Hoops, on 25 February 2016 - 04:05 PM, said:
I just seem to be going round in circles with the gas or no gas issue. I don't actually know anyone who has fitted an ASHP but I am hoping to visit one of the customers of the local firm who are trying to convince me of its merit
Nooo.. That's not how the decision flow is supposed to work. It goes like this:
Building on mains gas grid?
Yes: install cheap reliable advanced gas boiler and use a few quids worth of mains gas per year. The end.
No: go round in circles between: currently cheap but volatile finite oil, expensive monopolised lpg, very expensive high maintenance biomass, outrageously expensive ground source, cumbersome dirty medieval wood burning stove, overly expensive unecological ASHP that's useless for hot water, over complicated hybrid of the aforementioned with some PV and solar thermal thrown in around a thermal store
Yikes. The more you read into it, the more it will do your head in. Make the decision now to use gas, build your house right and you may not in the rest of your lives spend as much on gas as your ASHP will cost (7k+ if you do it through an MCS co in order to get the RHI grant, which may be a white elephant if the low payments never recover the premium of paying the co)
ASHP have some benefits: they can cool the house too (no RHI compliant install does unless it has been messed with since registering for payments), and in some scenarios they can be a DIY install. They're predominantly crap at producing hot water (your ufh runs on warm water, which they do well) but there are a select few that do well, usually by relying on another technology like a gas boiler for a boost.
When you go to see your people bear in mind that people seldom want to admit to being responsible for making a bum decision and will often talk something up if they aren't privately so enthusiastic about it. Specifically ask them how much time the unit spends defrosting itself in spring and autumn when the world is quite damp but not so cold that the water in general air hasn't frozen on something else before blocking the ASHP up. If they know and can give you detailed assurances that it's a minimal amount of time because they've compromised their lifestyle and adjusted their hot water expectations to match the technological and physical capabilities of he unit, then be sure you're happy to make the same adjustments. If the news that it regularly blocks up with ice and must murder it's own efficiency unblocking itself is news to them/they just set 55 on the thermostat, pay the electric bill and let the unit worry about itself then (sorr to say) they probably won't be the right people to give an honest in depth appraisal of what living wih an ASHP is like. Unless of course, you're happy to take the same approach!
For what my father in law paid for his ASHP, plus what I've been quoted for mine, plus some reasonable chipping in from 3 neighbours, I reckon we could probably have got mains gas brought the quarter mile up the hill to our site. I do still wonder why we didn't consider it way back then. Lack of foresight was probably one, his brother ranting on about how amazing ASHPs are another. His brother builds houses that footballers buy though; not exactly the sort of people who care about the electricity bill if the system sizing was wrong or it spends a lot of time defrosting
Edited by cjard, 26 February 2016 - 01:13 AM.