JohnMo

Grant install a modified Y plan, to make it easy for installers. If you went with the Grant badged unit, you need to educate yourself on how they should be installed, or go elsewhere.

Before saying you need xxkW, you need to look at the various performance tables of different heat pumps, as one 3 kW heat isn't he same as another, they give different rating to suit what they want to sell. Main issue isn't really the size anything up to about 6kW should be ok. Main issue will be have a design that doesn't require a buffer for the shoulder season, so engaged always open system water capacity is important, roughly 40L. That will allow the HP to run without short cycling and for defrost. If you can get your head around a single zone heating system, that where you need to heading, simple weather compensation your install can be very simple.

Sorry no photos You will have timber strapping on the wall. Prior to install of cladding, basically close the gaps at the bottom with mesh. So once the cladding is in place there are no gaps.

Good representation of what I was trying to say. Short and fat a good place to dilute supply water with return water. Result hot water from HP going in and warm water going out. With a 4 port there should be no need to have the two pump flow rate matched. They are hydraulicaly seperates, so basically two systems meeting at the buffer. Look at a three port also.

To add a volumiser needs one open loop/radiator downstream of it

A 4 port in normal operation, all water goes in to and out of a buffer. A 2 port only the excess water flows through the buffer. The buffer is always open to the flow and return. If everything is closed downstream of the 2 port buffer all water flows through the buffer. Just the same as a 2 port. A 4 port hydraulic sepereration across buffer a 2 port no hydraulic sepereration. That's the main difference, plus less mixing. So in defrost the heat pump would just pull on your buffer volume in either case. A volumiser either sits in the flow or return circuit only. Does not give hydraulic sepereration. But in defrost the HP can use the stored volume

That is the least efficient way to plumb a buffer for a heat pump as the mixing within the buffer requires the heat pump to operate at a higher temperature than it would otherwise. Better to use the same volume and pipe as a volumiser or as a two port buffer. Or better still don't have one and make sure your zone sizes are big not small.

Those prices are just taking the pi**. The quote says I am not interested in the job, just go elsewhere, or buys the bits you want get the plumber/electrician to hook up. Design help from on here.

Put it on Colling duty, run it off your solar. Heat your hot water 4 times as quick as an immersion, as you get a CoP of 4 ish in the summer, immersion CoP of one. So even on a poor sun day you should get a bigger chunk of your hot water at zero cost.

I looked and you have to an internal and external unit, even on the monobloc, to get them to work. The monobloc has most of its electronics within the indoor unit. The prices gets very large very quick.

That's possibly me thinking these super modern heat pumps, would be ahead or at least match of my gas boilers 10 to 15 year old technology.

May depend if you are UFH or rads. Or just spend the time fine tuning weather or load compensation. Not sure it does much more than that anyway.

Just had mine delivered, it was originally supplied to Beneath Heat in Essex, may worth contacting them. There is a 9kW on eBay?

I am, they are exactly the same, even the manual for the heat pump is the same, except manufacturer name. Name plate engineering at its best.

Anyone know or have access to the installer password for the above ASHP?

As @Temp says well insulated house with UFH heat pump will be cheaper to run. Heat pump give great efficiency if the flow temps are low. The thing with heat pumps the design needs to be well thought through. Your mentality needs to be different from normal gas, as they won't work that way without you needing a second mortgage. Your cylinder needs as big a coil as you can get 3m2 or better. Your run times for UFH or rads need to be long and low temp. Buffers will kill efficiency and so will lots of zones. Done right SCoP of over 4 should be achievable. If you want your heating on a couple of hours in short blasts and lots of zones, then gas maybe a better choice.

Your house is pretty much the same size as mine, although mine a single storey, so most likely a bigger heat loss; way more floor and roof to loose heat too. Whole house is done with 7 loops and one zone, pipes are on 300mm centres. Even before Christmas at -9 our flow temp was only 34 degs, housecat our chosen 19 degs. We have just over 500m of 16mm pert-al-pert pipes in the floor. Mine started with loads of zones and it just didn't work. Doing it again I would do 200 to 250mm centres to make the floor more responsive. Things to do A heat loss calc. Your max heat loss could be closer to 3 to 4kW. Download a copy of loopcad, and build your house and do a proper design your self. If you single zone or two zone with the correctly sized heat pump you should not need a buffer. Electric towel rads. Do bathroom at 150mm centres, you can get them warmer than the rest of the house on same flow temp. Or electric UFH. Once you know size of heat pump shop around, call people once you have internet prices, they will all try to beat others prices. I ended up buying a 6kW heat pump for £1300 the other day, from eBay, so there are bargains out there. Viesmann sell the same heat pump for over £4k.

https://www.vpshotwatercylinders.co.uk/product/gledhill-stainless-lite-plus-heat-pump-cylinder-210-litre/ 3m2 Or https://www.cylinders2go.co.uk/shop/renewable-energy/200-litre-telford-tempest-heat-pump-cylinder/ 3.3m2 Coil area is the most important thing, otherwise you spend an age trying to heat the cylinder up and you will use loads of energy and still have no hot water. Couldn't find the oso, but think you need the geocoil on that range. Heat loss will be way less than they claim, as they are rated at the same temp something like 75 deg. Your cylinder will be at close to 50 deg.

The cylinder should have its own flow temp, not the temperature it's at or target temperature. It's flow temperature from the heat pump. So when your heat pump gets a signal to heat cylinder, it moves the 3 port valve and flows at a different temp to what you have set the central heating flow temp.

There should be 2 different setting for flow temp. Your heating runs at one temp and then cylinder heating should have a different figure. So when cylinder heating the heat pump should ramp up to max temp. If you are just adjust the heating flow temp you are not changing the cylinder heating parameters.

Or anti freeze valves, at around £100 each.

Over flow tank for central heating is the easy bit make it pressurised. Radiators need to be sized to suit the room requirements, skirting heating pretty small output, but it depends on your heat losses. You would need to do a heat loss calc, to establish what you need kW wise and then look at the options. A combi can be a good option, but you have to plumb it differently from normal. You need a small preheat cylinder, the below shows a 25 and 50l cylinder that sits below the boiler. Some reading info Combi-SuperFlow-White-Paper-v1-2-4.pdfCanetis-SuperFlow-Product-Sheet-WE-050318.pdf I have a similar system and water production is great. Certainly you get the cylinder and a combi that takes pre heat water for less than sunamp. And it will take up less room.

Data about unistore, it only has a 1.3m2 coil, typical heat pump cylinder would have a 3m2 coil. That would give faster heat up times for the same flow temp. So spending less time at a low CoP and therefore a better annual SCoP. It's also a steel enamel tank not a duplex stainless steel one, so has a anode to be replaced every one to two years.

So just 2 x 2 port valves and use the power from heat pump to energise a change over relay. Power one relay to to have flow through heating, power relay from heat pump, power moves from one 2 port valve to the other, opens 2 port to cylinder?

Dumb question Looking for a 3 port diverter valve, to move flow from heating to DHW cylinder heating, not both at the same time. Everywhere I look a mid point valve comes up. What's the difference is just wiring or are they completely different things?