Heat Pump design, supply and install

[PaulD]

Any recommendations for a company to design, supply, install and support a UFH/ASHP/DHW solution, we have a large class Q in Derbyshire 

 

Currently considering Alto Energy in Oxfordshire - anyone had any dealings with them ?

 

TIA !

[JohnMo]

I would split the tasks to different people, UFH and DHW could be your local plumber, heat pump most likely not your local plumber, without some assistance I e. The the design already done.

 

But it's all quite straightforward broken down to piece parts.

 

DHW is just UVC with 3m2 heating coil. Size will depend on house size number of occupance.

 

UFH heating pipe layout will depend on single floor or multiple levels, heat losses upwards and downwards. But once these are known quite straightforward.

 

ASHP really depends on heating demand, need for a buffer will depend on number of zones you break you UFH into. One zone likely no buffer required. Any more than that a buffer likely to be needed.  A buffer can kill efficiency if you are not very careful with its design. Then all you really need is a 3 way diverter valve. And size the piping.

 

Going to one company and taking the grant, will be expensive.

[Big Jimbo]

@JohnMo So lets say im building a new house, and i know the floor area. Know the window sizes. Know the room volume. Know all the u values of the walls, floor, roof, doors, and windows. So knowing that a new house has to achieve an airtightness of 6, I assume that all of the above figures are used to calculate what size heat pump you will require for heating. For the DHW side of things, number of showers, baths, sinks etc.  If you then go above and beyond with your build, and get say an airtest result of 1.8 will that mean that the chances are you air source heat pipe is sized too big ? If it is then does that mean that cost wise, it will be more expensive to run than a correctly sized unit ?

[JohnMo]

1 minute ago, Big Jimbo said:

So lets say im building a new house, and i know the floor area. Know the window sizes. Know the room volume. Know all the u values of the walls, floor, roof, doors, and windows. So knowing that a new house has to achieve an airtightness of 6, I assume that all of the above figures are used to calculate what size heat pump you will require for heating

Basically yes

 

But using your example of airtightness from 6 to 1.8 would also mandate MVHR on a new build, so that would be a dramatic decrease, you come down a size or two on heat pump. If you are trying for 6, you aren't trying anyway, so not likely to be taking airtightness measures. You are going to have 100mm dia holes in every wet room for the fans, so reality you will leak air anyway.

 

Running cost could be higher, buffer sizing may also increase, with an oversized heat pump.

 

But you wouldn't do the final spec on heat pump until you know what your the most likely heat needs are. Would be better to specify after an initial air test, which would be prior to plasterboard. 

 

Over specced UFH doesn't matter, cylinder will be the same

[Big Jimbo]

Thanks @JohnMo. I have built in Masonary previously and acheived 1.8 on my airtightness. I'm planning on HVMR. My question related more to if i was to ask a company to size an ASHP for me from paper before the house was built. My only thought now would be how leaky my Medium Density internal block walls would be before plastering.

[JohnMo]

I have noticed from conversation here and looking at MCS calculation sheet, is they make no allowance for MVHR, so will always provide an oversized heat pump for low energy houses.

 

You may be better sizing yourself with assistance on here. Buy and free issue to plumber to install or do it yourself. I pre ran all our cables terminating everything except the fuse box. The electrician ran through everything and did final connections, cost about £200.

 

Materials for our install excluding cylinder and heat pump, were about £1500, but that included a long external run and all insulation.

 

Your blocks could leak quite a bit without the plaster sealing the surface.

[SteamyTea]

20 minutes ago, Big Jimbo said:

My only thought now would be how leaky my Medium Density internal block walls would be before plastering.

I found this, if it is any help.

https://lignacite.co.uk/products/lignalite/

 

Seems they are around 9 m³.h^-2.m^-2 when untreated, so pretty poor.

[Big Jimbo]

@SteamyTea so that puts a bollox on an early air test before plastering. I could always seal the walls with some of that fancy air paint, but the prices are eye watering.

[SteamyTea]

Just now, Big Jimbo said:

@SteamyTea so that puts a bollox on an early air test before plastering. I could always seal the walls with some of that fancy air paint, but the prices are eye watering.

I don't think tape is a get out of jail card here.

If you must build in leaky block, I would have thought that parging it as you go along is not going to slow you down any, may even work out easier and cheaper, less battle fatigue.

[Big Jimbo]

@SteamyTea That's not a bad idea.

[SteamyTea]

1 minute ago, Big Jimbo said:

@SteamyTea That's not a bad idea.

Sometimes I have them.

Would there be any reason why you cannot parge both sides of the block as you go along?  Wall ties may bet in the way, but they can be navigated with a hand brush.

 

So something like build up 4 courses of block, parge, batten, cables/services, put right, put right, put right, insulate, put right, put right, put right, and then the visible finishes.

[Big Jimbo]

I doubt the Bricklayers would give me the time for that. But i could do the inside.

[SteamyTea]

1 hour ago, Big Jimbo said:

I doubt the Bricklayers would give me the time for that. But i could do the inside.

Make it part of their job, if they are any good they will be pleased to.

[JoeBano]

Thought about solid plastering instead of dot & dab plasterboard?