No circulation after reaching op. temp

[WILLIAM ALDRIDGE]

Forgive me if this has been addressed elsewhere; I did a cursory search but didn't see anything helpful.

I have Rinnai - 69K BTU - 95.5% AFUE - Combi Gas Boiler - Direct Vent (Model: E75CN) water-heater for my radiant heating system (and domestic hot water). When the thermostat calls for heat, it fires up and circulates the water through the radiators, as it should. The problem is that when the water reaches the operating temperature (~190°F), the circulating pump shuts off, even though the thermostat is still calling for heat. This makes the actual heat transfer from radiators to room to be not so great. Why doesn't the pump keep running if the thermostat is calling for heat? Is there a way to change this? Should I install a secondary circulating pump?

I'm also having a second issue. My system needs to be filled and the auto-vent program needs to be run every few days (neither heat nor domestic will work until I do this). I can find no leaks in my hydronic system. What could be causing this? Air is getting in the system somewhere. I have an auto-bleeder installed just in front of the heater--could that be bad?

 

[Reach4]

I'm also having a second issue. My system needs to be filled and the auto-vent program needs to be run every few days (neither heat nor domestic will work until I do this). I can find no leaks in my hydronic system.

It could be that your thermal expansion tank is undersized or defective.

 

[Sponsor]

 

[Terry H]

Have you turned the temp down to see if it will maintain a lower temp?

 

[Fitter30]

Look at pg 57 parameter 3 contacts 22-23
https://www.google.com/url?q=https:...FjAAegQIAxAB&usg=AOvVaw2I58pzSKxfT1VZmnjBk55L