That is precisely what we have and for the same reasons. It is true, though, some engineers/companies will not perform service work at height, so it may limit your future choices when it comes to servicing. If an installer fits it there, it would make sense for them to agree to service it.

Also be warned, though heat pumps are generally quieter, they do still emit vibrations that may annoy you when inside the house under some conditions. Ironically, we don't notice ours when it's working hard, but when the compressor is operating at low speeds, it can be felt rather than heard on that side of the house, feeling a bit like a distant idling truck. It has never caused us an issue, but it is something to consider if the location is backing onto a bedroom, for example.

Posted by: @stevehsp

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A possible drawback the designer pointed out to us might be servicing - some engineers might not be keen to climb up a ladder onto flat roof to look at it. Is this something I should be worried about, have others run into this, or is it not really a concern ?

Yes, this is a valid consideration. I've heard similar concerns from both manufacturers and installers. While accessing equipment via a ladder onto a flat roof is generally safer than working directly from a ladder, it can still deter some service engineers.

Another factor to weigh is maintenance: if components need repair or replacement, the accessibility challenges might make some professionals hesitant to take on the job. It's worth discussing this with potential installers upfront to gauge their comfort level and ensure they're equipped to handle future servicing needs.

Thanks both

It can be positioned so that it's not on a bedroom wall, and only the spare room is on that side of the house. I'd hope we'd be OK in that respect but of course we'd never be sure until it was done. Having it in the garden would probably mean being directly below a bedroom window so that's not ideal either.

I'll ask the installer about the servicing he might take on, good point. But at some stage I guess the manufacturer might need to come out. I note you say 'some' not 'all' engineers / companies might be reticent to take this on, so that's good! Perhaps it's worth contacting the relevant manufacturer before finally deciding.

@arundalep I think the access is now a major H&S issue for all companies; we recently had FTTP installed and the route had to be more circuitous than we thought it might as the installers are strictly forbidden from gaining access via flat roofs now. Toodles.

Posted by: @stevehsp

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I'll ask the installer about the servicing he might take on, good point. But at some stage I guess the manufacturer might need to come out. I note you say 'some' not 'all' engineers / companies might be reticent to take this on, so that's good! Perhaps it's worth contacting the relevant manufacturer before finally deciding.

Possibly you could have movable barriers available.  The principal risk I think is forgetting you are on a flat roof, stepping back and...  barriers prevent this.

@jamespa We have 4 solar panels on a flat roof and the 3 sides away from that which attaches to the house had scaffolding and barriers in place before the roofers arrived. The next year they had to erect another set of scaffolding and barriers to make changes to the panel mountings as they vibrated against the micro-invertors whenever we experienced high winds. Toodles.

Posted by: @toodles

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@jamespa We have 4 solar panels on a flat roof and the 3 sides away from that which attaches to the house had scaffolding and barriers in place before the roofers arrived. The next year they had to erect another set of scaffolding and barriers to make changes to the panel mountings as they vibrated against the micro-invertors whenever we experienced high winds. Toodles.

Yes it can be a problem.

When we put our solar panels on a flat roof one very serious consideration was access to clean the windows!  The window cleaner is happy.