flow control valve?

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Old 11-01-08, 12:16 PM
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flow control valve?

We have a two zone forced hot water system (oil fired boiler) and one zone (only one baseboard radiator in this zone) is hot even though thermostat is not calling for heat. I assume it is a leaking flow control valve, maybe due to some contaminant. Can I shut off the water and unscrew the valve top and try to clean it and reinstall or am I likely to introduce air into the lines (or worse)? How straightforward is this fix? Thank you for any advice.
 
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Old 11-01-08, 06:11 PM
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You'll need to drain the system before opening up the zone valve. When you get it apart, and reassemble it, maybe it will work?

But, first, with your voltmeter, check that voltage is turning on and off at the zone valve. Have somebody move the zone thermostat up and down, and see if you hear the valve operating.

Another idea is to lightly rap on the valve with a plastic or rubber mallet to see if the valve frees up.

Probably the best choice is to replace the valve, which will require draining the system.
Doug
 
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Old 11-01-08, 08:48 PM
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Thank you for the reply. I am a complete novice when it comes to plumbing but I thought a flow control valve was different than a zone control valve. The valve I am speaking about has no electrical connections and just opens when the circulator is activated, and closes when it is off. (A zone control takes the place of a circulation pump, maybe?) I turned the stem counterclockwise hoping it would "unstick," but it did not seem to effect it as when I returned it to the original position (should be closed) we continued to have the radiator and pipe downstream hot. If I take the valve out by unscrewing the whole top portion, do you think I would still have to drain the system with this type of valve? Thanks again!
 
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Old 11-01-08, 11:41 PM
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Hold on a minnit, before you take that valve apart !

Make sure that it's not in the OPEN position ... that screw thingy on top raises and lowers the 'disc' inside. I can never remember which way is which ... fully one way is FLOW CONTROL, fully the other way is OPEN, and anywhere in between is partially open ... so perhaps you just need to figure out which way to turn and go all the way in that direction and see if the problem don't get fixed real easy...

You might have that part already figured though, but it's a good idea to check the direction ... I seem to recall that it should be counter-clockwise for flow control ... is that how you have it ?

What brand valve are they ? B&G ?

And yes, you will have to drain the system, unless you can valve off sections to isolate them... you may not have to completely drain, just enough to get the water level below where you are working.

Oh yeah, and I hope you have some BIG wrenches !
 
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Old 11-02-08, 07:00 AM
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flow control

Ah, yes thank you! Of course I would have to drain at least to below the valve, wasn't thinking about that! Yes, it is a B&G valve and counterclockwise is open and clockwise is closed (or "automatic"). I have tried that, to no effect. Maybe I'll try draining...or maybe call in a plumber as I have never drained and then bled the system and the radiators have no bleed valves. Maybe I should have an air scoop installed as I have on the other zone. In any case, thank you for your help...at least I know what I am getting into now.

chris
 
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Old 11-02-08, 08:22 AM
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Do try Doug's idea of rappin' on it with the 'bald headed end of a broom' though... don't KILL it, just rap on it ... maybe some debris is under the seat.

Is this a system that you have lived with for a while ? and it's always behaved this way ? or a 'new to you' system ?

It is always possible that the system piping could contribute to this problem even if the valve is functioning properly. Depending on pump placement, etc, the momentum of the moving water might/could be lifting the disc slightly.

Some systems need flow checks on both supply and return ...

Post some pics on Image hosting, free photo sharing & video sharing at Photobucket if you want us to look at that possibility.
 
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Old 11-02-08, 12:09 PM
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flow control

Excellent, thank you both! I did try the light rapping but this time I turned the valve counterclockwise to open, then rapped firmly with the rubber end of a large screwdriver, and when I reseated the valve it seemed to seat further down. I have waited several hours and it seems to have worked, no warm pipes or radiator downstream of the valve! Thank you again.
 
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Old 11-02-08, 12:43 PM
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Oh, I get it - we're talking about a B&G Flo-Trol lift-check valve, not a zone control valve.

My system had two 1.25", 57-year-old B&G Flo-trols, one for each loop. One was leaking past the seat, and the other was leaking out the bonnet packing. I decided to replace both of them this last summer. (By the way, the new B&G flo-trols look almost indentical to the ones from 1951, right down to the paint color.)

Exercising the manual operator and rapping, like you did, might help, at least temporarily. B&G sells a kit to rebuild the packing. If you ultimately go that route, you can try smoothing out the seat and disk surfaces with a fine crocus cloth.
Doug
 
 

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