JohnMo

I have an Atag, they seem to a good boiler. Need for a buffer is down to heat output of boiler compared to heat required for the building. You need to know the heating requirements of the building to make that call. You can get an idea of the heat required from an existing EPC or use the tool on here (boffins corner) to calculate yourself. The worst case for short cycling is when its 10-12 degC outside, as the heating required is very low. Try not to have to many zones and certainly make sure you have no really small ones.

WC vs load compensation. You can have both. Master thermostat, just decreases flow temperature, but it applies to all rooms not just the room the master thermostat is in.

Hire a decent one, you will only be disappointed, they were only shredding small stuff.

Insulation?

Agree no-one seems to know the difference between a screw and bolt, even lots of so called engineers. A wood screw is just a type of fully threaded self tapping screw, but designed for used in wood. By definition a part threaded wood 'screw' is really a self tapping bolt design for use in wood.

10 to 15mm - 10mm is a 1/3 the volume, so instead of 50 seconds for 16m you will be closer to 12 to 15 seconds for you 12m.

You can also get noise attenuation wall vents

Lorry turbo impellor?

I did say small gaps , not huge ones

Been making mods to my DHW system. Combi boiler, but has a buffer with DHW coil upstream, with solar PV immersion. Plan was in summer no gas usage as the buffer would be hot enough and pre heated water would pass straight through the boiler. But that didn't work very well. Every time I opened a hot water tap, the cold slug of water between the buffer and combi would cause the combi to fire up, so was using a couple of kWh of gas every day even with a buffer at 60 degC. So installed on of these https://wattswater.eu/catalog/safety-control-accessories-for-heating/valves-for-solar-applications/thermostatic-kit-solarkit/ Now using no gas.

But you need an undercut of 10mm if you have MVHR or MEV for ventilation purposes. So they will never be great. Fire doors are solid so may have better accoustic properties. Fire seals will stop the noise transmission where you don't need gaps

If you run mechanical equipment in a steady state condition there is nothing to wear so the equipment lasts a very long time. Each time you stop or start mechanical equipment there is wear of the moving parts; as lube oil and mechanical tolerances get to their design conditions, the same is also true of stopping mechanical equipment.

But the maths is slightly different for the floor with UFH as you have a dominant downwards heat flow because the it has a high delta T than the upwards flow. Subsoil temp stabilises at approximately 8 to 9 degrees below the floor and the ufh water flow is circa 30 degrees, so the delta T becomes 21 instead of 13 (used in the linked maths. Heat Flow Q = U*A*dT Heat Loss E_heat = time*average_heat_flow = (days*24hours/day) * U * A * (Average_dT) For me average dT across 6 month 'heating season' is 21K (i.e. 21 Celsius) --> E_heat = (183days/yr * 24hours/day) * 0.13W/m2K * 1m2 * 21K = 11990Wh/yr = 12kWh/yr per m2. That is heat energy, to understand what I'll pay, I need to know how much heat costs me. Using an ASHP with a COP of 300% (reasonable) and an electricity rate of £0.3/kWh electricity, I can calculated that heat costs £0.3 / 300% = £0.1/kWh heat. 12kWh * £0.1/kWh = £1.20/yr per m2. 0.01 change in U value then the cost difference is (0.01 / 0.13) = 1/13 of £1.20/yr /m so £0.092 per m2. My 192m2 floor has a U value of 0.01, so plugging the figures in gives me a saving of circa £70 every year on downwards heat loss by improving on a u value of 0.13.

Have you purchased the ply yet? 22mm interlocking waterproof boards may be better, fully glued with D4. Perimeter screwed. Gap around wall for expansion. If ply, fully glue with D4, leave gaps between panels for expansion and around room edges. Glue should expand to fill small gaps instead of shims.

If well insulated flow temps are so low you won't be able to tell the difference. So choose whichever. If you are using a contractor to install go with there recommended layout. MVHR does not move heat, as flow rates are way to low. It's only replacing around a 1/3 the volume each hour. What's your floor build up?

Just been through my pricing again two Titon MVHR units - £250 and £320 each Direction grilles x2 £340 (total for both) Everything else £1200 So around £2110

I think MCS sort of kills the option for cooling in the UK without modification. If you only need a small amount of heat why not keep the money in you pocket and just go Willis heating. But no cooling or something like a Dream heat pump from Ebay for second hand money, they do heat and cooling

Someone on here mentioned they were the Rolls Royce of heat pumps, think they come with a similar price tag. There is thread on here looking at standby energy consumption (can be huge), so would be worth having a read of that also.

Download LoopCad for a free trial. Also found these on the internet, so you work out flow temps spacing etc.

WC, the circulation pump runs 24/7. Heat pump or boiler will kick in to manage the flow and return temp. Ours has a summer set point, so you set the outside temp you want the system not to heat. Ours allows three different set points, for temp, which really means the flow rate is reduced or increased. You can get different temperatures in different rooms by balancing the system, reduce the flow rate in the rooms you want cooler. Sun out or wood burner on, will affect the return temperature as not so much heat is being transferred to the room. So the higher return temp will tell the boiler it can switch off, the circulation pump stays on. I have made some mods to our heating system and started the heating up, the return temps from the floor at start up were 25 degC. Had the CH running for an hour boiler didn't fire up as the return temps were too hot. Had to increase the boiler set point much high to get the boiler to fire up.

My filters are g4, you are better off with f7 on the supply side g3 or g4 on the extract.

I to was quoted £10k. In the end after quite of research I did my own system. Got surplus mvhr units (2x) from eBay and sourced everything else, ended up spending around £3k.

I suppose it depends on you perimeter to area ratio, to what the overall u value becomes. Our house is long and thin, so needed way more to achieve a good u value. Also we had no disposal costs as everything stayed on site.

I would go solid floor, with plenty of insulation below - 150 to 200mm PIR. Install blinds on windows as evening solar gain will be high in Autumn and Spring as the sun doesn't go that far west before getting very low in the sky.

We have Silks Sarnafil on our roof. Reasons, only supposed to be installed by correctly trained fitters. Fully welded install so less chance of leaks. Our Sarnafil has a loose fit fleece between it the plywood deck.