Hi Matt
No MMI here, I’m on the generation before that, but I wouldn’t have any hesitation wiring one up, I had to lend tools to the sparky who did mine 
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The problem is I can’t access the grant as far as I know, so it’s £3500+ I think for the unit. At an estimated saving of £100-£150 a year through better SCOP (I have solar+battery so only pay 10-15p per unit on average through the winter) it doesn’t stack up. What I need is a clause in the grant that says if your heat pump is ‘faulty’ you can access the grant.