@dssr

You will have had a detailed heat loss assessment but even they can be inaccurate. Going by your oil usage a quick and dirty calculation would put your heat loss at about 4kW, so a 6kW heat pump should be fine. As for running costs it very much depends on the quality of the install. A good one should beat oil going on average prices, but you will also supplement your energy costs with solar.

The length of the external pipework will affect how much heat is lost outside and so your SCOP (efficiency) shorter is better.

I have a 2 bed partial stone cottage and have no problem heating it comfortably with a 5 kW heat pump to put your mind at rest. (adding an extension too)

Posted by: @bontwoody

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@dssr

You will have had a detailed heat loss assessment but even they can be inaccurate....... so a 6kW heat pump should be fine. 

The length of the external pipework will affect how much heat is lost outside.

As it's a grant funded initiative, I don't get to see the assessment or have any input. I may be privy to the manufactures equipment being fitted a few days before installation.

Does that mean the ASHP under these conditions will make 22 degrees inside?

What about this 12 metre maximum distance from ASHP to existing system?

I'm unable to find any regulation that stipulates a maximum length of the flow and return from HP to System. Obviously, the longer the run the more the loss. However, I'm talking about 7 metres from an outside wall to the cylinder (two metres of which is outside for now, but is on the footprint of a future extension.

@dssr I imagine most rooms in your house will have been speced at 21 C, but I would be surprised if you couldn't increase that to 22 C, there seems to be a bit of room for maneuver in your heat pump size. Its only really an issue on the coldest of days even if your heat pump was undersized (which I dont think it is).

I think I have heard 12m before, certainly my brother in laws pipework is about that long. The heat loss will obviously depend on how well they are insulated and the temperature around them (ie inside or outside). As long as they are 28mm copper, flow rate shouldnt be a problem.

If you are getting insulation upgrades too, then there is definitely nothing to worry about with regards getting to 22C. We keep our living room at that, but other rooms a bit cooler.

Could the ashp be wall hung? Then it could be higher up clear if the wheelchair path if it is a gable end? Just a thought?

@judith

Good call Judith, Here is an example of how it might look @dssr along with some performance information

and here is a video which mentions pipe distance, which i happened to come across

https://www.youtube.com/watch?v=9hVgzvkujM0

Thank you all for the excellent feedback and advice.

My situation is unique in that I'm at the behest of the Gov ECO funding scheme. The installers take directions from the LA and another Gov body. They also work so tight to the MCS Standards that I don't have the same flexibility has a paying customer to make any changes. The whole thing is a check box exercise to meet net zero standards, the end user is completely excluded.

My dilemma is, do I walk away from an install that would otherwise genuinely cost me between £12-15k and update my CE system, or move the Heat Pump later. It's the holes left in the brickwork and other damage inside the house from the install that will be problematic. 

Can you provide some photos of the proposed position and potential alternatives then someone (who is probably not me but better qualified) can comment?

Posted by: @judith

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Can you provide some photos of the proposed position and potential alternatives then someone (who is probably not me but better qualified) can comment?

Sorry, I missed your post when my threads were merged.

It's more complex than a photo. The installer have selected the location and will not budge. I asked about wall mounting as suggested and they've also ruled that out. They appear petrified of the regulatory body as it could lose them the lucrative contract with local authorities under the HUG scheme. I've since found others in the same position.

I can either walk away, or take what is being offered and move it all in the spring when it's warmer.

Walking away from free stuff doesn’t seem a good idea.
But the extent of the modifications you list “holes in brickwork and damage inside the house” in order to get the essential wheelchair in can only be commented on when people know how much. 
For example I wondered if the path can be widened but you may have a fence or neighbour's boundary in the way?

Holes are easily filled and possibly even cosmetically OK but altering internal pipes might be more of an issue. How much making good internally is in the HUG scheme?

Posted by: @judith

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How much making good internally is in the HUG scheme?

Good question, and one I have been trying to establish from a range of agencies, including the 'overlords' of the scheme. The Net Zero Hub.

I have been told 'Associated works will be required to make good any areas of the building in accordance with PAS 2030 regulations'. However, I'm unable to find this information.

@dssr A late friend and neighbour of ours was our plumber and decorator for many years; he once said to me ‘When you have any work involving chasing out any plasterwork - tell them to leave it uncovered and I’ll re-plaster for you.’ His reasoning being that many workers are just not cut out to be plasterers and that their mess takes more clearing up than someone competent doing the tidying up work. Just saying… Regards, Toodles.

Posted by: @dssr

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Posted by: @judith

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How much making good internally is in the HUG scheme?

Good question, and one I have been trying to establish from a range of agencies, including the 'overlords' of the scheme. The Net Zero Hub.

I have been told 'Associated works will be required to make good any areas of the building in accordance with PAS 2030 regulations'. However, I'm unable to find this information.

 

A quick Google suggests that other than having to comply with building regulations, the contractor need only provide method statements for the work. I would recommend approving the details in the ('any'?) method statements before agreeing to the work.