HughF

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…

I’ve got the smallest vaillant cylinder, the 150 slimline (1m2 coil) being driven with a 9kW ashp - works perfectly… Glyn Hudson uses the same on a 5kW Samsung, again no issues. The vaillant cylinder is a decent one, coil is at the bottom for maximum efficiency.

125mm ish here…. No stat, fixed flow temp of 28… might turn it off next week, it has been on 24/7 since late October. Works perfectly.

Gas out, ashp in - house is warmer, larger and comfier for a little less per annum… And I don’t need to pay a gas-safe guy to mess with it, and we can get rid of the combustion appliance inside the house . Win-win… 1946 end of Terrace, on a hill, facing SW, 50mm cavity… it could cost Me £500 more per year and I wouldn’t care, it’s a superior way to heat a home. As for which one to install, one where the room controller/thermostat will adjust the weather comp curve for you instead of just turning the unit on/off. So Vaillant or Mitsubishi.

I know Tim well, I helped with the first stage steel column welding repairs (but wasn’t on camera, my mate David was)… He’s legit, his build is legit.

Brick/block makes more sense here…. Easily available materials, easily understood, easily tied into existing structure.

I use mlcp extensively, I’ll measure fittings bore for you this weekend. p.s. Unless you’ve got naff all water pressure, the reduction from the fittings won’t make any noticeable difference. your issue is 100% the incoming supply. Your plumber should have advised a new 25mm mlcp into the house.

Do that by rad sizing, not by zoning or trvs… heat pumps like direct, open, systems.