New Goodman AVPTC and hydronic heat wiring for heat

stoker420

Hello, I searched the topics and could not find an answer to my situation.

I installed a AVPTC air handler with communication CTK04 thermostat and I need to connect my old hydronic oil fired boiler. And I'm not sure how to wire it. My old system had a hydrostat at the exchanger and one on the boiler, attaching pics. I see in my board I have connections for an electric heat W1 and aux W2 when I call for heat I get 24 v across W1 and C, I need to turn that into a signal for my boiler to activate. How should I wire it? Should I upgrade the control unit on the boiler. I eventually will be installing geothermal and bought this unit to get me through the next 5 years or so. My old unit had to be replaced after 26 years. I can't afford electric heat here in New England and don't have space in my panel for another circuit anyway.

stoker420

P.s. it's not a heat pump it's a 2 stage communication ac unit outside.

Jamie Hall

You can — and should — leave the aquastat on the boiler alone. That control turns the boiler itself on and off in response to the circulating boiler water temperature.

Now. The next question is — what on the system transfers heat from the boiler to whatever transfers it into your house? The old system. Figure out what that is. Then use the W1 and C connections, which provide (you say) 24 VAC power, to activate a relay. The dry normally open contacts of that relay can be wired in place of — or in parallel with — whatever old thermostat controlled the old system.

HVACNUT

Wiring diagram for the air handler?

No separate relay board needed for hydro coil?

stoker420

Like this an isolation relay is that what I need?

stoker420

Install the relay and it is up and working, now I have to shut it down until Thanksgiving because that is the rule

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1814568#Comment_1814568

You use holidays to control your HVAC system?

That's strange I use temperature.

I find it tends to keep the house comfortable.

HVACNUT

https://forum.heatinghelp.com/discussion/comment/1814568#Comment_1814568

Is it still a communicating system, or did you change it to 24 vac? Because if still communicating, the diagram doesn't make sense because the thermostat doesn't have a W1.

EdTheHeaterMan

From what I can gleam from the photos, you are still using a communicating thermostat to operate the AC system. The control board on that air handler has a 4 pin white molex plug at the top to activate a heat relay (for electric heat probably). That White and Blue wire is sending 24 volts to the after market relay you added to the floor of the control cabinet. The contacts on that relay are operating the boiler circuit.

That relay should operate the boiler but you still need to contend with the air handler blower. That may still be blowing cold air when you have a call for heat. You may want to check that out. Let me know what happens after Thanksgiving. If you are blowing cold air when the boiler is running (and before it heats up enough) then you may need to rethink that design. The aquastat on the coil should make on temperature rise and perhaps we can do something with that to reduce the blowing cold air problem.

I solved that problem for another HeatingHelp.com visitor last year