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Honeywell Zone Valve 8043 Model
Honeywell Zone Valve Problem - I have a Honeywell zone valve (8043E). I have spent time trying to understand exactly how this valve works, and I am pretty close, except for one thing: the motor. When the thermostat makes, that causes the slow-motion motor to turn, which opens the valve.
Eventually, when fully open, a tang presses the end switch to turn on the circulator pump and ignite the boiler (via red wire circuit). Though the thermostat is still closed (because we’re heating), something causes the motor to stop. What is this mechanism?
Honeywell Zone Valve Problem
I can’t imagine it is controlled in any way by the end switch as the only electrical connections to the motor are the two yellow leads that connect to the thermostat circuit. When the Honeywell motor on the zone valve is isolated, and 24VAC is applied, it will run until the cows come home. I have tested this. While running, I have grabbed the brass gear and applied resistance. It does not stop; it continues to run. So “resistance” is not the mechanism to make it stop. I don’t believe in magic. What causes the Honeywell motor to stop at the top of the zone valve open arc? Please help! Thanks!
Honeywell Zone Valve Problem - Reply
Thanks for the question and for visiting High Performance HVAC!! Honeywell zone valves are pretty straightforward on how they work. I can’t say about the valve you have right now, but all the valves I have worked, along with valves powered by actuators, come either Normally Open, Normally Closed, or Modulating. The power to the motors for these valves typically remains constant until the circuit is open, whatever method is used to control the valve. The Honeywell 8043 is Normally Closed. When it is powered up, it opens. When the power goes off a spring return closes this valve.
Specifications Sheet
Honeywell Zone Valve
I have read the specifications sheet for this valve along with other specification sheets. Quite frankly, this is not something I have ever thought of. Any zone valve I have worked on or installed, either worked or didn’t work. I can only surmise that there is a mechanism that will allow the valve to open. A mechanical stop built into the valve. The Honeywell motor energizes and the zone valve rotates to the mechanical stop (in the open position). The motor remains energized until the thermostat (call for heat) opens and de-energizes the Honeywell motor.
The spring return moves the valve to the closed position. I can also only surmise this question is out of pure curiosity on how the valve works. Since the valve is simple and straightforward on the operation, troubleshooting is similarly straightforward. Installation is simple with both the hot water boiler piping loop and the wiring. It is important that the valve is installed according to the flow arrow. The head should be removed for sweat connections to prevent damage. Once the soldering is completed the head replaced on the valve. Wiring involves three separate connections: The transformer for 24-volt power, the thermostat to provide control, and the end switch to control the circulator pump.
Conclusion
Honeywell Zone Valve Problem - The bottom line answer to your question is the thermostat controls the opening of the valve. When the thermostat satisfies the motor is de-energized and the valve closes by a spring return.
Honeywell Zone Valve Problem
Zone Valve Questions from our Readers
What is a zone valve end switch?
A zone valve end switch is a switch that closes when the valve opens. On a call for heat from one of the zones in the boiler loop, the zone valve opens. Once the valve fully modulates open, that action closes a switch on the end of the valve, called an end switch. That completes a circuit and tells the boiler aquastat control (or other control) to turn on the circulator pump. When the thermostat is satisfied, the zone valve closes. That action breaks the circuit and turns off the circulator pump.
How does a Honeywell zone valve work?
See the answer to my previous question above.
Have 3 zone vales that rattle my pipes when they shut off what can i do to fix it they are about ten years old
The original reply was correct, but it was not complete. The motor remains energized for the entire time that the thermostat is calling for heat. The motor is stopped by a MECHANICAL end stop when the valve reaches the fully open position. It is NOT electrical, at least not in the Honeywell 1000 series power heads.
The purpose of the end switch is to send a signal to the boiler and/or circulating pump, telling them it is okay to fire up and circulate water. It does NOT stop the power head motor
The secret is that the motor is a special low power 24 volt design that is built intentionally to stall in a safe condition when a mechanical end stop is reached. The output gear reaches stall torque, which is higher than operating torque while the valve is opening. Motor current should increase slightly at stall, but I have not done this test. The original reporter says the motor never stops, but this is probably because they did not grab the output gear hard enough to stall the motor.
My 1999 system has the Honeywell actuators. In northern MN winter, I definitely can tell when zones go open, but now that there is warmer weather, I’m still getting some heat through the zones. Supply and return are both warm to touch as well as floor. I manually shutoff the loop ( ball valve) and everything cooled off so I’m getting circulation when it should be off. It is happening on a few of my zones. Is this more likely 20 year old actuators that aren’t completely shutting off, or the 20 year old valves that are leaking.
Have your plumber or HVAC company (whoever you call for service) check the flow valve (usually located near the boiler). It’s possible that has malfunctioned and needs to be replaced.
Zone valve runs hot.
I am surprised at how hot the little motor cover stays. Too hot to keep you fingers on it. The zones tend to run a long time as big areas to heat. We replaced a zone valve where the end switch failed. The customer was worried about the hot motor. The new zone value does the same thing. The valves are on the return side of his slab heat so the fluid temperature is rarely over 85’F.
Why does the zone valve feel so hot?
85 is not so hot for hot water piping. I would expect the temperature of the water in the pipe to be much hotter since a good boiler system should have a delta T of no greater than a 30-degree difference from the return to supply with proper piping and controls. Those motors are designed to operate in high temp environments. The only time it should be replaced is if it fails.
You do not have a correct answer to the original question. They wanted to know what stops the gearmotor at the end of its travel. They correctly assumed that the motor does not stay energized during the heat cycle.
An end switch stops it.
I am trying to determine why my new Honeywell zone valve opens once the thermostat creates demand and the boiler temperature satisfies the aquastat, but then closes after a few seconds and then opens and closes a few times during the cycle.
I can’t answer the question without troubleshooting. Maybe someone else reading this has had a similar experience and can help?
This is usually a bad connection somewhere, a bad thermostat, an overloaded or defective transformer, low 24VAC power (Wires too small or too long) or a heat anticipator setting that is wrong in the thermostat. Anticipator: The load the valve puts on the thermostat will cause the thermostat to actually heat up and it will turn off early in anticipation. If this setting is really small the thermostat will over anticipate the heat and turn on and off repeatedly.