HughF

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.

Same unit here, went in last September driving a mixture of rads, fan coils and a ufh mixer. DIYd the install myself. Works a treat, occupants happy. Might turn it off later this month, although we did have a frost again last night.

Yes, 3 port mid position valves are pure evil. However, Pretty much every single pre-plumbed heat pump cylinder from all the major suppliers use a 3 port diverter.

I’m not arguing you can’t do it, I’m arguing that no-one does (as it’s unnecessary imho). My Vaillant certainly doesn’t have it wired up thus…

Show me a pre-plumbed heat pump cylinder than has a hi-limit stat wired to the 3 port and I’ll show you a unicorn.

1946 end of terrace on a hill, facing south west…. we had a 10kW gas boiler when we had single glazing. An ashp can easily heat any house. Any heat source will fail when the heat loss is greater than the input, that’s basic physics.

Our ashp can easily heat the place to 24 degrees…. It’s all about radiator sizing…

Ufh flow temp is 20.5, you sure about that?

516eur seems reasonable…. We’re £100/week during the depths of winter. Backstop rate, 28p/kWh and 50p/day standing charge. All electric house, bit of car charging, lots of tumble drier use.

Similar gas numbers to us… two heat loss calcs came up within 200w of each other at ~7kW at -4. I fitted a 9kW unit. Hard to say what the running costs are , but they’re no more than we spent on gas and the house is warmer, and has been extended.

Heating still on 24/7 in North Somerset. House still at 21 degrees all the time. Might turn it off in a few weeks.

Because of the efficiency hit…. As simple as that. Same as buffers and llh’s, all best designed out of a system.

Yep, more than happy to trust my install to a £30 valve I got from AliExpress….. I see the chance of a power cut, when the house is empty, in the winter, for more than a day, such a tiny chance, that it’s hardly worth loosing sleep over.

You need one, at the lowest point of the system. Glycol should be resigned to the bin, horrible stuff.

It’s a split, so you’ll need f-gas to install it (technically)…. Although personally I’d just get on and do it.

Yeh, found it now... LG aren't the easiest things to find details for. It's nicer in some ways than the Cool Energy, but much worse in other ways...

You can get away with 10mm gap if you use interlocking PIR with taped joints, but that's such a faff to do properly, just got full-fill rockwool.

I'd much rather not re-invent anything and just buy the correct part from City plumbing...

I’m involved in the installation of an ex display therma-v that didn’t come with the in-room display/controller and the dhw tank sensor. I’ve got part numbers and sources for those, but could someone sanity check my thoughts: It’s a 2 core cable from the display to the heat pump? The therma-v has a built in flow/buffer temperature sensor? There isn’t a volt-free call for heat input, just a 240v thermostat wiring strip? I should add that I don’t have the manual, just going off the wiring diagram on the inside of the door. @adam Huttel