JohnMo

CoP at -10 and 55?

As I mentioned above the outside temperature used in all cases is -10 so ignore SCoP as it has nothing to do with it. SCoP is a different measure all together.

They are measuring different things. SCoP is looking at the likely performance over the heating season, at all the different outside temperatures you are likely to get. Space heating efficiency is at a set temperature of -10 deg C and as far as i can see takes the full system efficiency for a nominal system.

I would work out the flows you need in each room first. Then they are set. A big room depending on how many people, needs a decent flow. Although there are two of us and dog, the lounge is set for around 60m3/HR. In general use CO2 levels are around 600ppm, but when we have 6 people in the room after an hour or so CO2 levels are getting to over a 1000ppm. So happy with the setting. Our lounge is 36m2 but 6m tall.

I think Panasonic made a big thing on how their unit doesn't switch the internal unit off during defrost. So most likely most will pause the internal unit while defrost occurs.

Go on to manufacturer web site download the datasheet it will give pressure drops per meter per bend and by flow rate. It may also state the longest run acceptable. But simple terms. The longer the length of duct the bigger the pressure drop, the more bends, the bigger the pressure drop, more flow the bigger the pressure drop. The bigger the pressure drop the more work the fan has to do to over come it. So fan speed is increased - more noise, more electric. So worse case you need a bigger unit to compensate. Flow rate is to do with noise also, more flow more noise.

I will make some assumptions Your UFH pipes are on 150mm centres. UFH flow temp is 35. If so your input to floor is around 50W/m2. Assume at temperature of defrost, the output of the ASHP is 7kW. 7000W / 50W/m2 is 140m2. So if your total floor area is at or around 140m2 you are driving the heat pump very hard. If it's about 17 to 80m2 you aren't.

2 x 90mm. Whole house is 90mm. Double runs in master bedroom and lounge. Other runs are single.

Our bedroom is circa 15m and has two outlets, you are likely to need 2x90, otherwise you will be setting fan to higher speed to get the flow to where you need it, with increased noise etc

Are you trying to run the heat pump like a boiler and having shortish periods blasting heating. I also have an A rated house and my UFH pipes are at 300mm centres, which is really wide, so output from the floor is low compared to usual. Even so at -9 my UFH flow temp is 35, any other time it's between 25 and 30. Yet your temp is always 35 for your UFH and 45 for the rads. If would turn your temps down as suggested by @ProDave and run for longer, that my be your fix.

For 16mm you really need a magnetic drill. For what it will cost get your local fabricator out to do it for you, they will provide everything. Likelihood of wandering off centre is high with a hand drill, and if it's powerful it is also likely to grab as you break through the other side.

If it's noisy it's a good indicator that the unit was either undersized or the ducting was not correctly sized or installed badly. MVHR should at normal flows be almost silent. I think you are looking for the wrong information, getting the design right is key, a quiet unit badly installed will be noisy

Trouble with EPC on older buildings can be rubbish in rubbish out. The assessment is basically what is or isn't seen or assumed. Unless they are corrected by the home owner, the rubbish output remains. But I have to say 95m2 mid floor flat using that much energy needs some work to reduce the heat losses.

Because a 4 port buffer (connected to flow and return) acts as a hydraulic break in the system. Without the additional pump the water would just flow from the HP to buffer and back to HP. A volumiser come insulated and without. Grant do some nice insulated volumisers.

Our carpet underlay in the bedrooms is what looks like a perforated standard underlay (although we specified UFH underlay), we also used expensive wool carpet. Both do a really good job of isolating to floor heat from the room, so UFH is pretty rubbish in the bedrooms, good job we like them cool.

Big cost is the basement do you need it, will you use it? Why do you need 500m2? Big area - big costs, £1500 m2 sounds on the low side, for someone else doing the work.

Heat-Pump-Guide.pdf Page 35 tells you how to work out system capacity required. Take away engaged volume of water i.e. smallest zone, you are left with required buffer. Best efficiency comes from a volumiser, so add capacity to return side, then there is no mixing of supply and return flow.

Hot water return circuit is NOT a standard install, you would have needed to ask for that prior to work starting. Pipe sizes depend on pressure drop. Why do you think you need 28mm. If it's 28mm on a domestic hot water feed to the taps, then you may get fed up waiting for the hot water to arrive, it would take an age. My feeds to bathrooms are 15mm, the furthest away can take a couple of mins for the shower to come hot. Pipe length and volume all have an effect on hot water delivery time.

There was a house builder near Nottingham or Lincoln using them on near passivhaus builds. They were all ceiling mounted. How good - no idea. If they are just heating the person not the room maybe they could be cost effective, would need presence sensors that knew you were coming in to the room a minute or so before you actually did, so they would be up to temperature before you walked in to the room. But any part of your body in a shadow of the IR heater would stay cold, feel cold. UFH heats the room and the body, you have a room temp of 19/20 and feel comfortable. As mentioned above, at less than 1/3 of the running costs due to CoP.

I dod the UFH install my self. But the loops took less than two days to install on 192m2. Including filling and leak testing. I think you are being quoted circa £20k to much. So let's break the cost down - in your case say 2 guys 4 to 5 days, would be ample to install the loops and connect to manifold. At £50 per HR. So £4000. Ever if it's double that, you are still way to expensive. Materials UFH pipe £62 per hundred meter. Let's say you need 1500m = £930 Two Ivar manifolds, mixers and umpsat £400 each. £800, let's say £200 for other stuff. One-man one day for filling, purging and commissioning £400 Total £6400 round u to £7000. So in a similar ball park to @Conor

I have been caught by that also. Nice easy money making scheme by wholesalers.

UFH shouldn't feel warm under foot. The surface temperature is well below body temperature, so doesn't feel cold but also not warm - in my experience

Someone is taking you for an expensive ride. Remember you still need to heat DHW IR will not do that.

Not exactly the same, but pretty similar

Easy way to look at things. Follow the line of insulation around the building (window is classed as insulation) there should be no break in the line upwards/downwards or vertically. It should be continuous across all elements of the building. The more insulation the better. Your block/brick returns make a gap in the insulation, so are no good as they act as a bridge from the heated inside to cold outside of the building. The cavity should continue to the window, either full fill that area with insulation or use a cavity closures. The window should straddle the insulation, so it gives the line of insulation mentioned above. Be careful with your choice of aluminium windows, as there are mostly poor performing ones out there. Make sure you get a whole window U value, before your commit to buying. Many try to give you just the glazing u value of 1.2 to 1.4. but have seen whole window U values for double glazed higher than 2, because the frame isn't well thermally broken.