JohnMo

The formula for calculating ventilation heat loss is: Rate of heat loss = V x ACH x DeltaT x 0.33 So if we take the efficiency of MVHR as 85%, some better some worse. The formula becomes to calculate savings V x ACH x DeltaT x 0.33 x 0.85. So if you flow rate through MVHR as 0.3 ACH. A 200m² house with 2.4m high ceilings, inside temp 20 outside temp -3 (200 x 2.4) x 0.3 x 23 x 0.33 x 0.85. So you are saving just over 900W against a ventilation heat loss of 1100W, without heat recovery. That is worse case. So a more average winter temperature of 6 degs The saving becomes an hourly savings of 600W throughout the heating season. 600W x 24 hrs x 180 days. So about 2500kWh. So @joth numbers are in the correct ballpark. So a CoP of 4 or gas, so around 5p per kWh. 2500 x 0.05, is about £125 a year. My first quote for MVHR was £10k so that for us would have been about 80 years payback. As it is I am still looking at 16 years as DIY installation. So you only paid £1000 for the full system?

Good old days when energy was a cheap, no-one cared how much energy they used. And the whole house was cold except 2 foot away from the heater. If you want an even spread of heat use several heaters.

Mine are directly over baths or shower areas. But other will say the complete opposite, so make your choice. Difficult to tell from the drawing is it one large kitchen diner? You seem to have 2x extract one over island and other over sink? If one room one extract is fine, but not above hob, as you will fill the system with grease.

Especially with UFH. Pipe from heat pump to 3 port diverter. Each side of diverter, to either to UFH hot port or cylinder top coil tapping. Return piping from UFH cold port to heat pump, cylinder return tees into return from UFH. Strainer in return line prior to heat pump and after tee. Heat geek design done. 22mm fine up to 6kW generally, unless long runs. Up 10kW 28mm on primary runs. Bigger the heat pump the better the quality of 3 port diverter you need, to reduce pressure loss. The other thing to assess is system volume, for cycling.

Maybe a combination of cycle fatigue, or just not suitable for the usage. More suitable for a hose pipe. I would look to replace, with something pressure rated https://www.pipestock.com/pp-hose-adaptor-female

Just looked at our lounge out of interest it's about 36m², so we have 36m² UFH. Looking at skirting we have have about 16m linear length of skirting (doors and lots of glazing get in the way). So to match area skirting would need to be very tall. I did try going the skirting route early on in the design, and could not make the numbers work, even for gas without big flow temps, which I was trying to avoid. Plus UFH is so cheap in comparison.

Just get a heater with power setting and put thermostat on full. But if you only need 700W you will slowly get hotter and hotter, without some sort of control

100mm

That really depends on the slump you ask for, when requesting the concrete. We used a structural grade concrete (forget which) but quite high slump with fibre reinforced. But we have the structural ground bearing slab below the insulation. We did ours prior to walls going up, very exposed site. Disadvantages, in cold weather if ice foams on the slab, because it's very well insulated, it stays covered in ice for days. If you have water in UFH pipes you also need antifreeze. Due to the slab size 192m² there were a few dips and high spots, ground down high areas, self leveling on low spots. Damage during build none

From photos that is obviously just a preliminary test. So as not your final test, (as the plasterboard and second fix not complete), you have plenty of time to get things fixed to your liking.

To add to the above. If you zone your property, that is have thermostats in many rooms with different time controls, asking for different rooms to be heated at different times, you will drive yourself into having a buffer. Why? To protect the heat source, could equally apply to boiler or heat pump. Reason for this is to stop short cycling and give the heat source suitable circulation route. Plus for a heat pump suitable capacity to allow defrosting by providing a minimum required volume.

Not that I bothered with grants, but why aren't you eligible? Any new house should be eligible and you get more money than England.

Exactly my thoughts too. Especially on a new build. UFH materials less than £1k, 2 or 3 man days to install full house. Panasonic ASHP £2.5 to 3k, cylinder £1k - then install how you want

Maybe true, but he could also be adding a dose of common sense to the install, so maybe a good company to discuss things with

We use 4G, I tried additional antenna, but by the time added the cable length I needed I was back to the same signal strength as without. In the end I just moved the router about until I was enough. I only get 3 bars on the signal strength, but it's stable and fast enough. Finding the best service provider made the most difference and best router

To get bus grant the install has to comply with MCS rules. MCS rules should be reviewed. But they require all habitable rooms to be heated. MVHR is just ventilation - does not contribute to heating, does not move heat about to any degree. They can't as such, the same high temp is generated by the heat pump, if you want a lower temp it's mixed down as well as a high temperature it's done by mixing. They can at the expense of CoP and actual running costs. They have to do a full system design, token efforts aren't really allowed. The grant money isn't just for you, it's for future owners of the house also, they need to design for certain room temperature, sticking in a pocky radiator because it suits you doesn't comply. You either take the grant and follow the rules, or don't bother with grant and do want you want. I chose the later. Paying a £6k deposit on a system where you are getting a £7500 grant is questionable.

I just walk away and leave everything set as is.

The glazing is normally the worst performing aspect a good quality windows. You are after two things airtightness and no thermal bridges. So is insulation spray foam better or equal performance (U value) compared to the window frame - yes/no. Is the spray foam airtight if installed correctly - yes/no

You may want to try purge ventilation, as interim measure. You basically open all windows and interior doors fully, everyday for 3 minutes. Then close them. Most the building heat is within the building fabric, air contains very little heat energy.

The trouble is if you hardwire, you pay the electrician to install wires, you end up paying £50 per thermostat (could be way more or a little less), then you get talked into auto balancing actuators at another £25+ each. So an 8 room house you end up spending several hundred on need less stuff, plus labour to install it... Leave the contractors they will also insist on mixers and pump. I have so much needless stuff I have removed it's unreal.

With an ASHP with no radiators you can, if you wish drive the UFH from the circulation pump within the heat pump. So no mixer or pump needed on the manifold. I would state to the UFH contractor you are going to run weather compensation. I would install an electric towel rail in bathrooms and use that to dry towels when heating is off and drive the room temp up if needed. If you want the bathrooms warmer than the rest of the house on the same flow temp and on a single zone, just put more pipe (closer pipe centres) in the bathrooms. Given a choice of heat pumps, I would just go Panasonic.

We are using the same, our first one failed after 2 years, but it was operating in a near sand pit, so no surprise really. But they are pretty cheap to get new and all parts are available to repair.

Or a big one

You need proper ventilation strategy, air through trickle vents, but what's driving the throughput? Ideally you have cross ventilation - air comes in via dry rooms and out wet rooms. Under doors need a 5 to 10mm gap so ventilation doesn't stop with doors closed. dMEV fans in wet room would provide the motive force for air movement. Then you need to make sure the house is heated, this drives the humidity levels downwards.

Need proper ventilation and filtration then. Business-esque prices also.