Four zone boiler system, one zone could no longer fire boiler

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Old 01-04-12, 12:41 AM
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Four zone boiler system, one zone could no longer fire boiler

I have an old HydroTherm boiler, serving four zones. Everything worked well until today, when suddenly the 2nd floor zone could not start the boiler any more. All other zones still work fine. The thermostat for the problematic 2nd floor zone still could open that zone's valve, so that if another zone fires the boiler, hot water could still flow to the 2nd floor zone.

I tried swapping the thermostats from the working 1st floor zone, but the problem persisted. I can't think of anything that might have changed today which might have caused the problem.

Any advice on what to check?

Thanks in advance.
 
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Old 01-04-12, 05:58 AM
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Can you switch the heads on the zone valves? That would determine if one is inoperative.

Instructions are online on how to remove and replace them.
 
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Old 01-04-12, 03:39 PM
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Make/model of the zone valves please?

It sounds like the 'endswitch' in the valve head has gone caddy wompus.

Happens...
 
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Old 01-04-12, 09:07 PM
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Thanks very much for the replies!

NJ Trooper, from the molded digits on the valve body, the zone valves appears to be Taco 571-2. I took a picture, but am not sure how to post it here. Hmmm ..., I see "You may not post attachments" under "Posting Permissions." So maybe I cannot. Please let me know if there is a way.

TBurr, could you please post a link to instructions for replacing the zone valve? By "switching the heads", do you mean pulling the lever between "Auto" and "Open"? I could pull it with little resistance when the thermostat requested heat; and there was quite some resistance (I did not force it) when the thermostat did not ask for heat.
 
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Old 01-04-12, 09:33 PM
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Here's a link to a PDF that explains how to change the power head:

http://www.taco-hvac.com/uploads/Fil...ry/102-076.pdf

Here's a place on-line to buy a new head...

Patriot Supply - 555-050RP
 
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Old 01-05-12, 07:44 PM
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Thanks for the links. Is there a test I could do, say with a multimeter, to confirm the diagnosis?
 
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Old 01-05-12, 07:47 PM
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Sure...

Disconnect the wire from terminal #3

Connect multimeter set for 'ohms' or 'continuity' measurement between terminals #2 and #3

With valve closed, meter should show open contact...

With valve open, meter should show continuity...
 
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Old 01-10-12, 08:27 PM
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Replacing the power head solved the problem!

Hi NJ Trouper,

You nailed it! The problem went away after I replaced the power head. Thanks very much for your help!

The bad power head shows open circuit between terminals 2 & 3 regardless of whether the valve is open or closed.

Now I have another question. The 1st floor zone's temperature seems to take much longer to rise for the same amount than the 2nd floor zone. This has been the case before the 2nd floor zone's power head failure. Both zones use the same Taco valve. I wonder if this is because the 1st floor zone's valve is aging, and how likely replacing its power head would improve the situation. Asked another way, is it likely that the valve is not open all the way when it opens? The valve does fire the boiler and open/close reliably. How can I tell if it opens all the way or only partially?

Best regards!
 
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Old 01-10-12, 09:27 PM
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is it likely that the valve is not open all the way when it opens?
No... not really... the contact between 2 and 3 isn't made until the valve is pretty much all the way open.

Is the 1st floor larger area? more or larger windows?

How about the amount of radiators/baseboards installed in relation to the square footage?
 
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Old 01-12-12, 09:29 PM
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Same square footage between the two floors. 2nd floor does have slightly more baseboards: 53 feet on 1st floor and 65 feet on 2nd floor. 1st floor does have a double-layer glass door to the deck, with floor to ceiling double-layer glass windows on both sides.

I set the 1st floor thermostat at 55F overnight, and 68F for waking up at 4am. By 7am after a regular cold night, it usually heats up to only ~62F. For comparison, the 2nd floor usually takes maybe 15-30 minutes to rise 2~3F. Note that the daily temperature swing is much smaller for the 2nd floor than the 1st floor. The 2nd floor almost never gets below 60F, even if heating was turned off during the day.
 
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Old 01-13-12, 06:26 PM
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So... going with 550 BTU / foot at 180 water, you have about:

29150 BTU heat emitters on the 1st floor, and

35750 BTU on the 2nd floor.

Usually the lower floors are harder to heat to start with, and you've got significantly less heat output downstairs... in addition to that big glass door.

How's the insuation in the home? A REAL energy audit would be well worth the couple hundred bucks to have it done. It should include a 'blower door test' that measures the amount of air infiltration in the home.

Insulation and air sealing are fuel that you only pay for ONCE!
They are the single biggest bang for the buck in fuel savings.
 
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Old 01-13-12, 06:29 PM
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One thing you can do, if you haven't already, is brush and vacuum out the baseboards... at least on the lower floor. You would be surprised how much more heat comes out of them when even a light coating of dust is removed!

Yes, it a major pain to move the furniture and spend hours on your knees with a brush and a vacuum... but you would get more heat... guaranteed!

(unless you've already done it!)
 
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Old 01-13-12, 09:29 PM
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Yup. Did that last year. REALLY hard! A small paint brush worked the best for me, not that it worked well. Do you have recommendations for what brush to use? Also my vacuum did not have enough suction to pull dust balls from between the fins. A hair drier worked better. Any tips there?
 
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Old 01-14-12, 08:58 AM
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Do you have recommendations for what brush to use?

Any tips there?
I ended up finding an old 'drafting table' brush that I cut down that worked pretty good... not too many bristles, and kinda narrow...


image courtesy westnc.com

There was some discussion in another thread a while back about using a 'Scunci' steam cleaner... sounds like a good idea... you need concentrated stream of air to move the dust out... and the steam might tend to keep the dust from going airborne.

When I got this place I ended up making a HUGE mess with my air compressor... it took forever to get all the airborne dust out of the air.

What seemed to work best for me though was to run a large capacity shop vac under the fins, and 'blip' the air compressor nozzle on top... keep the air pressure as low as possible... blowing right into the vacuum on the bottom. MOST of the dust can be caught this way.
 
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Old 01-21-12, 09:08 AM
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How to tell if there is air in the pipes?

Hi NJ Trooper,

How do I tell if there is air in the pipes? I read a few posts on the forum but did not run into an explicit description.

A few days ago I had a burst radiator in the den zone. Inadequate insulation on the pipe where it went down to the open crawl space below the deck door. The repair person cut out the burst section and replaced with new pipe. I did not see him do anything about getting out the air.

I have an "Extrol" expansion tank by the boiler, but that's down in the basement. I wonder how air in pipes on upper floors can ever get out.

The pressure gauge now reads just under 20. Should I lower it to ~12 PSI? This is a two-story colonial with the boiler in the basement.

Thanks.
 
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Old 01-21-12, 10:50 AM
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How do I tell if there is air in the pipes?
Two ways...

1. You would HEAR it. Slurping and gurgling when the zone was running.

2. Enough air and you would not get any heat when the zone was calling.

The repair person cut out the burst section and replaced with new pipe.
And hopefully you've taken insulation steps to prevent it from recurring?

I wonder how air in pipes on upper floors can ever get out.
There is 'supposed to be' adequate flow... at least 2 fps , up to 4 fps , which would pick up any air in the system and transport it back to the air removal devices... there should be an 'air scoop' and automatic air vent to take care of this.

In some cases, if there isn't a fast enough flow rate, or upon initial filling, you would need to use air bleeds which might be installed on the baseboards themselves, or, if you have the correct valving (known as a 'purge station'), you can 'power fill' the system and push the air out a drain...
 
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Old 01-21-12, 12:41 PM
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Thanks a lot! I do get heat and don't hear funny noises, so I'd guess there is no issue with air. Adding insulation around those pipes is high on my to-do list. Before I get that done, I'll waste some energy and periodically run hot water in that zone.
 
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