commercial boiler safety valve inspection frequency.

[greyhound]

hi all,
i am new to here so treat me gently and not sure if this is a bit big for most on here. i am recomending that a boiler safety valve be replaced due to its age on a 331 kw boiler, on a sealed system. it has a pressurisation unit with hp and lp switches and 2 expansion vessels, i need to check but i think they are 75 litres each, under the 250 bar litre limit each for inspection, do they count individually or do you combine the volumes.
the existing safety valve isnt marked but 2.5 - 3 bar would be ok.
my question is does the site need a writern scheme or should i recomend routine servicing of the safety valve.
many thanks.

 

[Dotty]

Hello Greyhound and welcome to the forum.

Commercial safety valves have to be treated much the same as domestic ones in that they should be inspected periodically. However as with domestic safety valves they can have a tendency not to reseat themselves after an inspection. 3 bar SHOULD be fine but depends entirely on your pressurisation set settings.

You'll have the working pressure which, for arguments sake, we'll say is 1.3bar, this would theoretically give you a low pressure (pump on) limit of about 1.0 bar and a high pressure (pump off) of about 1.5 bar. your alarms would be set as low pressure alarm at 0.5 bar and high pressure of 2.7 bar, either pressure reached should shut off the heating system. Pressure vessel pressure's should be roughly 90% of your working pressure. In this example 3 bar would be fine, this is also assuming this is a LTHW system.

Also check your boiler's MI's. If you dont have them PM me. I've loads of commercial stuff cos that's the sector I'm in.

So in a nutshell, check the settings on your pressurisation set and your boiler and size your safety valve accordingly.

 

[greyhound]

thanks for that info,
i was more after if it should come under a writen scheme and the required or recomended maintenance if its outside the pressure regs.and yes it is lphw.
many thanks.