JohnMo

Hiaer R290 monobloc 4kW. Snip from the data book - even does 80 Deg flow if you ever needed it

Typical of someone looking at the numbers instead of how it feels. We have room sensors in each room, but they have no numbers to see. We sit very comfortable at 19 to 20. In fact I get complaints if it gets warmer especially at night in bed.

Couple of motivations. First just bought a hot tub, and want to heat by heat pump, so need a 6kW heat pump. Which I have and it's too big for our house, main due to poor modulation with output being about 4kW, again a heat demand of 3.5kW at -9. Due to cycling my overall SCoP is around 4. Even though when actually running the CoP is closer to 5 to 6. The new 4kW has a min modulation of 1kW at 12 degs, so will run continuously when needed, without any or very little cycling. Expect to see an uplift to a scop of 5. So a 20 to 25% reduction in the heating costs. Coming from less cycling and ability to run cooler flow temps, as a result of not having to compensate for cycling. Plus we need a heat source the hot tub, so a better heat pump for house covers both. Unexpected issues we have covered by log stove, power cuts have battery and if that runs flat, a generator, that can power whole house including heat pump. Have an immersion for DHW heating on really cold days, but heat pump can do 4kW at -10 at 36 degrees flow and we have a heat demand of about 3.5kW for the odd day at that level.

It is already by default as it asks for internal wall area and roof area, so is you have vaulted ceilings the roof area will be greater than a flat ceiling. Minimum flow temp is a product of running dT (difference in flow and return temperature) and compressor restart hysterisis. So mild day let's say floor temp is pretty close to room temp at 20-21 degs. So if you are heat soaked the whole floor is at 21 degs minimum. When running ASHP lets say you had it set to run dT of 4. Flow at say 25 return 21. So mean flow temp of 23 degs. Your pipes in the floor will radiate heat outwards while they are hotter than the screed. The further the energy moves from the pipe edge, the lower the temperature gets. So if the pipe starts 25 degs by the time the gets to floor surface it may be 22 degs, the further water travels along the pipe the more energy it gives up to the floor. So once at the end of the pipe, it will 21 degs, starting at 25 degs (this why UFH is rated a mean flow temp, because it's the average temperature). Then you have restart hysterisis, it normally set dT plus a temperature margin to stop fast restarts so say it's 5 or 6 degs with your dT 4. So now your return temp reads to drop to 20 or 19 degs before the compressor will restart. Which could takes days - so we have an issue. The issue being you get one cycle and then the compressor in the ASHP doesn't get a permission to start The work around is we reduce dT and reduce reset hysterisis. To some thing like 3 and 4.5 degs. So it's unlikely you will get a flow temp lower than 25 and in a low energy house you can make it work. Your WC curve will be pretty flat as well, maybe raising temp 4 to 5 degs by the time you get to -3. The heat pump I referenced, I have just bought one (4kW) to replace my 6kW one which doesn't modulate well at all. Will need a gap in the cold weather to get it installed. The 6kW will be repurposed as heater for a hot tub. I am doing the simple install, UFH only in heat and cool mode. Doing DHW via immersion during peak. So parts list gets super simple. UFH and manifold, couple of ball valves for manifold isolation, 2x anti freeze valves, strainer/ball valve at ASHP (required for warranty) plus an isolation valve on flow out from heat pump. Fill system with inhibited (corrosion and biocide inhibitors - not antifreeze or glycol). Expansion vessel and relief valves are in monobloc. A direct cylinder (half the price of a heat pump cylinder). I paid £2500 including vat for Hiaer monobloc, you can claim the vat back on a new build.

You need a heat pump, does around 3.5kW at -3, but that will also run happily at 10 degs at just above 1kW at around 25 Deg flow temp. Here's a starter data book, full of information. The 4kW monobloc looks right. To buy you need the outdoor unit and wiring centre. Wolesely selling now and a 4kW is £2500 for both units with 6 year parts warranty. https://www.gaf.be/pdf/r290_monobloc_engineering_data_book_20240808.pdf

Not quite.your single floor area is 131m², your actual house floor area is 262m². If you had heat on both floor the floor output would be 3156/262. If you are only heating via one floor your floor output needs to 3156/131. So you stop at the 24W/m².

One of these? https://coolenergyshop.com/products/cool-energy-reverso-towel-rail-water-fan-coil-ce-bt400?srsltid=AfmBOooq7706CGmIshZFQdCuvbdMxRj_pSnjyrd_Yw3GQiz-wMRnHEQj

Think the thicker ones, roof installer did everything including nail supply.

1, 3, multi storey building you state the ground floor area. 2. Unfortunately ASHP don't make this easy for anyone and none use the same reference scale. So you to dig about and find technical data books, which in general will give a range of valves for low, middle, nominal, and max output, for various flow and outside temp. 4, if you have downstairs heating only it needs to provide all the heat output for all floors. So by way of example, 200m house with 100m2 on each level. Total heat energy required required is 10W/m2, if supplied over two floors of heating. To compensate for one floor providing the heat, you need to output 20W/M2. But total heat load remains fixed by heat loss, you have how its delivered.

Flow temp isn't exactly related to floor temp, it varies by floor design, floor covings, pipe spacing, flow dT and pipe depth The deeper the pipes, the wider the pipe spacing, the more the flow temperature is diluted as it radiates radially out from the pipe across the floor. If your well insulated and have a floor surface temp 24, get the shorts and tee shirts out and the windows.

🥵

Last time we saw that temp was 23 Dec. Plenty of defrosting going on, so CoP took a hit, but other than no issue. Just ordered my smaller heat pump, so no concerns.

Weight I believe, think they had issues before

But have floor output set at 50W/m² which huge, suspect you are nearer to 15 or below. We are 192m² living space, on 300mm spacing, our flow temp goes up to about 34 at -9,no way you would ever need over 30. Our heat loss with a very poor form factor is about 3.5kW, in fact just bought a 4kW heat pump. Do your own calculations, do not over size your heat pump. 7kW sounds huge.

Made from scratch by a local company, 4 miles from the house.

If you haven't try restarting the unit

Our glazed doors only came in double glazed, I upgraded to Krypton gas, quite happily sit next to them when it's super cold outside.

Bad idea for summer. But balance output, no issue, UFH in a low energy house is pretty good at self regulation, as floor temp isn't much warmer than room temp. So room heats up, floor stops output.

My stock answer is single zone, no mixers or additional pumps other that provided by heat source. Keeps it simple and costs low. All you need is pipes and manifold, no actuators or zone valves. If heat pump run everything from heat pump controller. Best design is to match floor output to room demand for each room. Then balancing is easy. No need for additional loops in halls, just space the loops transiting through halls out as if it was a loop. That hall is massive, would be stealing some space from it, for other rooms.

That's ok for cold, but you will waiting for ever for hot to arrive. I used a 15mm pipe from cylinder to a central manifold then 15mm to each wet room then split it to each outlet in the room. I would keep it simple just use Hep2O and add insulation if you have a secondary return system in place. Maybe some thin insulation if you feel you need it otherwise.

Not with a listed building on site. Ground mount them?

It will not need an additional jacket, keep your money in your pocket. The what steel is just a shell protector with insulation side. Mixer on the UFH, it's mixing the flow temp down to limit floor output and protect the floor. It will have a temp control knob,if you increase that the flow temp through the floor increases. The basic mixer just work on a ratio control, it's assuming 70 Deg hot water from a boiler, if you can turn it up do so. Adding even a couple degrees to flow temp will have a big effect on room temp (after 24 hrs) Other thing are you running the heating on all the time or an on off time cycle?

We are similar, but one room is 6m high and all glass bay window 6m tall also. We started zoned to death and it just didn't work for us, at the time the boiler just suffered from short cycling. We went fully open, single zone after a lot of iterations, and full weather compensation. Halved the gas usage at the same time. Now with ASHP we operate just the same. Now never feel this, full time heating also allows you to run the house way cooler, with no ill effects. In summer we just switch the heat pump to cooling to make the most of cold tiles and manage house temps. The mother of poor efficiency.

First complain to landlord or their agent, they are responsible to fix it and provide you heating that works. Start looking for a better rental property?

On a typical day we add 7 to 10kWh so we add 0.4kW heat pump sizing. This will vary by house size. But can fall back to immersion if we need to.