UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

zeupater

Cardew wrote: »

However no ASHP will output 15kW under all conditions!

Hi

Agree, but it was really only a sanity exercise to gauge the size of the system ...

HTH
Z

Cardew

AsaMac wrote: »

I live in Devon and have a big old house (1850) with 4ft thick flint walls, new double glazing, underfloor heating downstairs and radiators upstairs. My loft is fully insulated and I already have solar PV.

I currently have an LPG system which costs me about £1200 a year, I use the hot water and heating as sparingly as possible but the house is about 190m2 (6.5ft ceilings though) so it takes a lot to heat it up.

I've had a quote from Ecovision of £9k for a Mitsubishi Ecodan 14kW and a Mitsubishi 250L Cylinder and the marketing says:
Expected annual saving compared to LPG: £600 x 20 = £12,000
Expected annual RHI payment: £853.95 x 7 = £5,977.65
Replacement cost of LPG boiler within lifespan of heat pump: £3,000
Total 20 year (lifespan of heat pump) benefit: £20,977.65
So that's a 6.5 year period to break even. Seems not bad.

Has anyone got any advice, opinions and insights?

Firstly, as stated above, your UFH and radiators will be inadequate, presumably the £9k quote doesn't include those.


I love the word 'expected' - I expect to win the lottery this week!


They 'expect' the ASHP to cost £600pa. Taking electricity at a cheap 12p/kWh, that means you will consume approx. 5,000kWh.


If you are lucky enough in a retrofit to get the average system COP of 2.45(obtained in the EST trial) the ASHP will produce approx. 12,250kWh pa. I suggest that ain't enough for a large old house.

TiredGeek

AsaMac wrote: »

I live in Devon and have a big old house (1850) with 4ft thick flint walls, new double glazing, underfloor heating downstairs and radiators upstairs. My loft is fully insulated and I already have solar PV.

I currently have an LPG system which costs me about £1200 a year, I use the hot water and heating as sparingly as possible but the house is about 190m2 (6.5ft ceilings though) so it takes a lot to heat it up.

I've had a quote from Ecovision of £9k for a Mitsubishi Ecodan 14kW and a Mitsubishi 250L Cylinder and the marketing says:
Expected annual saving compared to LPG: £600 x 20 = £12,000
Expected annual RHI payment: £853.95 x 7 = £5,977.65
Replacement cost of LPG boiler within lifespan of heat pump: £3,000
Total 20 year (lifespan of heat pump) benefit: £20,977.65
So that's a 6.5 year period to break even. Seems not bad.

Has anyone got any advice, opinions and insights?

Cardew has correctly pointed out your UFH and radiators probably won't be up to the job if they've been sized for a gas boiler. You'll struggle to sort the UFH but the radiators could be upgraded....


My place is roughly the same size, roughly the same age and roughly the same construction, but completely the other end of the UK. I needed TWO 14kw ecodans to be able to cope in the depths of winter
Sorry, but I think 9k is quite a bit short of the final figure for a sorted system.
As for running costs, very much a guessing game. I don't think it'll be half the cost of gas though as you need the heat pump running for longer to get the house to the same temperature. From my use I'd say expect about a grand a year to keep warm. The RHI might just make the investment viable if you can sort your plumbing issues....

greenerheat

Andy_WSM wrote: »

The manufacturer recommends this can be done. The advantage is that the loft is ALWAYS warmer than the outside temperature, more so in the Summer, so plenty of very cheap hot water coming up. The other night it was -4C outside and the loft never dropped below -1C (I fitted a remote thermometer so I can check this). Right now it's 2C out and 5C in the loft. On the other side of the coin, despite an outdoor temp of just 7C yesterday the Sun was warming the tiles meaning the loft was 15C, so the unit ran even more efficiently yesterday than it would have done if it was outdoors.

You will never pull ALL of the heat out of the loft as the loft is ventilated (as it should be) and you can feel a draft up there.

If at the very worst case the temp in the loft drops below -5C (very unlikely here) then the unit will shut down and I'll have to run the immersion for hot water and plug a fan heater in. I can't imagine that ever happening though as I am near the sea...

Draining of the condense is easy as the unit has a tray built in to catch the condense and it's simply a case of connecting this to a drain, which I have up there anyway as I also have whole house ducted A/C. The other bonus is that the condense goes into my rain water harvesting system, which in turn is used to flush the toilet and run the washing machine!

(You can tell I'm impressed with it, can't you?!)

Have you considered what the salt air will do to your evaporator, any ASHP we install within 5 km from the coast are specially treated for this.

Elizbathmartin

Several of the HVAC service providers are claiming that they are bets in the town while on the other hand if we take a look at the consumer feed back most of the time they are not satisfied with such kind of the services. It's better to look around for the best one instead wasting money and time in hurry.

Norris1

I am having 2 aircon units installed in my house, but I don't know whether to go for the traditional inside and outside units, or the ones where they are all in one and in the unit inside the house, with just an airduct outside.


The in/out installer who is giving me a quote at around £2500, says that the all in one units are noisy, not so efficient at cooling and expensive to run. Does anyone know if this is correct?

Andy_WSM

Norris1 wrote: »

I am having 2 aircon units installed in my house, but I don't know whether to go for the traditional inside and outside units, or the ones where they are all in one and in the unit inside the house, with just an airduct outside.


The in/out installer who is giving me a quote at around £2500, says that the all in one units are noisy, not so efficient at cooling and expensive to run. Does anyone know if this is correct?

The all in one units are called "window ratlers" in the States, where they are very popular. They are a lot cheaper and designed that you can slide them in and out of a pre-formed hole (or window opening) for replacement. In the US you can pop along to Target Supermarket and pick one up off the shelf for £100 and fit it yourself.

My last house had an all in one in the dining room and a split in the living room. The all in one could be heard upstairs as it would resonate through the wall. The split, virtually silent.

Splits are by far the best unit. Hardly any noise inside. Obviously you can't so easily fit or change a split yourself.

matelodave

I've been and stayed in many places where the "through-the-wall" units have been installed and they drive you nuts. The compressor unit is integrated into the unit together with the fans - they start & stop with a shudder and generally rattle whilst they are running. They are bad enough in an office or living room but a nightmare in a bedroom
Split units have the compressor outside so you can't hear it indoors. The indoor units usually have a tangential fan which is much quieter than the propeller on an integrated unit.
I'd go for a split.

Robwiz

Norris1 wrote: »

I am having 2 aircon units installed in my house, but I don't know whether to go for the traditional inside and outside units, or the ones where they are all in one and in the unit inside the house, with just an airduct outside.


The in/out installer who is giving me a quote at around £2500, says that the all in one units are noisy, not so efficient at cooling and expensive to run. Does anyone know if this is correct?

If by the all in one unit you mean a portable, why not give one a go and see how you find it? A reasonably-sized one (12,000 BTU) can be had for around £330 and the quoted noise level is 42-50 dB (about the same as a dishwasher running in the next room).

An all in one will have a lower coefficient of performance (around 3) compared to a split (between 4 and 5) so will use more leccy. But, the up front outlay is much lower and there's no installation cost – you're looking at £330 per unit against £1200 for a mini split. When I did the sums, an all in one worked out cheaper over the first eight years assuming 960 hours of use per winter. On that basis, I'm going for an all in one.

teecee90

Hi

I am embarking on a new business venture and have just agreed terms on an industrial unit. The main workshop/warehouse area is heated with an LPG fired space heater, which I have not plans to change. However, the offices are currently heated by what look like basic wall mounted convection heaters controlled by separate timers on the plugs.

I want to to install air-conditioning in the main customer waiting area (approx 50m2), sales office (Approx 50m2) and meeting room (approx 30m2). If I can fit units that double-up as heaters even better.

Can anyone suggest a suitable unit and approx cost for supply and fitting? Also, can anyone suggest a reliable and value for money installer in the Cambridgeshire area?

Thanks