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Using Air Conditioners with R290 refrigerant (propane based) in a room with little natural airflow.

Guest JimmyMulvihill

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Guest JimmyMulvihill


I need some advice on a topic that may affect quite a few people with the same issue. It is regarding the change that the UK has made towards air conditioners that use a propane based refrigerant, R290, and whether this is safe to use in an environment with minimal air flow? 

I run a rehearsal studio for local bands to play in, and for the sake of soundproofing all of the windows are bricked up, and we have built a "room within the room", where we leave an gap of about 18 inches from the outside of the room, and then build a new internal room from industrial cinder blocks. As a result the thermal insulation is incredibly high, so we have air conditioners that expel the hot air in the room through a pipe that is fed through both of these walls, so make sure that the room doesn't overheat.  We've had them in place for about 15+ years, never had any issues with them. 

Recently one of our portable air conditioners died, so we purchased a new one.    
In the past the air conditioners we had ran on either R407c or R410c refrigerant gas, and having investigated it we were told that this gas had low flammability at ambient temperatures and atmospheric pressure, it was non-toxic, and it was Hydrofluorocarbon based.   We checked this with the local council authority, everything was fine.  We purchased a new air conditioning unit on Amazon, not realizing that the gas within it was different, and upon its delivery, and upon reading through the manual we saw that it now had a gas which was called R290.  Having investigated it, it seems that the R410a and R407c gases were phased out in 2020 by something called the "Montreal protocol", (which was an international treaty designed to help protect the ozone layer,) and now R290 is the standard in the UK.    Not having come across R290 before we did our investigations and found out that it's propane-based, as opposed to Hydrofluorocarbon based   As we were planning to use it in a windowless studio, with no natural ventilation within it, we did a bit of investigation, and we realised that this might not be safe to use in such a situation. As a result, we have NOT installed it.  We tried to find an old air conditioning unit that used the old gases, but despite contacting 80+ places that sell portable air conditioning units, we couldn't find any that sold air conditioners that ran on anything other than R290.  It seems to be the only type of coolant that you can get in an air conditioner in the UK now.     We contacted the manufacturer of a unit, DuraComfort, and explained how we planned to use it, and they said that the unit was safe,  it had all the relevant safety certifications, etc. We then explained to them that we were planning to use the unit within a windowless room, and they replied by saying that they believed that it was still safe to use in such a setting, but that we should do our own research to ensure that this was the case.  

We checked with the local council, but they said that they couldn't advise on it.   I know quite a few other rehearsal studio owners,  so I sent a few messages around and asked if any of the other studios knew anything about these changes in gas, and none of them seem to realise that there had been a change in the refrigerants used in air conditioners.  Their knowledge on the matter was basically non-existent.  Quite a few of them had bought air conditioners since 2022, but they didn't even know that there was a difference in the types of refrigerants.  There were no notes on the advertising of the new air conditioning units that said that the switch in refrigerants have been made, the information is buried near the back of the manual, but not many people who run rehearsal studios read through the manuals as thoroughly as we did. These units are also designed to be installed without any professional help, which I feel makes the likelihood of installation mistakes all the greater. 

Our issue is that everyone that we chat to (manufacturers, people who work in H&S, air conditioning engineers) says that there's no track record of these air conditioners being unsafe and therefore they are perfectly legal to put into rooms.   However, am I being paranoid to think that this just means that there's no track record of any of these units exploding, and that this isn't a good metric to use for safety?  I am more than happy to be corrected on this, but my thinking is that if the logic is "no past fires = safe", then that means that action should only be taken AFTER there's a fire, in which case it's too late.     Very few businesses operate in a windowless environment, and the nature of soundproofing means that you literally need to make the rooms as air tight as possible, since sound moves through air, so you need to create a mini-vacuum.    Thankfully it doesn't happen to our studio, but I've even heard of stories about people creating a pressure lock when they slam the door too much in their soundproofed studio, and where it's really difficult to open the door because slamming the door has basically created a suction/pressure lock within the room, due to its airtight environment.    (This doesn't happen in our studio, but I've seen it happening in other studios)   As I say, soundproofed studios are (I believe) quite rare in how airtight the rooms are. 

Anyway - sorry for the long message, I've been looking around and cannot find anywhere that can advise on this, on whether these units are safe, and I didn't want to wait for a calamity to happen before attention is given to it, so would anyone be able to either¬†advise, or to suggest an organisation that can do so?¬† ¬† ¬†I can then pass the information over to the other studio owners, who may have the same issue as us.¬† ¬†Thanks for your time!¬†¬†ūüôā


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This guide may help determine if the design and installation is OK.


Note that:

Systems, or part of a system should not be located within a space or room where its volume is such that an entire refrigerant leak would cause a refrigerant/air mixture of a
concentration higher than one-fifth of the Lower Flammability Limit (LFL) of the refrigerant (equation 2.2). If this is not possible and the installation is in a machinery room then the use of a refrigerant leak detector and mechanical ventilation should be employed. 

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