Air Source Heat Pumps - Any good in practice?

weewards

Hi, I have researching Air Source heating systems and find very conflicting information. The Energy Saving Sites say its cheap to run but a few people I have spoken to say the opposite, one stating that they were told their house would cost only £300 per year to heat but actually cost £2000.

We live in Scotland & the wife likes (would like) to be warm!

Personal experience would be a great help please?

[Deleted User]

I posted quite a lot about our Mitsubishi EcoDan 14kw heat pump some time ago. Nothings changed, still brilliant after several years. Location rural Scotland, old house with a total electric bill ~£800 odd pa. We do have solar pv which helps. Cheers

matelodave

I've got a Daikin 11kw heating a 140m2 detached bungalow - my wife is also a chilly mortal and so the unit is on almost continuously as we are both at home all day. We are all electric except for a log burner used in the venings in the winter


Our average electricity consumption over 5 years has been around 7500kwh a year (all electric - no solar panels) worst year (2012) about 8500kwh (around £1000), best year (2014) less than 6000kwh (£700)


The main thing is to make sure that the place is insulated and draught proofed as well as possible. The heating system should be matched to the house (heatpump, heat emitters and controls).


Most problems are caused by poorly spec'd systems or trying to put a heat pump on an existing heating system which was designed for a conventional boiler.


Heatpump systems work differently to conventional systems and need to be understood properly to get the best out of them. Trying to run them like a conventional system will increase costs significantly and not give satisfactory performance

Cardew

There are loads of posts on MSE about heat pumps if you do a search, and like everywhere else on the internet, the opinions vary considerably.


As said above, they have to be installed correctly, in a suitable house and operated correctly.


The Energy Saving Trust carried out a 12 month trial on a load of heat pumps and the results were disappointing to say the least. They extended the trial for a further 12 months, and allowed all the manufacturers to modify the installations. Even then the results were hardly exciting. Overall the average COP for all ASHP was 2.45 i.e. for 1kWh input you got the heat equivalent of 2.45kWh. So if you achieved average performance, with electricity @ 12p/kWh your heating cost would be 4.9p/kWh. As it is colder in Scotland your cost might be slightly higher.


Given the dramatic reduction in oil prices to well under 3p/kWh an ASHP does not compete favourably against oil or gas CH in running costs.


The cost of installing a system can be eye-watering - up to £10,000, but RHI can offset this.

[Deleted User]

Cardew wrote: »

There are loads of posts on MSE about heat pumps if you do a search, and like everywhere else on the internet, the opinions vary considerably.

Yup

Cardew wrote: »

As said above, they have to be installed correctly, in a suitable house and operated correctly.

Yup

Cardew wrote: »

The Energy Saving Trust carried out a 12 month trial on a load of heat pumps and the results were disappointing to say the least. They extended the trial for a further 12 months, and allowed all the manufacturers to modify the installations. Even then the results were hardly exciting. Overall the average COP for all ASHP was 2.45 i.e. for 1kWh input you got the heat equivalent of 2.45kWh. So if you achieved average performance, with electricity @ 12p/kWh your heating cost would be 4.9p/kWh. As it is colder in Scotland your cost might be slightly higher.

Electricity @ 12p/kWh :eek: this is MSE 10p/kWh is more likely.

Cardew wrote: »

Given the dramatic reduction in oil prices to well under 3p/kWh an ASHP does not compete favourably against oil or gas CH in running costs.

ASHPs and Mains gas CH are two entirely different markets.

Oil has only been recently been cheap and stinks. Never met anyone, even now who's oil or Biomass running costs beat not only my ASHP but others too.

Cardew wrote: »

The cost of installing a system can be eye-watering - up to £10,000, but RHI can offset this.

RHI - As Churchill would say, Oh Yeess... Making an install much the same as mains gas CH...

CashStrapped

This document may interest you.

It is a summary of a study conducted by Nottingham University into the effectivness of retrofitting modern energy saving practices onto old housing stock. Specifically 1930s semis as these make up the majority of housing stock in the country.

What makes it uniqie is how they conducted it.

They actually built from scratch a 1930s house to 1930s standards. It was however packed full of sensors. They then slowly retrofitted it and measured what effect each energy saving method had on the house.

Not only this, but they even retrofitted it in different orders to see what order to do things was the best.

They also included MVHR's in this study.

What makes the study really interesting is that it reflects the average house owner. It very much hilighted that it was not so much the product that was used but how well it was installed that made the biggest difference.

They had the sensors and the technology to go back and see how well things worked. Many times the contractor had to go back and extensivly re-do the work. This would not have been apparent to the average homeowner.

So the varity of experience that people have can often be down to how well all (not just MVHRs) energy saving products are installed. They also suggested that the attention to detail required would be beyond the majority of contractors and homeowners...which I can believe.

Do read the whole document as it covers many other aspects of retrofitting an older property.

Enjoy!

http://www.lboro.ac.uk/microsites/enterprise/calebre/project-calebre-summary.pdf

lstar337

jeepjunkie wrote: »

Electricity @ 12p/kWh :eek: this is MSE 10p/kWh is more likely.

You would be hard pressed to find that in my region, without a massive STD charge anyway.

12p is far more accurate in my opinion.

[Deleted User]

lstar337 wrote: »

You would be hard pressed to find that in my region, without a massive STD charge anyway.

12p is far more accurate in my opinion.

Copied from my E.ON Account.

E.ON uSwitch Fixed 1 Collective Oct 15
Unit rate Normal 9.345p per kWh
Standing charge 16.422p per day

Cheers

lstar337

jeepjunkie wrote: »

Copied from my E.ON Account.

E.ON uSwitch Fixed 1 Collective Oct 15
Unit rate Normal 9.345p per kWh
Standing charge 16.422p per day

Cheers

I don't doubt it is possible, but 12p is a better average price.

Smiley_Dan

CashStrapped wrote: »

This document may interest you.

It is a summary of a study conducted by Nottingham University into the effectivness of retrofitting modern energy saving practices onto old housing stock. Specifically 1930s semis as these make up the majority of housing stock in the country.
...

Thanks for this. It's confirmation of the growing recognition that whole-house, holistic retrofit is the only way forward. Not piecemeal, unambitious tick boxes like "CWI" and "2G".

Of course, what makes this more complicated is that this then has to be extrapolated across all building styles, in fact all buildings, because different buildings perform very different.

Let's hope Amber Rudd is reading. Fat chance!

CashStrapped

Smiley_Dan wrote: »

Thanks for this. It's confirmation of the growing recognition that whole-house, holistic retrofit is the only way forward.

The problem, as the study highlights is that the attention to detail required to ensure the retrofits (specifically the mvhr) work and are effective may be beyond the quality control of most installers and home owners.

In fact I am sure somewhere in the summary, even with all the equipment at their disposal the study could not get the air tightness of the old style property (without spending a considerable amount) down to a level which made the mvhr fully effective/worthwhile.

This would not be a cost effective solution for many home owners