Bosch Greenstar temp drop

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BigJ273

Minister of Fire
Feb 15, 2015
739
Maryland
Here’s my scenario

I have a Bosch Greenstar 151 combi boiler. We usually burn wood for heat, but once the stove goes out the boiler kicks on. Last night I woke up at 3am to shower. When I got done I walked into the laundry room and noticed the temp on the boiler was reading 68 degrees Fahrenheit. I thought this was low, as it normally stays above 100. The pressure was reading normal. Nothing was running at the time. I turned the thermostat up and the heat kicked on like it should and the boiler heated to around 155 like it normally does. Once the heat shut off I ran the hot water and the temp dropped on the boiler but it cut on once it reached around 117, like it normally does.

My question is, why did it drop to 68 and not kick on? This is the second time I’ve noticed this happen this year. The pressure was fine.

Side note: it was pretty cold last night and I don’t think the heat had cut on yet since the wood stove was running