sammiepammie

Ah, that makes sense. Although I think we might finish a full tank with 4 of us…anyway, will have a look at UVCs and forget about the Sunamp.

Thanks both, that’s helpful math! My sums came to approx 10-12 kW/day to take the water from mains temp (10-15C ?) to 60C- so at 12p/kW that would be £450 ish or £900 on full price electricity. Agree that the sums don’t add up… any ideas on the A2A and in particular where the indoor units should go?

Hmmm, but then we need to heat up a whole big tank in winter….when there is no solar. I liked the idea of the Sunamp but the payback as you say is likely very long - I thought it would be about double the price of an UVC.

Yes, have considered that but thought maybe only for the east & north facing windows. The frames were a lot bulkier if I remember correctly (VEKA Halo). The biggest windows are on the south side and we enjoy a fair bit of passive solar heating here in winter (& overheating is not problematic in summer).

Thanks steamy tea, that’s helpful. 200l should be fine for our needs. The sunamp would be easier to place in the house, a bigger cylinder would need to go in the loft i think

Yes, we need double the size cylinder really. Thinking either just standard electric cylinder or maybe a mixergi or even sunamp.

Haha, yes, like warming up the soil - I don’t know if there’s much insulation under the UFH so assume non. We only use it during cheap or negative pricing sessions really, its expensive to keep running all day long (11kW/hr for 3 zones when its cold) We use about 5kW for DHW per day- all is used in the mornings only really - the current tank will be empty with no time to reheat for the next shower. The cylinder is only 100l currently - so, 3x short warm + 1x coldish unfortunately….it wasn’t a problem until the kids started showering in the mornings too. I sometimes shower at night if we have enough PV to heat the water but prefer mornings.

Hi, Considering options for space heating/ DHW for a 4 bed house. Build end ‘50s, detached, 140m2 over 2 floors, South England. Filled cavity walls, loft insulation, all current (DG) windows will be replaced with new DG PVC units over the next few months. No gas connection, no wet system in place - so all electric (panel heaters & old electric UFH) and an electric HW cylinder. We installed a 10kW wood burner in the large open plan living room a few years ago and added a 7.4kW PV system this year with 10kW batteries and an Eddi hot water diverter. Prior to solar install, we used about 7000kW per annum - and that is being pretty tight with heating and hot water. I think this year we’ll end up around 4500kWh import. Octopus Agile incoming and fixed export. Solar has covered all electricity/DHW requirements this year from April to October, surplus (3000kWh) was exported. I have calculated the heat requirements (via city plumbing site) for the open plan living at around 5.1kW. The total for the whole house would be about 11.5kW - does that sound about right? Considering A2A to get the house to more comfortable temperatures without having to feed the wood burner all day long. We also need to replace the old hot water cylinder with a bigger one to suit a family of 4(2 adults & 2 teenagers). Plenty of space for outdoor units, currently no ceiling boards downstairs so pipes/ducts not really an issue there either until we (finally) board this up. Hoping to fit the new HW cylinder in the loft- and get rid of the cold water storage tanks. I’m not sure how many units we would and where to place them? the downstairs is pretty much all open plan (60m2) apart from the hall/wc. The stairs are in the middle of the open plan living room so the warm air will likely flow upstairs. The kids bedrooms upstairs (10m2 ish each)needs warming in afternoons, nothing else upstairs needs heating really dusting the day. grateful for any advice!