u/effingitup

My landlord is getting quotes on replacing our AC unit with a heat pump, but he warned us that he wouldn’t want us to use it for heating. I’d like to question/validate his concerns so I could benefit from the heat savings!

Some context
- We live in a 120 year old triplex with a flat roof. Our 3rd floor unit is 1250sq ft.
- This is in Montreal, Canada. Last year we got one snowfall of 75cm, freezing rain storms and a few power outages. Weather is just getting worse
- The current AC compressor unit is on the roof. It would be replaced with a heat pump unit (model TBD) on a stand
- There was a leak that took 2 years to address, so the roof membrane, lining and flashing were replaced in 2024 and are still under warranty. None of us want to go through that hell again so I understand why he has concerns about damaging the roof.

He’s worried that there will be so much ice accumulation (edit: during winter use) around the unit, that it will put undue pressure in one spot, creating another issue. It is difficult to access the roof during the winter, so regular maintenance will be sparse.

- Has anyone experienced damage to their roof due to the weight of the unit + ice accumulation (edit: during winter use) ?
- I see that people combat buildup with heated trays and a gravel bed for ground-level units. I don’t think this is feasible. Are there other roof top solutions?
- If we ask for a taller stand, will wind exposure be an issue? Should the installers be doing anything different with the installation?
- He also thinks we could minimize wear and tear on the unit by just using it as an ac, and continue using the existing, inefficient baseboard heaters. I think I just need to shrug at this one (unless there is a benefit to using it on a regular basis)

I did a cursory search of this subreddit and couldn’t find anyone with these concerns. If it has been answered I’d gladly read those threads. I can get more info on the existing quotes if that helps!