@iancalderbank

It doesn't.  Heatpumps containing R290 (which effectively *is* propane - just 'refrigerant grade' ie specially clean or something?) are DIY-fitable on the very basis that the refrigerant has 100th the global warming potential (GWP) of R32 and are usually marketed as 'easy-fit'.  The refrigerant is factory installed into the outside unit (in split systems) and a special valve attached there-to is used to first purge the refrigerant lines and then fill them with the R290.  It is a very easy process and avoids any need for (jobs-for-the-boys) F-gas certified installer.  Electrically, the 'DIY' aspect is another matter tho I have seen some easy-fit systems come with a plug.  So, *truly* DIY.

@robl So dangerous that 2,756 million homes, caravans and boats use propane for space and water heating!  Health and safety gone mad (as flaming - forgive the pun - usual)!!

Posted by: @martinwinlow

↑

(jobs-for-the-boys) F-gas certified installer.

I'd be a little cautious about this generalisation Martin. Most F-Gas refrigerant engineers have specialist training and competency that comes at a premium, not to mention, as per CORGI, NICIEC et al, the annual costs they incur to be accredited & registered. The main issue with DIY split installs is loss of pre-charged refrigerant. Lost charge is usually due to very poor flare connections on the indoor and outdoor units, the connections not made with the correct tools, and/or they are used by inexperienced hands. Add to that the knowledge and equipment to add the correct quantity of charge to the system where longer lines are used, etc. Another common issue is non-compliant electrical connection to the outdoor unit, usually the lack of a lockable rotary isolator.

Propane in small charge quantities isn't an issue, and as you say, Propane is used internally in all manner of leisure homes, fixed and mobile, boats, and many domestic homes. Not to mention methane natural gas. For sure the regulations concerning the siting of external ASHP monobloc R290 units need reviewing to better reflect the extremely low risk profile. The chances of a propane leak magically finding an open door or a window adjacent to the unit and forming an internal vapour cloud above the LEL, oh and also an ignition source, are incalculably small, but that seems to be the working assumption the rules concerning the location of outdoor R290 units are written around.

People have died and been seriously injured working on A3 class refrigerant systems where they are untrained and/or incompetent. The risk is real. Most accidents have occurred when breaking system containment using hot working methods when the charge has not been evacuated and recovered prior, or no standing pressure checks have been made. Refrigerant oils are miscible with refrigerant vapour, and will release refrigerant gas from the oil even when the system pressure is almost atmospheric. For that reason vacuum pumps are used, to ensure full and safe refrigerant charge recovery, and a dehydrated system prior to breaking containment or recharge. The regulations that exist to ensure only accredited F-Gas technicians trained to work on A3 refrigerant equipment with good reason. 

REFCOM and Cornish Trading Standards successfully prosecuted heat-pump installer, Adrian Miles, who was adding coolant to heat-pumps without the necessary safety credentials.

However... he was prosecuted only for fraud (misrepresentations to customers) and not for working with the refrigerants.

More recently there has been a prosecution in Jan'24 of Appliances Direct who were supplying split-system heat-pumps without ensuring that they would be installed by F-gas registered engineers. But that too wasn't a case based on an individual actually charging a unit with gas. They only pursued the supplier of the heat-pumps.

In neither case does REFCOM state what the refrigerant chemical actually was.

So I remain sceptical as whether REFCOM and their legal advisors think they could pursue a case against a (competent) DIYer who charges a heat pump for his own use. That might be particularly difficult if the charge used propane.

In any case, if the system was leaky, even the Prosecution couldn't make the charge stick. 🤨 

... I'll make my own way out.