Posted by: @adamk

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Also I’m not entirely convinced the heat loss the last company did is that accurate 

I apologise if this has been covered already but have you got any way to sense check loss calculations eg from past usage.  The two, three hour full professional surveys I had done on my house both said 16kW, the actual loss is 7kW.  This may be extreme but illustrates how far out surveys can be 

@jamespa I’ve had a few done most come out around 7kw so that’s probably about right, but the loss per room I’ve only got one and it’s been corrected a few times but one bedroom is still listed 2m2 smaller than it is.

@jamespa to be that far out the assessor has got the insulation thickness of the floor, walls and ceiling too thin.

i have 150mm thickness but its celotex not rockwool, took ages to explain that to the assessor who could only input thickness and not the true R rating.

@adamk Sounds encouraging, what about any independent measure of total loss eg from current gas/oil consumption.

Rooms share heat to a fair extent so it's debatable how much precise room by room losses matter, so long as they are roughly right.  If in doubt oversize emitters and turn down the lsv (or flow temp if they are all oversized).  Much more important to get the total right so your heat pump is right-sized.

Posted by: @agentgeorge

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to be that far out (16 kW Vs 7kW actual) the assessor has got the insulation thickness of the floor, walls and ceiling too thin.

I got the calculation details for one of the two surveys, they ignored any fabric upgrades they couldn't see (principally insulation for the solid walls) even though I made a big point of telling the surveyor about them, double counted room to room losses and overestimated ventilation loss.  I presume the other surveyor must have done similar.  GIGO

@jamespa what I didn’t want to do was oversize too much then end up having the HP cycling. What I have noticed is most companies I’ve contacted want to fit a 45L Vaillant buffer/volumizer? Yet after watching this weeks QA vid a guy on there said no buffers.

Posted by: @adamk

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@jamespa what I didn’t want to do was oversize too much then end up having the HP cycling. What I have noticed is most companies I’ve contacted want to fit a 45L Vaillant buffer/volumizer? Yet after watching this weeks QA vid a guy on there said no buffers.

The guy was right as regards buffer tanks, avoid.  However a 2 port volumiser is ok. Unfortunately terminology isn't quite consistent.

Check that it's got 2 ports only.  2 ports good, 3 or 4 ports bad.

@jamespa “They are all equal but, some are more equal than others.” 😉

just trying to roughly get an idea what price an install should be if the following has already been done.

1) upgraded some 15mm copper runs to 22mm. 15mm for the last 3m worst case.

2) the above mentioned 22mm and about half the rads (15mm feeds) fed from 28mm flow and return.

3) 28mm primaries run from plant room and lagged and core drilled through back wall.

4) plant room 1300w x 900d x 2300h

5) new meter box on same side of house as plant room and heat pump, so easy run along wall for cabling.

6) no rad changes as part of the quote.

i would think the only work needed is heat pump base, heat pump mount, 28mm primaries up back wall in primary pro lagging, pipe work for HW tank and rad circuits in plant room, electrical work for plant room and heat pump, smart controls, commissioning.

@adamk, in terms of ballpark pricing, if we assume a straightforward install of a mid-size unit (say 8–12kW), with a standard heat pump ready HW cylinder and proper controls/commissioning, you’d expect to be in the region of £9,000–£12,000 (pre-BUS grant).

That assumes you’re going with a reputable installer using quality kit and doing things by the book: no cut corners, proper lagging, flow setting and performance commissioning. Some might come in a bit lower, but I’d be cautious if it drops below £9,000, because at that point they’re likely clawing it back somewhere else (labour, electrical spec, shortcuts, etc.). The caveat there will be the size and brand of ASHP. 

Estimated time of completion is another benchmark. If they say it’ll be installed and commissioned in a couple of days, run.

Posted by: @adamk

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just trying to roughly get an idea what price an install should be if the following has already been done.

1) upgraded some 15mm copper runs to 22mm. 15mm for the last 3m worst case.

2) the above mentioned 22mm and about half the rads (15mm feeds) fed from 28mm flow and return.

3) 28mm primaries run from plant room and lagged and core drilled through back wall.

4) plant room 1300w x 900d x 2300h

5) new meter box on same side of house as plant room and heat pump, so easy run along wall for cabling.

6) no rad changes as part of the quote.

i would think the only work needed is heat pump base, heat pump mount, 28mm primaries up back wall in primary pro lagging, pipe work for HW tank and rad circuits in plant room, electrical work for plant room and heat pump, smart controls, commissioning.

I agree with @mars. 

My install was not dissimilar.  I got a 7kW Vaillant, 200l cylinder and 4 rads (including one fancoil) for 12.5K les grant.  Im in the south east of england, prices may differ elsewhere.  In my case the 16A feed for the ASHP was already in place  (my friendly electrician did that for £180 - I ran the cable he connected it up), but the pipework run from the ASHP to the point where all the existing pipework converged was a bit of a nasty and took a whole day, even though I had done most of the 'building' work to expose the voids where I wanted it hidden and then made good afterwards.

The whole install was six long days with one person doing the whole thing roughly split as follows

• Receive & check deliveries, site ashp, base on top of existing paving, run primaries to location of existing boiler - 2 days total
• Fit DHW tank & vent pipe - 1 day (8am-9pm without a break!)
• Radiators - 1 day
• Wiring, flush, connect up, debug, commission - 1 day
• Remove old cold water tank, insulate, tidy up generally, commission internet gateway - 1 day

I watched the guy more or less throughout and he worked very hard, so I dont think it could reasonably have been done in fewer man-days. 

@editor guess the reason im asking is cause ive looked at the break down on heat geeks quote system and then stripped out what ive already done and im getting around £2800 after BUS for 7KW Vaillant with 250L HW tank and me doing the base. but so far cheapest is £3800, maybe there doing the base like the HG quote suggests?

I noticed that on different days the Heat Geek website gives different prices. sometimes about £5.5k and other times £7.5k (above BUS).