We had a Bosch Combi 151 installed aprox 2 years ago and have had ongoing issues. Since it started to get cold this past Fall, the unit has been unreliable.
We're on propane, the house is a forced air system, and we use a Nest thermostat. It's a weekend house, so we keep the Nest on eco for most of the week.
I'm not sure if we have a single issue here, or multiple separate problems.
The primary issue is that the system will blow cool air for quite a long time when the Nest is set to 72. Over several service calls, the installer was unable to replicate the issue. One of the service guys simply set the two dials to max I suppose assuming this would raise the temperature quicker and eliminate the cool air issue. It did not work. This same technician informed me that the valve on the back of the unit needed to be replaced, which was recently done.
On the most recent service call however, a different guy from the installer did in fact see the issue - the pipe leading to the air handler was not hot, when it should have been. He was able to determine that a valve inside the unit was not switching back over to heat after being switched to hot water. He adjusted this valve and the appeared to fix the issue. Unclear if it is actually resolved fully, but we appear to no longer have that particular problem. However, he also reduced the two nobs on front to lower temp levels - and now I am noticing that when set to 72, the temp never quite gets there - it gets to about 68 after staying on for a long time - then shuts off.
The second issue is the condensate pump - or the valve that leads to it - appears to have some issues. The pump turns on randomly every hour or two and makes a fairly loud noise for maybe 10 seconds. I can hear it from the living room above where it is in the basement. On a recent visit to our house, shortly after turning the temp up on the Nest (after it was on eco for the week), the pump was making quite a bit of noise, so I went to check it, and it was splashing water all over the basement floor, and the pipe coming from the back of the boiler was shaking repeatedly. Today, this happened again - loud noise from the pump - went downstairs to check, and water was splashing and the pipe was shaking. Unclear if this is related to the valve issue above or not.
Im really not familiar with this technology so im really just trying to understand are these common issues? Is the pump issue possibly related to the valve that was replaced? Is the pump and valve issue connected to the internal valve issue (the one that switches from hot water to air and back)?
If the forced air is no longer getting us past 68 degrees, is that due to the dial setting on the front of the unit?
Is there any reason we wouldn’t increase this to 5.5, 6, or max for hot air? Would this dial setting have anything to do with the valve/pump issue?
If feels like we have a ton of problems here - im trying to be patient with the service tech guys, but this issue has been ongoing for many months now.