R290 Heat Pump and Foundation Air Bricks

L8Again · 2026-01-15T09:35:32Z

I am going around in circles. My property has foundation air bricks sited below the damp proof layer to ventilate the void under the property's suspended concrete floor. I have spoken to the UK Technical Team for a well known German HP manufacturer and they are adamant that the air bricks need to sit outside of the R290 protection zone. An Octopus Energy representative has posted on another forum 'Air bricks are not a concern.' This is reflected in the following guide: Clearly, both HP manufacturers cannot be right. Searching for Regulations on this is something of a Fools Errand. The Heat Pump association states the following: 'Where defined within the manufacturer safety-related protection area, there must be no:- - permanent or temporary sources of ignition during normal operation, such as, but not limited to, open flames, electrical systems, sockets, lamps, and light switches, electrical housing connections, sparking tools, or objects with high surface temperatures, etc. - building openings, such as windows, doors, light shafts, flat roof windows, and ventilation system inlets and openings, - property boundaries or neighbouring properties, walkways and driveways and public access areas - ground depressions, dips or low-lying recesses, and any water or sewage services, and no open pump shafts, etc.' I am considering either a Stiebel Elton or Valliant R290 heat pump but air bricks would be an issue. The irony here is that a Cosy heat pump safe zone would just fit between two air bricks. Any thoughts/advice or should I give up and look at a R32 filled heat pump?

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L8Again

(@l8again)

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Topic starter 16/01/2026 8:26 am

Having worked in a safety-critical industry for over 40 years, the last thing one does is leave procedures etc open to independent interpretation. This is the first step in aligning the holes up in a Swiss cheese.

i confess that I am surprised by the Octopus Energy’s rep’s comment. He has been adamant on a number of occasions that air bricks are not considered to be a R290 gas problem. This view is backed up by the table that I posted above. Is he now saying that air bricks are a constraint?

The technical dept that I contacted was Stiebel-Eltron. They copied me an extract from their installation training manual that rules out air bricks within the protected zone. For confirmation, I sent them a photo of the type of air bricks within installed in my property. The advice did not change.

Yes, I could block up an air brick but as the house is built on clay this is probably not a good idea. A recent foundation survey found water 2 feet down from the soil top on a hot summer’s day. Blocking the air bricks off would breach Building Regulations and probably invalidate the NHBC Warranty.

There is an irony here. Looking at the air brick pattern, an Octopus Cosy HP with its small width and 500mm side protection would just fit in one wall position without compromising safety. I am not that keen on the Cosy given its link to one supplier that may not be in the HP business in 10 year’s time.

Given my age, I was hoping for a minimum disrupt option that a R290 HP offers but I sense that I need to look more carefully at alternative R32 models.

This post was modified 1 hour ago by L8Again

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Mars

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16/01/2026 8:41 am

@l8again, I’ve received a lot of feedback on the subject from senior people in the industry. I’ll collate the replies and post them here later today, but it’s rather inconclusive tbh.

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