Heat Pumps: anyone have one/thought about it?

reef said:
I changed the weather curve overnight to 42C at -6 and 28C at 15. It always runs a couple of degrees warmer than the curve, so this gave a leaving water temperature of 31-33C when it was 11-13C outside through the night. It ran very nicely indeed, doing a 12 hour run where it used a steady 350-400w of power, consuming about 4.8kWh in total. COP was about 4.8.

The house is a nice 21C throughout, despite a very strong wind all night. I need another cold night like the night before to test it properly though, as last night was mild. It should tick along at 37-38C LWT, instead of the 40-42C of yesterday morning, which it didn't like. I suspect with the Daikin, it's happy until the LWT is too high for the heat loss of the house, so it can't shed the heat quick enough, return water temp rises too high and it keeps cutting in and out. As soon as I ran an offset yesterday of -4C, leaving water dropped to 38C and power use dropped from an average of 1.8kW to 900w, for a mere 3C drop in LWT.
Click to expand...
Seeing similar behaviour on my 4KW unit with maybe a 50W or so lower power draw at steady state. I think I'm heading for a narrower LWT range of say 28C low to 38C high. Just need the proper cold days to confirm too.
 
Grant Aerona R32 13KW. And external volumiser with 3KW backup heater. 250l Grant cyclinder. Eddi hot water inverter.

House size 294sqm and garage/annex room 47Sqm.

Modern construction and insulation (2016)

Underfloor heating downstairs, rads upstairs.

We changed from an oil boiler in 2023. Wouldn’t go back. The heat is good, it’s been more economical than oil and has contributed to take our house from a C-C to a highB-A in terms of the EPC, making the house more valuable.

Have made some adjustments to the parameters along the way and really happy with how it performs.
 
Hi, just had an Octopus heat pump 'eco' / low flow temperature installation quote of around £4200 for my brand new 4-bed detached house (100 sqm, currently with a gas boiler). This includes a new 200L water cylinder and 5 radiator changes, with a Cosy 6. The actual work is described as straightforward, in terms of no planning permission, plenty of space, etc.

Thought this seemed a little high? I was expecting a new build not to need as much work, given that the insulation is all up to spec and the house feels very warm to me subjectively. I need to look into the figures properly but I'm not convinced this kind of up-front cost will pay for itself very quickly. Any opinions on whether this is reasonable?
 
Seems reasonable, they have upped their prices to be more in line with the wider market. There was no way they were making a profit on a £1k install.

The material cost of the install with a new cylinder is only just covered by the government grant. You’ll be surprised about how much kit and people will turn up on the day to do it.

The insulation just means you need smaller radiators than a less well insulated house. That doesn’t mean they are big enough though.

The radiator changes are needed because your existing ones will have been chosen for a 50-60c water temp where as the eco install targets 45c so you need bigger rads.

I paid 3500 (plus £7500 grant) for mine with 9 radiators, there is absolutely no way they made a profit on it. I had an average salary of 4 people on site for an entire week.
 
They definitely didn't make a penny on mine. I had 9 radiator changes, slimline tank, 6kW Daikin and three guys working for 4 days and it came in at £605! Just the sheer amount of materials filled our double garage beforehand.

I would talk to them and see what it would cost without the radiator changes. You might find it's cheaper to do the 50C flow install and buy and get fitted the bigger radiators yourself.
 
Yeh heat geek is a bit cheaper than they used to be but I think that’s focussed on their ‘zero disrupt’ higher temp model.

If you need a cylinder and want a lower temp install, it’s still pretty spendy.
 
Thanks, I looked at Heatgeeks, but they aren't interested because they can't find my address (presumably because it's a new build).

The cost Octopus quoted for a high-temperature installation is still around £3600, so my thinking is that £600 to get the radiators done at the same time probably isn't worth skimping on.
 
Last edited:
arty said:
It just gives me the 'We are not ready for you yet' page when I enter my address and click on an installer. No contact details in sight.
Click to expand...
If I use PE9 2AZ which is in Stamford as per your location and pick an address it gives me various results.

Earth Nrg
Kraken Plumbing & Heating Limited
B-THERM
 
arty said:
Thanks both, will explore further.
Click to expand...
Add the Adia heat pump interface to your research. Removes or delays the house side upgrades until some data is established. Seems the sort of tech Octopus or Heat geek should be adopting.

www.adiathermal.co.uk

Comfort in every room. Savings on every bill

Smart heat pump control that works with your existing radiators. Auto-balances heating, tracks flexible tariffs, and saves money on every bill.
www.adiathermal.co.uk www.adiathermal.co.uk

 
Last edited:
arty said:
Hi, just had an Octopus heat pump 'eco' / low flow temperature installation quote of around £4200 for my brand new 4-bed detached house (100 sqm, currently with a gas boiler). This includes a new 200L water cylinder and 5 radiator changes, with a Cosy 6. The actual work is described as straightforward, in terms of no planning permission, plenty of space, etc.

Thought this seemed a little high? I was expecting a new build not to need as much work, given that the insulation is all up to spec and the house feels very warm to me subjectively. I need to look into the figures properly but I'm not convinced this kind of up-front cost will pay for itself very quickly. Any opinions on whether this is reasonable?
Click to expand...
I had a very similar quote from Octopus, 4 bed detached, I thought also that it was high considering we had a previous quote on our 3 bed semi from Octopus of £2500, I'm waiting for a quote from heat geeks.
 
Managed to get a really nice run last night for over 7 hours now I've changed some settings. The key ones were changing the emitter type to radiator from fan coil, which allowed a higher delta T of 10 (5 on fancoil) and raising the minimum flow temperature from 28C at 15C to 30C at 12C. It appears with my 10mm microbore setup to work much better. In the 7 hours it ran it used 2.5kWh, ticking along at around 300-400w the whole time, creating 13kWh of heat, giving a COP of 5.2. Leaving flow temp was actually higher than when it was cycling the other day (31-33C compared to 30C before), despite the higher COP. House is 21C throughout.



Just need a colder day now to see how it works then.
 
I’ve just checked and my ‘blast the heat overnight’ approach seems to be paying dividends at the moment with all this mild weather.

I’ve had my heat pump kick on during the day for a few weeks now.
 
b0rn2sk8 said:
I’ve just checked and my ‘blast the heat overnight’ approach seems to be paying dividends at the moment with all this mild weather.

I’ve had my heat pump kick on during the day for a few weeks now.
Click to expand...
Yep, that's exactly what I'm doing on IOG too. I'm running on pure weather compensation with no input from the madoka. I can just set a positive offset on the LWT if we want it a bit warmer and it'll run happily until I turn it off in the morning.
 
You must log in or register to reply here.
Back
Top Bottom