Hello everyone.
My wife and I bought our home in July 2014. It has a DC90 Ultra High Efficiency furnace and a heat pump/exchange system. I'm pretty sure it's from the early 90's. It's beige in colour. Shortly after moving in we replaced the original thermostat with a NEST unit.
This evening I noticed that the home was starting to feel cold (north of Toronto, Ontario Canada). I checked the NEST and it showed that the start-up of the furnace to return the home temp to the set temperature was 'delayed' by 3 minutes. There was a message on the screen that said the 'boiler' was shutting off frequently during the heating cycle. It advised that this may be an indication that something was wrong with the furnace. Sure enough, once the timer elapsed, the furnace can be heard coming on but the fan would not. It did this a couple of times and then it stopped coming on all together.
At this point the NEST had a fault notification that there was no POWER coming to the NEST from Rh wire. I ran the troubleshooting (breaker, power switch, etc.) but these didn't correct the problem.
I turned the NEST off for a couple of minutes. When I turned it back on, the furnace turned back on and the fan kicked in. But this only lasted a couple of minutes before it shut off again. It's done this a few times now. I've now turned it off to be safe.
Any ideas?
Thanks.