Why did you choose an air source heat pump?

[ToughButterCup]

23 hours ago, DamonHD said:

.... heat pumps are the main focus of my PhD research!

 

Part of my reasoning is here: https://www.earth.org.uk/note-on-combi-replacement-dilemma.html

 

An interesting read that .... worth re-reading for me anyway if only for the bibliography

 

 

Especially this article : Myths about Heat Pumps

Edited 1 hour ago by ToughButterCup

[Dillsue]

46 minutes ago, Oz07 said:

Alright in theory, try finding one in practice. 

For a like for like swap it's no different than a boiler swap and maybe easier as there's no flue??

 

I don't know what the current installer skills are but when the current install base of HPs start to get to the end of life I'd like to think(hope!) there'd be alot more HP savvy plumbers around. Getting back to the "should you be worried about replacing a failed HP" question, I think the answer is no but be prepared to pay a bit of a premium to get it done by someone who knows what they are doing.

[jack]

We self-installed a 5 kW Panasonic Aquarea in 2015. Our electrician did the wiring (very simple) and the plumber took care of the plumbing from where it entered the house. We probably paid £400 all up for the installation, maybe less. I did the pipework from the plant room, through the underslab insulation, and plumbed it into the unit.

 

As to why we went with a heat pump:

• Despite there being gas on the road and the bungalow we were replacing being built in the 1950s, there was no gas to the property. It would have cost us time, money, and disruption to install gas.
• We wanted to avoid paying two lots of standing charges.
• We'd used an induction hob at a friend's place and wanted one of those instead of a gas cooker. 
• We were going for PassivHaus class insulation and airtightness, so we knew that we wouldn't need a massive heat source to heat it. The idea of a low-and-slow option seemed more compatible with the house's thermal characteristics.  
• We wanted the option of cooling. Having lived with it for about 8 years (we didn't enable it for the first couple of years), this is probably one of the best reasons to choose ASHP in a well-insulated house with UFH, imo.
• We (well, I!) wanted some sort of home automation, and I felt that an ASHP offered more interesting control options than a boiler. We haven't actually integrated the ASHP in the way I'd thought we might (the modbus module for the ASHP was too expensive to justify), so this point was somewhat moot in the end.
• We installed a lot of solar (8.5 kWp) and I thought we'd be able to at least partly power the ASHP with excess solar. With the benefit of hindsight, I'm bot sure this was a great argument. I'm genuinely unsure how often we generate excess energy at a time when the house needs heating. In the shoulder months we often don't need heat, and in winter when heat's required, we often generate very little solar, let alone excess solar. 

I don't remember whether I considered E7, E10, or any other time of use tariffs at the time we made the decision to go with an ASHP, but cheap overnight rates have since become of the strongest reasons for using an ASHP imo.

 

For example, I have our system set to prioritise heating during the 6 hour cheap window with have with Intelligent Octopus Go. I allow a little bit of overheating during that period, and allow things to cool down a little more during the expensive period before turning on the heating. There are sometimes periods of several days where the heating is only on during the cheap period, which is quite satisfying to see given it's about a quarter of the price than the peak rate.

 

The main concern I had was DHW recharge time. That hasn't turned out to be a massive issue, except when our younger one - Mr three-hour-shower-of-power - is home for the holidays. Upon reflection, I'd have gone for a larger tank than the 250 L one we installed. That would have allowed me to lower the DHW temp even further, while ensuring ample hot water.    

 

17 hours ago, MikeGrahamT21 said:

Does anyone worry about the thoughts of replacing the heat pump should it fail? Have just had a look at Vaillants which seem to have 7 year warranty, vs their gas boilers which have a 10 year warranty. Obviously the first install with conversion from gas/oil/lpg gives you the £7.5k grant, but if it should fail out of warranty then essentially its full price for another, the thought of that scares the hell outta me having one. Appreciate in 7 years time they maybe a lot cheaper, but only maybe.

I don't know how repairable boilers are, but I get the sense that ASHPs could have a very long life, at least while parts are still available for any given model. How repairable any particular issue is depends on the failure mode.

 

About three years after we installed the unit, either the control board or the pump failed. Apparently both are replaced at the same time, because it isn't possible to tell why one or the other failed, and one of them failing can bring the other one down with it. Sounded like bollocks to me, but I did a bit of research at the time and this seemed to be a common view.

 

I don't recall what that cost us, because it was tied up with some other work, but certainly it was several hundred quid. I think the pump alone might have been £400, which sounded like an utter rort for a smallish pump, but I wasn't able to find a cheaper equivalent.

 

It's since continued running without issue for a further 7 years.

 

If something catastrophic happened and the whole unit needed replacing, I'd just go and buy a new one for £2-3k and install it myself, reusing the existing wiring and plumbing. The units themselves aren't that expensive, even for decent brands. For example, the current equivalent of the model we installed is about £2700. 

[Oz07]

14 minutes ago, Dillsue said:

For a like for like swap it's no different than a boiler swap and maybe easier as there's no flue??

 

I don't know what the current installer skills are but when the current install base of HPs start to get to the end of life I'd like to think(hope!) there'd be alot more HP savvy plumbers around. Getting back to the "should you be worried about replacing a failed HP" question, I think the answer is no but be prepared to pay a bit of a premium to get it done by someone who knows what they are doing.

Fair point another 10 years probably a lot more guys will have experience of them 

[JohnMo]

1 hour ago, Oz07 said:

Alright in theory, try finding one in practice. 

Well aren't you the negative one