JohnMo

So how does that work, if they are helping balance demand are they sucking energy out of the battery or is just by being installed its assumed that house demand will be next to zero in peak times? Without PV you generally as a residential customer, get nil for exports, unless on a one-off scheme for say a Tesla battery

£35 x 12 x 10 is £4200 so doesn't much in the scheme of things Web site says "Midway through the contract, you’ll have a choice: either continue with the monthly payments or pay a settlement fee based on the contract’s remaining value at that point" so it may be an expensive option? Only thoughts are - do they have the ability to suck your battery dry, at any time they want, so they get paid for export and you pay to charge the battery? Things that sound too good to true, normally are

Why? Our 6kW inverter runs both, obviously you can't run all the induction hob rings at once. Or just go GivEnergy AIO AC coupled, none of this EPS nonsense, it all works as normal in a power cut, that is the whole house electric carries on as normal, as well as the PV. So no change over switches needed the Gateway just does it all automatically. So much so you generally know nothing about power cuts that occur.

This is interesting, I recently switched from ASHP heating DHW to direct immersion, have I noticed a step change in running costs? - no. Our heat pump is fair distance from cylinder (a good 20 to 25m), it reports a CoP of over 3, but reality of kW of heat actually delivered to cylinder and the efficiency of a heating element in the water, means electric costs isn't much different, between heat pump and immersion. Immersion slightly more expensive, but not really noticeable. The other thing is PV, we get clipping (reduced output, even in February) of generation based on export limits, so using more electricity at midday is better than loosing it via clipping. Which with 3kW immersion is easy to manage with a simple timer. Cylinders there could be £6-700 difference in price between a direct and heat pump indirect cylinder - that buys a lot of electricity. On good tariff that's about 1.5 years of free DHW just on cylinder price.

A direct invented cylinder is about the 1/3 the price of an indirect cylinder. Time of use tariffs make it a viable option. Plus you could use a smaller cylinder charged to a higher temperature if you needed more capacity. So 300L v 400L. Not many years ago our 5 bed house had a 120L cylinder - how things change

But your cylinder average temperature most will not. My cylinder has the thermostat 1/3 up and it can read 7 degs, after a large draw off, but the water coming out of the cylinder is close to 50. So mean temp is quite a bit hotter.

We have a 6m overhang, but its the westerly afternoon sun in spring and autumn that gets in, can get really hot. Today sun all day solar gain from a low sun, so a benefit. So a cylinder with 3m2 coil as used by heat pumps, used with a gas boiler are great, either low flow temp or super fast reheat. Or you could do a cylinder heated by a heat pump, as in an all in one unit

In heat mode you get hot and stay hot until you open the windows. Your heat pump can only do heating or cooling, not both at the same time. You don't want to heat at night and cool in the afternoon, that's an expensive folly. Heat and cool is a seasonal thing not a day to day thing. You need separate thermostats for cooling, if the ones you have cannot be selected to cooling. You change the ASHP and the thermostats seasonally all to together. Any more helpful?

Our new build was completed with gas boiler, soon after moving in solar gains were painful. Bought a cheap ASHP to allow cooling via UFH. A year later the gas was disconnected, and ASHP used for heat and cool. Was cheaper then gas, no gas standing charges for one, using a time of use tariff, some solar and battery, makes ASHP as cheap as chips to use. I would drop down to 200mm centres and run from a single manifold (our floor area is 192m2 and we have 7 loops on 300mm centres). Run direct from a good boiler, so no pumps or mixers. UFH design, you need it room balanced by design, as far as possible, so room loops need to output room heat loss and each room receive its heat loss via the UFH. This makes balancing easy, I have all loops fully open at the flow meters and let the ASHP decide the flow it wants or needs. So operation can be two ways, WC or simply a fixed flow temp and a thermostat to limit, a single thermostat will do or a few, but don't bother with manifold actuators, so one thermostat needs heat all loops come on. Get an under floor wiring centres with some bells and whistles, so the room thermostats are actually temperature sensors and the can doo heat and cool, for when you install the heat pump. Boiler get a system boiler, not heat only one. Run PDHW (priority domestic hot water), this drive two temperatures from the boiler, one for heating the other for DHW heating. Get a heat pump cylinder, nothing else. Reheat times super quick and best boiler efficiency.

Think you should of asked the questions before you parted with the money. You really need an UFH controller that can heat or cool, this would reverse the logic of the thermostats. And reverse when the call call for heat or cool happens. Your heat pump should be switched between heat/cool, this can either be from the controller or a zero volt input is typical. Your whole system would have been simpler, no actuators, one proper thermostat or use the controller only as the better option. Condensation risk is managed by setting the correct flow temperature so 16-17 degs for floor. Floor sensors are way too late.

Maybe by area or post code?

For the cost of letting a company get on with it, there isn't much money to save by DIY, a lot of risk of fuc*ing up and getting an utter mess that isn't level, isn't flat etc. The other thing is the effort needed, self leveling or otherwise, to think to can do it yourself is a dream, it's a team effort, controlling people that haven't done many times before - life is too short. Couple of points here If the EPS is that fragile, the EPS design is not correct, if you need shuttering the EPS design isn't correct. You have already stated your no expert, so not sure your experience or lack of, is an added value here. Let the experts do the job, they are cheap for experts, build the walls yourself and save real money.

1st March export rates reduce to 12p/kWh, from 15p. So may need to flip to a different tariff for summer, such as Intelligent Octopus Flux

One day grants will go, they then become slightly better trained (or some will become) plumbers, looking for work like everyone else.

Well aren't you the negative one

So you can't use it then, you can ask the reason, but doesn't really change anything. What the fascination of SCC?

Possibly, but you need to go to your structural engineer to ensure it is of a suitable structural strength.

Go and read the bus grant rules for home owner and installer, then you will know what is or isn't acceptable first hand. Better than reading a load of second hand information - that could be 3rd or 4th hand. Always read source information for yourself.

Once a heat pumps heating a heating system, the system stays as is, you are only removing the old heat pump, basically power, communication cable and two flexible pipes. So new heat pump is just a simple reconnect everything to new heat pump. But cost of a Vaillant heat pump can be stupid expensive. As said I did it myself (had assistance moving the new heat pump only) in 5 hours to be exact, from switch off old to switch on new. So a company is likely to charge half a day for plumber, plus electrician or maybe a day each. But who knows.

I just replace one - the old one is being used for hot tub. The new one was a mornings work to install - I did install the wiring centre that came with new one, and pre-invest a cable the old unit didn't have. Cost £2100, plus some new insulation near heat pump. If you install a Vaillant you could be 3x that. In 7 years time, grants will not be available, so suspect like solar PV prices, will drop like a stone

If you are doing a new build and it's not signed off, permitted development doesn't exist. You're legal obligation is to follow the agreed plans or do a variation. If you have a need for visibility splays, your into planning and highways approval. There is highways documentation that has full details of visibility delays (they change with speed limit and gate placements and how much of the driveway has to comply with highways road spec - that part only certified people can install the tar and sub surface.

You can do that, you basically connect to ASHP as two zones. Get the ASHP to control an electronic mixer to the UFH. Set the two flow temps in the controller and it will control fan coil and UFH flow temperature independently - note your heat pump generates the higher heating temp and lowest cooling flow temps of the two zones so you take a slight cop hit. Although set up as two zones, you operate as a single zone, so no buffer or additional pumps needed.

Have one fan coil in summer house and it runs same temperature as UFH. In cooling mode 16-17 degs, so have no condensation drains installed.

Depending on heat pump it could be a screened pair cable or multiple cables. And ideally doesn't want to be in power cable duct.

Not all dMEV fans are equal, some are quite noisy, I installed one in the summer house, next day removed it as it made racket and installed Greenwood CV2, totally silent.