JohnMo

That was my first unit and then moved to Greenwood and you cannot tell it's running. I would just do two dMEV units, as recommended in March. Yes - See above. My wife hated the first unit we installed before the noise.

Zones means a buffer, so really would not go that direction. You need to look at system volume and flow rates. But if you have fan coil up and downstairs why bother with UFH? Your making life complex and expensive. Why isn't it important, if the heat pump is short cycling you may not get any cooling effect. Plus constant stop and starts will decrease the life of the unit. I did timings last year based on PV being available, this year on and forget, runs as it needs 24/7 uses nearly no electricity. House much more steady temperature also, peaks in temperature when sun comes out are quicker brought down. Set a weather compensation curve for cooling and heating and have the system self modulating so it's either heating or cooling and never off. A simple high hysterisis thermostat to flick between the two, or simple switch. Keep it simple.

You have chosen everyone that carries a huge price premium. Nothing wrong with Grant, but hook up as per Chofu (original manufacturer), my only choice would be Panasonic if buying at full retail. But really depends on how the system is designed, good heat pump in poorly designed and/or operated system is a p*ss poor heat pump. Mediocre heat pump can be a really good one in the correct system. MVHR, nothing wrong with a Titon HRV unit, UK manufacturer, good technical support and spares if you need it. Also remember MVHR is ventilation it runs 24/7 365 days, it doesn't need lots of bells and whistles, once your house dries out boost is rarely needed so a simple momentary switch is all that is needed. Also look at the cost of filters as you will be changing every 6 to 12 months. Costs can soon mount up.

Uw value. That is the whole window U value as opposed to UG which is just the glass. How are they installing them. You really want them foamed in with airtight expanding foam. This will give a good degree of airtightness and eliminate the thermal bridge around the frame. Many will install in the hole and then cover everything leaving a void and you get mould around the window.

Mine runs via two thermistors, one temp above for heating and the temperature below for cooling. A simple pipe stat x2 could do that. Normally open for one normally closed for the other.

Mine is, but you can also set it to sniffer mode, so the circulation pump run for a couple of minutes and off for 5 minutes.

No, but it would run in the summer when the sun's out and that would be it. Unlikely to get enough power to start in winter, most the time, especially when you need it.

None. Currently just run the fan in the fan coil in manual at lowest speed. No, short cycling is uncontrolled short running and off cycling. I had 6 starts over a 6 hour period. Typically you would have many (10 to 20) restarts an hour and very limited heat or cooling given to the house. Typical short cycle is a couple of mins running and a very short off time. What you are seeing is capacity control when running below min turndown. Yes but then you run into condensation issues in the floor. So it's all a balancing act, long runs are great, but if you have condensation issues not so great.

You can run heating at 70 degs on timers and zone valves, it isn't efficient. Trying to similar with a heat pump ends up with huge running costs. You can run the heating at low flow temps slow and steady in all the time. It is efficient. Apply the same logic to cooling. Well insulated you can set the system so it's self modulating. Responding to demand. Even in 300mm pipe centres in a 100mm thick slab, you can see the heat pump responding quickly to solar gain. We get the solar gain around 3 to 3.30pm. This is a snap shot of the heat pump flow temp. The dips are the compressor starting and running. Prior to 2.15pm heat pump is off for two hours. Then an 11 min run and off again until 3.30pm. Then a 20 min run and off for 20, on for 20 etc, in direct response to solar gain.

None, just a heat pump, don't be too greedy with flow temps. My WC curve for cooling is 14 at 30 and 14.5 at 20. Compressor restart hysterisis is 4.9 and shut-off is 2.8. Been cool and not much solar gain for the last few days ASHP compressor hasn't started at all. Any condensation you make is a result of the internal temperature and humidity, keep the temperature steady you shouldn't have issues, if you let the temperature swing about with timers etc you will be chasing your tail to keep condensation in check.

My pipes run outside to summer house so are insulated. But not insulated within the summer house. The UFH manifold isn't insulated either. Neither seem to get wet, possibly due my short run times The target flow temp is 14.5. but the way it's all setup the flow temp can go down to 11.7. But the heat pump compressor rarely runs more than 40 mins (mostly 12 mins) before shut off and then just circulates cool water. Once the return temp hits 19.4 the cycle starts again.

For the pipes just make sure they are barrier pipes, so you don't get air entering the system over time. I am just using Hep2O. The fan coils will have a condensate collection point and a connector to run to drain. I decided running a drain away was too much work, so thought I would suck it and see and if I needed, I could put a small container underneath to catch drips. Which so far I haven't needed to do.

Not us that needs to be happy, it your house🙂

Although I said I had no pumps that was related to heating. I do have one these, they have a timer and thermostat. Runs in the morning and in the evening. https://renewableproductswarehouse.store/products/lowara-secondary-return-pump-ecocirc-pro-15-1-110-ru I got mine from eBay for £125.

Wouldn't you do this. To get the levels where you want them? Doing mine again I would miss out the GSE flashing and do lead instead

I'm not at the stage of needing to actually find a UK supplier, but Daikin advertise I found the following two important parameters you need to be able to adjust: Fan starting temperature for cooling and heating. This is the water flow temperature being detected by the fan coil to give a permission for the fan to start. Not all units have these as adjustable, so worth checking. My default settings were 15 degs for cooling and 32 for heating. These were reset to 18 and 21. I found some cheaper units were factory set to 35 for heating only. Also check the flow output at different flow temperatures, once you get to UFH flow temp the output of fan coils drops. My unit can do 6.5kW a delta 50, at delta 10 it's closer to 1kW.

Look at Cool Energy web site

Get the flow temperature correct you can leave the heat pump to manage cycling based on demand. You can set a very simple WC for cooling. Mine is 14.5 at 30 OAT and 15 at 20. The heat pump senses return temp and starts compressor based on need. Sun comes out return temp rises heat pump compressor starts. That's all @Dave Jones is using and says his bedroom remains well cool. This our summer house, you can clearly see when the sun came out with a steep rise in temp and equally quick drop in temp. For comparison the house (temperature sensor in hall) house is just UFH cooling. The real spike in the living room is much bigger, but the cooling effect similar.

Yes but a ground bearing slab. With block and beam I would have some insulation below the pipes and plenty above. Assume the space will be vented below B&B, so if cold outside the space below would be similar.

Our Myson in the summer house. Big one and 4 pipe K2 heat exchanges piped in series, so I can run the same flow temps as UFH

I would do a simple wall mount one. Panasonic, Cool Energy or Myson are good ones. Condensation drain, yes if flowing 5 Deg water. But if the water is going through the UFH also a flow temp of 14ish would be better to keep away from condensation issues in the floor. If you don't involve the floor in the flow path you will need a 50 plus litre buffer also to stop short cycling. Our summer house fan coil has been running for the last 6 weeks, pipes not insulated and no condensate drain, zero drips. Just run the pipes from your UFH manifold as a separate loop.

The same conclusion I came to. Basically letting it run as fast as it wants in cooling mode and heat pump seems happy. UFH seems very quiet, advantage of no pumps in the house.

Doesn't remove corrosion, not does a power flush. But VDI prevents corrosion as far as it's possible by elimination of the properties that allow it to happen i.e. bug growth (reduced mineral content), oxygen and reduced electrical conductivity of the water.

Many have tried, but never heard anyone say it works as expected. Don't waste you time trying or your money - flow rates are too low to work. As I said deliberately MVHR is for ventilation. But you can do some heating with it max heat rate based on passivhaus flow rates at 10W/m2. But is way from efficient with a heat pump as the flow temps need to high. Keep ventilation and heat/cooling as separate things. You can buy combined units but if one thing goes wrong, the whole lot stops working. Keep it all simple.

All our cold pipes run below the insulation in the floor (200mmm PIR). They are in flexible conduit cast into our concrete subfloor. Keep well away from UFH as you will have a breeding ground for bugs in the warm space. Also who wants warm 'cold' water. Legionella growth chart - UFH temps are the correct temperature for slow and optimal growth dependent on flow temperature.