Combi Boiler Draining

[Lemond2008]

I want to drain my Combi Boiler system, but it says in the instructions not to use the pressure relief valve screw. However, this seems to be the only drain in the whole system. Any ideas why it says I can't drain it through here? The Combi is a Vaillant VUW232

Thanks

Jim

 

[Deleted member 105431]

the isolation valves have a 10mm brass (hexagonal) drain nipple

 

[JPC]

NO DRAIN POINT ON THE PIPEWORK ?

 

[JPC]

sorry re caps

 

[gas4you]

If you use the PRV you run the very real risk of a bit of crud in the system water sticking to the PRV seat, so it will not close again, resulting in a continuous leak and having to have a new PRV fitted.

 

[Lemond2008]

Thanks folks. The PRV getting jammed seems like a sensible reason not to recommend using this as the drain. Just checked the system again and found whe drain valve on one of the radiators - thankfully close to the outside drain!

 

[ChrisR]

If you're draining the system though it's worth checking that the PRV works. Yours is probably 10 years old. They do block up, and seize, which makes the boiler dangerous. It's called "servicing"!!

 

[Lemond2008]

Thanks Chris - PRV does work. Not sure if this is one of the standard 'service' checks. Would hope so, the amount some people want to charge!

 

[ChrisR]

NO. People wouldn't touch it for fear of it letting water through afterwards, which would be pretty normal. The Vaillant ones aren't a very cheap item.

 

[Deleted member 105431]

The Vaillant ones aren't a very cheap item.

but they are well made and servicable.
I've never tested a prv on a service-its not nessecary imho.