Bosch Greenstar temp drop

bigj273

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

GW

either there’s not a problem or maybe reword the description a little—-what was the thermostat set at? The house was colder that it was supposed to be? Just because the boiler says 68- that doesn’t indicate a problem. It means the boiler isn’t doing anything at that time

Could be a thermostat issue. Do you have multiple zones or just one? If multiple- you likely have a zone controller that indicates when you have a call for heat

Do you have the FW200 control on the greenstar? There’s some factors that make it hard to offer lots of input

bigj273

The thermostat was set at 67. The wood stove had been on all night so I do t believe the heat had kicked on. I had just got done using hot water so It had just been on for the dhw side. I just assumed there was a low point setting where it would have kicked on to keep the temp up.

psb75

The boiler only does what it needs to do to satisfy the thermostatic demands for heat (1.) central heating and 2.) domestic hot water). Hence its high efficiency. Enjoy it.