HughF

An aircon can heat the place just fine and you don’t need to fit radiators then. yes, you’re doing the heat loss calcs wrong. The heat loss has nothing to do with the delta-T of the rads. It has everything to do with the delta-t of indoor to outdoor temps. I know you aren’t planning an ashp now, but I really like a freedom heatpumps toolkit spreadsheet for doing heat loss calcs. It seems to have a nice mix of stuff in there, does rad sizing for you too. They were emailing it out to anyone who asked on their YouTube video, but that video has since been removed. I've attached it here 1702058696_2021FreedomHeatPumpstoolkitV3.3forallinstallers-Copy.xlsx

I’ve got 100 in my garage and have high point loads (machinery), 100mm in a residential floor should be fine, surely?

My neighbours, who also bought it cheap and had it left over from a recent job. I come home to find a 5ft high stack of it on our lawn, wife says ‘neighbours are storing that there till someone collects it’ 😂 Neighbour comes home from work and a quick exchange is done… I’ll use it somewhere, sometime.

https://electricaldealsdirect.co.uk/air-conditioning-centre-6-kw-air-source-heat-pump-super-inverter-system-ahp60.html £1900 gets you the 8kW version Specs (sort of): http://www.airconditioningcentre.com/wp-content/uploads/2018/10/ACC-Brochure-2018-SMALL.pdf AHP60Spec.pdf

Looking back at the LG range again as it appears from watching every YouTube video I can find that the new colour programmer/controller is the nicest on the market in terms of UI design. And the way the weather comp can easily be nudged up and down if the rooms feel a little cold or hot would suit the way we like to operate. I don’t fancy the idea of an additional controller or room stat. And the price is hard to ignore.

Providing I can figure a solution to get air to the air bricks on the back of the house, for ventilation under the suspended timber, how does the following build up sound: 75mm reinforced concrete with 16mm al-pex tied to mesh slip membrane 140 pir dpm 60 eps sand blind 150mm type 1, whacked Bought a job lot of cheap 140 pir on impulse the other night so trying to figure out how best to use it 😂 Will the bco be happy with that buildup given that we’re building over a sewer, the long way, all the way to our boundary. This is a standard rear extension on an end of terrace.

Size the rads for a flow of 45 deg and you’ll be future proofing yourself. As I said, irrespective of what you use to generate the heat, do try and do a heat loss calc and rad sizing exercise. It’s well worth an hour with a tape measure and half an hour in front of excel.

You’ll need to insulate properly no matter what heat source you use though? Unless you have a never ending bucket of £20’s…. The tech won’t change in 10 yrs, it’s basic physics and thermodynamics. But you can bet your house on the fact that electric:gas will end up at 3:1 and when that happens you’re definitely better off with air source. Heck at the current 28p/7.9p you’d be better off if you can get an scop of 3.55 or better.

The 9kW inverter one?

All good discussions, thanks…. I figured that a plate heat exchanger running the dhw from a 55 deg TS would be ‘enough’. Perhaps I should play with this. Trying to maximise cupboard space and minimise short cycling whilst giving enough hot water . @dpmillermay I enquire what brand of ashp you’re using?

Well yes, obviously it’s the sale of new ones that’s stopping. I’m not that daft 😂

If you do the calcs you might be surprised at what little heat you need. A 7kW LG therma V is about 2.7k, and you can self install… If it were me I’d sack the gas off now, it doesn’t have a future.

Don’t discount air source… do the heat loss calcs and go from there. You’ll end up on one eventually, when the boiler ban in 2032 comes in.

You still need/should be doing a heat loss calc for each room so you can size the rads and the boiler correctly. With part L coming in from June, it will be a requirement anyway.

Thinking more about the dhw requirement, and having watched the RED heat pump introduction on freedom heat pumps YouTube channel, and seeing that they use an open vent TS for their dhw, has got me thinking. has anyone successfully done dhw with air source using a (large) plate heat exchanger directly on the flow and return loop, standard thermal store style, using a flow sensor and a shunt pump? Edit: now I think about it, this won’t work at all. The stored energy in the TS water is required to cover the instantaneous demand of the plate heat exchanger. No way that can be taken from the flow/return loop directly and instantaneously.

Run the house details through either the mcs heat loss spreadsheet, or the freedom heat pumps sizing spreadsheet (I found this one easier to use and a bit more comprehensive, pm me for a link) and then see whether you can fit the required sizes of rads onto your walls. Start there then move forwards.

I did consider manifold'ing this install but I'm pressed for space and don't think I could accommodate a manifold in the current airing cupboard...Shame, it would be a lot easier and cheaper as I've already got the manifold

0.96 Uw

I'm planning a new CH system in our end of terrace. I'm a press-fit kinda guy and have both M and U jaws so can press both copper and MLC. Can anyone see an issue with using 25mm MLC for the feed/return and T'ing off in 16 to the rads, given that I'm planning to feed this from a 8/9kW (max) ASHP? I guess I should bring the feed/return into the building in 28mm CU then drop down to MLC after the 3 port as I don't have jaws for U profile in 32mm. I've got coils upon coils of both 25 and 16 in stock

23% uplift in cost with my supplier on a 3 pane window with 1 side and 1 top opener.

Very interesting discussion, I've learnt a lot, all of which can be applied to my system as I plan for UFH in the extension and new, upsized rads everywhere else. Goes against what I've read in JCs book, but makes perfect sense, so I'll go with the blending valve set recommended here...

I was thinking of screed-in-joist for my suspended timber upgrade - is it really that bad?

Sorry, you’re correct. It was website/browser (probably the latter) troubles not updating the price shown as I toggled the glass type.

Wood? You’re brave…. 😂

My reasoning is not to save on window costs by having off the shelf, it’s to save having to mess the builder about and allow him to make openings that match a certain course of blocks.