trying to understand my boiler, what is the difference between these zone boards?

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drewdin

drewdin

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Kind of a vague question, i have been troubleshooting my thermostats and i had some questions on why i have two separate zone boards. This boils down to i was told to make sure i have relays on my thermostats and i see two out of the three zones, but the one without a relay has some temp settings.

Can someone help me out and explain the difference between the two zone boards? thanks

2014-01-07 19.10.11.jpg

2014-01-07 19.08.21.jpg
 
Post schematics. They may be pasted on the inside of a panel somewhere.
 
I’m no heating guy but the top photo looks to be the control for your boiler and the bottom photo is the relay outputs for your two pumps each being controlled by a separate thermostat. I see two pairs of thermostat wires coming in and two power leads going out to the pumps red and brown and a common. Power coming in on the orange and yellow it looks like with a neutral.

I don’t see anything plugged into the third relay for zone 3. Do you have 2 or 3 zones and how many thermostats?

on edit

Looking at it a bit more I see a curly wire coming into the top box that’s a thermostat wire also. Could maybe the basic hi / low control box be able to control just one zone and then you add a lower box depending on how many zones you need in addition.

Just guessing here but maybe your house started out single zone and then someone wanted to break it up or extend it and the other box was added.

The upper box with the temp settings I’m sure is controlling all the zones temperature wise.
 
Last edited:
What HVAC symptom/problem are you pursuing?
 
i have a NEST thermostat, is uses the 24vac supplied by the zone controller for power. I was having some issues where it was getting a low battery and disconnecting from the internet.

I found that it was faulty firmware and after an update it it started working fine. There tech support had me checking for relays and checking the voltage, etc... and it was just a programming error on their end...
 
I'm keeping my 1982 ~80% efficient furnace for as long as I can because I cannot possibly repair the newer ones.
It also helps that the maker sent me a factory manual (for free, on request) and that this furnace uses relay logic with no computer/CPU.
 
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