Flow control valve stuck closed??


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Old 11-29-11, 11:58 AM
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Flow control valve stuck closed??

It seems most times flo control valves get stuck open and then you have the zone too hot due to runaway heat. I am wondering if mine is stuck closed cause the radiant heat in that zone never reaches temperature (70 degrees) and thus the cirulator is always running. The other 4 zones upstairs with baseboards are working fine, pressure is at about 17lb. and boiler temp is at 180 degrees.

It seems that the hot water pipe going into this flow control valve is hot but the pipe out of it is not. I am very worried to try to open it manually since the valve is original 1961? If in fact its stuck closed, if I try to bleed this zone, would nothing come out of the purge valve located on the return since the flow control valve is closed?? Any input is greatly appreciated!!
 
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Old 11-29-11, 12:32 PM
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Your flo control valve should have a manual operator on top. Turn it fully counter-clockwise to jack open the valve. If the valve is stuck closed, then that should give you flow - but then you will get gravity flow when you don't want it. Maybe exercising the operator a few times might clear any internal crud that could causing it to stick? Or, try rapping on the valve body with a plastic-headed mallet.

When flo-control valves start acting up, it's best to replace them or rebuild them. Bell & Gossett offers overhaul kits for their valves - but I decided to just replace them with new.
 
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Old 11-29-11, 12:49 PM
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Sounds good... thank you! Ever see them start leaking or break when you try to manually open one that hasn't been touched in ages.

What if I tried bleeding the zone that has the flow control valve stuck closed? What will happen?
 
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Old 11-29-11, 01:18 PM
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I never seen one break but they may leak from where the stem goes into the body. Its has a packing type nut you can snug up to stop it. Some dont have this and need to be rebuilt.

I dont think you can purge properly with the control being faulty.

Usually open and closing them a few times fixes it. Or I rap on it a few times always seems to work. It is usually crude and deposits that make them stick.

Thats my experience.

Mike NJ
 

Last edited by lawrosa; 11-29-11 at 01:59 PM.
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Old 11-29-11, 01:49 PM
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Originally Posted by George2002 View Post
Sounds good... thank you! Ever see them start leaking or break when you try to manually open one that hasn't been touched in ages.

What if I tried bleeding the zone that has the flow control valve stuck closed?
The stem packing might begin to leak, in which case tighten the packing nut.

I agree with Mike - I wouldn't expect purging/flushing would help or hurt, but you'd then need to eliminate any air that gets into the system.

Realistically, you need to bite the bullet and replace the flo-control valves after 50 years of service. If you can get it working now, maybe wait until next spring? Otherwise, you'll be risking another problem on some Super Bowl weekend when the temperatures are frigid.

While you're at it, make all the other changes that need to be made - for example, replace the relief valve, add isolation ball valves around the pump, replace the boiler gauge, replace the aquastat, and add a low-water cutoff.
 
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Old 12-03-11, 06:17 AM
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I tried opening the flo- control valve manually and the thing would not budge... I even loosed and even removed the packing nut, and still nothing. Gee.... its only 50 years old.

So I removed the Bell and Gossett 100 pump to inspect the impeller for my cause of no heat in that zone: Well, that was it. The metal impeller was totally shot. Just a follow-up for all my pals in cyberland...
 
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Old 12-03-11, 08:31 AM
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That indicates that the lift check is solidly stuck into the seat.
 
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Old 12-03-11, 09:25 AM
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The metal impeller was totally shot.
What ya mean it was shot? Can you photo it and let us see?

Well that was it.
So you've replaced the part and now the heat works in that zone?

============================


Your system is zoned with a pump for each zone, correct? and the pump you took apart serves only that one zone that's not working?
 
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Old 12-03-11, 09:14 PM
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I wound up removing the Bell and Gossett pump all together, and installed a Taco 007 in its place. I now have heat in that zone so the flow control valve was not the issue to begin with.

I will try to take a pic of the impeller that was all messed up next time I am over at the apartment building
 
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Old 12-03-11, 09:15 PM
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I'd still like to see a photo of the trashed impeller if it's possible.
 
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Old 12-07-11, 07:10 AM
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As promised, here are a few pics of the steel impeller I pulled out of that old Bell And Gossett pump. Based on the date code on the bearing assembly, it is from August 1961, which makes sense since the building was built in 1961. Who knows how long that zone had poor heat because this a rental and just got a complaint of poor heat a few weeks ago. As of today, I have 4 of 6 zones running Taco 007 circulators. I rather not think about all those loose pieces of rusted impller debris floating around my system.

Pictures by greekguy7 - Photobucket
 
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Old 12-07-11, 04:39 PM
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Oh my! That sure is a mess! and only 50 years old...

Thanks for the pics!

Glad you got it working... might not have been a bad idea to see if you could get a quantity discount on the 007s! I bet yer gonna need a couple more soon!
 
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Old 12-07-11, 05:45 PM
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I'm trying to remember the impeller of the B&G, HV, 60-yr-old pump that I replaced. The pump was working OK, and the impeller seemed alright too. It certainly wasn't nylon or plastic, like modern Tacos - either bronze (most likely, I think) or iron. If a bronze impeller, if that's what it was, became so moth-eaten in 50 years, I would suspect either real bad boiler water or some very bad bronze. Even a cast-iron impeller shouldn't wind up looking like that.

Can you check if the remnants of the old impeller are magnetic?

The only other thing I can think of is cavitation, which could destroy an impeller (and could also destroy the new impeller). Do any of your pumps sound like they are pumping marbles?
 
 

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