HughF

Interesting. Do you have a DHW coil or do you use a plate, flow switch and shunt pump?

Yep, incompetent installer. Now there’s a surprise 😂

What is your other heating energy option? That’s the deciding factor here. Do you need a certain scop to beat natural gas? If your only option is electricity then compared to resistance heating, any heatpump will beat those on costs. Then it’s just payback inside the units lifetime to consider.

Interesting, a TS heated by an ASHP. What do you heat the TS to in order to get a decent DHW temp?

I’ve spent nearly 20yrs welding stainless, mostly for the marine and hospital/catering industry. Trying to keep the performance of the original material, post welding, is always a challenge.

Buy it and diy install it, there is zero justification for paying an installer, unless you’re the sort of person who doesn’t understand plumbing. But then you probably wouldn’t be on a self build forum. When I’m in front of the laptop I’ll upload the freedom heat pumps sizing/design toolkit spreadsheet. It’s pretty decent (but has a few flaws)

Ah, ok. Thought it was a renovation project. Thanks for clarifying

What amount of building work were you doing that meant you had to deal with that regs requirement? Was that windows and doors replacement , central heating replacement, or something else…. Curious…

I'm looking at retrofit, just to try and improve indoor air quality in winter (summer is fine, we open the windows), not looking to meet regs on a new build.

The more I read about vaillant and their controls, the more I like them. If you’ve got a chance to go with vaillant, choose them. But make sure you get their sensocomfort controls and all their balance of system components too.

Surface mount the mlcp and box in, no need to mess about with long drill bits. I know it looks a bit council house, but it looks fine in my council house 😂 Ditch the idea of the TS, the losses will be crazy as they’re never insulated well enough. Upsize the rads for a 50 deg flow, job done. Add the odd fan coil unit if you want cooling in the summer time.

I'm in the same position, looking at dMVHR units. Lunos are still around, I was chatting to them at the Installer show last month. They do seem to be a bit on the pricey side. Just come across these: https://www.ventilationland.co.uk/product/40954/decentralised-mvhr-unit-o100-mm-with-switch.html?utm_source=googleshoppingUK&utm_campaign=googleshopping-FeedUK&gclid=Cj0KCQjwzqSWBhDPARIsAK38LY9sv8y5tPeyEPH6lJdO42VQvR7AagTCv5jhXEym6Mpwy0W1M5whOLAaAv7EEALw_wcB From a Latvian manufacturer. They are the standard 70 secs one way, 70 seconds the other way sort of thing with a ceramic heat exchanger. They seem fantastic value at that price... No idea if they're any good or not.

Rust on the corners where they’re welded up. Heat from welding causes a reduction in the chrome content and hence the stainless part. Electrolytic weld cleaning or pickling paste is usually used to restore the stainless part, post welding.

The way around it is to grab yourself a copy of either the freedom heatpump toolkit, or use heat punk (www.heatpunk.co.uk) and design it yourself. Including measuring up all the rooms, it took me about an hour to get a heat loss calc done and rads sized using the freedom toolkit. Choose a heatpump that works with homely and you won’t need to do any commissioning, homely does it for you. As I’ve said before in this thread, it’s not rocket surgery this stuff. Splits, yes, monobloc, no….

Ouch, 8 compressor failures.... I assume they rotor locked and took the PCBs with them?

Why are you even considering going down the mcs/bus grant with this? All it does is inflate the costs for everyone. Just buy a unit (personally, not r290 based, siting them is a faff) and pay a plumber to install it. It’s a pretty simple plumbing exercise really.

It’s a CoolEnergy with a carel controller.

I was going to say (but nick beat me to it) that I’d mitigate this by either fitting a flap type nrv or a 2 port valve into the return line, right next to the buffer tank.

Interesting to hear Wil, cheers. Compressor failure is indeed rare but I’d guess that’s certainly the cause of the hardware over current fault code. Mine will be easily accessible in the garden, not planning on sticking it on a roof. Hope you get a resolution to your problem quickly, I’m sure you will, I’ve been super pleased with the help I’ve received from Chris so far.

Bang on the same gas usage as us, near enough...

Well, ended up with a better deal than I expected on a pre-plumbed vaillant off eBay. Picked it up on Saturday when I was that was doing some other business that way (mid wales). More junk to clutter up the shed, for now.

Nice to see you over here too. I was going to say ‘post this question on buildhub too’

Yep, that’s the one.

I'm considering using one instead of a rad/towel rail in the bathroom... and possibly fitting one in each bedroom for cooling in the summer. My wife is of a certain age and she doesn't manage with the heat very well, my sis-in-law who lives with us isn't far behind either.

Homely will integrate with Samsung heat pumps over modbus and should give you a considerably better user experience than using a Hive.