Boiler turns off after a few minutes

Tom78

Hi all. I need some help if possible. I have an old American Standard GPH boiler. Earlier this fall I replaced my relay and the aquastat. Now it runs at most 3 minutes and shuts off the burners and pilot light. I’m not sure why it’s doing this. Could I have miswired it? The pump runs no issues. It’s all one zone.

The aquastat is a Honeywell TA418A1023 new, old stock and the relay is a Resideo RA832A, I replaced that because I’d have to slap it every couple of days last spring to make it work. I’ve also replaced the thermostat a Honeywell CT87K, with the same unit, just new.

I’ve included pictures of all of them. Thanks for any help you can give. I’m hesitant to call a tech out because I don’t want them to say I have to replace it, I know that I just can’t afford to for another season at which point I plan on buying a mini-split system.

mattmia2

What was the old aquastat set at? It looks like you have the new one set at 110 degrees with a differential of about 10 degrees which is far too low for a conventional cast iron boiler.

You should really get a good tech to look at this. A competent tech won't tell you to replace it unless it is leaking or you have a combustion or venting issue that can't be fixed. Finding a competent tech can be difficult.

Tom78

The aquastat is set the same as the one I pulled off of the boiler was. I just adjusted it to match what that one had on it. I've never played with any of the dials. Could that be what the problem is?

EBEBRATT-Ed

Make sure the sensing bulb is pushed into the well as far as it will go.

109A_5

Hello @Tom78,
What is this boiler used for ? DHW only, Hot water heat, Both ? The aquastat pictured seems like it would be for the low limit, what controls the high limit ?

Tom78

EBEBRATT-Ed said:

Make sure the sensing bulb is pushed into the well as far as it will go.

I'll check that to make sure. I thought I did, no harm in trying it again.

Tom78

109A_5 said:

Hello @Tom78,
What is this boiler used for ? DHW only, Hot water heat, Both ? The aquastat pictured seems like it would be for the low limit, what controls the high limit ?

Its for hot water heat, it has 12 big cast iron radiators it supplies. As far as what that aquastat controls I don't know and I don't know what controls the high limit. It always shuts off right around 22-25 PSI and 180-190.

109A_5

Hello @Tom78,
Maybe more pictures of the whole overall boiler system and all controls would help.

I would think in that temperature range the aquastat would keep the boiler warm for DHW, which seems like you don't use that feature of the boiler system.