I had one installed eight years ago when I bought my house. I’ve used it to heat the entire place, but this winter, I struggled to maintain even 20°C indoors on really cold days.
Well, today I finally brought my air compressor inside and gave the guts of the indoor unit a thorough blasting - and now it feels like an oven in here. I’ve been lowering the thermostat all day, and it’s still way too hot. It literally feels like it’s putting out twice the heat now. I was expecting a slight improvement, but nothing like this.
I got around to cleaning our outside unit last year, and didn’t think it would be a big deal as it looked pretty clean at a glance. Once I got the sheet metal off and started looking and spraying, good lord it was filthy. Now that it is near new again inside, I plan to just take the top off every year and do a regular rinse to keep that buildup down. I can’t say how much better it works now from numbers, but it has to exchange heat far more now than before from the sheer gunk I took off.