ASHP installation cost

LolekUK

I've recently enquired pricing for an ASHP system, with whole new radiators (wet system) and water cylinder.

I've had few quotes, but they vary in pricing. As some I assume are through MCS certified "surveyors" (and not actual installers) and the cheapest I guess from an Installer/Plumber that is also MCS certified and is doing the actual job. Of course, I like the cheap one and I liked the guy, seemed to be knowledgeable and walked through all the pipe routes with me etc. The more expensive ones, said there would be another survey from actual installer to go through everything.

150m2+ property, 4 bedrooms, utility room, 2 bathrooms, office, large living room. 

Do those numbers sound about right? Is it doable at £13k or is there something wrong? or perhaps something wrong with the more expensive ones
1. £13,000 (which with RHI of £11k+ is very tempting)
2. £16,700
3. £18,712

8.5 Mitsubishi Ecodan,
210l tank
13 radiators (different sizes)
pipe work around the house for radiators
wireless thermostat controls
Mel Cloud

Thank you in advance for any comments

Reed_Richards

My house (a bungalow) had 14 radiators before the ASHP was installed and ended up with 2 more, 16.  It needed a 12 kW heat pump and I got a 300 l tank.  My cost was similar to your quote number 2 but I also re-routed all the heating pipes from under the floor (where they were getting a bit corroded) to the loft - which was a lot of extra work and pipes.  So on that basis £13k might be doable, depending on how much pipework is needed.  I also went with the installer who would do the actual job and was very pleased with how diligent he was.

shinytop

LolekUK, our house is about the same size as yours but a bungalow; 14kW Ecodan, 250l tank, 14 Stelrad radiators in 2 wireless zones, all new pipework (we had no CH before) was about £16.5k.

Your Ecodan is about £1k less than mine, you have a smaller tank and 1 less radiator. Your low quote is low but not silly.  The high one looks....high.  Don't forget any supplier will have to go through the same MCS process (detailed room by room heat loss calculations, etc.) for you to get RHI as well as getting a system that actually works; it's worth making sure your cheap one is doing this.

An 8.5 kW Ecodan was borderline for us so we went for the bigger one.  What's your annual heating and HW usage from your EPC? 

LolekUK

shinytop said:

LolekUK, our house is about the same size as yours but a bungalow; 14kW Ecodan, 250l tank, 14 Stelrad radiators in 2 wireless zones, all new pipework (we had no CH before) was about £16.5k.

Your Ecodan is about £1k less than mine, you have a smaller tank and 1 less radiator. Your low quote is low but not silly.  The high one looks....high.  Don't forget any supplier will have to go through the same MCS process (detailed room by room heat loss calculations, etc.) for you to get RHI as well as getting a system that actually works; it's worth making sure your cheap one is doing this.

An 8.5 kW Ecodan was borderline for us so we went for the bigger one.  What's your annual heating and HW usage from your EPC? 

Thanks for this @shi@shinytop

The installer gave us 2 options, 8.5kW and 11.2kW. Apparently, the current requirement is 6.6kW+ so 8.5kW should be ok and the 11.2kW option was given to us (additional £1k) if we ever thought of extending the house etc (which we wouldn't as we already have extension done).

From the EPC,
Space heating: 20095
Water heating: 2299

Perhaps yours slightly more expensive due to being a bungalow also? Our first floor is boards so are going to lift them up and run pipework underneath. For the ground floor - just doing drops down from 1st floor.

Reed_Richards

My bungalow occupies a larger ground area than an equivalent house would so the pipe runs are very long which might increase cost but there was no troublesome floorboard lifting involved. 

I had two EPCs, two years apart with no significant changes made.  These determined:
Space heating:  17236 or 15900
Water heating: 3802 or 2987

And yet I needed a 12 kW heat pump (11.2 kW would have been okay).

I think there is a case to be made for over-sizing the radiators and the heat pump.  You should get a detailed heat loss calculation that determines the size you need for each radiator.  This is based on the heat loss on a cold day in winter.  But if you need the capability of coping with severely cold weather and/or warming up the house quickly from cold then you should over-size the radiators and increase the heat pump output to match.  You may be told that this will cause the heat pump to cycle but most of the year your heat pump will be doing that anyway    

shinytop

Reed_Richards said:

My bungalow occupies a larger ground area than an equivalent house would so the pipe runs are very long which might increase cost but there was no troublesome floorboard lifting involved. 

I had two EPCs, two years apart with no significant changes made.  These determined:
Space heating:  17236 or 15900
Water heating: 3802 or 2987

And yet I needed a 12 kW heat pump (11.2 kW would have been okay).

I think there is a case to be made for over-sizing the radiators and the heat pump.  You should get a detailed heat loss calculation that determines the size you need for each radiator.  This is based on the heat loss on a cold day in winter.  But if you need the capability of coping with severely cold weather and/or warming up the house quickly from cold then you should over-size the radiators and increase the heat pump output to match.  You may be told that this will cause the heat pump to cycle but most of the year your heat pump will be doing that anyway    

@Lolekuk, sorry I made a mistake; we had a choice between the 11.2 kW and the 14 kW. Our EPC numbers are almost the same as yours. Our house is quite well insulated too.  Going by mine and @Reed_Richards ASHPs, maybe consider the 11.2 kW?  

Our installation was relatively easy; a lot of the pipe runs are through the attic and no floorboards involved either.  

matelodave

Our 140m2 bungalow has an 11kw Daikin with underfloor heating all over and I wouldn't think that a smaller unit would do the job. We did get a couple of quotes for 8kw units but even my own calculations worked out that they'd be inadequate.

One of the major reasons for dissatisfaction with heatpumps is that a lot of them are underpowered and thus require use of the boost/back-up heater when it's cold. This reduces the COP to 1 which will pulls the efficiency right down and increases running costs.

Possibly OK if you've got really good insulation but I'm of a similar opinion as the others that 8kw may not be enough. You really need to study the calculations to see how the unit sizing has been derived.Look at the figures for both 8 and 11 kw units to see how they compare. In my opinion you can always turn a bigger unit down but there's not much you can do if it's undersized in the first place.

LolekUK

Thank you all for your input. 

I've been trying to find some online calculators to work out required pump size but couldn't find one. Is there anything available out there?

Thanks.

LolekUK

LolekUK said:

Thank you all for your input. 

I've been trying to find some online calculators to work out required pump size but couldn't find one. Is there anything available out there?

Thanks.

P.s. ecodan tool, didn't ask too many questions (re insulation, windows, heat/water requirements) and suggested 8.5kW pump. I hope there is something better available

matelodave

There are plenty of on-line heat loss calculators which allow you to input wall, window, floor and wall sizes, together with their u-values so you can get a fairly accurate indication of the the individual room and whole house heat losses.

It will give you a bit of a sanity check against the heat loss calculations given by the heatpump installer. You could consider that a decent set of controls that allow you to zone part of the system so they aren't all heating at the same time might reduce the size and capacity of the heat source.

Even a wet finger in the air guess of 8kw/150 m2 = a heating capacity of just 53w/m2 which is quite low.unless you've gt pretty good insulation.

Our bungalow at 140m2 with 11kw has a heating capacity of 78w/m2 and it's reasonably well insulated with cavity wall, 300+mm of insulation in the loft and 20 year old double glazing. I guess a house of equivalent floor area will have a roof of half the size and you'll get the benefit of heat rising from the ground floor but in the end there's no subsitute for a proper detailed heat loss calculation (which will have to be done anyway if you want to claim RHI).

It's not possible for any of us to give you definitive advice because we've only got experience of our own installations and have no idea of the specifications of your house or proposed system.

Reed_Richards

LolekUK said:
.... ecodan tool, didn't ask too many questions (re insulation, windows, heat/water requirements) and suggested 8.5kW pump. I hope there is something better available

What is better is the very detailed heat loss calculations your installer is obliged to do as part of the MCS certification process.  This will tell you the heat requirement of every room and thus the radiator size (for whatever water temperature is chosen).  Add together the requirements of all the radiators then increase this to allow for the time when the heat pump is maintaining the hot water in the tank or defrosting itself and you get the minimum heat pump capacity requirement.

The trouble is this does not happen until you have signed-up for the work to be done.  That, and the new EPC certificate if you have one more than two years old, should happen before anything else so your installer knows what size of heat pump to order. 

Not sure I agree with @matelodave that zone controls would help; you surely have to make contingency for all zones being on at the same time.

Edit.  As an aside, typically gas or oil boilers are way oversized compared to the radiator requirements.  I think this is so they can heat the hot water cylinder or direct hot water quickly as required.  This also benefits their ability to bring the house to temperature quickly from cold, but only for as long as it takes for the central heating system water to reach its specified temperature,  after that it's just down to the radiator outputs.