Argo ARM842 switching relay troubleshooting

ccoyle

I’ve got a gas water heater supplying an indirect fired tank. 4 zones total with one being a loop between the tank and heater. The house has hot water but the baseboard heat isn’t working. I’ve since changed the relays and I’ve still got this red led showing. All thermostats still have power but no call for heat seems to be going through. Is it possible the board went bad or is there something else I’m overlooking

neilc

fresh batteries in the thermostats?
what type thermostats?
besides the relays, anything else change sinse it worked last? like thermostats?
try turning off the priority switch on the right,
circs start now ?
post a wide view of the rest of the boiler and circs

109A_5

Hello @ccoyle,

Does the Red LED ever go out ? If not your DHW may be always calling for heat and the Priority is locking out the rest of the zones. Turn the Priority off, troubleshoot the constant Priority zone call issue.

neilc

bad circ on domestic?

Argo does say priority will switch off after 30 minutes, just in case , , ,

ccoyle

So nothings been changed anytime recently. Turned off the priority switch and the call for heat is going through now. Red led stays on at all times so I’m thinking there’s an issue with the priority. Water in all the taps recently became way hotter than normal so it appears the priority may be always calling for heat. Not really sure as to where to start troubleshooting next. The indirect fire tank has a temp setting but no readings on it and turning that colder seems to have little to no effect

EdTheHeaterMan

What type of indirect water heater do you have? (picture please).


There are some Weil McLain tanks and some Triangle Tube tanks that have a problem with water filling up the thermostat compartment. Then corrosion seals the thermostat contacts together and the DHW gets too hot and the house gets too cold when the priority switch is on.

ccoyle

It is a Weil McLain, not too sure where to find a model number. I attached a couple pics. Would changing out the thermostat or draining the tank possibly solve the issue?

EdTheHeaterMan

You have the one that I am referring to. You need a new thermostat for the water heater.
https://www.supplyhouse.com/Weil-Mclain-633-900-130-Residential-Thermostat-Aquastat-Kit-for-Weil-McLain-Indirect-and-Gold-Plus-Water-Heaters

ccoyle

I’ll look into picking one up tomorrow, thanks for the help

EdTheHeaterMan

After replacing that thermostat, I never put the cover back in place. that is low voltage wiring and does not need to be in an enclosure. I just leave the dial laying out on the top of the tank. That way water in the thermostat well does not cause a problem.

The proper fix is to install a new thermostat well, but that is such a problem for those tanks. Depending on the date of install, you may have some lifetime warranty left as long as this is not a warranty replacement already. If the tank is not leaking too much at the thermostat well, then just replace the thermostat and be done with it until the leak becomes too much.

ccoyle

No idea if it’s still under warranty, if I had to guess it’s roughly 15 years old at this point. I shouldn’t have to drain the tank to replace the thermostat right? Just kill the power before removing it, clean out any water in the well, and it should be a straightforward swap after that from my understanding

HVACNUT

Did you try jumping out the thermostat or measure voltage?

ccoyle

Ended up changing out the thermostat. Couldn’t get an 1 to 1 replacement but this one seems to be working. Red led went out. Each independent zone seems to be working now. There was corrosion in the well and on the bottom of the thermostat but nothing on the copper “bell” but no apparent water, possibly the thermostat just went bad?