Are R290 heat pumps permitted beneath/under a window?

[Dan G]

I've read this thread but am still a little confused; could a R290 ASHP be sited beneath my kitchen window, on the patio below it? The window sill is 1.5 m above the patio, and there are no other doors or windows for several metres in any direction. It would be a single fan unit (heat loss 3.5 kW!)

Edited August 28 by Dan G

[JohnMo]

21 minutes ago, Dan G said:

I've read this thread but am still a little confused; could a R290 ASHP be sited beneath my kitchen window, on the patio below it? The window sill is 1.5 m above the patio, and there are no other doors or windows for several metres in any direction. It would be a single fan unit (heat loss 3.5 kW!)

Read the manufacturer instructions for the unit you are interested in. The instructions trump everything else.

[Dan G]

Pretty sure my interpretation of the manual isn't going to change the opinion of an installer.

Edited August 28 by Dan G

[JohnMo]

41 minutes ago, Dan G said:

could a R290 ASHP be sited beneath my kitchen window, on the patio below it?

No, if it's a Vaillant, you are unlikely to be in a protective zone height wise, so the first clause doesn't get you. But in a different sector states the second clause.

 

1. Vaillant says for example

A protective zone is defined around the product. There must be no windows, doors, light shafts, cellar entrances, escape hatches, flat-roof windows or ventilation openings in the protective zone.

 

But even with a window move and outside the protective zone it also states the below.

 

2. Avoid choosing an installation position which is near to a

window.

 

Interesting my R32 does not mention windows at all.

 

 

[JamesPa]

4 hours ago, Dan G said:

I've read this thread but am still a little confused; could a R290 ASHP be sited beneath my kitchen window, on the patio below it? The window sill is 1.5 m above the patio, and there are no other doors or windows for several metres in any direction. It would be a single fan unit (heat loss 3.5 kW!)

The protected zone as specify by vaillant (as I read their diagram) does not extend above the unit. That's logical too, propane is heavier than air.

 

I'm not sure about @JohnMos second sentence,  in my version of the manual this comment is only attached to the instructions for wall mounting not floor mounting - is it an instruction for safety reasons or just a recommendation eg for noise or structural integrity (since wall mounted is more likely to be close to a bedroom in the house they draw/the structural integrity of a wall reduces close to a window).  Surely if it's outside the defined protective zone then it's outside it, end of?

 

You could always call tech support if your chosen manufacturer will speak to mortals (some will, some wont, if its Vaillant they will).  That should convince your installer (or not depending on what they say)

 

Here is a samsung diagram, again the zone extends below but not above the unit, the dotted lines show that if there is any doubt.

 

Of course what the installer will do (not what the manual says) trumps everything else!

 

 

 

Edited August 28 by JamesPa

[JamesPa]

Further to the above I tried to find the source regulations (which seems to me to be the best approach in cases of doubt).  I had expected to find UK or EU regulations which govern this and are definitive.  Unfortunately I failed. 

 

Worse still this link https://internationalfireandsafetyjournal.com/besa-highlights-safety-risks-of-flammable-refrigerant-gases-in-hvac-systems/

suggests there may be no source regulations, at least in the uk

 

It seems nevertheless that somehow the heat pump manufacturers have converged on a set of rules, but their origin remains obscure.

 

Hopefully someone will know what the origin is and will post it, otherwise it really is down to individual heat pump manufacturers (and in practice installers).

 

It is beginning to look like it may be a bit of a mess.

Edited August 28 by JamesPa

[mk1_man]

I have just fitted a Vaillant ashp, a window above the unit and outside of the protected zone is permitted.  You can also have a window that extends to the ground as long as it is non opening or at least the element that is located within the protected zone is non opening i.e. split unit. 

[sharpener]

9 hours ago, JamesPa said:

there may be no source regulations, at least in the uk

 

and there has been some discussion on the Vaillant FB group about drains and airbricks which were formerly not allowed in the exclusion zone, but now apparently it is OK so long as they do not communicate directly with habitable rooms. So in a typical UK house with a suspended floor it is OK for a flammable air/propane mixture to accumulate in the void beneath it.

 

Sometimes it is clear that the advice is based on German house construction methods without much consideration of what is done elsewhere.

 

Given the quantities of gas involved (900g in a 12kW HP) the whole business is a farce when you consider what you see done with twin propane gas bottle installations for cooking off the main gas supply.

[ReedRichards]

8 hours ago, sharpener said:

and there has been some discussion on the Vaillant FB group about drains and airbricks which were formerly not allowed in the exclusion zone, but now apparently it is OK so long as they do not communicate directly with habitable rooms.

Really?  My heat pump is right next to a drain which carries rainwater off the roof to a soakaway.  Hitherto I had thought that precluded my getting an R290 heat pump when my existing one needs to be replaced.  

[sharpener]

10 hours ago, ReedRichards said:

My heat pump is right next to a drain which carries rainwater off the roof to a soakaway. 

 

I am assuming if it goes to a soakaway it doesn't also take grey water from e.g. the kitchen sink as you often see with pre-WWII houses.

 

Depending on the age of the building it will probably be a trapped gully, in which case the propane which is denser than air but not denser than water cannot get into the underground pipework so you are OK.

 

If not you could either replace it with a trapped gully (if it also takes surface water) or use a rainwater downpipe to underground drain connection which is not open to the air/propane. I would think the simple rubber cap type is adequate.

 

In the extreme you could build a gas-tight housing round it higher than the top of the HP. This might be as simple as extending the 110 mm underground pipework upwards and doing the transition from downpipe above the level of the HP.

 

But I don't think they care about drains much, even if they used to. Have just checked the MIs for my new Vaillant R290, they expressly state (section 4.2) "Open gullies or downpipes within the protective zone do not pose any safety risk."

[JohnMo]

Or just fit an R32 heat pump where ever you want. Nothing special about R290 it doesn't make the heat pump more efficient. R290 has a lesser global warming effects - but only if it all leaks out.

[Dan G]

On 28/08/2024 at 23:38, JamesPa said:

Further to the above I tried to find the source regulations (which seems to me to be the best approach in cases of doubt).  I had expected to find UK or EU regulations which govern this and are definitive.  Unfortunately I failed. 

 

Worse still this link https://internationalfireandsafetyjournal.com/besa-highlights-safety-risks-of-flammable-refrigerant-gases-in-hvac-systems/

suggests there may be no source regulations, at least in the uk

 

It seems nevertheless that somehow the heat pump manufacturers have converged on a set of rules, but their origin remains obscure.

 

Hopefully someone will know what the origin is and will post it, otherwise it really is down to individual heat pump manufacturers (and in practice installers).

 

It is beginning to look like it may be a bit of a mess.

My understanding is that there's nothing in building regs or permitted development legislation/regulations pertaining to R290; installer guidance

[Dan G]

But

41 minutes ago, JohnMo said:

Or just fit an R32 heat pump where ever you want. Nothing special about R290 it doesn't make the heat pump more efficient. R290 has a lesser global warming effects - but only if it all leaks out.

Johnmo that's why I would prefer R290 over R32; but if there's less than a kg of refrigerant in a unit a leak would negate less than a year, probably a lot less than year, of CO₂ savings from having a heat pump fitted. So fair point.

 

I'd like/need a heat geek mini store though (combi replacement in a small house); I have seen comments that "R32 heat pumps would struggle with the high temperatures required by a mini store so you'd need R290", but I've not evidence for that.

Edited August 30 by Dan G

[JohnMo]

4 minutes ago, Dan G said:

I'd like/need a heat geek mini store though

They look clever, but for me a couple guys testing with a couple of the same make heat pumps isn't enough. Do you have room for a small shed outside? Have you thought about a small insulated shed outside and put a cylinder in there, with most the other bits and pieces for the heating system, expansion vessel etc? That's where most my stuff is (except the cylinder).