Heat pumps - What’s your experience of the benefits and downsides to an ASHP?

Number 1 thing I would want to know is about costs. What are the comparative costs for replacement boiler vs new install ASHP over 5 and 10 years? Installation and any other work needed to make everything work at its best, plus ongoing running costs for 5 and 10 years, based on today's energy rates would be good enough. At what point would we expect to break even? And any subsidies available and how that affects those figures.

I want to do it for the environment, but it also has to make financial sense and be developed enough to do the job it's meant to do. What I've heard about most is that it can struggle to keep the house as warm as a gas boiler system. I'm willing to wait a bit if the technology is developing fast atm. 

Number 1 is cost. with a gas boiler and moving it was £4k. With a green energy loan over 10 years (interest free)and RHI for 7 years. it works on a 60/40 in favour of ASHP.  RHI is not much.  It was £203 this year. 

To give better value a pellet boiler may have given me more. However you need space for the boiler and the auto feeder and the sacks of pelletts. 

Who knows which is better value for money. Problems are few and far between. Serviced often and keep the pipes well insulated and you can save. 

This months gas bill and usage.  In the summer with solar panels as well , i only pay the service charge. 

Thank you for that. My cooker is almost 20 years old, so it wouldn't be an issue to drop the gas (hob only) and go induction hob, so we'd be able to drop gas and the standing charge all together so there's that saving as well.

When we had the solar installed they gave us projections for when we'd be breaking even, that's something I'm interested in for ASHP. I know the projections were exaggerated by some installers but we've kept an eye on it and it's been about right. 

Benefits: They reduce the amount of CO2 you're responsible for. Obviously the way the country's electricity is generated has an impact on this but the country is gradually moving to lower carbon electricity.

Disadvantages:

Cost. They're expensive, even with govt subsidies. There's an argument that the subsidies actually increase costs but that's probably a debate for a different thread.

Controls: They're too complicated. I've seen lots of discussion about compensation curves, flow temperatures, target temperatures etc. While the geeks among us might be happy playing around with the heat pump settings to get the best out of it, Jo Public just wants a system that works. The controls and user interfaces need to be better.

Response: We're all used to being able to switch a gas boiler on and the house heating up quickly. You can't do that with a heat pump. This means you need a different way of thinking about your heating.

I haven't mentioned running costs yet. One of the first questions everyone asks is if it's cheaper to run than a gas boiler because we're conditioned to expect new stuff to be cheaper and/or better. The answer is "maybe". Some people find a heat pump is cheaper to run. Some find it's more expensive. For various reasons I can't tell how mine compares.

Some great insights being shared already, both from those with a heat pump already and a prospective ASHPer, @Gum168 !

And a clear theme emerging in terms of what might be the biggest factor to consider:

So cost (as expected) is the big one!

Really interested to hear more about this green loan, @Heatherd - Was this a government-backed loan or via a bank or other lender? How did you go about calculating the cost-difference to a standard gas boiler replacement - Was this straight-forward or would you recommend seeking out professional advice on this one?

This is another common concern, @Gum168 - after all if you might be incurring higher costs you’d want some reassurance that you’ll be kept nice and toasty as a result. Hoping this is one for our ASHP trialist to clear up, @juliamc, @Bell, @PHILLI2, @Buriton57 - How would you compare the heat output or home comfort levels since getting your gas boilers replaced for an ASHP?

So these companies that fit the ASHP put you in touch with people who can help you fund it. mine was the energy funding trust. They give you a loan over 10 years (mine is £38.30 a month for £5700. 

I have a hybrid system Diakin altherma , half ashp half gas.  When  house starts to warm up off ASHP it takes ages as it does it slowly. No piping hot radiators. just constant heat. Mine is set on 40% gas 60% ASHP. Heat wise it is thee same., just takes longer. During the day is fine when it is during thee summer as costing me nothing with solar. In winter my electric goes to £57.82 from 0, my gas is £29.74. plus all service charges. 

Ah, interesting, I didn't know there are hybrid systems like that, I assumed any top up heat is from other electric heat sources. 

We are in a rural area and there are many villages that don't have gas and we are the last village to the west of Hull that has does. So with the price of oil I know that many in the further out villages are looking into ASHPs. However the local heating engineer who does our servicing said he's not yet convinced that they are quite up to the job yet. He said wait a few years if the boiler is OK.

So, quick question, how is hot water heated? Due to the solar we use the electric immersion element in summer, and gas in winter. TIA. 

You can get the water heated off the solar. That means a super insulated water store. with an IBOOST to help. Check out with https://www.in2gr8tedsolutions.co.uk/ i used them for the batteries but they may be able to give you some advice. I have no water tank . Daikin EVLQ08-CVA3 Hybrid Heat-Pump kit & 33kw Boiler System this is my setup. Cheaper than just gas boiler with cold water tank.  but you can get  https://www.alibaba.com/pla/Heat-Pipe-Collector-Solar-Hot-Water_62478785455.html?mark=google_shopping&biz=pla&pcy=GB&searchText=Split+Solar+Water+Heater&product_id=62478785455&src=sem_ggl&from=sem_ggl&cmpgn=12243057487&adgrp=120239342154&fditm=&tgt=pla-1125668278518&locintrst=&locphyscl=1007330&mtchtyp=&ntwrk=u&device=c&dvcmdl=&creative=496052926216&plcmnt=&plcmntcat=&p1=&p2=&aceid=&position=&localKeyword=&pla_prdid=62478785455&pla_country=GB&pla_lang=en&gclid=Cj0KCQiA8vSOBhCkARIsAGdp6RRS5b66moQfCf1aomX3Pap8k6H64vEn3XaKtqjIUJVZFRPsI38EJYIaArMCEALw_wcB maybe. cannot find them now. 

A heat pump will heat your hot water. It doesn't heat it to as high a temperature as a gas boiler but it will get it hot enough for all domestic use. Most people have a larger hot water tank to compensate for the water being at a lower temperature.

Thank you, that's useful information from both of you.