PeterW

You may have cause for reclaim based on reasonable quality - it’s not reasonable to get bulging in walls with render and I would want to know why it’s done that. Stairs - that’s just internal humidity Grout worries me more - that’s a wet room so is it properly tanked underneath and does it need to be stripped and regrouted for water resistance.

Sounds like a failed impeller as cavitation isn’t that loud normally. How old is it ..?

what is the mesh system ..? Not seen that before ..?

Cavity material is excluded - it is combustibles within direct line.

Yep - take a piece of C-Stud and turn it over so it’s resting on the edges and use a bolster to put a bend in the back. Then flip that inside the two pieces you want to join and put a couple of wafers either side. You can also use it up for noggins

Mounty will lift 1 tonne max and this is a 6m long pack - you would have to hand ball it off I expect. Do you really need 330m of 7x2..?

Do you mean JJI type with the OSB web ..? They can be drilled - manufacturers guidelines tell you where and by how much

Paying about £32 inc for 9x2 C24 currently in 6m lengths so that’s pretty good price. Downside is there will be about 1.8 tonnes and you would need a flatbed wagon as it’s likely fork lift loaded and your delivery costs will negate any saving.

Not quite sure why you’ve headed down that route but there are better options using PIR and a vapour barrier - this will give you much better insulation levels and be simpler assuming the old front wall is just brick and not rendered ..? MVHR can go through floor voids - you only need to use a cupboard somewhere as a riser and then plan carefully. Biggest issue you will have with a semi is next door, and also the floors as they tended to be suspended timber and a pig to insulate properly but there are options.

TS needs to be sat at 65°C plus, preferably 70°C to get decent amounts of hot water - you can soon run a TS cold if it’s under sized.

Drayton Digistat+C RF will do that for you - just not the phone / app bit

But this is a sample of one…. It’s not representative ..!

Based on what ..?? A lot of houses have over sized rads to start with - you’d be surprised how little they need increasing especially if you go with the heat pumps with the 48°C flow temps. And you can’t compare a combi to a system boiler - chalk and cheese and also efficiency is wildly different ..!

That is a very dangerous route to go - there is zero incentive to hit your price point by the builder !! I can get a quote from 3 merchants and them be £3k / £4k / £5k but you’d accept £3k… but by looking properly the true price is £2k… you think you’ve got a good deal but you have overpaid ! My gut feel is your builder has got lazy and you’re just paying whatever he wants to charge - that isn’t good and you will get shafted.

Sorry..!! Domino means to put a pair of smaller tanks in line - basically you have one that is “hot” and then the second that is either cold or pre-heat into the first - basically you’re separating heat sources. Some needs some clever switch over valve work but you can make it work fairly simply.

Solar coil ..? Going with solar thermal too..?? If so you want a decent size cylinder - counter intuitive but heating toward 300 litres as you want the ability to store a lot of heat as you can’t do anything else with it. Domino tanks and pre-heated solar tanks are all options but they need clever planning.

To use the phrase @Nickfromwales and I use regularly … at least Dick Turpin wore a mask… The Sx unit on your quote is available on the internet with a 10 second search for £2200 inc the VAT… now work down your list and do the same - even using all the stuff they list (75% of which I am not even sure about) you can save 25-40% online. Same boxes, just not from CEF and your sparky (or whomever) quoting you list plus pricing … Either BPC or Blauberg can do all of that for less than £3k - it’s not rocket science and whomever is selling you the need for £500 CO2 sensor modules needs to be be shown the door and a size 9…

As @JohnMo says it’s about coil size (surface area) - also as you get toward tank temp then the delta reduces and you’ll struggle to get it to condense anyway.

So if I drive a petrol car and I’ve got a heat pump, it becomes neutral..? Or do I need to be vegan to own a petrol car now ..? And what if I own an electric car but an oil boiler ..? My point is that statements such as that above that need to either include whole life emissions or they need to use the same basis and are theoretically modelled or they become pointless.

I think the term you’re looking for here is greenwashing as those statements are neither linked nor relevant. A boiler also has all these things… and therefore this can be discounted. You ignore end of life recycling in this instance though, and I would also be concerned about the question and quotes on leakage from transmission systems as they are random statements. If you want to make comparisons then they need to be whole life and not just bits you have the data for to illustrate a particular view.

TBH this is a system design to meet a basic requirement - I would put in an R32 ASHP but again I wouldn’t look at the short term plan if this wasn’t about a saleable property. As I’ve said though - I’ve got minimal info so it’s a lot of guesswork

It very much goes on DHW requirements, and flow rates etc are vital as are usage patterns. For example in your instance I would go for a pair of 180 litre slimline tanks in a tandem arrangement. That allows an extra volume when you need it but isn’t included in your standing heat losses. There are a lot of moving parts in the design of this sort of system and one size doesn’t fit all - you need to start from base principles. I would also consider if you’re not going to keep this and want it saleable in 3-4 years then go with a single large tank (300 litre min), and a 28kW heat only boiler with a 100 litre buffer tank for the UFH assuming this is in solid/concrete flooring. Benefit of gas and a buffer is you can also run towel rails off it, and if you put an immersion in both DHW and buffer you can use them as dump loads for PV.

Interesting my local timber merchant has dropped their prices on C24 timber by 25-30% this week .. “Pre-Covid Prices” apparently .. Flip side is that bricks are holding their prices but availability has extended to 27 weeks on some from order date..!

No it’s not but could be .. as it depends on demand and flow requirements for the bathrooms and concurrency etc But for that you need a plan, a spec and a set of calculations … not a bunch of guesswork and a heating engineer talking out of his ar$e… It does - but you don’t run them permanently… and this is why you need a design and a spec and then decide what to do. Start with a blank sheet of paper, work out your DHW requirements and then find your overall fabric heat loss and you stand a chance of getting a sensible design.

Sharp sand and carry on …!