Zone Valve not closing?

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Old 11-27-08, 07:59 AM
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Zone Valve not closing?

Hi -

I have a forced hot water oil boiler that has two Taco heating zones valves connected. (They are really beefy cast iron jobs - under a year old) The zone valve I think I may be having trouble with is the valve for my upstairs zone.

Here is what is happening and what I think should be done about it, I would appreciate any feedback you can offer:

On two occasions now I have noticed that my upstairs rooms have become much warmer than the temperature the thermostat was set to. The first time it happened I noticed that while the thermo was set to 62, the room was at 66 and the baseboards were still hot. I figured something was wrong, so I tried turning the thermo down past 60 but it was not clicking off. So being the logical person I am, I turned the the zone up to 72. I then heard the thermo click on and the boiler turn on. (When the baseboards were hot before the boiler has been off, it was just circulating hot water from a previous boiler run) Then I turned the zone back down to 62 and heard it click off. After a normal amount of time the baseboards became cool to the touch. The second time it happened, I recognized the problem and did the same fix which worked again.

This happened over the course of two months in the fall. I'm not that upset by it frankly since the boiler was creating the hot water anyway it was just moving it into the zone - and since I know how to make it close I can basically avoid the problem happening in summer months. (Since it seems like it happens once the zone has to turn on the begin with: Ie zone was set at 62, room hit 60-61, boiler goes on, warms room to 62-63, then valve gets stuck open.)

Obviously this is not optimal, and I do not want the valve to become permanently stuck open or worse (in the winter) permanently closed.

I also thought it could be a thermostat issue, and to cover that I am actually going to be replacing that zone's thermo with a programmable anyway. (Not because of this, I was just going to do it anyway) So that could help rule out the problem.

The only reason I suspect the valves is because on one occasion I was in my basement and hear a high pitched squeal coming off that zone valve. The good news is, if I want to replace it, I have a manual shut off valve right after each of the zone valves so I would not have a "water dumping into the basement problem".

Any thoughts?

Has anyone replaced a valve before? Is it horrible?

Are there any other things it could be that I should think about/rule out?

thanks

and Happy thanksgiving.
 
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Old 11-27-08, 09:11 AM
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Zone Valves

You describe the zone valves as beefy & cast iron. That doesn't sound like a zone valve to me. If there is a brand name & number on them it would help. Better yet would be pictures. You can post them on photobucket.com or similar photo hosting site & provide a link here.
 
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Old 11-27-08, 09:37 AM
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Good point, they may be circulators as well as the valves? The model is Taco 007-F5

Here's a picture of what we're working with. it's the black one that I think is the culprit:

Sorry for the picture quality, just snapped it with my phone: http://i461.photobucket.com/albums/q...150/007-f5.jpg
 
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Old 11-27-08, 09:45 AM
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Taco 007

They are indeed circulators. You don't have zone valves unless you have multiple zones off of one circulator.
The circulator is connected to a relay somewhere. Follow the wire from the circulator back to the relay & please give me the make & model from it. I suspect you could have a sticking relay or possibly a sticking flow control valve. Do you have a volt meter & know how to use it?
 
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Old 11-27-08, 10:00 AM
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No voltmeter, but probably can get my hands on one. The wires go back to a box connected to the right side of the boiler. Taco SR 502.

Once I get my hands on a volt meter, whats the next step?
 
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Old 11-27-08, 12:01 PM
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My guess is one of Grady's ... FLOW CHECK hanging open allowing gravity flow in the heat circuit.

Put up more pics ... I know cell phone pics 5uck, but they are better than nothing ... show us everything connected to the boiler.

In order to change the circ without spilling much water, you need to have valves above AND below the pump.
 
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Old 11-27-08, 12:47 PM
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Voltmeter

You need to determine to which terminals the suspect circulator is connected & check voltage between those terminals. If the circ is getting power when it should not, you will show 120 volts.
The next step would be to determine to which terminals the thermostat for that zone are connected, disconnect one of the wires, & check voltage at the circ terminals again. If voltage is still present, the relay is stuck. If voltage goes away, the problem is in the low voltage wiring or thermostat.
 
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Old 11-27-08, 07:32 PM
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Grady, your testing method makes sense.

One problem I am up against in testing is that the problem has only happened twice in the 6 months I have lived here. But I think what I have gathered from the advice here is that somehow the circulator is not being told to stop circulating.

Though it does seem like the boiler gets the message to stop boiling.. This leads me to believe the thermostat is probably working correctly, but come to think of it now I have never been present when the zone actually clicks off and the circulator keeps going with the boiler off. SO I cannot say for sure whether the thermo actually clicks off.

What I think I'll do is replace the thermostat since I was going to do that anyway and see if that does anything. (I doubt it will, but I also have my doubts the problem will pop-up soon or at a time when I can troubleshoot)

But if it does, I think the course of action is for me to then check the voltage in the places mentioned. In terms of checking the voltage going into that box - are the white cables removable??

I've linked some better pictures, as requested earlier, for your viewing pleasure. Cheers:

http://i461.photobucket.com/albums/q...0/DSCN2102.jpg
http://i461.photobucket.com/albums/q...0/DSCN2103.jpg
http://i461.photobucket.com/albums/q...0/DSCN2104.jpg
http://i461.photobucket.com/albums/q...0/DSCN2106.jpg
 
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Old 11-28-08, 05:49 AM
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how is the hole where the wire comes into the stat,make sure it is sealed a draft(cooler air) from the insides of the wall could drive the stat to over shoot.stick your nose up to the opening to feel even the slightest of air infiltration
 
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Old 11-28-08, 06:02 AM
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Don't go disconnecting any wires ... you shouldn't need to ... but I don't think the circ is your problem...

I'm still down with Grady's 'other' suggestion, that one of the flow check valves is hanging open intermittently.

This pic shows them...



While it IS possible that the relay panel or thermostat are at fault, it's much less likely than the flow check problem.

If you are lucky enough to catch the bad dog in the act, give the flow check that feeds the zone a smart 'rap!' with the bald-headed end of a broom.
 
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Old 11-28-08, 12:24 PM
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flow check valve?

which piece is it that I should hit?

If that piece is after the circulator - does it stop water trying to be circulated upstairs?

Sorry - don't yet understand all the intricacies of forced hot wate
 
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Old 11-28-08, 12:49 PM
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Originally Posted by sminker View Post
how is the hole where the wire comes into the stat,make sure it is sealed a draft(cooler air) from the insides of the wall could drive the stat to over shoot.stick your nose up to the opening to feel even the slightest of air infiltration
That thermostat actually undershoots the target temp...

don't know if that has any implications
 
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Old 11-28-08, 04:21 PM
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which piece is it that I should hit?
In that pic, vertical pipe branches to two ... each branch has a hunk of bronze on it ... tee shaped ... knobby thing on top ... then the plastic pipe ... Do those plastic pipes go to the zone that keeps heating? Those bronze things are FLOW CHECK valves that only allow flow in one direction (see the arrow? that's the direction of flow) and only when a circulator is running.

If that piece is after the circulator - does it stop water trying to be circulated upstairs?
It would work the same before or after the circulator... only allow flow in one direction, and only when the circulator is running.

Keep the concept of gravity flow in mind... hotter water is less dense (lighter), and will float to the top of cooler water ...

Your system is several 'loops' of pipe, supply pipes (hot water out to the radiators), and returns (cooler water in from the radiators).

Let's say that the thermostat calls for heat, and the boiler fires, heats up and satisfies the thermostat. Heat call ends, but boiler is still hot ... check valve hangs open ... rut row ...

Now, there's nothing in the way of the cooler water in the loop from flowing back to the boiler (it's heavier, so it will just fall down the pipe by gravity), and pushing the hot water up into the loop. No pump, nothin' ... physics only ...

When that happens, that zone will probably overheat ... and that's what I think is happening. BUT, it could still be the circulator/relay problem.
 
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Old 11-28-08, 04:29 PM
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Flow Control Valve

The valves in Troopers picture are one type of flow control valves. Honestly that particular type is quite rare around here. This style is more common:
TACO - HVAC
 
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Old 11-28-08, 04:30 PM
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Originally Posted by bir5150 View Post
That thermostat actually undershoots the target temp...

don't know if that has any implications
It could mean that the 'anticipator' in the thermostat is set wrong... what kind of thermostat you have ?
 
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Old 11-28-08, 04:37 PM
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valves in Troopers picture
Grady, that's bir's actual valves, one of his pics ...

Early on bir said this:

I was in my basement and hear a high pitched squeal coming off that zone valve.
I wonder about that ... possible that that flow check is sticking CLOSED sometimes also ?

Grady, whattaya think would make the circ squeal? ... dry bearing ? dead head ?
 
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Old 11-28-08, 04:45 PM
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OOPS---Grady Goof

OK, if those are Bir's valves why didn't I see them in the pics?

Just found out why. In the post the links go 102, 103, 104, & 106 with 105 being absent. On a hunch I just tried 105 & bingo, valves.

Squealing circulator, hummmmm... Maybe made of pig iron??? Sorry I couldn't resist. Those things are water lubricated so if a valve stuck closed, I guess you could get it hot enough to loose lubricity?
 
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Old 11-28-08, 06:12 PM
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Originally Posted by NJ Trooper View Post
In that pic, vertical pipe branches to two ... each branch has a hunk of bronze on it ... tee shaped ... knobby thing on top ... then the plastic pipe ... Do those plastic pipes go to the zone that keeps heating? Those bronze things are FLOW CHECK valves that only allow flow in one direction (see the arrow? that's the direction of flow) and only when a circulator is running.



It would work the same before or after the circulator... only allow flow in one direction, and only when the circulator is running.

Keep the concept of gravity flow in mind... hotter water is less dense (lighter), and will float to the top of cooler water ...

Your system is several 'loops' of pipe, supply pipes (hot water out to the radiators), and returns (cooler water in from the radiators).

Let's say that the thermostat calls for heat, and the boiler fires, heats up and satisfies the thermostat. Heat call ends, but boiler is still hot ... check valve hangs open ... rut row ...

Now, there's nothing in the way of the cooler water in the loop from flowing back to the boiler (it's heavier, so it will just fall down the pipe by gravity), and pushing the hot water up into the loop. No pump, nothin' ... physics only ...

When that happens, that zone will probably overheat ... and that's what I think is happening. BUT, it could still be the circulator/relay problem.
Ah that makes sense. Now that you explained the physics part of it I now get why the circulator may not need to be on for hot water to be getting upstairs. Although I do think you have a valid point about the relay because I have been able to remedy the issue by faking the thermo into shutting the zone again.

Also, the pic of the valves is actually two pipes with the plastic coming out of each - it just looks like one with two branches the way I shot it...
 
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Old 11-28-08, 06:16 PM
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Originally Posted by NJ Trooper View Post
It could mean that the 'anticipator' in the thermostat is set wrong... what kind of thermostat you have ?
I have a classic Honeywell round thermo. 2 wire set up. I was interested in how the thing worked, so I found a manual and was reading about cycles per hour and the anticipator and the non-digital set up all seemed pretty imprecise which is why I was just planning on throwing in a programmable digital anyway.

How did I get going on my thermostats?
 
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Old 11-28-08, 06:19 PM
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Thanks!

Just wanted to thank everyone for all the info here over the last 48 hours. I have a lot of good angles to attack this on. And actually learned quite a lot about how these things work (rather than how I assumed how they work..)
 
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Old 11-28-08, 07:47 PM
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bir, your new t'stat may or may not have an anticipator setting. Many of the newer models actually have a little bit of 'smarts' in them ... they track the temperature swings for a bunch of cycles and set the 'anticipator' to match ... cycles per hour is related, but not exactly the same thing ... I don't fully understand that cycles per hour thing myself.

Ya know, I looked at that pic, and thought... 'somethings wrong' ... and now that you told me that, sure there's something wrong! There's a pipe coming out of a non-existent tee fitting !

OK, so ONE of those must be going to the overheating zone ... that's the one to persuade...

If that check valve is hanging, and it's very intermittent, that means that when it does hang, it's probably by a thread ... so even the act of turning the circ on and off might be enough to dislodge it and allow it to seat again.

Squealing circulator, hummmmm... Maybe made of pig iron???
Grady Funny!
 
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Old 12-02-08, 09:11 PM
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flow check valve (99% sure)

OK, I'm pretty sure I know what it is:

I caught the zone in the act, so I went to the basement and listened to the circulator. (I can hear when its going, its quiet but you can hear it) and I heard nothing.

I smacked the flow check valve for the zone a few times and then it seemed like the zone cooled down.

Now that would seem to indicate its the valve... but this is where I may need another physics lessons:

If the first destination on the heating circuit, if you will, after the flow check valve is the master bedroom and the last stop is the en suite bathroom and if the flow check valve is allowing cold water to fall back into the boiler wouldn't that mean the path of less resistance for the hot water which wants to rise "backwards" through the zone? So I would expect that bathroom to get hot but its the baseboard in the master bedroom nearest to the valve that gets hot first.

The physics may still confuse me, but I think the fact that after I hit the valve the incident stopped is evidence enough. Unless its a coincidence... or maybe a conspiracy.
 
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Old 12-02-08, 10:43 PM
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"If the first destination on the heating circuit, if you will, after the flow check valve is the master bedroom and the last stop is the en suite bathroom and if the flow check valve is allowing cold water to fall back into the boiler wouldn't that mean the path of less resistance for the hot water which wants to rise "backwards" through the zone? So I would expect that bathroom to get hot but its the baseboard in the master bedroom nearest to the valve that gets hot first."

Technically water can flow either way but since the heating return line feeds into the bottom of the boiler the temperature at the bottom of the boiler may be a couple of degrees cooler than at the top of the boiler therefore the hotter water will migrate up and out the supply line.

Also, any hot water heating system is operating under pressure (12-20 psi) which can easily allow hot water to gravity feed the rads.
 
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Old 12-03-08, 06:17 AM
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Pex?

Looks like non-oxygen barrier PEX was used to connect circuits which could explain accellerated corrosion and eventual sticking of flow checks.

I would check the autovent to make sure it is still functioning also.
 
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Old 12-03-08, 03:01 PM
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Good point...

about the non O2 barrier PEX ...

bir, can you read any writing on the tubing ? What does it say?
 
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Old 12-03-08, 07:19 PM
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Pex

Good catch ZL700. I hadn't noticed the pex either. I've never seen barrier pex in blue. Not saying just because it's blue it isn't barrier, just I've not seen blue barrier pex.
 
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Old 12-03-08, 08:49 PM
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I'd be surprised if that tubing didn't look white in person ... that concrete wall is awful blue too ... seems like the color balance is pretty skewed in that shot.
 
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Old 12-04-08, 05:13 AM
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Originally Posted by NJ Trooper View Post
I'd be surprised if that tubing didn't look white in person ... that concrete wall is awful blue too ... seems like the color balance is pretty skewed in that shot.
Yep, the flash washed it out. The tube is kind of grey. No writing on it though.
 
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