Here's an Oxy Moron for You. High Efficiency Furnaces Don't Work in Extreme Cold
True, Dr. Google and several furnace companies say so. Our furnace was coming on many times in short succession yet we were feeling cold. It won't heat to more than 16C (~65F). We checked everything, AMs and PMs are correct, programme is correct, piping outside is not blocked by snow. Seems these furnaces burn so efficiently they leave a lot of moisture in the air. We do not notice a humidity problem inside but apparently lots with these furnaces do. Then, in cold weather, this moisture freezes in the intake and out take pipes and blocks them off and the moisture or lack of air flow, not sure which, flips a switch limiting how long the furnace stays on.
We are lucky, we do have heat and it's enough for warmth but we have to wear extra clothing inside. It's just started this nonsense again this morning, it was fine the last couple of days in our warm spell. Sheesh. The furnace man is on call, says he expects the pipes need to be bigger. I guess he's waiting to get them.