gregh

It will be electric + PV diversion (so the ePV models)

Thanks Damon, very interesting that you are managing with an even smaller unit. Are you particularly sparing with showers etc? We are two adults and one child (two in the near future). Larger house (5 bed) with occasional family houseguests. Expected usage would go way up in a few years when we have a couple teenagers. Maybe I was mistaken!

After looking at a lot of options for our DHW I thought I had settled on a simple direct UVC with a timer. However in practice it's looking like the space requirements for even a slim tank are going to mean less desirable compromises elsewhere (eg. shrinking a room, covering a window..). So I'm reconsidering Sunamp as the small footprint would solve those issues. I know there are mixed feelings on the forum about Sunamp and whether they are worth it, but for those that have one - how has the sizing worked out for you in practice? Did you over/under size at all? Having spoken with a local supplier, I think we are sitting on the edge of the 210 or the 300. The latter is a bit of a premium both in terms of the unit itself and the install (it weighs a quarter of a tonne!), so if we can make the 210 work that would be my preference.

We are getting prepared for a renovation and reconfiguration of our house, and would like to fit MVHR. While I hope we get a bit of energy efficiency from it, the primary reason is for indoor air quality. A few of our neighbors on one side seem to enjoy burning rubbish (garden or otherwise), and when they do the smoke seems to seep in through the trickle vents, even when closed (old covers) and the fireplace+vents. All of those are going in the reno, so hoping we can control the indoor air better. It's a renovation with solid joists between the floors and there will be some steels going in through the middle of the house as we open it up, so not the easiest MVHR retrofit. I've identified two potential places to sit the unit itself and pull in outdoor air, and would be grateful for any feedback on how I should approach this. For reference, looking at the drawing, joists run top to bottom on the top half of the house, and then in the entrance hall switch and run left to right over the lounge. Option 1 (green on the plans) would put the unit in the utility cupboard, pulling in air from the front of the house. Advantage of this location is that it's probably best from an air quality perspective - it's mostly houses behind us that seem to burn rubbish (so completely opposite side). Unfortunately much harder to run the internal ducting from here. Would mostly have to go under joists on the ground floor (lowering ceiling) and then up through the ensuite and into the cold loft for the first floor I think. Option 2 (pink on the plans) puts the unit in a bedroom/office cupboard. This space is where our stairs currently are (being moved), so advantage here is there is a lot of currently open space to use. Also easier to run ducting between the joists on both floors. Disadvantages are 1) do get some smoke coming from this side as well; 2) will have a couple of outdoor A/C units effectively right under where the intake duct would likely sit. Option 3 (not shown) is to put it in the cold loft. Much easier to run internal ducting from here, and could sit it on the same side as option 1. But would be a lot of extra work to insulate it properly I think. Also more trouble to access the unit when necessary. Anyway, any and all feedback is much appreciated!

Preserved just as it was in Victorian times. It's a shame the planners can't apply their logic to more widely. Who wouldn't want to bring back child labour, toilets in the garden, and living to the ripe old age of 45!

Yes. A friend was trying to do external as part of planning app for extension. Brick 1930s semi in South London. Planners refused (it would "ruin the character of the street", his house being rendered), he appealed, and they came out to see him. Woman said something like "if we allow this, it would become a precedent that we allow people to externally insulate their house!" to which he replied, "well, yes." Appeal refused 🤯

Except most planning authorities block this for aesthetic reasons

I'm convinced air-to-air has to be an answer here. Even if the government isn't willing to subsidize it! Generally more efficient (SCOP >5 in many cases) Usually less expensive, and can be done incrementally If you want to fully electrify, DHW can be a bit of a challenge, but there are options depending on individual circumstances.

Do you find having a unit in the bedroom disruptive at all?

Thanks yes I was wondering about sizing for cooling rather than heating. Based on the heatwave last summer (our only summer in the house so far), I would say GF needs very little cooling. Large eaves overhanging most of the perimeter, including south/west, so solar gain reduced. FF is another story, there were a few unbearable nights last summer so may consider that on what we do up there.

Anyone had experience with sizing A2A heat pumps (ie. Mini/multi splits) for heating loads? Have had a few quotes for fitting out our house now, and sizes from contractors have varied quite a bit. I’ve tried my best to approximate heat loss requirements using MCS heat pump sheet, as well as Jeremy’s sheet from the forum, and approximating existing radiator input. Often coming out with significantly lower numbers than any of the contractors. A couple examples: (House is detached chalet bungalow from late 90s, brick with filled cavity walls on GF, timber frame with 50-100mm insulation on FF. Located in South East.) Our lounge is a 25m2 room with 3 external walls and decent amount of glazing. MCS calc indicates probably 2kw losses, radiators (3) seem to add up to about 2.2kw. Contractors suggesting a 3.5Kw or 5Kw wall unit. Seems like 2.5Kw at most would be sufficient?? Looking to do ducted to 3 bedrooms upstairs, one about 20m2 and the others both 12-14m2. MCS seems to be about 1.2kw for the big one and 500-700w for the other two. Contractors wanted to do a separate 3.5Kw unit for each bedroom, and one contractor said 5Kw for the large bedroom. I am thinking we could get away with a single 3.5Kw unit ducted to all 3 rooms! (Daikin even does a plenum with motorised dampers to control individual room temps to a degree) So am I missing something? Or are the contractors just vastly over sizing (as seems to be the case with many in A2W?) The units themselves aren’t massively different in price as you go bigger, but the running costs almost certainly will, particularly if they end up significantly oversized. Any input is appreciated

Can anyone with experience comment, is this safe to do? Ie. heat the water in UVC up to 90°C to store the energy? Thinking more about the tank, assume you would fit a thermostatic valve to keep taps and showers safe.

That is my biggest concern with EASHP - in theory the install shouldn’t be much different, aside from a couple of extra holes for the air supply/exhaust. However I can imagine your average plumber not wanting to take the risk on something new like this, and the handful who have experience with these charging a premium… might still explore it

I believe at least the Edel has terminals to receive solar excess as well. Still not sure the payback is worth it, but one to consider.

Not with UVC, no. We also want to lose the tank in our loft. Am also going to try to find an UVC with a couple PT1000 temp sensors if I can (might be a custom job). Can hook them up to the eddi and make it a little "smarter", if I understand things correctly.