One loop cold in my four zone system

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Old 01-23-12, 09:31 PM
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One loop cold in my four zone system

Here's my problem....

First, some background information. My boiler is a coal/oil combo boiler serving a 4 zone system and another DHW zone. Everything works fine accept for one loop. The zone in question is split into two loops. I have designated them Loop 1A & 1B on my schematic. Loop 1A is works great but Loop 1B is cold. In normal operation, the supply pipe to the first fin tube hot but after that the pipe is cold and no heat is coming out of the fintube. I am not sure what to do.

It should be noted, the house is a 1 story ranch 2500 square feet. The basement is about 2000 square feet unfinished

The schematic is pretty accurate.

John
 
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Old 01-24-12, 10:54 AM
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Hi John, you may have an air blockage in that part of the system... or hopefully not so, but it could also be caused by frozen pipe... since it appears that all this piping in in the basement, the chance of the latter is not so great.

Do you have electric zone valves operating the various zones?

Take a look at the pressure/temperature gauge and tell us what the readings are.

You may have valving around your boiler that will allow you to direct a forceful stream of water through the non-heating zone that will push any air blockage out...

Take more pictures... in focus, well lit, large enough to see details... try to get some wide enough angle to see the entire boiler and all the piping around it, from several angles... then take some closer shots that show all the valving around the boiler.
 
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Old 01-24-12, 03:26 PM
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I can confirm it is not a frozen pipe. The ambient temperature in my basement is 60F and it is not a bit damp. I suspect air as well. I'm just not sure how to get rid of it or diagnose it.

The zone valves are all electronic. Pressure is 20 lbs and Low limit is 180F High limit 200F. The original boiler was an old Burnham oil boiler. All the baseboards are original to the house although I think the ones in the basement were added in after the original install.

Pictures are here.
 
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Old 01-24-12, 04:46 PM
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Low limit is 180F High limit 200F
a 4 zone system and another DHW zone.
What exactly do you mean by 'another DHW zone?

Do you mean the coil inside the boiler that provides the DHW to the home? If so, that's not really considered a 'zone'. I see that you've got a 'storage tank' for the how water also...

I believe the coil inside your boiler is feeding this tank... and that aquastat strapped onto the pipe leading to it is controlling a circulator that pumps the hot water from the coil to the tank... What is the setting on that aquastat?

The settings on your aquastat are way high ... you don't need 200 water to heat your home, and since you've got the storage tank it is HIGHLY unlikely that you need 180 water going to that tank... I would strongly urge you to turn it down to a HIGH of 180, and the LOW as low as possible consistent with enough hot water to the home. I would start at 140 and if the hot water suffers, go up 5 at a time until you have ample supply. Save yourself some fuel... turn 'em down!

on to your air problem next...
 
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Old 01-24-12, 04:56 PM
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Is that normal for the oil burner to be removed from the boiler like that?

That seems terribly dangerous to me... isn't it possible for that thing to fire up and burn the house down?

I don't think I see any fuel lines connected though... and aren't those the fuel lines coming down the wall with valves on them?
 
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Old 01-24-12, 05:28 PM
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OK... I still have more questions after viewing the pics...

In photo #8 (and closer in #7) there is a closed valve all the way at the top of the pic... what's that valve for, and why is it closed? If that's the return from the non-functioning zone, there's your trouble right there...

Have you looked for any air bleeders on the baseboards? That should be your first check... and the easiest solution to try first if you have them. Look on the elbows where the pipes turn to go back down into the floor.

If you find none... continue:

Are you familiar with the operation of the 'fast fill' lever on your pressure reducing valve? That's the bell shaped one to the left of the expansion tank in pic #7 and 8. The one on the left, not the one on the right with the pipe on the bottom, that's a pressure relief valve.

If you were to lift that handle, you would bypass the regulator function of the valve and allow a fast flow through the valve. You will be using this valve to purge that zone of air.

Hopefully your installers have installed the WEBSTONE purge valves in the proper direction! If those are the 'T ball drains' they are reversible...

What you may need to do is this:

1. Turn off the boiler and allow to cool to 100 or less.

2. Manually open the zone valve to the zone you wish to purge.

3. Connect a hose to the hose connection on the webstone valve above the circ pump. Direct the hose to a laundry tub, floor drain, or out a window. CLOSE the large ball valve handle on that valve.

4. CLOSE the large handle on the webstone valve on the supply pipe coming out the top of the boiler.

5. OPEN the ball valve on the drain with the hose attached.

6. LIFT THE 'FAST FILL' HANDLE on the pressure reducing valve.

At this point, you should have a strong flow of water through the 'bad' zone, and out the hose. Allow to run until all air is out of the zone.

7. RELEASE the fast fill handle.

8. CLOSE the hose drain.

9. OPEN the other two ball valves on the supply and return.

10. Return boiler to service.
 
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Old 01-24-12, 05:34 PM
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Have you verified that the zone valve in question is opening?

Bleeding air from a loop below the main, like your basement baseboard, is often difficult - and that big ell in the piping doesn't help any. Ideally, you should have a ball valve isolation on the supply to the baseboard, followed by a hose bib. Put both valves toward the top of the supply line. To bleed, shut the ball valve, and open the bib to get a power flush.
 

Last edited by gilmorrie; 01-24-12 at 06:10 PM. Reason: mixed up supply vs. return
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Old 01-24-12, 05:48 PM
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Ok - I've lowered the settings LL to 160 HL to 180. The Aquastat on the DHW line is set to 130F. And yes, there is a 5 gpm coil in the boiler feeding the water storage tank. The valve that you see closed is the return for the other loop in the zone that's good(loop 1A). I had it closed to force flow into the the bad loop. It helped a little but not enough. The oil gun is not connected yet. That is a summer project.
 
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Old 01-24-12, 05:59 PM
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Gil - Yes the zone in question has two loops. If you view my schematic in the photos, you will see Loop 1A & 1B return on the same valve. Loop 1A is fine.
 
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Old 01-24-12, 06:01 PM
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John, in that case, when you do the purge steps, keep that valve closed... you want all of that purge water forced through the bad zone.
 
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Old 01-25-12, 08:31 AM
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Trooper - You were right! The air has been purged and the loop is working again.

I appreciate your help. This is our first winter in this house. Heating with a boiler is brand new to me. Throw coal on top of that and you have a big learning curve. We heated our city home of 21 years with a natural gas forced air furnace and the house was always cold & drafty. We are loving our warm country home.

Thanks again for the help...John
 
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Old 01-25-12, 05:25 PM
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Great! glad to hear it...

Come on back if you have any more problems, questions!
 
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