Does anyone do indoor Air Source Heat Pumps?

hamble_turtle

Almost all ASHPs I see advertised look like air conditioning units bolted as an afterthought onto the side of the house. Does anyone sell units to put in your loft?

As I live in a sort of terrace with no back garden, I've nowhere to hide an external unit (except possibly on the roof in the gutter behind the facade), and the noise would probably not be appreciated by the neighbours either. Housing one internally would avoid the visual issues, and would surely be easier to sound proof, but I can't see much about.
I've seen https://www.dimplex.co.uk/product/11kw-internal-air-source-heat-pump-li11tes but a) it's discontinued and b) it requires 3 phase power
and  https//www.weishaupt.co.uk/produkte/waermepumpen/waermequelle-luft/weishaupt-luft-wasser-waermepumpen-zur-innenaufstellung describes internal systems but gives no way to get prices and may be defunct.

So - any idea if anyone does do them or why not? Obviously I understand you'd need to duct the air in and out of the unit but that shouldn't be too hard in a loft.

Coastalwatch

Wow, what a great question!

Other than having two ASHP's fitted on the external side of the gable end of our bungalow I've little experience to pass on. However, the units fitted are barely audible when in the garden and we've had no one complain about noise. We barely notice them running when in the garden.

Think I woud be a little concerned about them being in the loft. Not so much in winter when you might only have to duct the external flow, but in the summer when lofts tend to get very warm the ashp's may struggle to supply cooling air when requested. As I say I've little knowledge so can only suggest the it's a question for manufacturers and/or installers. Others of course may well advise from a more knowledgeable base. Good luck.

ABrass

The heat exchanger needs to use external air to suck heat from. You can suck the air in through a duct, but that means a relatively small fan spinning very fast to pull that air in. Generally the faster the fan the noisier it is, large slow fans are quieter moving the same amount of air as a smaller faster one.

With the external units they have big, slow fans directly pushing air through the heat exchanger. Plus it's on the other side of a brick wall to help dampen the sound into your property.

hamble_turtle

I wasn't really considering using it for cooling (the house is pretty cool in summer) and was looking at an air to water system as we're not ducting air all round the house, but its good to be reminded it's a possibility, and I wonder if a warm loft would be an issue - ours doesn't get that hot and it could be vented but...

Martyn1981

Funnily enough that would also solve a problem I've run into, which is that the unit has to be located at least 3m from the boundary to avoid needing planning permission. For a slightly smaller than 2m unit, that means you need an 8m wide property. Ours has a side driveway so just, just makes it, so long as we site the unit across our back door!

England has a far more sensible 1m rule.

But a bigger problem we've discovered is that for our smallish gas consumption the units are completely unviable, something you may want to check being a terrace property. Basically, for twice our heating/water needs (which is estimated at ~10,000kWh (actually use about 7,000kWh of gas) the cost would rise 10-20%, and be fine.

hamble_turtle

@ABrass mm I guess duct diameter might be an issue (although I can have a 1x1m sized duct in the roof if needed and if I can make it weather proof.)

hamble_turtle

@Martyn1981 We're on oil (or were on oil until boiler went bang last week) and its a high ceilinged Victorian place with 4 beds so we use a fair bit. I'm not sure quite how much heat we need to keep the house warm but 2x 2KW fan heaters (and closing every door) took hours to raise the lounge and dining room to 20C yesterday (we turn them off overnight). Today it's sunny so it's ok with just one 1.5KW electric radiator.

Cardew

I believe NIBE have some involvement in indoor extraction ASHPs. It may be worth talking to them.

https://www.nibe.eu/en-gb/products/heat-pumps/exhaust-air-heat-pumps

I know nothing about their systems, but some years ago there were some highly critical threads on MSE about NIBE systems fitted to Council/Housing association properties; I don't know if the issues were solved.

geminair

You can't put an air source heat pump inside the house because it will effectively turn the room into a fridge. It will keep cooling the same air around it until it can no longer extract any heat.

EricMears

geminair said:

You can't put an air source heat pump inside the house because it will effectively turn the room into a fridge. It will keep cooling the same air around it until it can no longer extract any heat.

That's a bit like the tired old riddle about what happens to room temperature if you run a fridge with the door open.  In any closed system (i.e. running such a machine in a single room) the room temperature has to increase as the motor will give out some heat and the transfer of heat from one part of system will be less than 100% efficient.
Providing your ASHP has the two 'halves' separable,  you could for instance use it to heat a lounge by extracting heat from the kitchen.

Martyn1981

geminair said:

You can't put an air source heat pump inside the house because it will effectively turn the room into a fridge. It will keep cooling the same air around it until it can no longer extract any heat.

Hiya, the OP isn't suggesting that they take the heat from the air in the loft, just that the normally outside unit be housed indoors:

So - any idea if anyone does do them or why not? Obviously I understand you'd need to duct the air in and out of the unit but that shouldn't be too hard in a loft.