Boiler Constantly Going Through Heat Cycles

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Old 01-20-15, 08:11 AM
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Boiler Constantly Going Through Heat Cycles

I would appreciate any help with this as it's been causing some sleepless nights for my family and me. I'm fairly new to HVAC so excuse me if my terminology is wrong. I have a Weil-McLain HE-5 Series 3 boiler which provides heat to 4 zones. I have a separate water heater.

The problem is that there seems to be a constant call for heat. I have all thermostats off but the boiler goes through a continual heat cycle until it reaches the high limit of 180-ish degrees, cools down, then kicks in again. When I make a legit call for heat, everything *seems* to be working fine. I have 3 electronic zone valves. When the stat calls, I see the lever go to the open position and the circulator come on. I fiddled with the valves and none seem to be stuck. When they are open, the lever goes back and forth easily, and otherwise there's a slight resistance. I have seen the boiler running with all 3 valves seemingly closed (lever has resistance), which I didn't even think was possible.

Before I get to the photos, I should say my problems began several weeks ago with a completely different issue (but maybe related). After several hours of normal use, or even days, I would find that there was no heat at all and see that the draft inducer blower was on, but no heat source. The only way I could get it working was to disconnect one of the pressure tubes (the red one going from pressure switch to heat exchanger), after which I'd hear a click, and once reconnected the ignition sequence would start. I did check that the tubes and flue were clean.

I find it really odd that I go from not getting heat often enough, to getting too much of it now. I have a multimeter but not entirely sure how to use it or what to check to be honest. I'd really appreciate any suggestions.

Here some photos.

Overall heating system setup. Note that one of the manual valves on the right is in the "Off" position because that zone was getting too hot.

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Close-up of zone valve setup.

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Wires coming from zone valve assembly to outside of boiler.


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Inside boiler.

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Insider boiler wiring.

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Close-up of aquastat/limit control.

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If there are any other photos that would help please let me know. Again, thanks for any guidance here.
 
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Old 01-20-15, 08:29 AM
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provides heat to 4 zones. I have a separate water heater.
You have FOUR heating zones...?

I have 3 electronic zone valves.
But only THREE valves?

Don't I see four valves in this pic?



I'm inclined to believe that you may have a sticking relay causing the heat to run...

At the lower left of this pic, above the burners, there is a 4" box with a transformer and a relay (in a white socket) on it.

These relays have a tendency to stick for some reason.



Give that relay component a little 'love tap' with the handle of a screwdriver. That may unstick it and the boiler should stop firing. If so, replace the relay.

Later I can give some instruction on the use of multimeter if you want to verify this by testing.
 
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Old 01-20-15, 10:29 AM
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NJ Trooper, you've got a great eye. That is indeed a 4th valve sitting horizontally on the pipe. This is a new house and I'm still getting my bearings. That valve is a Honeywell while the other 3 are Flair, if that matters.

I will try your suggestion. I'm unable to babysit it at the moment but will monitor later. Just to be clear, this is the relay you're referring to?

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Also, if I do need to switch out the relay, I can't seem to find a part number. I see printed on the side:

POLE 1 - 60HZ
12AFL 60ALR 125V
6AFL 35ALR 250V
POLE 4 - 60HZ
1/10 HP 125/250V

Is there a generic part I can replace this with? Thank you.
 
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Old 01-20-15, 10:56 AM
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Yes, that's the relay.

I'm wondering though... is it possible that the 4th zone is actually calling for heat?

Make sure that the valve that you closed is not cutting off heat flow to a zone where the thermostat is calling for heat. If that's the case, it will keep calling... and calling... and calling...

Also, it may not be a good idea to close that valve in any case, you don't want pipes freezing. It happens, more than you want to know.

Better to figure out WHY that zone is overheating and see what can be done about that without having to shut the valve.

Also, this pressure switch problem sounds like something completely unrelated to the issue at hand...

my problems began several weeks ago with a completely different issue (but maybe related). After several hours of normal use, or even days, I would find that there was no heat at all and see that the draft inducer blower was on, but no heat source. The only way I could get it working was to disconnect one of the pressure tubes (the red one going from pressure switch to heat exchanger), after which I'd hear a click, and once reconnected the ignition sequence would start. I did check that the tubes and flue were clean.
 
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Old 01-20-15, 11:08 AM
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Old 01-20-15, 11:09 AM
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Your thoughts are appreciated NJ Trooper. Yes, I agree that shutting off the valve manually is risky. I did it just to bring the heat down to that zone but have since turned it back on.

The 4th zone is actually the basement and is linked to an old mercury stat. It's entirely possible it could be a problem with that stat since I actually turned off the other 3 and left this one at its lowest temp (there's no on/off switch) while the boiler was heat cycling. Would you suggest I test the voltage at this 4th valve to see if it's reading 24AC when I think it should not be? The actual valve switch seems fine however as it's not loose and doesn't seem stuck.

I agree the pressure switch problem seems unrelated. I guess I'm just totally confused why the first problem completely went away and I have almost the complete opposite issue...
 
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Old 01-20-15, 11:12 AM
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This should be the relay for your boiler:

510-350-223 - Weil Mclain 510-350-223 - Plug In Relay w/ 24V Holding Coil
Thanks so much for that information!
 
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Old 01-20-15, 03:19 PM
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Trying to think of the simplest way to TS this...

The 'love tap' on the relay is first. So try to catch it in the act and see what happens.

Looking at this picture:



I have to wonder... what the heck is that coil of wire hanging there? It looks like about a hundred feet of thermostat wire coiled up! Maybe the installers forgot the wire cutters back at the shop?

Is that what I think it is? really a crap load of wire just balled up there?
 
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Old 01-20-15, 03:45 PM
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I have to wonder... what the heck is that coil of wire hanging there? It looks like about a hundred feet of thermostat wire coiled up! Maybe the installers forgot the wire cutters back at the shop?

Is that what I think it is? really a crap load of wire just balled up there?

Read more: http://www.doityourself.com/forum/bo...#ixzz3PPNL3oSX
Haha, yes that is just a crapload of excess wire that the installers never bothered with. It's an eyesore but doesn't seem to be doing any harm as far as I can tell.

Still waiting for the issue to crop up. Strangely things are behaving normally so far but I doubt for long.
 
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Old 01-20-15, 04:13 PM
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While you're waiting for it to stick on, let's talk about what a 'next step' might be, or even a concurrent one.

You asked about looking at zone 4 valve/thermostat... let's instead go all the way back to the boiler and monitor the two wires coming out of that rat's nest near the valves that actually trigger the boiler to fire.

In this pic, I believe that the two yellow wire nuts are the 'thermostat' connections to the boiler. The wires should end up landing on the "G" and "Y" terminals of the transformer/relay combination.



If you monitor the 24VAC on those 2 wires, what you should see is:

When there is NO CALL for heat --- appx 24VAC

When there IS A CALL for heat --- appx ZERO volts.

If the boiler is running and you have 24VAC there, it probably means the relay is sticking. Give it a love tap and see if the boiler goes out.

Of course if you have ZERO volts and the boiler is running, it means that one of the zones is calling for heat.

This type of test will tell us which direction to troubleshoot, toward the valves/t'stats, or toward the boiler controls.
 
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Old 01-20-15, 04:26 PM
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It's an eyesore but doesn't seem to be doing any harm as far as I can tell.
Yeah, put it on your 'some day, when I get a round tuit' list of things to fix.

If it turns out that your pressure switch eventually needs replacing, I believe this is the one you need. VERIFY BEFORE PURCHASING! I can't be responsible for wrong parts ordered.

511-624-510 - Weil Mclain 511-624-510 - Pressure Differential Switch, 1.00" Setting, for HE, HE II Boilers (Sizes 3, 4, 5)

The terminal configuration is different, but they are marked with the same letters as the original.

In addition to the previous mentioned relay, a Honeywell R8222U1006 will work. In fact, that's what you will get if you order the W-M part.
 
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Old 01-21-15, 05:07 AM
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Just curious, there appears to be a fan center relay next to that relay,I wonder what it's function would be on a HWB.
GEo
 
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Old 01-21-15, 06:59 AM
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Many of the W-M boilers use that type of control and a separate high limit control instead of a typical 'integrated' aquastat. No idea why... but they do. One thing is certain... if the relay goes bad, it's a ten second $20 part change. Relay goes bad in a 8148 aquastat and your down about an hour or so and over $150 for the part... if you DIY.

Honeywell calls it a 'fan control center' when in fact all it is is a 24Vac transformer and a relay mounted on a plate.

It's used to switch circulator and provide power to burner...
 
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Old 01-21-15, 07:41 AM
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NJ Trooper, you may be a genius. The burner kicked in last night even though the temps were all above the set temp. I tapped the relay and the burner did shut down. It started up normally later when the stat called for it. So all signs are pointing to a faulty relay. I didn't get a chance to do the voltage test, but like you said this is a pretty inexpensive part so I'm going to go ahead and replace it.

I have a local heating supply company - maybe you know them since you're in NJ also? Wallington Plumbing and Heating Supply in Wayne. Hopefully they have the relay in stock and I can test this out today.

I'll keep you updated. Thanks again for your help.
 
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Old 01-21-15, 09:21 AM
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Nahhh, no genius, just been around the block a few times... you're not the first one to come here with a sticky relay in a W-M either!

Wayne is quite a ways north of me... I'm one of them rednecks that lives south of the Driscoll!

Honeywell R8222U1006
There are quite a few manufacturers that make relays that will work. They should have something that you can use. Give them the Honeywell number if they can't cross-reference the W-M number.
 
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