Beelbeebub

M y OP was trying to illustrate (albeit with a very simplistic test) that even a homethee is superficially "not possible" to convert to HP could be heated with the low flow required. Obviously upgrading the windows and incrwqcing insulation would help reduce bills and also reduce the size of the required HP. But they aren't necessary. You will get a greater carbon reduction (for the same running cost) by switching to a well sorted HP now than insulating and still running a gas boiler. Of course we should also be insulating. It's not either or.

You assume just because a property is ranked D or lower it is unsuitable for a HP. But neglect that if a property is electrically heated it drops several (about 2) categories vs gas. We have gone from E to C simply by swapping to gas. So there will be a plenty of perfectly suitible homes ranked D or E simply because they are using storage heaters. Just looked up 2 flats of ours. Identical except one has electric heating and the other gas combi Electric scores 40 points E Gas scores 65 points D

100% the Internet should never be a requirement for any of your house functions.

Yeah we tried some - need a second supply for the electronics and fan. Fan is quiet, but still noisier than no fan. Cost a packet Very difficult to use. Tenant had endless problems - "I wish I'd stuck to the old one" (she wanted the upgrade). In theory it predicts use and onky loads up with enough energy to supply next day. In practice it means you can't change the output easily and if you do up it, you run out early. They do have much better insulation and heat retention though which helps prevent th "hot mornings, cold evenings" issue. If they did a dumb one with simple 2 dial controls and ideally no need for a separate always on feed for the controls that might be useful. Still weigh a sodding ton, which is no fun hauling up 5 flights of stairs! 😁

It varies by area but I think the national average is around 9% Are you haply with the system? £4200 is not a crazy amount for a new heating system. Yes, the anti HP brigade bang on about how you can get a new boiler for under a grand, but unless you are doing a really simple like for like swap of a heat only boiler with a cheap non vat one man band fitter you're going to be closer to £1,500. Add in upgrades due to new regs (eg condensate drains) and some replacements of old parts like valves and rads and you coukd easily be towards £3-4k. I've had quotes for £5-6k for fitting an a2a multisplit to a storage heater flat. That's probably less than fitting it out with a gas and rad system. https://www.ons.gov.uk/peoplepopulationandcommunity/housing/articles/census2021howhomesareheatedinyourarea/2023-01-05

I can only see them as a fit for areas of extreme visual sensitivity.

My main issue is the servicing/access issue. The install would be really involved. Roofing work, loft hatch, crawl boards etc. A box on the outside just needs some drills. Also, those units will always be lower volume manufacture vs. the beige box units. So will always be more expensive. Plus no good for flats! 😁

They don't have to be ground mounted. If you look around they are often mounted above head height on walls etc. Air to air units can be pretty small but some of the r32 based units aren't big, about the same volume as a washing machine (but wider and less deep). Yes, e7 tariifs etc make them cheaper to run but most e7 are around 10-15p a unit vs the 20-25p for standard rates. A HP would only have to have a scop of 2 to make it cheaper. That should be easy with a new install. The radiators (or fan coils) would probably be no bigger than the existing storage heaters. If we were happy to route the pipes on the surface at high level (to get past doorways etc) it would be a relatively easy install. As storage heaters are notoriously uncontrollable, you coukd probably set the system up with no zones and WC and it would still be far nicer than the old setup.

Yes. This. Maybe an increaced grant for replacing any electric system with an efficency of less than 101% (ie all resistance heaters) with a HP and associated plumbing etc. The only wrinkle is a lot of electric systems are in flats because of the difficulty of getting gas to them. This means the outside units have to be installed remotely or at height or there needs to be a building wide heat distribution system. A balcony system would be good, but that probably rules out alot of air to water systems just leaving air to air. Allowing hot water to still be risistance heated (cylinder or instantaneous) would help alot and DHW is typically not a large portion of demand.

Absolutely, the old single panel. Rads are only good for high temps - like 70C flows. Thats too high anyway. There's a really safety issue with flow temps that high. I use k22 by default and usually the largest one that can sensibly fit. I only drop down to K21 or p+ if there is a width consideration, eg narrowncorrodors or clearance for a door swing. As a result almost all the properties I look after can function at moderate or low temps. Typically 50C or lower. Tenants still tend to set the flow temps to 65C because that is what everyone thinks they should be. People expect their hearing system to be a scalding hot radiator for 15minutes followed by a cold radiator for 45 minutes whilst you mutter about the heating not being on. Anyway, that policy has put me in a reasonable place for switching over to Heatpumps eventually. I am being cautious though, as I am wary of making a change and the poor tenant's bills going up. So my first switch is likely to be adding a HP to create hybrid system so the tenant has flexibility and isn't "trapped" on one system.

I agree reducing demand should be a priority. But my point is you can still run at low flow temps in a relatively unimproved dwelling as long as you have reasonable radiators.

Found this, absolutely no idea how much it is, if it works or is. Just snake oil. https://denoize.com/

That outbuilding is going to bounce the sound stright back at the house. Drive along with your window down and note how much reflected noise you get driving pet a wall vs hedge vs open fields. Have a really good look at what you can do to that structure to reduce reflections. Climbing plants, cladding, hedge etc. One idle thought, the sound is most likely getting in via the windows etc. The sound will be a very consistent "droning". Ideal for some sort of active nose cancellation system? Do they do ones that fit to windows? They used to have transducer that would fit to glass to make them into speakers and could use them as mics.

Wouldn't the issue more be: the summer house heat losses were too high for the UFH to supply at a flow temperate similar to the house.

125kw of electricity consumed in a week? If you had a cop. Of 3 that would be 500kwh delivered in a. Week. Or about 35kwh a day. You don't mention the insulation levels, air tightness etc. But a 60m2 semi, stone walls, single and secondary glazed windows etc, next door to me used an average of 50kwh a day over Christmas. Is it possible your readings for generation are off, maybe the flow.meter is faulty (I believe the Samsung use a remote one)? Also, if you have the upstairs rads off thry won't be availble for defrost so your system volume might be too low (depends on how big a vokumisee/buffer you have)

We are drifting away from the thread. The point was; I had 2 unimproved victorian flats with reasonably (but not ludicrously) large radiators and was able to maintain a steady 18C in sun zero conditions with the boiler flow set to 40C. This implies a heatpump could efficiently and cost effectively do the same. There was a question about the defrost cycle which I believe would not impact the ability of the HP to maintain 18C. My conclusion is (and I don't think this is controversial) the factor that dominates whether or not a HP can cost effectively a building is the emitter sizing and not the levels of insulation. The insulation (heatloss) of a building dominates the sizing and hence costhence costatpump. The emitters (rads etc) dominate the Scop and hence running costs. (note dominate not exclusively control)

I'm saying that my poorly insulated but heavy walled flats won't cool down any noticeable amount whilst the defrost cycle is occurring. The only effect of defrost cycles would be to reduce the average power input. As long as that average power output is enough to maintain the desired temp there isn't a problem.

Agreed there is confusion but heavy masonry walls, especially external ones, do help stabilise temperature when the heat input (rads) is turned off for a period. The big passive concrete block in the middle doesn't do much (as you say, it delivers very little power) The same (or ideally greater) mass distributed in the walls and floor woukd stabilise the temperature more for a given insulation level. If you had 2 hollow cubes. One concrete with an insulation jacket and the other just the insulation (adjusted so U values were the same) They are both at steady state (say 20C inside and 0C outside for 1kw input) You then turn the heater off for 10 minutes. The temperature in the concrete cube will fall less in the 10 minutes than the plain cube. Though the plain cube internal temp will also rise faster when the heating is restored.

If you're up for a bit of tinkering how about a raspberry pi, or better yet a raspberry pico interfacing via an open therm interface unit. Gives you full control. Cheap and robust, especially if you use a pico. I've used an arduino to control my thermal store and boiler for a decade or so. Just uses relays to activate the boiler and some thermal dumps to prevent overheating (there's solar and wood boiler attached). Absolutely rock solid. No need for Internet or any other external stuff. Does interface with home WiFi so temperatures can be monitored and parameters changed without having to plug into unit in airing cupboard. Has a little LCD display with push buttons and dial for viewing data and switching seasons (in summer the thermal dump to the UFH is disabled and it just dumps hot water down drain, in winter it dumps into the UFH first)

I think we are at cross purposes here. I am *not* disputing that the amount of energy lost during a given "radiators off" period is governed by the insulation levels of the building (the U value) I'm simply pointing out that, in a heavy masonry building, the resultant drop in temperature due to that amount of energy being lost is negligible.

No, I'm not talking about the energy lost. I'm talking about the temperature inside. The high thermal mass of the building means the radiators being off for 5, maybe 10 minutes whilst the HP defrost results in a negligible drop in room temperature. If the thermal mass was low, the room temp would drop much faster Take a 2 liter coke bottle of air and a 2liter coke bottle of water outside on a cold night. Which one stays warm the longest? They both have the same thermal conductivity and thus losses for a given dT.

Had a property drop down from E to F because the assessor wouldn't look in the loft and assumed it had zero insulation and assumed a fake electric fire in the living room which was there to cover the fireplace was active (it's plug was cut off). As it was a rental and we needed it to be at least E, we used another chap who was a bit younger and brought his own ladder. Quick look in the loft (400mm insulation!) and some other corrections and we were back in business

It governs the heat loss but the drop in internal temperature is also affected by the thermal mass. Stop heating a tent and it gets cold almost immediately. Stop heating granite cottage and you won't notice for an hour or so. It's exactly why the HPs need a certain system volume. If thry only had 10 liters they might not be able to defrost before thry froze the water. If they have 200l the water temp will barely dip.

Boiler was running about 20-30 minutes per hour. Temperature rose fairly quickly showing that the heat input from the 40C rads was well above heat loss. I have no doubt we could reach 20-21C at less than 45C in these conditions and the heavy construction means the property wouldn't cool significantly during any defrost cycles. The takeaway is the radiator size is the important factor not the construction.

Waving the flag again for the £7,500 grant money to be used for a subsidy on the heatpump electricity used to ensure it never costs more than a gas boiler and any savings below that are paid directly to the home owner. Or maybe (brainstorming a bit) any savings are split between owner and registered installer. So installer puts system in. If the electricity used costs more than the gas that would have been used the subsidy pot pays the difference. If the electricity used is less than the gas (ie the scop is better than about 3.5) the difference is split between home owner and installer until the pot is spent. Then let the market decide