Zone valve or Tstat?

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slownsteady

slownsteady

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I have one zone on my boiler that just starting giving us problems. The room gets much warmer than the Tstat is set for. I have a Honeywell round Tstat ( 20 years old) and Honeywell 8043 zone valve. Since the Tstat has not caused problems before - and since the zone valve motors have had to be replaced on some of the other zones - i replaced the motor on this zone valve. But the room still overheats. I disconnected the Tstat last night, thinking that the valve would just stay closed, but the room was warm this morning. So what do I check next?:confused:
 
Sounds like the valve is stuck open or partly open.
 
I pulled the valve head off and I tried to operate the valve stem. It seemed pretty tough, but I don't know what it should feel like -how much resistance it should have normally.
 
it should have a manual slide switch on or below the head, is it locked open?


honeywells usually are normally open, its called "save the building"

when you loose power, they open.

can you verify power at head when stat is satisified?

or. move the stat, you can hear the valve open

check wire connections
 
Last edited:
I exercised the valve stem a bit, then spritzed it with a little white lithium lubricant and exercised it again. So far it seems to be working, but i am wondering when I will have to replace the ball.
While I'm learning about this, what exactly does the "end switch" do?
 
slownsteady said:
I exercised the valve stem a bit, then spritzed it with a little white lithium lubricant and exercised it again. So far it seems to be working, but i am wondering when I will have to replace the ball.
While I'm learning about this, what exactly does the "end switch" do?
Click to expand...

http://www.masterplumber.net/no_heat/standing_pilot_gas_boiler/no_fire/honeywell_zv.html

The Honeywell zone valve end switch is a little button inside the zone valve that is pressed when the zone valve is fully open. When this button is pressed it sends a signal to the boilers control or a circulator control that tells the boiler there is a call for heat.

If you look close at the image above you will see the words end switch stamped into the zone valve the two wires tied to the two terminals go to the T T terminals on the aquastat relay or to a circulator control or to 2 wires on the thermostat relay also known as a fan center, even though there is no fan. Some Honeywell zone valves do not come with the power block seen in the above image, but come with 2 yellow wires and 2 red wires. The red wires are the end switch wires and the 2 yellow wires are for the zone valve motor.
Note the lever under the power block. All Honeywell zone valves have this lever. It can be used to manually open a zone valve you just slide it over and hook it in to the little hook on the right. Even though this will allow water to flow through the zone valve, it will not depress the end switch button. the zone valve needs to be opened by power to open far enough to depress the end switch button

At this point we need to review where we are. All thermostats are turned up as far as they will go. The Pilot light is lit. The gas control valve is in the on position. You have power or are assuming you do for now. The boiler is cold.
Now slide the lever on your zone valves, if the lever moves easy with out much resistance the zone valves are open from the power source. This means your thermostats are working and the transformer for the zone valves is also working. Please note many times a separate 24 volt transformer is used for the zone valve, and some times (if you have many zone valves) you will have more then one transformer for the zone valves alone and a 24 volt transformer for the boiler functions. Sometimes there is only one 24 volt transformer that controls all of the boiler functions and opens all of the zone valves.
If the zone valves are open check the red wires for loose connections. Please don't go switching wires around this will only make things worse. Gremlins do not come into your home and switch your wires around so if the boiler was working fine before you had this problem, the wires are in the right place don't switch them around.
If the lever is hard to move like you are pulling against springs your zone valves are not open please go to the transformer page.
Please use the Open Dialog Service.
 
Thanks Frodo. When I went to the supply house, I asked for just the zone valve motor instead of the whole zone valve. I didn't know that the end switch was not part of that package. So I started to wonder if that could be the problem. Doesn't sound like it is (was). The room is holding temp now, so I'm calling this one fixed for now.
 
When we built my nephews house he was on the shortest shoestring I ever saw and we planned so many things to do it this way and then when he got money he could upgrade if he wanted. His house is a simple two story box house without a lot of wings and such and he wanted a few zones in his hot water system that we made from a regular water heater tank. What we did for his zone valves was just put in manual ball valves. He played around a little the first winter balancing the temps keeping the bedrooms cooler etc. He’s been there now for 20 years and I asked him if he ever got the electric valves and all that and he said he hasn’t touched those ball valves in 20 years once he got them set.

This thread made me wonder if anyone ever put in both a manual and electric valve both so when something goes down you could just shut off the electric and crack the valve to get some heat but not full blast.
 
If the electric is down, then the boiler won't fire up. I suppose if you have a gas heater with a pilot light, you might be able to work it, but that sounds a little unsafe to me.
 
In a pinch, I suppose you could pop off the motor and adjust the valve by hand, or maybe notch the lever at the bottom to park it at a certain position. I hope your nephew never has to put his house on the market.

I understand budgets and all, but with a programmable tstat he probably would have recouped his money in less than 20 years by not heating his bedrooms at all during the day.
 
slownsteady said:
In a pinch, I suppose you could pop off the motor and adjust the valve by hand, or maybe notch the lever at the bottom to park it at a certain position. I hope your nephew never has to put his house on the market.

I understand budgets and all, but with a programmable tstat he probably would have recouped his money in less than 20 years by not heating his bedrooms at all during the day.
Click to expand...

I don’t know about others but I have never had any luck with programmable thermostats in the real world family reality. They always seem to end up set to manual and get turned up and down as required. Example if I lived alone I would crank the heat down at 5 am and back up at 3pm if I had zones I would set the bedrooms to heat at maybe 9pm. That might work with one person and my dog would have to have an area on a zone to stay during the day. It gets 30 below zero here so it couldn’t be a matter of on and off it would have to be drop the bedroom and upstairs bath to say 45 when not used. Now you compound the problem with more people and if you have kids their bedrooms are not just used for sleeping they are a home within a home and people working varied shifts always cause adjustments. Then you have the issue you come home from work and find out you are going out for dinner so you go to shower and change and the bedroom and bath are freezing. Throw in things like the thermal mass of our bed and if the heat comes on at 9 pm and I go to bed at 10pm the room air is warm and the sheets are like ice. So you buy an electric blanket and have to run up stairs at 9pm to turn that on and wake up at 11pm to shut it off as its cooking you. I know the nest type and other smart Tstats are supposed to figure all this out.

Right or wrong it always ends up getting set to manual and you tweak it as needed or at best you just forget it and leave it alone and just be thankful you have heat. In the case of my nephew and I also kind of follow the same logic we both like the bedroom a few degrees cooler than the main house. I’m sure it wastes some energy but how much I don’t really know. More than likely with a two story house as opposed to a ranch of the same area core heating could be more advantageous than zone heating but I don’t know that for a fact.
:)
 
slownsteady said:
I exercised the valve stem a bit, then spritzed it with a little white lithium lubricant and exercised it again. So far it seems to be working, but i am wondering when I will have to replace the ball.
Click to expand...

Well, apparently this fix isn't lasting. The room was hot again this morning. My gut says the ball valve is sticking partially open, but since I didn't change the end switch the last time, I wonder if I should do this first.
 
slownsteady said:
Well, apparently this fix isn't lasting. The room was hot again this morning. My gut says the ball valve is sticking partially open, but since I didn't change the end switch the last time, I wonder if I should do this first.
Click to expand...

How did you make out with this?
 
I've had the tstat removed for the last couple days, as i am putting up new drywall there. The first night the room was still warm, so it ain't the tstat. Yesterday, I exercised the ball valve again and the room was chilly last night. But I'm pretty sure that I will have to open up the zone valve and change the ball.
 
I opened up the valve body today to replace the the ball valve inside. Unfortunately one of the four screws snapped off. Looks like I have to re-tap the hole. I don't have any gauges for that, so I'm sitting here trying to find the size of the thread before running out to the store.
 
Take one of the screws with you to get the size. It’s pretty hard to get a broken screw out. Sometimes you can run a drill in the tap drill size and then work the thread out with a prick punch and then re-tap. If that doesn’t work go one size bigger if you have the stock. Chances are if it broke off a easy out wont get it out.
 
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