Which ASHP model / brand to go with...

wiffola

I'm looking to retro-fit an air to water air source heat pump for all of our heating and hot water needs. We live in an 1895 cottage 90m2.

We'll be using oversized radiators on 15mm pipework, ideally without a buffer tank due to internal space issues.

All I would like is some advice on brands of ASHP. They all seems to have different COP's but I'm not sure whether they are all tested in the same conditions, and also how relevant these are anyways.

These are the units we have been quoted for...

1. DanFoss AQ 9kw

2. Daikin Altherma High temperature (Not sure what wattage - cant find the quote right now)

3. Mitsubishi Ecodan 8.5kw

This isn't a thread to talk about if it's the right option or not - been there done that and appreciate all the help people on here have given.

Any recommendations?

[Deleted User]

Let's hope this thread does not become side tracked as you say...

We put a 14kw EcoDan [15mm insulated pipes into UFH/fan convectors - 210lt DHW tank] into a 106sqm c1906 house with CWI which has transformed the house.

Not been through a full on winter yet but so far it's great. We have backup heating. Still trying to pin down running costs but so far is a fraction of our previous lpg useage. Now have Solar PV installed which has changed things again...

I know people with the low temp 11.? kw Daikin Altherma and they love it too only it has a lot stuff to house indoors.

As your house is quite old and not much smaller would an 8.5kw EcoDan cope on rads. Look into rads carefully to make sure it will not be costly to run through higher flow temps. That's why we ended up with fan convectors as the temp lift is much lower so higher COP.

Cheers

rogerblack

Unfortunately, there isn't a smiley with a train derailing.

Firstly - have you actually ensured that this will be adequate for the colder months?
My house is of a similar size and vintage, and in the colder months, needs more like 15-18kW to keep it adequately warm.

COP is one figure.
Ideally you want a nice graph.
Unfortunately, this is comparatively rare, I've only seen it for a toshiba AC.
The graph has COP versus air temp, and total heat pumped versus air-temp.

Both of these are important - it doesn't help you much if your heat pump is still at a COP of 3, at -10C, but is down to 1/2 of its output compared to 15C.
You'll end up spending rather a lot on topping up the heat if it gets that chilly.
Consider also the warranty terms, in both cases, and what the conditions are.

I'm at the point of considering air-source heatpump, though a fairly different system - running on economy 7, and using a stupidly large buffer-tank.

wiffola

jeepjunkie wrote: »

As your house is quite old and not much smaller would an 8.5kw EcoDan cope on rads.

Thanks for the help both.

I'm getting a SAP report done this week so will know more on exact sizing. This is what 3 individual installers have specified.

This thread is really just to see if spending an extra £3-4k on a DanFoss is worth it.

They look and sound great (the DanFoss AQ) but I'm just basing it on figures...

Ps. Jeepiejunkie whats your backup heating and is it linked with the ASHP? If so how does it work and perform?

Cardew

Without going over old ground, I suspect all of the major ASHPs meet their spec.

The crucial factor seems to be the knowledge of those installing. Personally I would concentrate more on getting some feedback on the installer and if possible get some sort of guarantee that the system will perform to a certain standard and have manufacturer involvement.

SunReader

Cardew wrote: »

Without going over old ground, I suspect all of the major ASHPs meet their spec.

Don't suspect anything when investing thousands in a long term energy solution.

Also it depends what spec you are looking at. Bear in mind that the COP figures are lab tests and a truer picture of performance for all year use would be the SPF figure, then there is the defrost cycle which uses energy. Also factor in the additional energy required to reheat you DHW at sub zero conditions: if electrical it costs nearly triple the cost of gas per kWh. Finally, the dB noise output might be a consideration depending where you place the condenser

I'm a firm believer in heat pumps, but sceptical about manufacturer's and BS EN 14511 figures. You really need opinions from experienced HVAC engineering professionals here imo.

Cardew

SunReader wrote: »

Don't suspect anything when investing thousands in a long term energy solution.

Also it depends what spec you are looking at. Bear in mind that the COP figures are lab tests and a truer picture of performance for all year use would be the SPF figure, then there is the defrost cycle which uses energy. Also factor in the additional energy required to reheat you DHW at sub zero conditions: if electrical it costs nearly triple the cost of gas per kWh. Finally, the dB noise output might be a consideration depending where you place the condenser

I'm a firm believer in heat pumps, but sceptical about manufacturer's and BS EN 14511 figures. You really need opinions from experienced HVAC engineering professionals here imo.

Thank you for your advice!

Over the last 4 or 5 years there have been literally thousands of posts on MSE about the pros and cons of heat pumps; that includes quite a few posters who install and commission heat pumps. Additionally the EST contribute and discuss heat pumps and the results of their extensive 12 month trial of both Ground Source and Air source.

Bedtime reading for you!

https://forums.moneysavingexpert.com/discussion/1464827
https://forums.moneysavingexpert.com/discussion/2964222
https://forums.moneysavingexpert.com/discussion/2959648
https://forums.moneysavingexpert.com/discussion/702257
https://forums.moneysavingexpert.com/discussion/3553313
https://forums.moneysavingexpert.com/discussion/2968958

[Deleted User]

wiffola wrote: »

Thanks for the help both.

I'm getting a SAP report done this week so will know more on exact sizing. This is what 3 individual installers have specified.

This thread is really just to see if spending an extra £3-4k on a DanFoss is worth it.

They look and sound great (the DanFoss AQ) but I'm just basing it on figures...

Ps. Jeepiejunkie whats your backup heating and is it linked with the ASHP? If so how does it work and perform?

Nothing fancy i'm afraid. Just flame effect fires fuelled by the LPG bulk tank [still 60% full despite topups suspended for almost a year] and multifuel stoves which can give out a silly amount of heat. And if things get really bad... oil filled rads. Imersion in tank for DHW. Not a practical solution but there if need be...

[Deleted User]

rogerblack wrote: »

Unfortunately, there isn't a smiley with a train derailing.

Firstly - have you actually ensured that this will be adequate for the colder months?
My house is of a similar size and vintage, and in the colder months, needs more like 15-18kW to keep it adequately warm.

COP is one figure.
Ideally you want a nice graph.
Unfortunately, this is comparatively rare, I've only seen it for a toshiba AC.
The graph has COP versus air temp, and total heat pumped versus air-temp.

Both of these are important - it doesn't help you much if your heat pump is still at a COP of 3, at -10C, but is down to 1/2 of its output compared to 15C.
You'll end up spending rather a lot on topping up the heat if it gets that chilly.
Consider also the warranty terms, in both cases, and what the conditions are.

I'm at the point of considering air-source heatpump, though a fairly different system - running on economy 7, and using a stupidly large buffer-tank.

Hello,

Have you had the opportunity to be in a house heated by an ASHP over winter or had any site visits:question: I had which swung it for me over the alternatives.

Just wondered as you are not a million miles away from me...:question:

Cheers

[Deleted User]

The last 8.5kw EcoDan I saw installed was in a 30-40 year old house that was completely refurbed with UFH. Lot's of insulation, low ceilings etc. Approx size was 140sqm.

rogerblack

jeepjunkie wrote: »

Hello,

Have you had the opportunity to be in a house heated by an ASHP over winter or had any site visits:question: I had which swung it for me over the alternatives.

Nope.
I feel a site visit is relatively unimportant.
I believe ASHP (or GSHP) can work, and can be cheaper (a little to a fair bit) than gas.
However, efficiencies in various installations vary considerably, meaning one can make sense, and the other not.
A site visit is unlikely to help, unless they happen to have the exact model of heatpump, external temperature profiles, and internal water temperatures are similar.
I'm perhaps somewhat unusual in that I'm only considering ASHP only because it has the potential to be very much cheaper than gas, in the case of a system running (for most of the year) entirely on economy 7, with a very large buffer store.

The considerable initial outlay is something I'm still running numbers on.