JohnMo

Cost versus diminished returns. It usually the frame that kills the whole window U value not the triple glazed glass. Passivhaus specs are based on comfort, and inside glass temperature compared to room temp at a given temperature outside. I have triple glazed and it's 2 degrees outside sat right next to a huge glass window, do not feel the cold outside, window is not making me feel cold, ( sucking the heat from me) a single glazed would and a double glazed may also but to a much lesser extent.

Without heat recovery you will loose heat no matter how you ventilate. So basically you have two options without major upheaval PIV, as linked too above. Seems to do what you want, basically it takes fresh filtered air and it blows through the house out open window vents and through any gaps in the building fabric. It has a suitable settings for a 3 bed house. The Other way dMEV, this pulls air out of the building via fans in wet rooms and kitchen. So you need a fan in each of these rooms instead of intermittent fans. You need vents in all other rooms. Fresh air is pulled in the vents and across the rooms to the wet rooms and out of the fan. You can add humidity controlled vents for a low cost, these will limit the ventilation when it's not needed. The link has the brochure and user manual, with the flow rates required etc.

No problem, it does tell a better story

Mine asked for same, told him it was a self install, gave my G98 registration details, he was happy.

Less steam = more condensing. The white steam is water vapour, a condensing boiler condenses the water vapour back to water and collects the latent heat, transfering it the heating system. To get condensing the return temp on a gas boiler needs to be below 56 degs (?). The further below that temp the the greater the condensing effect and more efficient the boiler runs.

That's a big heat input into a small space, take it has little or no insulation?

The mixer always moves excess heat back to the return. You could turn the UFH pump down, so it's taking less from the CH circuit, this would mean less hot water is being returned to the boiler. Just watch the UFH loop flows to make sure your flow is high enough to cope with loop flows. The UFH loop flow rates should really be defined by the loop length, so shouldn't be adjusted except for fine tuning heat put in to a room. Low flow rate on loop, gives a higher differential temp, but this means the 'mean flow temp' is lower, which equates to a lower heat output from the floor.

If you look at your manual for the boiler, section 5.12 allows to set the boiler with independent flow temps, for the cylinder heat and CH. Not sure if your installer did this or just what they normally do. If on S plan maybe not. If wired per manual you could lower your CH flow temp and the setting on your mixer. This would lower the output of the boiler to match more closely the mixer temperature. Also noted from the manual is your min turn down for CH is 4.3kW, this may be ok on a cold day - but any other time you may have some boiler short cycling. Low energy houses and normal plumbers don't mix very well, they try to do 'what they always do'

What boiler do you have? Any idea on what plan it's wired as?

The basics are For a given temperature difference between inside and outside the average heat loss will always be the same. If you increase the temperature difference i.e. its colder outside, you need to add more heat to floor to compensate for the heat loss. Your controller will measure flow and return and alter one or the other to a hotter set point as it gets colder outside, and less hot as the outside temp increases. Now if the sun comes out and even though its cold outside, if it heats the house through thermal gain, the thermostat will trigger and tell the heating to go off. Once the the houses cools the thermostat will then tell the heating to come back on again. Now the problems come form having a thick screed and react times. Our house has a 100m concrete floor and it takes about 6 hours to move a degree, so if I'm not careful the house temp can be all over the place. Its a bit of a process to find what suits your house. Trouble for most the controllers they are great for normal leaky houses, but low energy house with thick concrete floors it all a bit hit or miss with the control.

Comments on your layout Utility, very short run from manifold, not high flow rates, so not sure you require a double duct run. Similar comment to other extract duct runs. You could shorten supply duct runs everywhere by using coanda effect supply nozzles, these are wall mounted instead of ceiling, and the air will move across a ceiling for 4-6m, before dropping and then traveling across the room towards an extract. Something like these https://www.epicair.co.uk/collections/plastic-flat/products/supply-air-valve-coanda-effect-8960-90mm You seem to doubled up extract ducts, but supply runs seem longer and are single duct, so this needs sorting out.

For our master I did similar, one supply in bedroom 35m3/h, but a second one in a wardrobe/dressing room, think it was 15m3/h. Extract in ensuite set at 35 m3/h, so supply air over and above 35m3/h has to travel through the rest of the bedroom and down corridor to the next extract point, keeping the corridor supplied with fresh air also.

If the curve is set correctly the room temps manage themselves, with UFH the response is so slow feedback on room temp is pretty much meaningless for room compensation. As the flow temp is constantly being adjusted but floor takes hours to respond, when it the control changes the settings and it just chases its tail. Your thermostat just needs setting a degree or so over your target temp. If room temps are getting to high, compensation curve needs lowering, if individual room are getting too hot the UFH loop flow needs to be reduced.

I also had quite a few issues when I started using the UFH. Ours is 193m of UFH in 100mm concrete, which I think equates to 56 tonnes. So heat up times are long. Our first heat of the season uses loads of energy. You are doing the same every couple of days. Couple issues I see 1.Your flow temp in the floor is too high if you are overshooting that far. I have the temp set a 30 and batch charge each night, for a out 6 to 8 hours depending on outside temp, have a single thermostat set at 18.5, which in reality switches the heating of at 18.75 deg. The heat then settles at 19 an hour or so later. Once charged up the floor keeps the house stable for the next 16-18 hours, the process then repeats. 2. Can you reduce the firing temp of the boiler, it doesn't need to be that high, unless it that high for the cylinder? 3. Are you sure you are not short cycling - boiler running on off for short periods of 10min or less? 4. Do you have a buffer?

I'm still on gas but been doing lots of reading, I need a cooling solution as much as anything else. Heat pumps generally run a pressurised system same as combi, so if the freeze valves open the system would loose pressure. If the system is operation ie you have power, the pump would circulate to protect the system. Only in a prolonged power cut would the water drop below 3 deg and the valve open.

It has a lower heat transfer coefficient compared to water, so you have to run a degree or so warmer.

Two types of heat pump Monobloc, everything you need to get hot water is outside, water pipes connect to outdoor unit Split, smaller outside unit, but refrigeration gas pipes connect to indoor unit some of the stem is indoors, water connects to indoor unit. Hex unit, just a plate exchanger and pump in flashy box. Less efficient do to a temp drop across the heat exchanger. Glycol anti freeze, stops water pipes freezing. Without a heat exchanger the whole system has to have anti freeze in it. Split system refrigerant doesn't freeze at normal winter temp. Alternative to anti freeze is freeze valves, these open when they detect water temp at or below 3 deg, dumping water to the floor.

The above all run at 100% efficiency. So if 9kWh was available you would get 3 hours of heat for one the above rated at 3kW. Something like the below on eBay, would give you 9 hours or more based on the same output to the room and the same 9kWh eBay item number: 195191096004

If the heat pump is heating the air the ventilation efficiency at heat recovery is zero. You are not recovering any heat from the outgoing air. The heat added by the heat pump is being generated and used by the house the same as another radiator would. Efficiency improvement may be there but will not be massive. Assuming an ACH of 0.3 air transfer can deliver about 10W/m2 (if I am remembering correctly), without the air smelling of burnt dust.

I made a similar one. Then had someone with certified equipment come and 'official' commission so I got a test cert with calibrated equipment certificate. He remarked how close the initial setting were compared to final, I think one terminal was slightly adjusted. So works well.

PIV is a ventilation system, you are just blowing in, instead of sucking out. Assume ventilation rate is based on humidity CO2 etc? You may want to get humidity based trickle vents also, so if the humidity is below 50% the trickle vents close themselves and open as the humidity rises. I would use something like 0.3 ACH.

Couple of different ways to look at buffer and also what the heat manufacturer states as a minimum system requirements. Some manufacturer will have a minimum system volume and minimum flow rate. Some will specifically demand a buffer of minimum volume otherwise warranty is void. If you have UFH with a mixer valve you have no idea of the volume flow through system will always meet the min flow requirements as the mixer recycles a lot of the flow. Vaillant 8kW demands a flow between a min and max of 380 and 1400 l/h

I think it depends on make and model, some are just on or off others will modulate, but suspect most on the market are on or off. The only thing being smart is the internet connection.

This my system now. So basically a combi boiler that can take preheated water. It will do three showers at a time - just. Doesn't use much gas in the summer, uses mostly PV solar divert to heat.

You may be better with a big thermal store, size the boiler to charge the store, do as a DHW tank in tank or big DHW coil, seen them at 6.3m2 and 8.25m2. Charging coil about 2.5m2 in the same store, will work at low temps. 1000l? https://thermal-store.co.uk/1000l.php#1000l-lmt Then it would work down to about 50 degrees, or wack up the temp to 80 when you are full. No need for a buffer at all, just size to suit the storage you want and the DHW needs. UFH would come direct of the store, have a tapping for each manifold pump, would give you a simple system with full hydraulic desperation. Tonnes of hot water flow also.