HughF

Looking to jump ahead on an upcoming extension build and get the windows ordered. Construction will be rendered dense block/125 full fill/celcon. What are standard window sizes to match standard block+mortar joint multiples? 1200x1050 & 1800x1050?

You should just about be able to hack 25mm off the top and bottom of a standard upvc 70mm profile door with a tracksaw... it'll be touch and go though...

I wouldn't advise zoning your heating system too much if you plan to drive it with an ASHP... Lots of information out there about that, but Tl;dr - weather comp, ashp on 24/7, nighttime setback by 2deg...

I've used https://www.modernupvcwindows.co.uk/ for two doors over the last 24 months and have had excellent service. No complaints. I'm going to use them again for window replacement.

That seems a really low U value, compared to the entries that I have in my heat pump toolkit spreadsheet...? Attached for reference (look at the drop down values for window type on the heat loss calculator sheet)... Are my 12yr old windows really as bad as the spreadsheet says, U value of 3.10? 2100586189_2021FreedomHeatPumpstoolkitV3.3forallinstallers-Copy.xlsx

I've found their web ordering system and delivery updates to both be excellent. Fairly long lead times but both my orders have been during these recent odd times (lockdowns and subsequent shortages etc).

The profile, or the supplier? I've been happy with the two doors I've got from them recently.

Burbage custom/modern upvc windows. Deuceunic (sp) heritage 2800 profile. standard stuff…

Simple question really, looking at changing out all the windows around the place, mainly because the current ones are badly fitted (now there’s a surprise) and we don’t like the colour. It looks like I can get triple glazed for the same price, is that a worthwhile upgrade over standard double? I assume so. Looking at standard upvc from my usual, online only, supplier.

I was just doing a running costs analysis really, that's what's important for us moving forwards...

It's basically a full CH system rip out and upgrade that I'm planning.

Yes it should... well spotted

I'd need to up-size the rads anyway if I was replacing the current boiler with a new condensing one, to get advantage of the lower loop temps to push the boiler into condensing mode. The current rads/cylinder are in a bad shape anyway, so they would be replaced regardless of what heat source I used. I'm planning more investment in the property in the shape of as much solar as I can fit onto the south facing roof, so that sways in in the direction of ashp+uvc vs combi (which would be the gas option). Capital cost is less of a concern than running costs, the house is paid for, we're never moving and I make good coin. I think I could DIY the ASHP + UVC + rad upgrade for about £5k, vs probably 2-2.5k for a full combi swap, which I'd have to find a gas safe engineer to do, and takes up space in the bathroom.

Can someone check my maths: As per the attached, 20134kWh of gas through the smart meter for 14 months of usage 20134/17 = 1438 1438 * 12 = 17257 kWh/12 months In our current non-condensing baxi back boiler on a Y plan, assuming 75% efficiency: 17257*0.75 = 12942 kWh of heat energy delivered to the property. To generate that with an ASHP with an SCOP of 3.5: 12942/3.5 = 3697kWh of electricity required, at current prices for the year - 3697 * 0.28 = £1035.42 Compared to buying 17257kWh of natural gas at the new rate of 7.9p/kWh = 17257*0.079 = £1363.30 So, a £330 saving per annum (not including the gas standing charge, which can go as we cook on electricity). Obviously there is the capital investment, but the boiler dates from the mid 80's and the rads are all in need of replacement anyway, so that needs to be done regardless. Seems like a no-brainer...

Good point... But I think with the other issues, the oddly low max. flow temp, and the lack of a heat/dhw call differentiation, it's a pass for me.

Interesting…. Almost as equally useless as the inverter driven one then, unless you’re charging a thermal store or a sunamp pcm43.

The user manual for the Dream r32 inverter heat pump is attached. Happy reading everyone ESDAW-8KH-1DC.pdf EDIT: It would appear that the controller is fixed to the unit, and just has a single flow temperature setting, no mention of a DHW call or a CH call for heat in the manual. It also appears that the flow temperature can be set only as high as 40 degrees C (parameter P3). Both these things make it pretty useless for installing in a typical british home where we would expect to be able to get the flow temp up for a DHW coil, and to have a control panel mounted somewhere on the wall.

Thanks for the input, it seems like too good a deal to pass up at those prices. Unfortunately our heat loss (at present insulation levels) means we need around 6.9-7.1kW otherwise I'd be going for the smaller unit. That's almost on price parity with a good quality system boiler.

@ProDave given the current good value of the LG Therma V units (£2700 inc vat for a 9kW unit: https://www.tradesparky.com/solarsparky/heating/air-source-heat-pumps/lg-hm091mru44-therma-v-s-9kw-heat-pump), would you say they represent a good ASHP option, given that they are a known brand and not the usual generic chinese offering? If that price includes a controller, that's a decent deal.

How big is your buffer tank? You could decouple the supply and demand if the buffer was large enough. Room stats would just draw heat from the buffer as required. The buffer temp sensor would call for the heat pump to recharge the buffer as required. No different to a biomass boiler, just with lower temps involved.

Agreed, need the installation and controller manual before I make any decision. If I’m not going to heat my ‘spare’ 500ltr buffer tank, then I need an inverter machine with a decent weather comp controller. Looking at the manuals should give me that info. If I make use of my spare buffer and add a DHW coil in the top (cut the top off, weld it back up) then I’ll likely just buy a fixed speed model and charge the buffer as required.

Thanks for that, I've asked the question direct as I received the same response as @JohnMo

I’ve made contact with the seller through eBay and am hoping to get hold of a installation and controller manual.

EDIT: My mistake, it is the Freedom heatpump calculator spreadsheet I have used. Apologise for the error. I've attached it here, and a link to how to use it can be found at: 1893778935_2021FreedomHeatPumpstoolkitV3.3forallinstallers-Copy.xlsx