domestic hot water with ground source heat pump

thetourist

i am in the process of getting quotes for a heating system - i am using a ground source heat pump - what is the normal way of getting hot water with this system --- one guy reccomends a seperate heat pump for the hot water but i am confused about the scenario with the hot water cylinder - it seems that i'ts 1M in diameter and needs quite a bit of space - space that i hadnt bargained for - it seems like a good system though as the water gets up to 55deg and the main heat pump doesnt need to come on except for the central heating -- can anyone explain what he is trying to achieve with such a large cylinder or have i misunderstood or misled him - maybe it's one of the heat pumps itself he's talking about -- ??? what should i end up with -- 2 heat pumps and the mother of all cylinders - is that what is necessary - does anyone have any reccomendations - i really am suffering from confusion with all these cylinders and heat pumps and secondary heat pumps and am not sure how much space i need to allocate in my house for all the gear - though i suppose it varies a lot from system to system.

also as i mentioned in a different post i was hoping to put in a pressurised system - how would this work with the water heating setup

Victor

If you are using a heat pump (the reverse of a fridge), you need to store more hot water than you would normally, as the heat pump can only heat the water a small bit at a time, but does it 24 hours a day.

I'm not sure, but I think the heat pump for the heating system works in real-time (hence the separate pump) - the underfloor heating only needs to reach a temperature of about 26 degrees as opposed to more than 60 degrees with radiators. This makes underfloor heating ideal for children and old people as they are less likely to be burnt by hot radiators or sit around on a cold floor. The much larger surface area of the underfloor heating allows for the same heat transfer. Underfloor heating works best with a solid floor surface like stone or tile - carpet would have an insulating effect. Undefloor heating takes up less floor space than radiators (and no banding heads / knees off them), but reduces available height marginally (not really an issue unless you are about 7 feet tall and would hit the light).

The larger hot water cylinders, as contemplated by the plumber is normally called a calorifier. The larger tank allows the system to hold more, hotter water, than would otherwise be the case.

Consider adding a boiler house if you don't have space in the main house.

Borzoi

Most domestic situations that I'm aware off use the heat pump with the geothermal sink, to heat water to between 40-50C. This is suitable for underfloor heating systems to use. To supply hot water for cooking and cleaning it is more normal to use an immersion heater in the hot water tank to boost the water up to 65-70C, yes in summer you might have to use the immersion to heat all the hot water.

Do you intend to use the heat pump to provide summer cooling? In which case if we get a summer you can still be using the pump to part heat the domestic hot water system - it's all in the valves.

As for the size of the gear, it is bulkier than a domestic boiler, noiser too so you'll really need an outhouse/shed. There will be a larger volume of water involved, but that really should only relate to the size of the expansion tank - your hot water cylinder would be roughly as normal. What your man has proposed does seem abnormally large.

TBH these things can be done countless ways - get another quote from another company if the first guys plans don't suit. Just for the record my area of expertise wouldn't really include the plumbing of these things - but I know the hows and whys of how the work:D

thetourist

thanks guys - i think i'm gonna need to build a shed anyway -- does anyone know what the story is with planning permission for a small shed - or where i might find info on it - it's just that i already have the planning permission for the house and i am almost ready to start building - so i dont want to delay things any more if i dont have to.



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Victor

You can build the house away, you can add a small extension without requiring PP. Will find the details.