JohnMo

Couldn't you do that with a smart relay and or a timer thermostat? A lot of heat pumps have a double set point, usually activated via a zero volt contract. I have my heat pump set to 27.1 degs flow, as my base temp for WC and the second set point at 30. WC is normally based on the start point of 27.1, when second point engaged the WC base temperature jumps up to 30 degs. So use a simple timer thermostat, when not calling for heat pump runs at base temperature of 27.1 for WC. When calling for heat runs at base temp of 30 for WC. Thermostat set to 20 during the day (knowing WC normally keeps it at 20.5) and at night (E7 period) it targets 21. That way if I have plenty of solar gain in the day I am not running the house too hot. So during cheap periods, use the thermostat to ask for a higher temperature activating the second set point. Also use a smart relay to activate second set point when producing xkW from PV, battery is above x SOC (state of charge) and outside temp is below x degs. Simple home assistant automation. When the sun's out and battery is pretty much charged I can buffer the floor for a couple of hours for free, when in E7 period I also buffer the floor.

An example of how it looks, we have a fan coil in a heated summer house, with very different heating and heat loss profile to the house. Flow one flow temp, no mixers. This is overnight, orange line is the supply temp from the heat pump. The other two lines are temperature in the house and summer house. Outside temp dropped to 5 degs. The spike in the orange is starting to do DHW.

Not as far as I am aware. Clip the pipes to the insulation - screed, done.

If you running WC it's pretty difficult to overheat any part of the house. Unless you're curve is way out. Local rooms overheating via solar gain pretty much self manage anyway, delta T between floor and room decreases and output from floor stops. No controls needed. You can use your floor to buffer loads of heat and it really has very little impact house temp (to a point). Thicker the screed the easier and least fluctuation on house temp. With gas boiler I routinely heated whole house floor for 6 hours and lived of the heat for the next 18 hrs, about 1/2 Deg house fluctuation. Heat pump isn't powerful enough, to do that on a cold day.

On the MCS certified website Domestic_HW_cyl_selection_guide.pdf

1. Yes 2. No you can't do that and claim grant. You have to be merrily ripped of first. Pay many thousands and the grant just vanishes 3. Installed ASHP is vat free anyway, new build or otherwise. If you go under MCS and the grant the cylinder size is defined under a minimum size by MCS rules, can't choose a smaller size. I would price up yourself and then get a grant based quote. Why limit yourself to Vaillant? Buying again I would go Panasonic.

Today no sun, UFH not gaining temperature, very slight fall. Sunny side of house is timber clad on a 100mm ventilated cavity, but sunny side of house also has 50m² of glazing. Walls are externally insulated ICF. Although heat losses would be slowed down, air temperature rise through solar gain is at play. Floor just soaking it up and showing in the slight uplift in UFH temperature.

Methane? What do your drawings state? Is you house wrap certified for roofing applications? Suspect the joiners are wrong.

If you have choice of finding spaces for radiators or everything hidden, I would go everything hidden. Plus lower flow temperature for better efficiency. Wet UFH everywhere, plus you could add electric (in addition) in ensuite and bathroom, if you want if hot underfoot, and for off season heating. Add electric towel rads for bathrooms either way. You don't need much piping in the floor for UFH to work (if well insulated), we are on a loose 300mm pipe centre and it works fine

We went for borehole for various reasons. We pay way less than normal water. Think we paid about £140 for the annual service. The steriliser is just a light in a tube, bulb gets replaced as part of the service once per yearq. Our council tax water element of the charges is £500 plus waste water of £560.

Look at the data sheet and look at m² coil area. I just used an Ideal one 210L slim line, was about £800 last year. There are plenty of options out there. Or take a look here https://www.cylinders2go.co.uk/product-category/renewable-energy/heat-pumps-cylinders/?_gl=1*1ttl432*_up*MQ..&gclid=Cj0KCQjwmt24BhDPARIsAJFYKk3KvzDtUhGD5_9hmadZrcLf87Wv0TgcqsSxCr7QIu5Lmp0Sgy3PhBYaAniOEALw_wcB Will reduce reheat time, plus as more energy is transferred to water the return temp drops more compared to a small coil, so you get slightly better efficiency from the boiler.

So at that thickness you will have most likely two layers of rebar. They are usually 50mm of more below the surface. So zip tie at 200mm centres to rebar. Nothing will float up. You have two opinions with UFH pipes fill with air or water glycol, water glycol less likely to float. Plenty of examples on the UFH section on here.

Or ask yourself do you need the actuators? You could just run open loop and weather comp. Set your thermostat(s) to about 24 so the actuators stay open all the time, noise will never come back.

Think it's more likely the ground workers will be wearing wellies during the pour. How thick is your raft concrete? Confused by the comment on wet rooms?

We just did self storage in shipping containers x3, loads of house stuff in 2 of them and a car, 2 motorbikes and garage worth of tools in another.

Nothing to recommend. But look at noise also that varies between makes and models.

Couple of things Low flow temperature is required to get a low running costs. At 70W/m2 you will need 100mm pipe centres, even then the flow temperature is likely to around 40 degs or above depending on floor covering. Zones and loops are different things, loops are just circuits of pipe, while a zone is a controlled area of heating with its own thermostat. Lots of zones isn't the best thing for a heat pump efficiency and will drive you to a buffer. Also the insulation under the floor isn't the best for UFH will likely lead to excess downward heat losses, especially at elevated flow temperature. Not sure I would go with either the vendors you suggested. Get the whole heating system designed by your heat pump installer. Get them to do it as part of the grant.

It depends on pipe schedule (how thick it is) as pipe size is stated in nominal dimensions. Take a look below. https://www.valvesonline.co.uk/free-flange-tables?srsltid=AfmBOoqG7T3lPn0niO-55d0uNIKyHb0fiw_B9U79sEyC9H4moDn7wnUL

The important bit about extractor missed by many is the importance of the distance the hood is away from the pans. The further you are away the harder the fan has to work (as in higher the m³/h). Look at the instructions and set it the minimum acceptable. It will then work better at lower flow rates. To put flow rates into perspective 500m³/h is replacing the whole air contents of a 100m² house twice per hour. A small dMEV fan and the hood on recycle mode instead of extract, may do a better job overall. For normal day to day cooking you would not need to use the hood at all, only for smelly stuff.

The bigger your heat transfer area in the cylinder (the coil) the easier the heat source (boiler, heat pump etc) can heat the cylinder. A normal gas boiler cylinder a has a very small coil and requires high flow temperature. But I would Buy a the smallest a Panasonic heat pump you can get away with. Don't bother with the grant. £2.5k, you need a cylinder anyway, heating system sorted.

Do you have an electric backup heater? If you do I would be switching of the control of it in the controller.

Running cost of electric UFH will be pretty much 4x as much as the A2A. Do some work on the A2A replace if needed. All the hard work had been done it's all ducted etc. 3. Storage heater, you would normally have a storage heater in bedrooms?

House is as you describe about 3kW heat loss at -9. But we also have a garden room attached to the heating system with fan coil. We now run WC mode on an ASHP. I am flowing to the fan coil at the same temperature as UFH as it works pretty well. I have the circulation pump on 24/7 and the fan in the fan coil at min speed all the time also. The house floor is basically used as a buffer for the heat pump. Fan coil gets a flow temp of between 22 and 24 most the time and when the heat pump runs up to about 30. A lot on here haven't bothered with radiators in upstairs bedrooms. But I would treat the gas boiler the same as the a heat pump. As in - Design the radiators for low flow temp same as the floor. Treat as one big single circuit and run weather compensation. The bigger the system volume, the longer the run times. Then you need no fancy controls, no mixers run the whole lot from the boiler pump. Do a system boiler not a heat only boiler, then with a decent boiler you will get a modulating circulation pump, ideally a 4 pipe one or one with external diverter on PDHW, so the boiler runs two flow temperatures. Do not do S or Y plan. Run away from an installer that suggests it. Cycling and short cycling are different, a short cycle will use plenty of energy and little heat to the house, normally in the range of a couple of minutes or less. A cycle is the just the boiler doing capacity control, you have a run time generally a good 10 mins or more. Run time defined by system water capacity and min modulation kW. I would look at Atag boilers also. Out the box WC enabled, even come with the sensor. 3 port diverter valve ready. Just need a temp sensor for the cylinder and a single thermostat timer (ideally from Atag) They work differently from most other boilers, as they slowly ramp up to temp, and you can define the rate of rise in degs per minute. You can get full flow temp instantly if you want. And while your at it, do a heat pump cylinder, 3m² coil, so two options keep flow temp down for full condensation the whole heat period or super quick reheat times.

Prior to changing to heat pump, I would run the boiler and batch charge the floor instead of weather comp. So basically used a 0.1 hysterisis thermostat, set flow temp to 35, and let the boiler run, until the thermostat hit hit 20.6 (set to 20.5) boiler would shut off, would get about 0.5 Deg overshoot and house would settle to 21. From 9am set the thermostat to 20 until midnight then set to 20.5 to 9am. Boiler generally restarted at midnight, run for as long as need to get house back to 20.5. Generally 1 or 2 starts per day. This method definitely dropped gas usage quite a bit.

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