Just had our gas cistern inspected (apparently done every X years) and got a clean bill of health apart from one thing I hadn’t even thought of.
There’s always been soil on top of the concrete plinth that the cistern sits on and it was touching the bottom of the cistern at one end.
I was told to very carefully clear this soil out and keep it clear as there’s a secondary emergency pressure release valve on the underneath in case the main PRV fails. Understandably, having a flammable gas cistern burst is what gas heating professionals call a Very Bad Thing and should be avoided.
Proceeding with great caution, I unearthed the secondary PRV and cleared out all the soil, finding the Earth binding strap for the cistern. That it had been buried for the entire time we’d lived here wasn’t a happy thought.
Please check your cisterns very carefully and don’t whack the lower PRV with a shovel when you’re clearing any material out from underneath.