HughF

£4594 for the pump and cylinder (according to ecububl), so about £3900 to cover the rads, some pipework and their labour...

Baxi Bermuda installed in '86, still going just fine... It's had a new thermocouple, and a new click-click lighter, that's about it. 72% efficient though... Same, 120ltr vented cylinder, same single panel rads. New circulation pump 15yrs ago and a new 3 port valve head and new tank stat 5yrs ago.

You’ve got so many options….. personally, I’d look at something like the torfloor2 system as I really like the technical aspects of it. If you have access from below then you could use spreader plates but they seem a bit 2005….

The box in the garden isn’t really the important bit, it’s the controls and design that’s important. Ask him to tell you what controls package he’s going to fit and how he’s going to do the plumbing.

Even if I’m connecting onto a buried length of insulated twin pipework that’s 15m from the house? Compressor vibration I guess ….

The hoses are the right size, yep. It’s just that they’re giant tap connectors basically, so they’re a flat face washer seal at one end and (good luck getting that to seal onto a bspt nipple) and they’re 28mm compression the other end. Ideally I’d get some bspt male flexi’s with compression on the other end, screw them directly into the side of the heatpump, but I’ve been supplied these and might as well try and use them. Although, I do have some 1”/28mm SR unions in gunmetal, I could easily run some street elbows into those then put the flexi’s in a between a couple of sections of copper (if I had flexi’s with compression each end)…. But then I’ve got to do the outside plumbing in copper, and I prefer to work with mlcp. do I even need flexi’s? Decisions decisions

R410 makes for slightly simpler internal F-Gas plumbing as you don't need EVI, like you do with R32. Chris, the MD of Cool Energy says that as soon as the drop-in replacement for R410 arrives, they are ditching the R32 models (which they do supply, albeit out of stock at the moment) and going back to the simpler unit.

Does anyone have a convenient, online, supplier for bspp - bspt nipples in 1”? Stainless/gunmetal/brass are all fine. My Google-foo has failed me so far. I need to transition from bspt female on my heat pump to bspp flat-face seal (tap connector) for my flexi’s. I could use hydraulic unions (the bspp will have an internal cone seal) and bore the middles through in the lathe but that seems a bit drastic.

I know you have a volumiser/buffer of sorts, but how are you finding the pumps-in-series thing working out?

From what I can tell, it's an industry standard. The below taken from some Grundfos literature: Some medium UPM pumps are controlled via a digital low-voltage pulse-width modulation (PWM) signal, which means that the speed of rotation depends on the input signal. The speed changes as a function of the input profile. These communication signals are standardised in the VDMA Einheitsblatt 24244 "Wet runner circulating pumps - Specification of PWM control signals"

Can you let us know what heat pump you ended up with? I’m just juggling numbers about in my head to try and guess their labour component of the £8k bill

Have a look on the heat geek map, find a local heat geek and get them in. Tell them you want pdhw and weather comp, let them get on with it. There will be some re-piping and controls adjustment to do. Have you had a heat loss calculation done? Either your house is massive, or it leaks like a sieve if a 24kW couldn’t heat it properly.

I'm a road planings kinda guy.... love em...

Exactly.... OSB puffs up and the flakes come off. Plywood suffers complete delamination. There's a metric ton of literature and arguments over in the US about what's better, and it's generally considered to be OSB.

It's a done thing in the US when using Advantech Zip System sheathing. You could see if the Zip System tape is available in Europe or over here?

As it's technically an experiment (albeit an expensive one at current plywood prices), I'd stuff a dehumidifier in there and see what happens. And make sure to document this for future builds. What grade of ply did you build it with? Looks like shuttering from where I'm sat. OSB would have been my choice, it doesn't delaminate as badly when it gets wet, and you could have looked at importing advantech or similar, with its built-in waterproof layer.

Sounds good - should be easy enough to double up the pumps at the HP end if required, and piggyback off the PWM to the main pump to give PWM control to the other, external pump. I'm planning to run the PWM and PWM Common signals from my iVT-9 into the house to feed a second pump if required, but under full PWM control from the Carel pCO

To use less gas you need this setup as DHW priority, with full weather comp when on heating. The boiler is also probably far too big so needs range rating to the heating requirement. Urban Plumbers has a few videos on priority DHW: https://www.youtube.com/c/UrbanPlumbers/

Nice... I've got a book somewhere that Dad used as the basis of our design - I expect it's got similar pictures in.

The input is on a T, with an above ground access to the top of the T. It’s just the outlet that’s a bit odd. It has an above ground inspection, but it isn’t a T, it’s just an opening into the top of the tank, directly above the outlet pipe. I believe the way it’s supposed to work is this tank is a primary settlement and digestion tank, with the liquid then making it’s way to the secondary filter tank where the biofilm on the coke bed does it’s thing. I could add a downward pointing elbow into the outlet pipe but that would have to wait for a total pump out and a ladder access. Not sure I’m ready for that at the moment.

It’s encouraging that you’ve ended up with a cheap install, that’s good. May I ask what you’re getting for that? New ashp, uvc, rads etc?

Thanks everyone for your valuable input. It is appreciated.

Front porch and single story rear extension can both be done under PD, so just submit a building notice and crack on with it, telling your builder how you want the work done. BC can come and inspect the footings for the extension and at top of plate, and at sign-off. Nothing more to be done really. No need to do this work on a full plans submission imho. Thank your achitect for his work, pay his bill, pass the plans to the builder?

It's wired on output NO6 from the Carel pCO - a switched 230 output. Easy enough to disconnect if it's an annoying parasitic load.

I've been trying to get my head around the Carel cSuite software for programming these controllers, and it's a mighty clever beast of a development environment. It's built on full-fat visual studio with a graphical core for building refrigeration control applications. Quite a powerful bit of software. I believe they have pre-defined and tested 'applications' that you can drop into the controller and these are tuned to gas and compressor combinations. They've clearly spent a long time working on it.