Need help with central boiler system

[Kb12]

My central boiler system is blowing cold air through the vents in the house. The boiler is piped in series through the water heater then the heat exchanger in the furnace. The hot water is fine. I checked the temp on the inlet and outlet of the furnace HX without furnace running and it's 175ish on both sides. But within 4-5 minutes of of turning on the blower fan the inlet side drops to around 130 and around 90 on the outlet. Then once I turn the blower off the temp takes around an hour to recover back to normal. I'm thinking water is circulating through the system properly. I'm thinking the thermal valve (central boiler part # 250004) to be the problem. Before I go replacing parts I figured I'd get some opinions on the problem.

 

[2412]

Need to know how it is piped. Just having a part number doesn’t help.

Does it look like this? https://centralboiler.com/media/2631/install-central-boiler-standard-heat-pump-c240.pdf

 

[Kb12]

Need to know how it is piped. Just having a part number doesn’t help.

Does it look like this? https://centralboiler.com/media/2631/install-central-boiler-standard-heat-pump-c240.pdf

Yes exactly like that

 

[2412]

Check the temperature on each pipe at the valve. Do you have an IR thermometer?

Seems like the valve is probably bad. Central has rebuild kits for some of their valves, but I don’t know about that one.

 

[Kb12]

This issue is resolved. I just needed to replace the Thermostat in that valve.

 

[2412]

Good to hear. Thank you for reporting back.