Buderus GB142-60 AM10 Setpoint

jschmidts

New/Used install of boiler unit DHW off, Space heating temp dial set to 125 degrees. AM10 module is calling for a flow temp of 120, boiler maintains a 100 degree temp with a Delta T of 25-30 degrees. Bypassed the AM10 module, wired Relay directly to WA terminals cycles on, lights burner raises to 110 degrees than scales back to 100 degrees (relatively low fire) and remains. Chimney Sweep mode cycles burner between 100 degrees and high set point of 125 degrees(would get hotter if set higher). Any idea why the unit overrides the set point and lowers the fire rate to maintain this lower temp?

jschmidts

I am able to manually adjust load to maintain a water temp in manual mode.

Noel

The modulating point can't be the same number as the high limit off point, therefore it modulates to avoid hitting limit.

jschmidts

TY. The high limit is set to 125, the AM10 is commanding 120, and the GB142 rests at 100? Will I never see 120 degree flow? My understanding is that the AM10 module sends the target flow temp to the unit based on the heating curve and the boiler modulates to meet the target flow temp. Correct me if I'm wrong please. In this case the AM10 is sending a target temp of 120degrees. Without the AM10 and a high limit of 125 the flow rests at 100 degrees.

Dave_22

I was just about to post a question on this controller. I have the same issue using the analog in house thermostat (can't remember the model #). I woke this morning 3 degrees under the thermostat setpoint. When i checked the boiler, it was running at 135 with a 115 return temp. I have the space heat dial turned up to 190 yet the boiler runs like it just wants to maintain a 20 degree delta. My guess is it's just terrible programming of it's control system. it should raise the water temp as the in house temp begins to drop under thermostat setting.

jschmidts

Solved! my issue was the load setting. Set at 30% load Max.just couldn't keep up with colder temps.