Thinking about a mini split, looking for help$$

[Foxsea]

I'm waiting for 1986 vintage AC unit to pack it in, then I'll replace with heat pump into the original duct work. Gas furnace will become a backup. Air source heat pump technology has come a long way, the cold climate units are something to behold. I have a couple of builds at Apex that used them, owners are very happy.

Yes, like other things, this technology has come far ahead. 30 years ago, it seemed as though we were pioneers. I think the SEER was about 8. It may have been useful to about 10 degrees C. and it was noisy.

Our latest unit, a ducted, whole house system, replaced a 28 year old gas furnace. The SEER is over 20 and it's variable speed and quiet. It has a 10 year parts and labour warranty, too. This winter I don't think back-up heat ever came on.

 

[sly_karma]

The one item that needs to be addressed with cold climate heat pumps is condensate. There is a lot of water generated at the outside unit which will of course freeze. The unit needs to be located and mounted in such a way that the ice doesn't become a hazard or cause melt/freeze impacts on the building.

Apart from that, there are few downsides with modern heat pumps. In the most severe cold, when running on the backup coil, they're still 100% efficient. The best a gas furnace can ever be is ~94% efficient. In more seasonally normal winter conditions, they're up around 300% efficient; ie, delivering three units of heat for each unit of energy consumed. And of course the gas furnace offers no cooling function in summer.

Switching heat sources in an existing home is a tricky decision, with many more factors than simple coefficient of performance as outlined above. Available capacity in the home's electrical service is often a limiting factor, and then considerations like location of outdoor unit, overall cost, installation complexity, etc. In new construction it should be a no brainer, ducted heat pump is less money for more functionality, costs less to run, and doesn't pollute.

 

[Foxsea]

Valid point. Ours was draining to the patio, creating a hazardous patch of ice. A pan beneath it now drains to a rain water leader.

Modern heat pumps also have a good life expectancy. Our last house had a Bryant installed 20 years ago that is still running fine.

I'm also a big fan of this technology, recently installing a HP hot water unit. The more I read about the health impacts of gas appliances, either B-vented or unvented, the more delighted I am to be rid of ours.

The one item that needs to be addressed with cold climate heat pumps is condensate. There is a lot of water generated at the outside unit which will of course freeze. The unit needs to be located and mounted in such a way that the ice doesn't become a hazard or cause melt/freeze impacts on the building.

Apart from that, there are few downsides with modern heat pumps. In the most severe cold, when running on the backup coil, they're still 100% efficient. The best a gas furnace can ever be is ~94% efficient. In more seasonally normal winter conditions, they're up around 300% efficient; ie, delivering three units of heat for each unit of energy consumed. And of course the gas furnace offers no cooling function in summer.

Switching heat sources in an existing home is a tricky decision, with many more factors than simple coefficient of performance as outlined above. Available capacity in the home's electrical service is often a limiting factor, and then considerations like location of outdoor unit, overall cost, installation complexity, etc. In new construction it should be a no brainer, ducted heat pump is less money for more functionality, costs less to run, and doesn't pollute.