Solar Panel and Battery options for very high energy use family.

Martyn1981

Ohhhhh, lots of thoughts then.

Firstly, I don't know much about UFH, other than depth is an issue/important. So my immediate question was why you run it during the day, rather than just at night, on cheap rate? Do I assume it's quite 'shallow' and gives off heat fast, rather than taking days to heat up / cool down through a thick slab?

Regarding A2A units, again great news, if you aren't committed to a full wet ASHP system, as that would duplicate costs.

So, the hallway sounds excellent for a unit*. The only issue with the hallway, is how that relates to the stairs - for instance my hallway and stairs are together and open, so the heat will want to go up, more than 'travelling' around the downstairs.

The living room sounds interesting** too, you'd think the French windows would be an issue, I did, but turns out not so much. Our first unit went in the conservatory, not really a conservatory, a single storey extension between properties, roughly 2.4m cube. I couldn't find a way of plumbing it through to the living room neatly. My concern, was that with glass doors to one side, and a glass (double glazed) roof, it would leak too much heat. But the first A2A was just to add heat to the house in the shoulder months, when GCH need is lower, and outside temps not too cold. We do have honeycomb style blinds on all the glass to reduce heat loss (and solar gain in the summer).

Turns out, not really an issue. And now years on, with two units, we run the conservatory unit to heat that room, then through the open door to the living, then through open door to hallway and upstairs. As we don't seem to be using that much leccy, then the heat loss of 'the conservatory' not a problem, especially as it allows us to heat more of the house with the 3:1 benefit of a heat pump.

Just as an example of the benefits, when working out how we would heat the kitchen when GCH removed, I planned on adding resistive heating, either an immersion rod, insterted into the existing large rad, or a wall mounted unit. To estimate the heat output needed I got an oil rad to try to work out what would be needed.

I mentioned to some forum friends my plans, and the small window between the conservatory and kitchen, which is left open to leak some heat through. One suggested/joked about using a fan in the window space. I tried it, almost as a joke, with a small desktop fan, and it worked perfectly. Depending on the temp set on the A2A unit in the conservatory, and the desktop fan speed, I can get a temp of 18C-20C at the north facing external window that is at the other end of the kitchen.

Here's a pic of our kitchen heating system, feel free to think it's a bad joke, and couldn't possibly be enough, I certainly wouldn't have believed it. Window size, internal wood frame ~700mm by 500mm. Note the blue door, which points towards the A2A above to our right as we are looking. Open like that the door helps to direct warm/cold air into the living room.

This may not be the ideal solution to you, but if you are collecting opinions, then I can say it works fine for us. And we use some oil rad heating (boosted on cheap rate at night with timers) to top up upstairs during coldest extremes, when enough heat may not rise upstairs. A third unit upstairs would solve all concerns, but nowhere suitable on landing, and dare I say 'too much' heat for a single room.

A2A is something you can try/dabble with first for not too much money, maybe £1,200-£1,500 per unit. Not nothing, but if you'd appreciate the cooling, then good value I believe. And at worst, even if you can't remove the boiler, you will use far, far less oil. Then step two, which you may do anyway, is add a battery, charged from PV or mains cheap rate, and you can run the A2A's part or all day on cheap rate, rather than day rate.

*Location of A2A, subject to ability to run pipes to it, and an area of wall (no lintel) to pipe through. As you go further in, you may need to add the cost of a condensate pump to get rid of water, but that's not a big problem.

**But consider fan noise. The internal units are pretty much silent, but they have fans to disperse the heat/cold faster. And moving the heat/cold away, also allows for them to work harder. You might find the fan noise even at low levels an issue (or not). In our case they go from 0 to 6, 1 or 2 not really an issue, especially if telly, or similar is on, 3 up gets more powerful and noisy. We heat our house with two units, both with fans at 3, but one is in conservatory, the other in front room, which isn't used much, but we can dial the fan down a bit if we are in there.

There is a BUS grant now of £2.5k towards A2A install. But that will require the FF boiler be removed, so like us, you may need to get a HW tank installed, heated overnight, or install some instantaneous water heating.