He freely admitted he knew nothing about heat pumps, he was an ex BG employee
He couldn’t draw the floor plan of the house, I had to do it for him.
He was already in trouble with his employer for drawing the floorplans back to front, they needed to be looking at the house from the front, he could only do them backwards and got yet another telling off from the office at my survey.
He originally calculated over 12kW of heat loss and wasn’t in the least bit surprised even though I told him I expected around 5kW.
The office laughed at him when he submitted the calculation for verification and told him off yet again, I could hear the conversation as it was on speaker phone.
He had put the house down as solid walls.
I did inform Octopus that I knew he was clueless and had no faith in his work and my comments were duly noted.
What were they thinking sending somebody of that quality to do the most important part of the job?
He was a nice guy though.
Two weeks before the installation I had a visit from an installer to make sure everything was OK, I questioned the choice of heat pump and heat loss but still no alarm bells.
That visit was from someone who was leaving the employment that week I subsequently found out.
And no questions from any of the five employees that were present during the install, two installers, two electricians and a few visits from a supervisor to check the quality of the work.
Two further visits post installation, I was laughed at when I asked about OEM monitoring and told that I really didn’t need it and if it was his house he would just use it.
The second installation quality auditor seemed to think my heat pump was doing quite well even though I showed him all the other heat pumps here. Again I questioned the install but still no response.
How did I know it was the wrong heat pump, I’m an accountant, these people do this all day every day, you would have thought one of them would notice?
Design it down to the wire and rely on other crutches if you need to.
Wear an extra jumper on the odd occasion it’s actually that cold for a sustained period.
Low temperature radiators are handy when it gets cold. Drop your room temperature to 17C from 20C (say because it couldn’t quite keep up with the heat loss) and your rad output at a given flow temperature will pop up.
I laughed out loud when doing the calc for “frost mode” (could the heat pump stop the place from freezing when it’s -20C out - which is design condition here) and "reheat from frost mode (if flow temp at steady state design condition is 40C but you’re starting with a room at 5C not 20C the rads really kick out more heat)
Plan on the insulation of the property getting better not worse over time. It’s unlikely that this is the only measure you’ll take.
Any fix any stuffups with…an AC. We have fitted one of these to knock the edge off in summer. (a fortnight of 30C and 100% humidity knocked back to 24C and DRY is bliss). Noddy basic (doesn’t even have an electronic expansion valve; just a capillary tube) 9000 BTU class minisplit.
€630 inc VAT minsplit. Vac pump, gauges, flaring tool, and heated diode leak detector another €250 inc VAT if you don’t have these already. Lineset, cable, drain hose, floor mounts say €200 inc VAT. A round €1000 worth of bits. Call it €2000 fitted if you didn’t DIY it.
On paper it’ll chuck in 2.1 kW at -7C with a COP of just over 3 (need not worry about defrost at that temperature); 1.3 kW @ +2C with a COP of 4.6; 0.8 kW @ +7C with a COP of 5.5
Bit chilly at design condition (or beyond?)
Blast that into the house somewhere and open the doors and you’ll be fine.
Bit sticky in June/July?
1.1 kW of cooling @ 25C for an EER (COP) of 10.8; 1.75 kW @ 30C for an EER of 6.6 - hardly a criminal amount of electricity and at a time of year when it’s easy to offset against PV
Wanna heat back up from frost setting faster?
Crack it on at 2.9 kW at +7C with a COP of 4.5 (the COP drops at full load vs part load)
Better IMO to size the wet system to the wire (to maximise the everyday performance of it) and rely on being able to fudge it in extremis with an minisplit.
Put the split in the living room NOT the conservatory. That way you can heat the house with it with conservatory doors shut; and it’s no problem if you open the doors to the conservatory for the cold air to get into the conservatory if for some bizarre reason you wanted to use that in the summer rather than sitting in the garden under the shade of some PV panels / vines.
Not all is plain sailing mind.
Bolt it in. Flare up the pipework. Hook up the wires. Light the woodburner to warm up the indoor unit so that moisture evaporates at a sensible temperature. Vacuum it down. Release the refrigerant. Leak check.
Balls. Thought I’d made a bad flare until I realised that the unit was leaking from an internal braze (and the gas coming down the insulation sleeve) rather than my flare:
Those sniffers detect leaks down to 3g/year. (about what leaks from a car AC compressor rotating seal even by design). Cracking bits of kit for £60 or so. Don’t bother with soapy water etc. Nitrogen pressure test is nicer but lots more kit to have for the odd installation; and wouldn’t have made identifying the location of the (tiny) leak and showing it to the supplier easy.
Shut the liquid line, fun the split in full cooling override until you’ve drawn the refrigerant back into the outdoor unit, shut the vapour line and knock the power off. Call the supplier.
Local distributor to be fair took one look at the vid and asked whether I’d like to pickup a new indoor unit myself or for them to come swap it and weight out the refrigerant/weight in the correct amount in the event that a material quantity had leaked.
Not easy then but can’t grumble at that on a €630 widget.
Shouldn’t really do that in the UK because F-Gas regs. (you need a certificate to know that you shouldn’t let all the gas out before you’re allowed to touch these) Rest of Europe and the USA are less fussed. Can buy the units and the kit to fit them properly at B&Q. Don’t be irresponsible though and do get the tools including one of those heated diode detectors if you are fitting them.
Default assumption: house has no glass in the windows
They should leave it bloody blank in my opinion so that the installing company are forced to put their neck on the line to a degree by estimating a number.
Not that their necks are on the line. Like heck are RECC or MCS are ever going to dare terminate Octopus registrations. Those outfits exist now for the purpose of preventing the smaller players that are good at heating and don’t care for box ticking from entering the market.
I’d REALLY like DESNZ to offer the BUS grant to anybody who can PROVE they’ve fitted the kit correctly via a year’s worth of operating data. Buy the kit outright. (on a 0% card if you have to) Prove it works well. (with OEM etc) Get your VAT back and the BUS at the end of the year.
They don’t need to allocate much funding to that track but imagine the benchmark it would set for installation quality / the look of fear on Ian Rippin’s face if they were to do so.
It’s not an air source heat pump installed by an MCS union member. You’re allowed to fit gas boilers and stinky oil boilers wherever you like. The MCS union successfully lobbied government to make it illegal to fit heat pumps of any description unless you use MCS labour. MCS don’t do air conditioning so it isn’t permitted development.
However if you throw it on the wall anyway and nobody moans for four years it’s effectively legal from a planning consent perspective.
Unless your neighbours are awful people I would, given the price point, install it somewhere that it can’t be seen or heard and roll the dice on planning consent.
Yes, absolutely. For now, I would usually point people towards John Cantor’s website - https://heatpumps.co.uk/ - as a fantastic place to start their research. His book is a great read too.
I done some calculations, and reckon that 4 fan units provide an extra 330 W of heat output at Δ20, an increase of 25% on those radiators. This seems in line with independent testing that SpeedComfort mention on their FAQ page, if you extrapolate to the right towards 40C:
[Power increase in % vs. Supply water temperature in °C]
Correlating to some measurements I did of the whole system, this increases the total effective output at Δ50 by 1,500 W (but not real output at that temperature), and drops the overall flow temperature by 0.5 C.
Exactly. Why design for worst case, you are always compromising the other ~90% of the time. Pareto; design for the 80% and mitigate the other 20% in other ways.
@Stephen_Crown Your prior cat5e cabling was fortunate. I installed mine in a IPxx box that was given to me by the Octopus Solar installer when he was clearing his van out (!), running the cable through a handy gap behind the cover. In fact, it’s so much easier to access than inside the HP casing, I’d do it that way in preference. Signal isn’t great (-79dBm), but works. Could be ok for you longer term?
I wanted to go direct to EmonHub/CMS, so changed the MQTT reporting to one data point per message, and modified the MQTT topic, so it is registered automatically in EmonCMS.
What’s the suggestions with the outdoor unit in terms of condensation/excess water? It’d be on a north facing wall, little to no sun in winter, with plumbing available on the internal side of the wall to drain water away if that’s the ‘done thing’?
In terms of heat loss from the survey, ive not had the quote pack back yet but the bathroom and all 3 downstairs rads would be changed. Bedrooms are apparently fine. So removing the conservatory seems to have changed things.
I guess it cant hurt to ‘oversize’ the radiators though? All 4 bedrooms have single panel radiators that could be swapped with double.
This is my thinking on the subject and I hope it makes sense.
I have sized all my radiators in proportion to the heat loss of the room so that whatever flow temperature I run at all the rooms are the same temperature. If you go a bit smaller on rooms such as bedrooms then that is fine. You really don’t want radiators going in and out of play if that makes sense, it will wreak havoc with the efficiency and the feel of your home.
What you don’t what is trvs mucking things up and to that end I have removed all of mine and fitted Danfoss RLV-D lock shields to all radiators.
The trvs are unnecessary if the radiators are the correct size for the room.
Obviously, the bigger the radiators the lower you can go on the flow temperature.
If you can get Octopus to fit the radiators of your choice it will be the cheapest and most convenient option.
I would post up your radiators schedule when you get it so we can all have a look.
I don’t think the siting of the heat pump is of any particular concern, mine is on a south(ish) facing wall but when it is damp outside and cool then it’s damp everywhere.
Octopus are pretty good at actually fitting stuff and they made sure there was adequate drainage around the heat pump, I would have no concerns here.
I would advise you let us know your heat loss, radiator schedule and proposed heat pump so you can get some views on whether it will work well.
Until October 15th we had undersized primaries upstairs restricting 50% of our heating circuit (didn’t notice in the summer for obvious reasons).
The Double DHW is an initial daily schedule to 43 (during cheapest electric period) then every Tuesday 04:00 - 05:00, a legionella cycle to 60 (assisted by the immersion - currently not monitored).
The house is already heating to 21 all day long with a overshoot setting of 4 and a modulation of 5. The night time setback is 19 and the house rarely ever gets near that
Happy to discuss further optimizations but based on daily usage and what I am seeing the heat pump is likely oversized (Believe it should be around 5kw and not 9)
Even with oversized K2 radiators in every room the return temp is still getting to high and turning off the system.
They have done the same with your lounge as mine, included the heat loss in full twice as you have two radiators in the lounge.
What do they say your heat loss is?
The total from the radiator schedule is 7,418w with `both’ lounges included and 5,870w with the lounge only included once.
The 8kW is the correct size in my opinion as the 6kW won’t go any lower than the 8kW as far as I understand things as they use the same compressor.
You might like to check with Octopus, a few of us would like to know.
You have 6,009w of radiator output at a flow of 50c and a delta t of around 30c. I had around 9,000w of radiators at the time of my survey and I am doubling mine right now to cope with the 9kW heat pump! Yours would need to triple.
It’s also interesting that they have assessed your annual heat requirement as 7% more than mine yet you get a much smaller heat pump.
At a flow of 35c you would have radiator output of around 1,500w.
I wonder how low the EDLA08 can run?
I also see it is an EDLA08E2V3 and not and EDLA08E3V3, is that without a back up heater?.
