Dan F

We have nice 22C downstairs (family complain any lower than this!). Really annoyed that I can't turn cooling on/off based on slab temperatue though! That's 1.5kW for each FCU though right? I get around 1.5-2kW for the whole of the first floor (relative to MVHR supply temp, not internal temp).

It's a £15 resistor from what I remember, not a chip! I have cooling working perfectly, just imposible to control from outside Vaillant controls.

Not sure how/where it would apply here, but we solved our steel thermal bridging issues with https://www.armatherm.co.uk/

Our Vaillant has a dry contact for heating but nothing for cooling! Forced to watch slab temperature and turn GF cooling on/off manually. There not API or Modbus interface either. 😞 (using the contoller doesn't work given delay in change to room temperature).

They just called me. £133/m2! Why anyone would use it at that price vs. concrete-effect porcelain or real polished conrete I don't know. (apart from maybe in a wetroom). Be interesting to know how happy @SimonD is with his result and roughly what the Cemher system costs per m2.

@markharro Yes, cooling the ground floor via UFH is very effective, especially if you have a passive slab as the reaction time is slow and a slab at 19-20C will keep at least the ground floor cool for quite a while. The most effective approach to cooling the first floor using ASHP is via using fancoil units. There are a couple of thread in the forum already regarding this. You can use a MVHR post-heater, but these are much less effective and should only be considered if your cooling demand is very low (e.g passive standard + automated shading). They stop your MVHR from heating up the rooms, but won't really provide much active cooling. We have one installed (first floor only) if you want any more detailed in-use information. https://www.zehnder.co.uk/download/33114/121335/en_uk-100357.pdf

@Adsibob Did you use topcret in the end? How did it turn out? Rough price per m2?

@FrankGWhat model Ecodan?

I'd personally be talking to a UK-based reseller and getting them to advise, rather than looking at products on ebay. That said the cheapest (apparenlty german) inverter I sound which seems might meet your requirements is this one: https://www.zerohomebills.com/product/steca-solarix-pli-5000-48-solar-inverter-charger/

Does you water softener take salt tablets salt too, or are blocks a must? Our softener (Great Water Pro Series 1400) takes blocks or tablets. May be worth checking the instructions. If you can use tablet salt, this is avaiable at 60p/kg in 25kg bags at Costco and Wickes amoung other places. https://www.wickes.co.uk/Hydrosoft-Water-Softener-Salt-Tablets---25kg/p/221263

@Steve J I see someone recorded a video on this here: https://www.youtube.com/watch?v=pTfOYlboarw Of course, you battery system also needs to support this and have the necesary CT clamps. AFAIK the following systems support this: - Tesla Powerwall - Victron ESS - Sonnen I'm trying to find out if LuxPower, PureDrive (Soils inverter) support this. Given the crazy lead times on Powerwall I'm looking at other options.

Just that almost all contractors I've spoken to has been unhappy about using anything less than 20mm unless laying directly on concrete with tile adhesive. Something about: i) being too fragil to bed down properly on sand/cement based with mallet ii) while tiles are frost resistent, unless tiles are bedded perfectly, water can get under tiles and there is potential from cracking due to this in freeing conditions. Our are 14mm, not 10mm so tempted to insist on not using any concrete and just have them laid on screed on top of compacted MOT1, but not sure. Being quoted £200-230/m2+ assuming; sub-base, 125mm reinforced concrete slab, adhesive and grout etc. (excluding tiles).

We have 14mm 1200x600mm porcelain tiles that we want to lay externally. (Technically 20mm is advised externally, but given this is for the rear gaden where there will only be light traffic shouldn't be an issue with 14mm from a strength perspective) Have been getting some quotes in, but getting very different opinions on how best to lay it: 1) 125mm Concrete slab + sand/cement bed. 2) 150mm Concrete slab + tile adhesive 3) 50mm screed with some kind of mesh 4) Sand+cement 5) Fuga-Pave Not considered the pedestal, but might not be ideal only support large 14mm tiles on corners. Given tiles are 14mm and not 20mm some contractors want to avoid basic sand+cement approach, but 150mm concrete slab just seems overkill to me. @Adsibob What approach did you use in the end? Or what have others done?

I not exactly sure how SAP works, but we got A118. I assume thats due to PV?

Get yourself one of these?

@joth It's 15 kWh/sqm heating demand or 10W/sqm peak demand. So tight, but it is a pass. You are right you don't need a certified anything for PH certification, apart from MVHR that is. Even for Plus/Premium you don't need a certified ASHP, although a better COP does help with your PER score which may or may not be important depending on how much PV you have. You only need a small ASHP with those numbers. You do need to consider DHW reheat times though and/or look at non-traditional approches for DHW to workaround this. We have heating demand of 10W/m and around 30m2 treated floor area. We are using the 7kW aroTherm Plus which is more than enough for heating/coolig and we probably could have used th 5kw. Looks like the PH databse heat-pumps are only the all-in-one ashp/ventilation units, not standard monoblocs.

It will all depend on the supplier and how much you want to pay, but the suppliers we looked at (UrbanFront, RK Door Systems etc.) had standard sizes up to 1200x2400mm from what I remember. If the supplier you are speaking to can only do 2100mm then look elsewhere, you'll find 2400mm for sure.

- Norstone - Cupa StonePanel (sold in U.K. via Taylor Maxwell) We wanted to use Cupa StonePanel, but they were more expensive and there was no stock of the variant we liked (Nordic), so we ended up using ZClad Nordic. Builder found it OK to work with, only think I'd mentioned (also visible in photos on their website) is that horizontal lines between the panels are somewhat visbible, more so that with the StonePanel product anyway. Initially we considered Norstone (specified by architect) but wasn't cheap and they wanted to insist you used a specific backing-board that only they supplied in order for them to give you a warranty which didn't seem right.

I took another look at the datasheet and the quoted cooling power is for 28C air in. So, if MVHR is actually providing air at closer to 21C, then total cooling power is going to be closer to 1kW (of which 0.3kW is sensible power which matches what I see on the heat meter). So, it's less than I expected when Comfopost was added to the design, but still 3 times our total cooling demand and is on top of UFH. The datasheet actually shows 25% more total cooling output for HRV vs. ERV. The assumed humidy for HRV is 80%, where as the assumed humidity for ERV is 55%. (this matches humidy I see on ours)

With DMX are the dimmers centralized with each circuit wired back to the Loxone panel, much like with Loxone dimmers?

Any questions give me a shout. Only thing is that designer/electrician may not be that familiar with Loxone control. Did you decide between DALI, DMX, Loxone Dimmers etc?

I'm not sure. But, just thinking out loud: - The masonary construction may help keep first-floor day/night temperature a bit more consistent than with a timber-frame. We saw a difference of 1C between 6am and 7pm in January in north-facing bedrooms, which reduced to 0.5C in May. (No Comfopost in use) - But, I don't think it's necessarily going to help ensure that the first-floor isn't slightly warmer/cooler than the ground floor if your primary heat source is ground-floor UFH. - With the additional mass in the walls I would assume that it's even more important to keep first-floor temperature in check, as it will be harder to cool down via ventilation/comfopost if you need to cool the mass too.

Even single-phase? What if you sign-up on dumb meter, do you then go in a queue for smart-meter?

You can get more than that on Octopus Outgoing Agile. I was getting 25p few months ago on average, but now there is more sun not quite so much. Here is today. You can't use "Outgoing Agile" with "Go" for import, but you aren't going to want cheap nightime during the build anyway.

Yes, don't see why not. Our place, when we bought it, already had a 3-phase supply but a meter on just one phase. Also, it might be easier to get a supply in place with someone on a single-phase (which should happen quite quickly) and then request upgrade to three-phase afterwards. If this takes a while it won't be an issue if you aren't using it.