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ASHP - where to start?


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Hi folks. Finally starting our new build this year (well hopefully!) in the west of Scotland. We are going for an ASHP preferably with UF heating. The house is going to be "upside down" with bedrooms on the ground floor and living area on the first. My wife really wants UF on the first (living) floor, so looking for recommendations there.

We also have a plumber / heating engineer in the family who is offering to go on a course so he can become accredited and fit the system for us so we can get the RHI payment. Obviously, as he is not familiar with the different systems as yet, he is asking what we are wanting to fit. I'm starting to look around, but really need some advice. Thanks!

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Welcome 

 

if you’re planning a house that is airtight and well insulated, don’t bother with RHI as it will never pay back the “MCS Premium” that it will cost to get it installed. Beware you can’t just “do a course” to become MCS accredited and there is significant cost to the person who wants to become a registered installer. This isn’t just about becoming certified on an ASHP install, there is significantly more to it. 
 

I would focus on getting the heat demand down and then install the smallest ASHP required and leave it at that. Depending on location you can get heat pumps that are treated for coastal regions which may pay dividends as the heat exchanger will last much longer. 

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1 hour ago, PeterW said:

Welcome 

 

if you’re planning a house that is airtight and well insulated, don’t bother with RHI as it will never pay back the “MCS Premium” that it will cost to get it installed. Beware you can’t just “do a course” to become MCS accredited and there is significant cost to the person who wants to become a registered installer. This isn’t just about becoming certified on an ASHP install, there is significantly more to it. 
 

I would focus on getting the heat demand down and then install the smallest ASHP required and leave it at that. Depending on location you can get heat pumps that are treated for coastal regions which may pay dividends as the heat exchanger will last much longer. 

 

For installers in Scotland, it is worth noting that for ASHP installations, applicants can claim 75% up to £7500 'cashback' - virtually a grant - on their £10000 Home Energy Scotland loan when using an MCS registered installer leaving the remaining £2500 as an interest free loan. Prior to the launch of this cashback scheme a few weeks ago, I tended to agree with you, but this cashback scheme has changed this somewhat.

 

But of course, the installer will need full accreditation and their details are checked during the application process.

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Thanks both of you. I just noticed the grant myself tonight so I'll try and phone Home Energy Scotland tomorrow and get some advice. 

I'll also pass this info on to my plumber. He contacted me yesterday saying he could go on a 2 day course with Grant in March, but I guess he will have to look into it further to get full accreditation.

 

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I don’t think the grant is available on a new build. You would get the vat back though. I applied for the cash back loan. I got a quote for a 6 kw heat pump, about 12500. That leaves me 5000 to find myself, which is about 1000 less than what I would pay for just the boiler and installation parts. It’s financially worth it but I think the installer is making off with the majority of the grant as there appears to be about 5-6k of profit in a two or three day job.

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3 hours ago, davejura said:

Hi folks. Finally starting our new build this year (well hopefully!) in the west of Scotland. We are going for an ASHP preferably with UF heating. The house is going to be "upside down" with bedrooms on the ground floor and living area on the first. My wife really wants UF on the first (living) floor, so looking for recommendations there.

We also have a plumber / heating engineer in the family who is offering to go on a course so he can become accredited and fit the system for us so we can get the RHI payment. Obviously, as he is not familiar with the different systems as yet, he is asking what we are wanting to fit. I'm starting to look around, but really need some advice. Thanks!

Davejura.. I suspect that you secretly you want it too!...but.. just and so on.

 

I built a house with UF on both ground and upper floors, suspended solid timber joisted floor on both the ground floor and first floor. The first floor had the plaster board ceiling, 195 mm deep joists and 22mm chipboard, carpet on top. Glass wool between the joists 100 deep, netting over the top of the joists to which the UF pipes were attached to with bits of garden tie wire we cut up. The netting tended to hold the pipes up against the floor and surprisingly it all worked pretty well. Didn't destroy the carpet. It was all done on a shoe string budget a good 25 years ago. I still keep in touch with the folk that bought the house and it is all still working.

 

With hindsight I would have gone for the plaster board ceiling, some 9.0mm thick OSB board on ledgers attached to the sides of the joists, with a lean mix screed encapsulating the pipes. This adds mass, thus sound protection and spreads the heat more. The down side at the time was that this extra load of the screed added to the cost of the joists so I took a chance.

 

We know heat rises so keeping the bedrooms on the ground floor is a good idea as you know if you want a cooler bedroom to sleep in. All I would say is that at the concept design stage make an allowance for the extra weight of the screed when sizing your floor joists, keep your options open, at the very least if you don't at the end of the day go for a heavy screed then you'll still have a good stiff, non bouncy floor.

 

Oh, and the West of Scotland is a great place to live.

 

All the best

 

 

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  • 4 weeks later...

Just had our first quote in. £18k roughly, with UF heating upstairs and radiators downstairs. It's a Mitsubishi Ecodan 11.2kw system (we plan to go into the attic at some point, hence the bigger system). We are entitled to the £7.5K cashback from the £10k loan, but it does come off any future RHI payments, but better to get it right away when building is my thought. So basically, the system will cost us about £10.5k. Any thoughts?

 

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8 minutes ago, davejura said:

Just had our first quote in. £18k roughly, with UF heating upstairs and radiators downstairs.


That includes installing and commissioning the rads and UFH as well as installing the heat pump and cylinder? I’ve got 3 quotes and they range from nearly 30k to 12.5k. That’s for the heat pump and new cylinder as a retrofit as I have UFH already. 


 

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8 minutes ago, davejura said:

Yes it does, but not screed.

 


Here is one that was all in but was all UFH rather than rads. Smaller unit than yours though. 
 

@Redoctober what are your running costs like at this time of year please? 
 

https://forum.buildhub.org.uk/topic/9803-ashp-ufh-quote/?do=findComment&comment=166566

 

 

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We have UFH on both floors. Decided to use Beam & Block for both with insulation and UFH in screed on top. Partly because we had a previous house with a solid first floor and liked it a lot but also because we wanted tiled bathroom floors and this sorts it at a stroke. I know it was more expensive but never did an exact cost comparison. 

 

Only put 80mm PIR in the floor which was a mistake. Would put more if building again.

 

 

 

 

 

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I only had room for 70mm Pir in the floor downstairs so went with fan coils, very fast acting and wonderful in those rare heatwaves (cooling mode). I am considering replacing my old husky ashp I have had for the last 7 years but from what I read on here they weren't much good to start with.  

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6 hours ago, newhome said:

 

@Redoctober  what are your running costs like at this time of year please? 
 

https://forum.buildhub.org.uk/topic/9803-ashp-ufh-quote/?do=findComment&comment=166566

 

 

 

Hi - we operate a 3 bed detached house - 165sq m in total - and our water and heating is run on electricity only - no gas. Not sure how helpful it is, but my annual usage last year from February 2020 to date - so nearly a full year was / is around 7000KWH - our latest bill shows an average daily usage of 19.5kwh - So for completeness, we did have our adult son staying with us for that full period, so there was three of us at home throughout. None of us working. 

 

Obviously the cost of that usage will vary depending upon which tariff you are on but for us, our total annual energy usage came to about £950

Edited by Redoctober
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