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My ASHP installation journey in Monmouthshire, South Wales

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(@novemberromeo)
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I started this off in the 'introduce yourself' thread, but wanted to give updates and didn't want to hijack the conversation there, so have created a new thread....

 

I live in a converted barn in Monmouthshire (South Wales). It was converted around 10 years ago and we bought it 7 years ago. It currently has an oil boiler which has been working well. However, last month, our oil delivery driver spotted a tiny crack in the top of the tank and refused to fill it up. We immediately entered 'panic mode' at the fear of running out of hot water (not using heating at the moment but that will be needed in the next month or so...) as we only have about a quarter of a tank left.

 

I initially reached out to a couple of local heating companies to enquire about replacing the oil tank. It turns out that our current tank is located in a position that would not comply with current build regs (and probably never did) and so replacing it involves more than a simple swap-over: we'd have to either relocate it or build a fire-proof barrier around the tank to meet regs. Most companies didn't want to touch it with a bargepole, although one firm quoted £3,500 to replace the tank and make it regs-compliant.

 

Over the last few years, we've gradually installed air to air heat pumps in most of our rooms because in the summer the house gets very, very hot. It's south/south west facing and we have lots of floor to ceiling glass, so it basically acts like a greenhouse. We've been really pleased with the low running costs, which made me think about exploring using an electric system to replace the oil boiler.

 

Much googling later and I made a few enquiries to local MSC accredited ASHP installers. Our house should be well suited to ASHP because we have underfloor heating throughout - no radiators - and I was also optimistically hoping the costs would be favourable with the RHI scheme.

 

5 weeks in, I have:

* received one quote of £9.5k for install of 7kw Valiant Aerotherm Plus, 200ltr Valiant tank and Valiant controller. Estimated RHI payment of £9.1k. The quote was based on floor plans, an EPC from 2013 and the building survey we commissioned before buying the house. They've emphasised it's an estimate and will be confirmed after paying £500 for them to do the heat calc survey and new EPC. Originally I thought these guys were good, but I've emailed and phoned a couple of times over the last few weeks with questions and they've stopped getting back to me. Maybe they're just too busy.

* received one quote of £18.9k for install of 2 x 10kw Valiant Aerotherm Plus, 200ltr tank and controller. For this one, the company sent someone out to do a free heat loss calculation - they were here for about 2 hours measuring all the rooms up, so I'd imagine the 2 x 10kw spec is right but am hoping it is way over-egged. They've not included any information on estimated RHI payments.

* had a visit from a company to do a quick initial assessment and chat, he estimated 12 - 14k but wouldn't be able to give a final quote unless I paid £299 for a heat loss calculation.

* had a visit from another company to do a quick initial assessment and chat, he estimated 14 - 16k but wouldn't be able to give a final quote unless I paid £250 for a heat loss calculation. I actually felt the most positive about this company, all my communications with them have been really good, they are clearly knowledgeable and appear to have a good reputation. They also promise a 10 year parts and labour warranty, which is way more than the others. They have only been in business 4 years though so how worthwhile this will be remains to be seen. That said, I agreed to pay the £250 for the heat loss calculations, this happened last week, so I am expecting to hear the results of that and get a final quote in the next week or two.

 

I've found it really hard to assess and compare suppliers, particularly because they are unable to quote without first paying for the heat loss survey. Annoyingly, none of the companies were willing to accept heat loss survey results from another company, which would effectively mean paying for the same survey several times just to get comparative quotes.

 

One potential pitfall to my switch to an ASHP is needing a water tank. Our current system is a combi oil boiler and we have no standalone tank. We don't have any suitable space inside the house to locate a tank. Three of the suppliers so far have said we will be fine to locate the water tank outside next to the ASHP if we build a suitably insulated wooden shed structure. One supplier insisted this was a terrible idea and said the tank must be inside the house. I don't know who to believe. I'd welcome input from anyone in a similar situation.

 

I'll update you all in due course...


   
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(@novemberromeo)
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Joined: 3 years ago
Posts: 33
Topic starter  

Four weeks on from my last post....

I decided to pay two companies (the last two in my list above) to do a heat loss survey so they could quote based on my needs.

Company A quoted £15,495 inc VAT for a 8kw midea pump & 200l cylinder. RHI calculated at £9,947

Company B quoted £11,000 inc VAT for a 12kw LG pump * 210l cylinder. RHI calculated at £7,561

Company C (already quoted) £18,900 inc vat for 2 x 10kw Valliant pumps & 200l cylinder. No RHI estimate provided.

 

So, I've had three MCS accredited installers each do their heat loss survey and calculations and have wildly different results! 8kw pump, 12kw pump and 20kw pumps!

I phoned the MCS helpline for some advice, because frankly I do not know how they can get such vastly different results from doing what is supposed to be the same basic process of calculating heat loss of each room and matching that up to a suitable ASHP size.  They weren't particularly helpful unfortunately, other than to say that they advise getting quotes from three companies and going with the one you instinctively feel is the one you want to work with.   As a complete newbie to this, I feel totally unqualified to know who is right and who is wrong.

Does anyone have any advice on how to proceed? 


   
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Mars
 Mars
(@editor)
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@novemberromeo, wow, that's crazy. These are not near misses either. 20kW is a massive heat pump - what is the approximate area you're going to be heating?

Glad you called the MCS, and disappointing to hear that they're weren't helpful. I'll see if I can some replies from reputable and experienced installers.

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(@novemberromeo)
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Topic starter  

@editor thanks for your help!  We are in Monmouthshire, South Wales.

 

The EPC lists total floor space as 136 square metres.

Company A heat loss calculations show a total area of 153 square metres,  space heating requirement of 13,113 kWh/yr, hot water demand 3,3596 kWh/yr
Company B heat loss calculations show a total area of 153 square metres,  space heating requirement of 21,061 kWh/yr, hot water demand 3,057 kWh/yr
Company C provided no calculations.

I'm at a loss as to how they can get such different results!

This post was modified 3 years ago by novemberRomeo

   
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Mars
 Mars
(@editor)
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@novemberromeo, I don't blame you. The 2 x 10kW will almost definitely be overkill. I'll see if I can get some insights for you.

@bobbt9866 and @grahamh can you provide any assistance?

 

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Mars
 Mars
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@novemberromeo, do you have the heat loss calculations?

Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb

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(@novemberromeo)
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@editor Yes, I'd be happy to share them privately at this stage with anyone who's interested.  Reluctant to share them publicly at this stage because they have the company names on.  I'll PM you.


   
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(@kev-m)
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@novemberRomeo, my heating requirements and house size are about the same as your quote A.  I'm happy to look at your heat loss calcs and also send you mine.  I ended up with a 14kW ASHP but the 11.2kW model would probably have been OK.  As @editor says, 20kW is huge.  It would be useful to compare the total heat loss in watts and the watts/m2. 

 


   
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Mars
 Mars
(@editor)
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@novemberromeo, can I send these, privately, to a heat loss specialist to review?

Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb

Follow our sustainability journey at My Home Farm: https://myhomefarm.co.uk


   
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(@novemberromeo)
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Posted by: @editor

@novemberromeo, can I send these, privately, to a heat loss specialist to review?

@editor Yes, please do.  Thanks!

 

This post was modified 3 years ago by novemberRomeo

   
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(@batalto)
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@novemberromeo I posted a tool to do heat loss calculations on the forum. I'd say have a go and do your own so you can compare. It's very easy to do

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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(@novemberromeo)
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Topic starter  

I've updated the summary to show the calculated heat loss in watts and the heat loss W/m2 as per @Kev M's suggestion.

Company A heat loss calculations show a total area of 153 square metres, heat loss of 6,128w, heat loss W/m2 40, space heating requirement of 13,113 kWh/yr, hot water demand 3,3596 kWh/yr
Company B heat loss calculations show a total area of 153 square metres, heat loss of 9,776w, heat loss W/m2 64, space heating requirement of 21,061 kWh/yr, hot water demand 3,057 kWh/yr
Company C provided no calculations.

I am going to try using the Stelrad heat loss calculator tool as per @batalto's suggestion today and will see how that compares! I am also going to email MCS in the hope of getting a more helpful response than I got on the phone. 👍 


   
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