Boiler cuts out when it is cold


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Old 01-06-15, 11:03 AM
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Boiler cuts out when it is cold

I have a Weil-McLain Gold CGI boiler, and for the last week or so, it seems to cut out in the middle of the night. It usually restarts if I turn it off and on, but it can take upto a 5-6 hours of retrying this every 20-30 minutes or so. I've had servicemen over twice (always when it was back running) and they haven't been able to resolve the situation, but I've narrowed it down to the following when it cuts off.

1. When it cuts off the power and the TSTAT/Circ light are on. The rest are off.
2. The fan next to the boiler that provides air from outside for the combustion is on (and I feel air coming out of its vents)
3. There is no power back from the fan to boiler. I guess that this is the proving switch that verifies that airflow is sufficient. Since this in series with the temperature limit switch (which does provide power to the fan), I assume this is why the boiler cuts out.

My question is why the fan thinks there isn't enough pressure (and usually this happens only when it is cold, that is during the night). Is it that the proving switch is just defective?

Any tips or suggestions on next debugging steps would be appreciated.
 
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Old 01-06-15, 11:30 AM
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The fan next to the boiler
You're referring to a 'Fan in a Can' I believe? What the model number?

NOT the 'draft inducer fan on the boiler...

Is it that the proving switch is just defective?
Presuming that you mean the fan in a can, then yes, either the proving switch is defective or there is an issue with the wiring, i.e. bad connection...
 
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Old 01-06-15, 11:41 AM
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Yes. the fan-in-a-can. I'll note the model down when I get back home. thanks for the quick response.

with respect to the wiring, can the connection go bad by itself (this is the 3rd winter that we've been in the house and it is the first time that this happened).

thanks.
 
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Old 01-06-15, 12:06 PM
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can the connection go bad by itself
Sometimes connections can get corroded, and if not clean and tight to start can accelerate the process.

Sometimes furry little critters can cause issues.

More likely that there may be a problem with the proving switch.
 
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Old 01-06-15, 06:15 PM
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Hi, the fan-in-a-can is a CAS-4

I looked at the connections in the fan (from/to the boiler) and they look ok to my untrained eye. Is there anything I should check to narrow the cause down.
 
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Old 01-06-15, 07:34 PM
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Your system is chimney vented and you are NOT using the "CK" control kit, is that correct?

Was the need for the fan in a can established by determining that there were problems with inadequate combustion air?

If so, in order to get some heat into the home, would you be OK with disabling the fan in a can and opening a window?
 
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Old 01-06-15, 08:15 PM
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I am not sure what the "CK" control kit would be (how do I check), but the fan goes from the basement 'boiler room' floor through a cutout near the top of the room wall out to the outside.

The boiler room doesn't have a window and so I don't think that's an option. The boiler room is like a walkin closet off the garage in the basement. It contains the boiler, the indirect water heater and the air handler.

I am not sure why or how the fan decision was taken -- we bought the house about 2.5 years ago (the house is about 10 years old).
 
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Old 01-06-15, 08:19 PM
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IF the CK control unit is the one that I find the web that is also used to control a water heater, than I don't think I have it. The water heater is an indirect one powered by the boiler and is not connected to the fan.
 
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Old 01-06-15, 08:27 PM
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For the most part, btw, we do have heat -- jiggling with things (turning the boiler on and off or fiddling with the wires) usually causes it to refire. The irritation is in waking up in the middle of the night cold because (it seems) the fan thinks that there isn't enough air pressure. I assume there is actually air pressure because the jiggling causes it to work.

Is there a way to replace the pressure switch, or otherwise check its operation? The last two times I called the servicemen, the system started working and they werent' able to (or weren't that motivated :-) to figure out what exactly was broken.
 
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Old 01-06-15, 09:16 PM
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The boiler room is like a walkin closet off the garage in the basement.
If you leave the door to the boiler room open, and perhaps the door between the garage and the basement ajar, will the boiler have enough combustion air?

If so, and you do NOT have the CK kit, then you can TEMPORARILY move the wire that is on T3 in the CAS 4 over to T1 in the CAS 4.

If the problem is in fact the proving switch in the CAS, this will allow the boiler to fire without the proving switch in the circuit.

Since the CAS is in fact working, there should be no problem with this...

But it's TEMPORARY!

The pressure switch is available as a spare part:

46273100 - Field Controls 46273100 - Pressure Switch (for CK Kits, CAS-3, CAS-4)

These guys ship FAST! You'll have it next day... if you call them and you are on the Island, you might be able to pick it up.
 
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Old 01-07-15, 04:29 AM
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Thanks. I'll try that. FWIW, the boiler cut out again this morning. Around 6AM I woke up to the cold air coming out of the vents and the boiler thermostat below 70 again. I switched the fan from low-to-hi and the boiler worked (I've tried keeping the fan on hi all day, but that doesn't work either).

One question on the part -- does it come with instructions on how to install, or is it fairly straightforward.
 
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Old 01-07-15, 07:44 AM
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One question on the part -- does it come with instructions on how to install, or is it fairly straightforward
I've never replaced one myself, but can't imagine it's difficult. There are two hoses and a couple electrical connections that are probably 'push on' terminals.
 
 

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