Do Circulation Pumps stop water flow when off?

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  #41  
Old 12-05-13, 08:58 PM
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Ya know... looking at that 'lava flow' of solder on the outside, I have little doubt that there are also chunks floating around INSIDE...

And is that a piece of SCOTCH TAPE? Please tell me they didn't use scotch tape as a thread sealant!

Ya know what you could try? Give that thing a smart "RAP" with a metallic object on a stick.

Don't wail away on it like the Samsonite Gorilla, but try a few raps and see if it doesn't start working properly.

I would still have it replaced most likely... but it's worth a try in the meantime.
 
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  #42  
Old 12-05-13, 09:12 PM
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And is that a piece of SCOTCH TAPE?
Whatever it is, it's been there for 20+ years
That is quite a solder blob. Even I know it should've been wiped.
Between changing the water feed thingy and pump it certainly is a good possibility that crap made it's way to the check valve.

I always thought that there would/should be a check-valve but plumber insisted there was not. What do I know, I'm just a lowly homeowner

At least I now know the what and where that needs fixing.
I fully expect to be told that pump mounting is just fine the way it is... Guess I'll deal with that then.
 
  #43  
Old 12-05-13, 09:17 PM
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I fully expect to be told that pump mounting is just fine the way it is
You could pull out all the stops and show them the Grundfos install instructions with the big X through a vertical mount!

http://s3.pexsupply.com/product_file...FC-install.pdf

Keep us posted!
 
  #44  
Old 12-05-13, 09:49 PM
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Oh yeah, got that at the ready

Probably won't see him until next week. Will report back after his visit.

Thanks again guys.
 
  #45  
Old 12-06-13, 03:00 PM
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I've sketched out your system diagram and am still having trouble understanding how you could be getting ghost flow, even IF the check valve is below the house pump is stuck open.

In order to get 'reverse flow, the check valve in the PUMP would ALSO need to be stuck open. Not inconceivable I suppose, but it still goes back to how you did NOT get the ghost flow with the OLD pump which did NOT have a check valve.

'tis one of those things that makes ya go "hmmmmmm"
 
  #46  
Old 12-06-13, 03:30 PM
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The house pump's inlet is the house zone return I assume, making the outlet going to boiler cold side. (Confirmed flow direction).

The garage return is tee'd into that so with a failed check valve we would have flow going to boiler cold side and also garage return/mixer.

I.e. Zone-return--->HousePumpInlet/Outlet--->Tee-->Boiler
Tee-->CheckValve(failed)-->Tee2>---GarageReturn
Tee2--->Mixer Valve

With check valve not working we would have flow to boilerCold and to GarageReturn as well as MixerValve.

When GaragePump is on, higher pressure/flow makes the flow normal,
I.e. the 2 flows from the pump would meet at the boilerCold tee.

No?
 
  #47  
Old 12-06-13, 03:36 PM
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I've been looking at this for too long trying to figure out how there could be ghost flow unless BOTH check valves have failed...



Can anyone explain?
 
  #48  
Old 12-06-13, 03:45 PM
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Only one check valve was in use before changing to Grundfos pump. the one below the BoilerColdIn.

Is it possible that all would be good if Grundfos was installed as directed, not the way it is?
I.e. motor up.

Assuming of course check valve was not removed without marking it as such.
Which basically would have replaced the check valve that has failed/has crap in it.

BTW, nice drawing. I'm keeping it
 
  #49  
Old 12-06-13, 03:55 PM
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Is it possible that all would be good if Grundfos was installed as directed, not the way it is?
I.e. motor up.
No... the pump will still work in that position. The reason that position is not allowed is because of cooling and lubrication... the motor is lubricated and cooled (believe it or not) by the boiler water flowing through it. When it's mounted with it's butt up in the air, an air pocket will form at the top and not properly lube or cool the motor. This is from the factory rep at Taco... not Grundfos, but the principle is exactly the same. Taco DOES allow mounting the pump 'butt up', but specifies that system pressure MUST be 20 PSI or greater at all times. I was told that this pressure allows the water to get far enough up inside the pump to lube and cool. I still would not mount one that way in any case.

Assuming of course check valve was not removed without marking it as such.
Which basically would have replaced the check valve that has failed/has crap in it.
Yes, those check valves just pull out of the end of the pump. Grab with pliers and tug, it comes right out. Maybe it FELL OUT IN SHIPMENT and tech didn't notice?

Yes, it would have prevented flow through the loop, but the other check valve also would prevent flow up the cold return to the mixing valve and through the bypass, and back down through the house pump. But you had the green valve CLOSED and still had the problem...

Might get a clearer copy of the drawing here:

hwittendiagram_zps5e981e0d.jpg | Photobucket
 
  #50  
Old 12-06-13, 04:00 PM
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unless BOTH check valves have failed...
No... brass check valve is for ghost flow in main loop from grunfos.

internal grunfos check is for ghost flow from main pump...

I bet brass check is good... I bet grunfos check was removed and old pump check valve was removed by plumber when uninstalled...

Even if brass check bad, pump check would prevent ghost flow...
 
  #51  
Old 12-06-13, 04:06 PM
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But you had the green valve CLOSED and still had the problem...
The Green handle valve just goes between hot and hold of boiler. Would not impede flow from house pump boiler cold and via Tee to garage return.
 
  #52  
Old 12-06-13, 04:15 PM
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No... brass check valve is for ghost flow in main loop from grunfos.
I've got it drawn the other way... but I see what yer sayin'...

However... house has zone valves on all loops it seems... wouldn't be any ghost flow there.

Hwitten... can you get in there to the check valve and using a mirror and yer best bifocals, see if you can see an arrow that depicts flow direction on that check valve?

It would help to know for sure which way it's pointing!
 
  #53  
Old 12-06-13, 04:21 PM
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The Green handle valve just goes between hot and hold of boiler. Would not impede flow from house pump boiler cold and via Tee to garage return.
Think 'pressure differential' ...

If the brass check valve has failed, and the one in the pump is working, and the pump is installed in the proper direction, THEN:

When the house pump runs, water can be pushed UP the cold return to the mixing valve, turning RIGHT and flow BACKWARDS toward the tee connection to the bypass line, turning LEFT and through the green valve, and back into the LOWER PRESSURE at the house pump SUCTION side.

Remember that water will ALWAYS flow from high pressure to low pressure and take the shortest route to do so.
 
  #54  
Old 12-06-13, 04:21 PM
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According to "Pro" the old pump did not have a check valve. Looking in, I can see impeller from one end and nothing that could be a fitting/check valve from other end and the crap buildup is undisturbed inside.
 
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Old 12-06-13, 04:23 PM
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No... brass check valve is for ghost flow in main loop from grunfos.
Nope... if the brass check valve is pointing DOWN, you will never get ANY flow of hot boiler into the floor loop. The floor return water needs to get back to the boiler return. With the check valve opposite of how it's drawn, might as well just cut and cap the pipe there...........................
 
  #56  
Old 12-06-13, 04:25 PM
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This is a real mystery! ..............................
 
  #57  
Old 12-06-13, 04:30 PM
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It would help to know for sure which way it's pointing!
Arrow points UP. Tail to Garage.
 
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Old 12-06-13, 04:48 PM
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Arrow points UP. Tail to Garage.
Thanks, drawing is correct.
 
  #59  
Old 12-06-13, 04:56 PM
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I can't stare at that drawing any longer!

The way I see it, the ONLY way that the house pump can induce any flow in the garage loop is if BOTH of the check valves are stuck open.

There's no other way!

If the pump check is working, there's no way for water to flow backward... even if the brass one has failed.

It CAN'T!

I need a beer...
 
  #60  
Old 12-06-13, 05:10 PM
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With you on that beer...

I asked the pro if any check valve in pump when I first called. Answer: No.
That makes it possible he removed the one from Grundfos as the Taco didn't have one and simply didn't cover the checkmark on pump.

Of course he also said there was NO check-valve.

Tempted to add one in at an easy spot, I.e. out in the garage
 
  #61  
Old 12-07-13, 11:13 AM
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Tempted to add one in at an easy spot, I.e. out in the garage
Before doing that, if you want to have the pump installed properly, when the pump is removed to turn the flanges, check to make sure the check valve is in fact installed in the throat of the pump.

If there is a check valve in the pump, I see no way that there can be a reverse flow, and I see no way that the other pump can induce a 'forward' flow.
 
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Old 12-07-13, 11:24 AM
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Hopefully Pro will have time next week. In a cold spell (for us) at the moment and since I have heat I'm not going to bug him, now that I have a better idea of what may have happened and the corrections needed. Worse comes to worse I think I could tackle it myself, except for turning the flanges perhaps.
 
  #63  
Old 12-21-13, 08:45 AM
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Final Update, hopefully
Pro took a while to show up as our problem was much lower on anyones' priority list than folks without heat.
Anyways, he brought a Taco and as turning the flanges may have caused additional grief at solder joints we used the Taco. Confirmed that the Grundfos had no check valve installed and also confirmed that the new Taco DID have a check valve.

We decided to rely on the check valve in the pump and to postpone changing brass check valve until summer.

All seemed well, until shortly after he left
No water circulating. We figured perhaps an airlock somewhere so I played with as much as I dared to, to no avail. He came back following day and turned a few valves back and forth, including the mixer, and off it went. Gee, behaved just like a computer. Magically fixed when I get there (sometimes).

Been good for 24 hours+ now so everyone is happy. No reverse flow. Learned a lot about my heating system, thanks to you folks.

Thanks again and Merry Christmas.
 
  #64  
Old 12-21-13, 08:54 AM
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Confirmed that the Grundfos had no check valve installed and also confirmed that the new Taco DID have a check valve.
Great....Glad it worked out.

Still the old original pump must have had a check valve I would assume.....
 
  #65  
Old 12-21-13, 09:26 AM
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Still the old original pump must have had a check valve I would assume
Either that, or the changing of the pump put some 'crud' loose in the line and it got lodged in the brass valve at the boiler return.

No water circulating. We figured perhaps an airlock somewhere
Probably in the pump itself. Those pumps with the IFC in them are prone to that, more so when they are mounted and pumping UP, but still can happen horizontally too. Centrifugal pumps are NOT 'self-priming' so if there is air trapped in the pump volute after installation (or during operation), the pump won't pump... until the air is somehow released.
 
  #66  
Old 12-21-13, 09:31 AM
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Nope, no check valve in old pump. (Still have it). It worked because the brass in-line check valve worked. Best guess is that some prior work or just being idle all summer and sudden start caused crap to get into the in-line valve.

At least it's fixed. All is well that ends well, and this episode did
 
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