HughF

The stoves are in the middle of the property, no way to knock through to an outside wall. Stoves <5kW are assumed to be able to use the air in the room, no? That’s what I though the regs said. Wife does want a backup heat source…. So they need to work. I guess the only option is a grill in the floor in front of the hearth, or core drill through the slate hearths and the concrete underneath, at an angle, to intercept the floor void 🤦‍♂️

We’ve removed an open fire (in one room) and a gas fired back boiler in another. My wife wants a wood burner installed in each opening (I’ve tried to win the ‘take down chimney’ argument, and lost)…. All fine you would think. However, I went on an air tightness drive when we did the knock through rear extension (one of the fireplaces is now in this larger room) and sealed as much as a I could up with tape and fm330. The plan was always to buy stoves with external air input and draw from under the timber floor (we maintained ventilation to this floor void even though we built on the back with the extension) but I was working away when the builders did the floor and hearth, and there’s no pipework/vent through the hearth into the void. 1. Am I worrying about this for nothing and will the general air infiltration into the property (trickle vents on the windows, 1946 block/block rendered construction, triple glazed) be sufficient for 2x <5kW stoves? 2. If I’ve screwed this up, is there a concentric flu liner that I can install to provide combustion air from outside? 3. Failing 2, is it possible to draw combustion air from the cavity around the flue liner via a second opening in the register plate? I don’t anticipate these stoves ever being lit, as we have a perfectly functional central heating system that I installed new about 18months ago that does a fine job of heating the place to 22-23 in the depths of winter. But if they do (we have a power cut or a heat pump problem) then I’d like them to work safely.

No, it’s a monobloc with an integrated indoor unit/water tank. Fine if you want the schematic that’s included in the indoor unit, or want the convenience of a single box. Not the way I’d go though….

Exception rather than the rule….

Bumped into Chris from cool energy at installer last year, they’ve got an r290 product out now which although isn’t cheap, does have a lot of functionality. And yes, they offer an umbrella scheme. Still super happy with our old r410a unit, installed in complete contradiction to the manufacturers guidelines 🤣

1946 end of terrace, exposed, on a hill. Upstairs rads are off….you won’t need to heat upstairs

Just ignore the BUS and install what you want, it’ll work out cheaper. Ashp -> diverter -> ufh manifold |—> dhw cylinder Litetally £3ks worth of kit.

Frosted up this much after running for about half an hour this morning.

It’s ‘okay’ at heating - it really struggles to heat my room in this cold snap, but that’s because I don’t have much in the way of insulation or air tightness. In a proper house (this is basically a shack) it would be fine. Defrosts a couple of times an hour, uses about 800-1000w most of the time and puts out warm air. My a2w in Somerset is a far superior bit of kit, but it should be for the price.

This…. I’d ignore it and just crack on.

Everyone on our terrace has done rear extensions - no-one had a PWA, we just got on with it

Couldn’t see the add-on coils available separately, but their pricing is certainly attractive.

I already have the TS, 500ltr jobby (although it’s really a buffer as it doesn’t have a coil in)… options are cut it open and add a pair of stainless steel pressure washer coils in series, cut it open and add my own coil (I have a big enough lathe to swing a suitable former), or do dhw with a shunt pump and a plate heat exchanger and flow switch… I do like the coil idea as it doesn’t need moving parts.

Having to play catchup only affects COP if you have load compensation adjusting your LWT upwards to speed the recovery... If the recovery method is as simple as 'room is below setpoint, turn on heat pump' then the LWT will sit at the same point on the WC curve as if the HP was already running. In fact, it might end up running at a greater COP because it isn't cycling, instead running into a cold start scenario.

Anyone got an idea on the coil size in this? I’m looking to make/find/buy a coil that I can add into a 500ltr thermal store that will be heated by a chp plant, with a view to providing dhw through this coil. A 50m length of 22mm gives me a little over 3.5m2 of surface area, ideally I’d like a bit more than that.

I’d have gone for one if it was available when I did my conversion…. Be nice to have something in the cylinder cupboard that was the same size as the vented that came out.

Yep, just watched the video. Standard thermal store with a coil for dhw. Could do the same with a small direct cylinder, a phe, flow switch and shunt pump.

Yep, manufacturers data sheet…

I’d pick the unit with the widest modulation ratio, ignoring the type of refrigerant used.

Thinbed foam popular for internal walls in NL too

Split if you’ve got a long (>20m) pipe run externally…. Personally I wouldn’t bother with the f-gas bod and would just get on with it, but then I’ve got the gear from doing r290 mini splits and r134 cars. Monobloc is better in that you don’t need to find room for any internal components (provided you don’t get a Samsung )

The other thing to be aware, if your heat pump only had a dhw valve live (or a heating valve live) output, instead of a separate switched live for each valve, you’ll need some relay voodoo to control the 2x 2 ports. luckily mine has both, but I ended up using a 3 port anyway because it was already on the cylinder.

Yep, I figured most people will be running with radiators, hence my statement…

Best controls (room stat will auto-adapt your weather comp curve for you, yes I know Mitsubishi also has auto adapt). Best backup if you’re an installer (vaillant take care of it all)

My vaillant pre-plumbed cylinder came with a Honeywell 3 port…. Go figure…