Pitched roof mounted ASHPs next?

[Marvin]

The next design being tried out!

 

Will these work? Is this the next generation?

 

https://businessmanchester.co.uk/2022/11/03/bellway-installs-uks-first-roof-mounted-air-source-heat-pump-in-pilot-project/

[ProDave]

A solution looking for a problem?  What is wrong with an ASHP on the ground where you can service and maintain it?  Do you really want to get the scaffold out each time it goes wrong?

 

This test house they are building, it looks to be inside a commercial unit.  How is that going to work? or is it a massive environmental chamber where they can simulate all sorts of different weather?

[joth]

Flats and terrace houses.

 

But yes, terrible idea for serviceability if access was only from the outside. I think the idea is this is a loft installed unit, that just happens to protrude and vent out through the pitched roof a bit like a skylight frame would.

 

I'm extrapolating from this:

"Installing an air source heat pump within a loft space is a bold move"

 

If it can combine fresh air ventilation (MVHR) and summer time passive or assisted stack cooling it might be onto something 

[saveasteading]

2 minutes ago, ProDave said:

What is wrong with an ASHP on the ground

In a small garden it is intrusive.

Lots of houses don't have land at all.

 

In the attic so accessible.

Picks up heat from the roof, (facing south?)

Outlet oposite face to avoid short circuit?

 

But stopping it vibrating through the ceiling will be a challenge.

[ReedRichards]

My ASHP is way too large to fit through the loft hatch and too heavy as well, I would think.

[Radian]

2 hours ago, saveasteading said:

But stopping it vibrating through the ceiling will be a challenge.

I initially read that as the entire unit 'coming through the ceiling' 🤣

But as @joth says, if it can be serviced from inside the attic and incorporated within MVHR then there's a number of potential benefits. At least it's good to see stuff being innovated in this very slow moving market space - even if it's being done by a bunch of bell****

[saveasteading]

57 minutes ago, Radian said:

vibrating through the ceiling will be a challenge.

Yes that would be serious. The noise and vibration could be severe. I fitted a shower pump to  a board on joists, with rubber bedding under the board, and fibreglass under, but the noise is still there. 

[Radian]

3 minutes ago, saveasteading said:

Yes that would be serious. The noise and vibration could be severe. I fitted a shower pump to  a board on joists, with rubber bedding under the board, and fibreglass under, but the noise is still there. 

 

You're nearly there but I figured out an additional trick for that: Mass. Because the shower pump was boxed-in by a raised floor in a cupboard, I was able to stand the pump on a concrete paving slab which in turn was sat on a square of carpet underlay. I actually stood the pump in a plastic box after the previous pump leaked. A leak alarm also lives in the box. As with all sound transmission attenuation, the energy is absorbed by having to make something massive jiggle. The more mass there is, the less it jiggles for a given energy input. A further de-coupling through the underlay finishes off the job.

[Helen Carpenter]

I was asking about roof mounted ASHPs some time ago. Again the UK authorities lag way behind Europe. These units are now regularly put into pitched roofed terraced homes in the Netherlands, Bosch and HydrotopWorks BV supplying the heat pumps. They are inserted in the same manner as Velux windows. In the UK they are not permitted it seems because the said authorities envisage them to be the same as ground based units.

[Beelbeebub]

What if you had a slightly beefier version of those tank top mounted units that had some bigger ducts (say 250mm).

 

If that sat in the airing cupboard, which is often on the upstairs landing and the two big 250mm ducts went up into the loft so one sucked from the loft space and the other vented via a "chimney" (a steel pipe sticking uo thorigh the roof similar to a wood fire chimney).

 

First off any heat that did escape into the loft would end up recycled back. Int the house. Effectively infinite loft insulation.  It would also vent the loft very effectively to dry roof timbers etc.

 

Secondly, installation would be similar to fitting an unvented cylinder in terms of logistics. Just a big tank to lug upstairs (diameter around 500, 550mm).

 

Servicing would be internal.

 

Fan noise would be external on the roof facing upwards, so noise shouldn't be an issue even terraced street. The airing cupboard could have some more sound dreading applied to help and the mass of the water would act as a damper.

 

During the summer you are getting a boost from the hot loft and could vent the cool air into the house or could take from internal to act as air con.

 

The current units like the vaillant Astor are about 3kw output at a cop. Of 3 (ie input of 1kw) using 2x 170mm ducts.

 

A pair of 250mm ducts would allow about 2.5x the flow so could provide about 7kw output at a cop of 3.

 

If you had some fancier ductwork you might be able to squeeze a pair of 350mm equivilent ducts (a 500mm duct divided into a pair of semicircles that sewage to round ducts). Those would have 4x the area so could produce up to 12kw alright you might trade power for lower noise and maybe have 9kw which would dovetail nicely with a 3kw input.

Edited December 31, 2024 by Beelbeebub