification! I'll check it out tomorrow. I do have an extra actuator NIB here (previous owner left a bevy of spare parts) so I can compare action etc and see if she shaft seems to spin freely as well. Appreciate the guidance!!

Jamie Hall

You really need to go back and look at all the wiring. The thermostat should close a circuit when it is calling for heat -- doesn't matter what kind of thermostat. That should put voltage across Th and Tr for the associated zone valve. Wonderful. But. The end switch should not be connected to that circuit at all. The end switch closes when the valve is open. That jumper doesn't belong there at all.

If your system has only one circulator and the boiler, then the end switches of all four zone valves should be wired in parallel, so that closing any one of them starts the circulator and boiler.

Somewhere in your system -- and it may be nowhere near the zone valves -- it seems that someone got very creative with the wiring. It would probably help if you could draw a diagram of the complete wiring to figure out what is happening -- and what to do about it.

rick in Alaska

I am pretty sure on that older zone valve that you can not just pull the "powerhead"off without draining the system. The newer ones are a two piece unit that has the ball valve portion that is not part of the powerhead assembly.
What you would want to do is isolate that loop and pull the whole assembly off, then get a zone valve conversion kit (40003916-006) and install it. Then any new powerhead , such as the 40003916-026, would just mount on to that, and you would not have to drain the system next time if you needed to work on it.
Rick

hot_rod

It's a spring return valve, with wire disconnected from either TH or TR, it should spring close. If it does and flow still moves through it it could be the rubber ball inside the body has come off, or is chipped. That would involve getting into the "wet' side of the valve, draining or isolating it.

Also that valve is available as a power open NC and power close NO, be sure it is a NC "normally closed" version. Occasionally they get swapped by mistake.

The end switch wires would not have anything to do with the valve opening and closing.

Jamie Hall

Um. Actually, depending on what those wires are attached to out in the rest of the system, it's quite possible that a jumper wired as in the picture could hold a zone valve open, once opened, until power was cut off somewhere else. That's why I wanted a circuit diagram.

mattmia2

Jamie Hall said:

Um. Actually, depending on what those wires are attached to out in the rest of the system, it's quite possible that a jumper wired as in the picture could hold a zone valve open, once opened, until power was cut off somewhere else. That's why I wanted a circuit diagram.

That was my first thought given that it is somehow sharing a wire to power whatever the end switch controls with the t-stat, but they said they measured 0 v across the coil with it stuck open.

JUGHNE

To determine if the mechanical part of that zone valve is working, you could take all the wires off of it. (I mark with a sharpie....1 dot on the wire and 1 dot near that screw, 2 dots.....etc)
Then with some other zone calling that runs the pump and boiler
you can manually operate the lever, first closed to feel if the pipe stays cool about 2 feet away, then manually open the valve and feel for heat. Could repeat several times to see if the ball is sealing, I believe there are 2 springs that pull it shut, are they both connected?

hot_rod

Jamie Hall said:

Um. Actually, depending on what those wires are attached to out in the rest of the system, it's quite possible that a jumper wired as in the picture could hold a zone valve open, once opened, until power was cut off somewhere else. That's why I wanted a circuit diagram.

But if either TH or TR was disconnected the motor would not power open, regardless of a miswired end switch. Disconnect either would help determine if it is an electrical, or mechanical problem

Jamie Hall

True.

iced98lx

Hey Guys thank you all for the suggestions!! I really appreciate it!

With your help I was able to determine that all was working as expected for that zone electronically (meaning, no matter what other combinations of zones on etc it was not receiving thermostat voltage when it shouldn't have) and instead it was a mechanical issue. The valve itself just isn't springing back.

I greased the gears and visually inspected them (they look just like the new ones I have in my hand...) but the valve itself seems to turn just as free as the others in the system. That leads me to think the head on it isn't springing back with as much force so I'm going to just replace it.

Side note, you all politely pointed out that the wiring for these valves is... interesting. It sure is! 1978 original. The lack of troubleshooting has prompted me to commit to putting in the 2 ZVC404-EXP-4 zone controllers sitting here in the boxes. The wiring diagram on them is simple and easy to understand and it will help me troubleshoot what is going on and what zone is demanding what. Appreciate all the help and I'll report back if replacing the head solves the problem. If not, I'll have to dig out the valve and put a new one in, which will require emptying that zone sadly.

hot_rod

What size circulator? Has it changed recently? Sometimes a system with an oversized circulator will keep the valve forced open.
With 4 or more zone valves you really should have a pressure bypass valve. Or a delta P circulator.

iced98lx

hot_rod said:

What size circulator? Has it changed recently? Sometimes a system with an oversized circulator will keep the valve forced open.
With 4 or more zone valves you really should have a pressure bypass valve. Or a delta P circulator.

This is certainly a possibility, I don't know if it's oversized but it has a fairly new looking B&G series 100 pump on it, and what appears to be a B&G series 100 that let all the life out of itself on the floor next to it. There is no bypass/pressure regulator on the system.

I did add an air remover, I intended to add an auto fill but we're now considering just replacing the boiler when we convert from LP to NG.. Obviously the zone controllers, air remover etc can be resused so no harm getting those installed. Most of the boilers we're looking at are of condensing and modulating obviously and many feature built in constant pressure pumps which is ideal in our situation where have some pretty varied zone sizes.