R290 Heat Pump and Foundation Air Bricks - Air Source Heat Pumps (ASHPs)

RE: R290 Heat Pump and Foundation Air Bricks

petch — Wed, 11 Feb 2026 18:17:29 +0000

I have been having fun and games whilst getting surveys and quotes done for an ASHP install, and the one thing that is coming up time and time again as an issue is the installation location. It's under a window, there are some air bricks, there's an open drain, there's a neighbour's window.

I got so fed up I've gone and downloaded the instruction manual for my favoured ASHP, the Grant R290 12kW, and found the following

Air bricks are permitted anywhere within or outside the ventilation zone of the Grant Aerona 290 heat pump, including directly behind it.

14097

It's on page 23 of the installation manual.

Other than that, doors can't be within 300mm and open drains can't be within 500mm. Windows aren't a concern other than for noise. As far the the neighbour goes, it's the quietest (on paper) ASHP I've found and comfortably passes the sound calcs I've done myself

Now to just find a competent, competitively priced installer who is comfortable following the manufacturer's guidance and not some mythical regulations that seemingly do not exist! I'll keep my eye out for unicorns and flying pigs whilst I'm at it.

RE: R290 Heat Pump and Foundation Air Bricks

ASHP-BOBBA — Sun, 18 Jan 2026 19:33:18 +0000

@l8again I agree fully, so what we would do is offer you an R32 unit or fit the unit in another location. My point last time is if you have absolutely no choice then you could relocate the air brick 500mm further up the wall with a much higher flow brick if needed or calculate the F/A of the air bricks all together to see if you can afford to loose one or just move one, as mentioned on here before air bricks are very often over subscribed, a rule of thumb is 1500mm2 - per M of wall , most standard air bricks are 7000mm2 so every 2m is normal but you can get whole screen versions or high flow versions such as what I have attached below:

Also note: air bricks are under building reg part C, part F will not apply to air bricks and sub floor ventilation.

https://products.titon.com/product/q-plus-high-flow-brick/

RE: R290 Heat Pump and Foundation Air Bricks

L8Again — Sun, 18 Jan 2026 16:52:59 +0000

@ashp-bobba I can well see the argument for moving an air brick to end up with a compliant R290 installation; however, my reading of Building Regulations, and I am happy to be corrected, is if the relocation results in insufficient ventilation, damp issues, or violates safety standards (such as blocking ventilation), it will breach Building Regulations Part F (ventilation).

When You Are Breaking Regulations

Blocking or Reducing Airflow: If you move the brick and, in doing so, reduce the overall ventilation capacity (which must be at least 1,500 mm² per metre run of external wall or 500 mm² per m² of floor area), you are in breach.

Whether anyone would notice or care is a different matter, but the same can be said for having an air brick in a R290 HP protected zone

The answer is to change the rules not fudge a way around them.

RE: R290 Heat Pump and Foundation Air Bricks

JamesPa — Sun, 18 Jan 2026 13:10:16 +0000

Remember Part P requires keeping to the manufacturers instructions and is a legel regulation.

Can you provide a reference please for that statement. Nowhere can I see this within the actual regulations and neither can I find the work 'manufacturer' in the approved document, nor when I read through although I concede it possible I missed it.

I would actually be quite disappointed if this were the case, because it would let the installer 'off the hook', whereas the regulations, particularly those which concern safety typically typically put the onus on the installer to 'get it right' which is sensible since only the installer knows the full context and thus she/he is the only one in a position to assess risk.

RE: R290 Heat Pump and Foundation Air Bricks

dgclimatecontrol — Sun, 18 Jan 2026 12:58:24 +0000

R290 minimum 1m away from drains and air bricks, .5m for widows/doors Electrical isolator same distance. Refrigerant volume in HPs from .8kg Tumble driers use R134a although some newer ones use 290 or or mixture but the quantity is only around 100g. Most fridges use R600 butane but again very little in volume. Latest AC air to air are starting to use 290 but electrical componments sealed and fan goes into high speed mode if inbuilt detector detects a leak so as to disperse.

RE: R290 Heat Pump and Foundation Air Bricks

ASHP-BOBBA — Sat, 17 Jan 2026 18:32:11 +0000

@ringi Yep, but doesn't Part P only apply to the electrical aspect and has no baring on the mechanical or gas aspect of the works? Regardless though block the air brick, move the air brick or install away from the side of the building, easy....

RE: R290 Heat Pump and Foundation Air Bricks

Ringi — Sat, 17 Jan 2026 17:52:10 +0000

Remember Part P requires keeping to the manufacturers instructions and is a legel regulation.

RE: R290 Heat Pump and Foundation Air Bricks

ASHP-BOBBA — Sat, 17 Jan 2026 17:07:57 +0000

I still maintain its about risk assessment and justification as there is nothing in Law, just follow the manufacturers guide and place the HP in the middle of the garden or seal an air brick, move an air brick and place against the wall.

Also, i got to say, who measured that if the wind was a warm 3mph down the side path of your home that is 1.3m wide and fenced in that the gas bursting would not get moved 2m further down and would not go in the air brick 1.6m away? the whole ally is a risk, anything area lower that can pool the gas and the air can move or gas float it is a risk, but the risk is for a very short time as the gas would boil off rapidly enough. At least you can have the lighter fluid in the cupboard next to the oven (300gms) the BBQ bottle in the shed 1m from the house 3kgs and the R290 tumble drier in the boiler cupboard probably 400 gms.

RE: R290 Heat Pump and Foundation Air Bricks

ASHP-BOBBA — Sat, 17 Jan 2026 17:00:49 +0000

@l8again Hahah, this just makes me smile, i wonder how much refrigerant they hold? Also the Haier OEM tumble HP driers were getting recalled for exploding so at least the rule here would make sense not to keep R290 in the house as the risk is real enough the manufacturer recall them all on a safety issue.

https://www.which.co.uk/news/article/urgent-safety-notice-issued-for-85000-tumble-dryers-aHaXU4u7eTiV?utm_source=chatgpt.com

RE: R290 Heat Pump and Foundation Air Bricks

L8Again — Sat, 17 Jan 2026 16:53:38 +0000

Just to demonstrate how silly this whole HP R290 gas safety debate is, my Samsung R290 heat pump tumble dryer is happily sitting underneath my gas boiler in the utility room.

Anyone looking down on Earth from afar would think that there is no evidence of any intelligent life forms on our planet.