How to drain an unvented cylinder

[Volunteer]

Hi, I have a dual coil, unvented cylinder with what I think is a pressure relief valve fitted on the end of a 15mm pipe which is T'd off the 22mm feed from the boiler to the top coil. The valve is leaking when the boiler is on or off and I want to remove it for inspection but when cold main is turned off and I open a hot tap I suspect there is still water in the top 1/4 of the cylinder. How do I make sure I have drained the water level below the top coil input joint before removing the valve? Many Thanks

 

[Howsie]

Welcome along.

It's easy to do and is covered on the G3 course.

🙂

 

[Volunteer]

Thanks Howsie, are you saying it can not be done as a DIY job?

 

[Rickster123]

No this is not a DIY job. Welcome to the forum tho.

 

[Volunteer]

OK will try to find a suitably qualified plumber. By the way I have had a closer look and the valve is a Flamco Flexvent automatic air vent (10bar x 120 degrees)

 

[Howsie]

Thanks Howsie, are you saying it can not be done as a DIY job?

It's the law that you should hold a valid current G3 certificate to work on these things.

You can do anything you like to your own stuff. It's weather you do it right and safely, that's where the issue lies.

 

[Dannypipe]

Another forum member showed the results of incorrectly altering these systems. The cylinder shot 500 foot into the air. Genuinely.

That's the reason you must be qualified to work on these things. So despite the fact that this sounds like a very simple job, I would agree with Howsie and suggest you get a qualified plumber to look at it. Welcome to the forum!

 

[Volunteer]

Thanks guys, will do as you say.

 

[iiplumbing]

Mythbusters - Water Heater Explosion - YouTube

This is the clip posted by Tamz in another thread

 

[joni os]

Please get a suitably qualified engineer in. Who recognises a primary circuit.