single zone, two loops - one loop doesn't circulate

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Old 01-16-12, 01:29 PM
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Question single zone, two loops - one loop doesn't circulate

I have a single-floor ranch with a single heating zone coming off my Peerless boiler. I noticed that some of my baseboards weren't getting hot and assumed there was air-blockage. Since the baseboards don't have bleed-valves, I had to go to the basement to do it.

The heating hot water comes from the boiler, into the expansion tank, and then runs down the center of the house. About 10 feet away from the far wall the pipe splits. These two pipes run side-by-side to the far wall of the house, and then run in opposite directions around the outer walls, rising up into the rooms and then back down to the basement, until they return back to the boiler.

The 'front' side of the house circulates fine, I get heat. It's the back half of the house that doesn't generate heat. Feeling down the pipe coming from the boiler it's HOT, right up to the fork in the piping. The front half piping stays hot, but the piping running to the back half cools after about 6 feet from the fork.

I closed the flow valve where the front side returns to the boiler to shut it off and force all water into the back half of the house. No luck!

Next, I shut the back half's valve as well and then upped the PSI to 25 and opened the drain spout for the rear half of the house just above the closed flow valve. Water drains for a few seconds, and then the flow stops to a trickle. The PSIs stay up but nothing flows through the pipe. If I try the same thing on the front half of the house, it bleeds fine.

I'm assuming that at 25PSI any air in the system should get pushed out. This leads me to believe that something else is blocking the flow? Is it possible sediment could completely block the flow in one of the loops and not the other? Is there some way to clear it out, or is this something I must call a Pro. in to tackle?

Thanks!
 
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Old 01-16-12, 01:47 PM
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could be your froze up,get cold last night ? have one t'stat lower? north side?
 
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Old 01-16-12, 01:57 PM
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nope...not cold enough to be frozen. and there's only one tstat for the whole house.
 
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Old 01-16-12, 02:02 PM
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did your pressure gage drop when you drew water out of working loop and then refill?
 
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Old 01-16-12, 02:21 PM
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a little air below 32* and some wind is all it takes
 
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Old 01-16-12, 03:07 PM
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not cold enough to be frozen.
How cold is 'not cold enough' ?

Does any of the piping on that side of the house travel into 'unheated' areas? Can you see the pipe the whole way round as it goes up to the heaters, and then back down again?

I highly doubt it would be sediment... and I would think that 25 PSI would be enough to blow that through... ice crystals on the other hand... dunno.

Have you lived in the home for a while? It's always worked for ya?
 
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Old 01-16-12, 04:56 PM
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did your pressure gage drop when you drew water out of working loop and then refill?
Yep. With main loop valve closed I put pressure to 25PSI and opened the drain valve. Pressure came back down to about 13 PSI fairly quickly. With 2nd loop closed and its drain valve opened, no such luck. Pressure stays up at 25 PSI.

Can you see the pipe the whole way round as it goes up to the heaters, and then back down again?
Yah. I can walk all the way round the basement and see it go up into the house and then back into the basement at the end of each baseboard. Both front and back loops.

Have you lived in the home for a while? It's always worked for ya?
Lived here for 9 years. We noticed last winter that the bathroom and kitchen wasn't getting real warm, but wasn't bad enough to warrant looking into it. So, perhaps something has been slowly going wrong... ??
 
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Old 01-16-12, 05:00 PM
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perhaps something has been slowly going wrong... ??
Yeah, sounds like it...

Is it all copper piping?
 
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Old 01-16-12, 05:27 PM
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hope your using a hose not just bucket,put the bucket under relief valve and try to a couple more psi.with cir. running and good loop shut off crack opened and bad shut tight-then open boiler drain of bad loop. sounds like you have a hard purger.
 
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Old 01-16-12, 05:36 PM
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was meaning to ask you NJT how you made out with your earl spill and how the heck did that car end up in the hole?
 
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Old 01-16-12, 08:03 PM
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try to a couple more psi.with cir. running and good loop shut off crack opened and bad shut tight-then open boiler drain of bad loop.
What's the benefit of running with the main loop open and then popping open the drain on the bad loop? I wouldn't think that would give any more push in the bad loop than if the good loop were completely closed. Am I missing something? I'll certainly give it a try tomorrow...just trying to understand the 'why'.

Thanks!!
 
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Old 01-16-12, 09:57 PM
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operative word is "crack"open that will give cir. something to draw on.with luck might work and blow thru blockages.
 
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Old 01-17-12, 02:53 AM
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....and at sustain pressures and cir. on time thus the hose.can you do that?
 
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Old 01-17-12, 04:27 PM
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NJT how you made out with your earl spill and how the heck did that car end up in the hole?
The hole is filled in, next step is under the road and into the neighbors property... I'm never gonna be able to sell this place!

That's not just any car! That's a Trooper! PhotoShop m'boy, PhotoShop...

Thom, if I undertand your setup, you've got 'purge stations' at each loop return to the boiler, right?

Is there also a main shutoff on the supply line out of the boiler?

If you can COMPLETELY isolate the heating loops from the boiler, I might have an idea...

If you can snap a few pics... set up a free account at Image hosting, free photo sharing & video sharing at Photobucket and upload them there. Come back here and drop a link to your PUBLIC album.

You didn't answer:

Is it all copper piping?
 
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