1996 Burnham furnace - rapidly clicking relay

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Old 10-25-20, 01:37 PM
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1996 Burnham furnace - rapidly clicking relay

1996 Burnham - Rapidly Clicking Relay problem

My Burnham natural gas hot water furnace has been going strong for many years and still heats very well.
Recently it developed a problem with the relay on the control (Honeywell R8285D) clicking rapidly when the unit is shutting off after heat cycle.
The control board was replaced but no change.
Description of sequence:
I switch on the heat with one of the 2 thermostats.
The furnace would come on and work as intended.
The damper opens, the circulation pump turns on, the burner ignites. Then when the cycle ends the burner turns off, then the circulation pump turns off and then suddenly the relay would start to rapidly switch with a loud clicking noise for a few seconds.
I recorded the noise here:
https://youtu.be/aiUDSqK97sk
Additional observation is that it does not always do it. The furnace would run for hours without it during the day. It seems worse on cold mornings and colder days like today and is worse when the heat comes on in the morning.
This has been going on since the heating season recently started here in the Northeast.
It is a 2 zone system with electronic Honeywell programmable thermostats.
Any ideas what is causing it and what a possible fix it? Any help is much appreciated.
P.S. I already had a HVAC contractor check it out but despite me paying $137 for the call and the diagnostic he had nothing to offer. Could not fix it and left.
 

Last edited by Mick TheBrick; 10-25-20 at 01:47 PM. Reason: Update
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Old 10-25-20, 02:08 PM
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Welcome to the forums.

You have a natural gas fired hot water boiler. A furnace is hot air.
You paid the tech $137 dollars and he could not fix it and left.

In your video you are showing the fan center. Are you 100% sure it is that relay that is clicking ?
If yes..... you have a thermostat problem.
What is the stat you're using ?
 
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Old 10-25-20, 02:57 PM
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Boiler it is - thanks for that.
True that with the tech. $137 for nothing.

Yes, 90% sure it is that relay that is clicking. At least I can feel it clicking when I lay my finger on it during the described clicking. Also, it is pretty hot (to the touch).
If it is the thermostat then I can say that it must be the upstairs thermostat since the clicking happened when the downstairs was turned off (or way down).
The upstairs stat is a Honeywell TH8320U. Not sure how old but certainly 5+ years possibly 10 years.
This is the model:
https://www.homedepot.com/p/Honeywel...500D/100295793.
Is there a way I can test that?
Thx.
Mick
 
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Old 10-25-20, 04:41 PM
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Since you have two thermostats you must have zone valves or circulator pumps.
We'd need to know how they connect to the boiler.
 
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Old 10-25-20, 07:23 PM
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Yup, 2 zone valves, one circulator pump.
How they connect? Not sure how to describe that.
 
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Old 10-25-20, 07:27 PM
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Replaced the 2nd thermostat with a new Honeywell T9 that I still had. Did not help. Still the same loud clicking noise.
 
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Old 10-26-20, 05:40 AM
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Hi, if it still does it with a new Stat then go to the zone valve, post a pic of the zone valve, the Stat controls the valve and there should be an end switch on the valve that starts the boiler.
Geo🇺🇸
 
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Old 10-26-20, 08:51 AM
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So the relay has no issue engaging but will, majority of the time, struggle to disengage? Are things still running as it clicks or is the switch definitely open (ie no power out of the relay) when it continues to click? Try to find a pattern for when it clicks vs doesn't; is it zone specific? If it is zone specific, maybe the end switch on a ZV is malfunctioning. Is it temperature specific (I would focus on boiler temp, not ambient)? Is it equipment running specific (ie is the boiler firing or not firing when it happens)? Have any changes happened to the system since this started? Service or part swaps?

So you have a boiler with a dual zone heating system separated by zone valves. Are your heat zones radiant or hydroair? I think its a bit odd that you have a fan relay on your boiler but I guess a relay is a relay. I am curious as to how your controls are set up. Can you provide more details about the zone valves and the boiler controller (where you set temperature and what turns on your circulator)?

Two thoughts come to mind that maybe could cause this.

First thought is maybe the relay is sticking and/or failing. Inspect the mechanical part of the relay that actually moves to engage the circuit. DO NOT TOUCH IF YOU ARE NOT COMFORTABLE WITH ELCTRIC CIRCUITS; THERE IS A RISK OF SHOCK. With power off, manually move the relay back and forth to feel how well it moves. Check if its catching at all. Depending on the relay, this may not be accessible, which in that case, I would consider replacing the relay before spending $XXX on another service call. Although, I would be surprised if the tech didn't try all of this already.

Second is a loose wire somewhere that isn't quite making clean contact. This is unlikely since it engages fine but either way, I would trace through all the wires. As Geochurch suggested, I would focus on everything after the zone valve, as the zone valves are typically responsible for engaging the boiler (and circulator) after a call for heat from your stat.

Lastly, you could also place a voltmeter on the signal side of the relay to see if you get voltage spikes as the zone valve is disengaging. Relays are so simple that it could only be a couple of things. The relay is sticking as its trying to open (break signal at end of call). Or its getting voltage spikes as the call for heat is ending that causes the valve to quickly open and close again. I never heard of the latter happening but it would explain the clicking. Voltmeter should help you determine that.

Some model numbers and photos of the system will be helpful in trying to diagnose further.
 
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Old 10-26-20, 06:34 PM
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You are right, the relay engages no problem only when it it disengages does the clicking occur. and that not always.
Trust me I spent significant time in from of that boiler to observe and find a pattern. I do just not have enough knowledge about the system as a whole to understand what the reason might be. I am a mechanical engineer by trade with good background in electronics but never dealt with HVAC systems.

The heat zones are radiant. The relay is just a middle of the road Honeywell R8222 all purpose relay. The relay cannot be activated manually but it is brand new. So the is the whole HW R8285D Control Center.

I traced all the wires as far as they are accessible. Actually found 2 that were questionable. First thought “That was easy” however that did not solve it either.

Hadn’t done the voltmeter yet to check the signals where I would have to catch it when it actually does it. Unfortunately I am very busy at work right now and can only spend so much time in front of the boiler.

i am attaching photos that will hopefully provide more information.

What I am wondering is: What actually controls the relay to open (switch off)at the end of each cycle ??? That is kind of the final thing that happens in a cycle after the burner goes off, the vent damper closes, the circulator pump goes off, the zone valve closes (did I forget anything)?













 

Last edited by Mick TheBrick; 10-26-20 at 06:58 PM.
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Old 10-30-20, 09:15 AM
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I can't remember if I asked it above, but does the problem happen with both zones? Or just one?

So I can't entirely follow the wiring in all your pictures but this is in general how it should work. You have terminals 1-2-3 on your zone valve. 2 is a common terminal from your transformer (likely the stand alone transformer in pic 4) The hot side of that transformer goes to your thermostat "R". When heat is called at the stat, the R-W circuit is made (at the stat). This sent voltage back to terminal 1 on the zone valve. The zone valve charges and closes the 1-2 terminal circuit. This leads to a time delay closing of the end-switch terminals 2-3. This end-switch is what goes to your boiler and says turn on circ and fire if temp is low (the time delay allows the valve to fully open before engaging any pumps). So, if I am folllowing everything correctly, the 2-3 terminals on both zone valves should wire back to the honeywell fan relay in question. The honeywell fan relay has both a transformer and a relay; the transformer is what makes the end switch on the zone valves hot. Thus, when end switch (2-3) closes on the zone valve, 24V from the honeywell transformer now makes it to the relay on the honeywell, which closes and engages your circ/burner/limit controls.

Since the honeywell relay sticks on opening, I am wondering if the zone valve (2-3) end switch is sticking a little. TO ANSWER YOUR QUESTION, once heat is satisfied, the thermostat opens R-W, which breaks continuity at the zone valves 1-2. Once that is broke, the end switch at 2-3 on the zone valve begins to open, breaking continuity to the boiler (the honeywell relay). The valves have manual levers you can try to move and reset them. I would only think the end-switch is the problem if your issue is isolated to one zone valve. if it happens on both, then I would think its the relay thats malfunctioning.
 
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Old 10-30-20, 12:15 PM
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You have a flue damper so that means things need to work in certain order.
The zone valve end switches activate the fan relay.
When that relay closes it sends power thru the flue damper.
 
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Old 11-02-20, 05:26 PM
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Okay. Thanks a lot for the hints.
Problem is solved.
Finally had more time over the weekend and could identify that it was only in one zone that it happened.
I.e. the one zone valve was the culprit. Replaced the valve and everything runs great again.
Thanks again especially to pbct2019 and PJmax for spending the time to read my post and giving the right hints.
Cheers,
Mick
 
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Old 11-03-20, 07:55 AM
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Glad to hear we were able to help. I bought my first house back in 2018 and the HVAC was a mess. The members of this forum were a great resource for me to learn my system and eventually rewire the whole system. I figure its my time to also give back a bit. ;-)

Best of luck.
 
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