Drain off on unvented.

[PhoenixServices]

Just changing an oil boiler on a job and they have just had a megaflow fitted. The installer has put a lever valve in, on the cold in with a tee connected to the discharge below the tundish as a drain off. Is it allowed?

 

[Best]

I have heard that method mentioned on this forum.
Very clever & handy I think, - especially for an air gap unit, like a Megaflow, because they need the air gap redone often & therefore draining often.
I would think it is fine to tee in below the tundish because it will not interfere with the D2 pipes purpose & flow and also because when the drain is ever opened the cylinder safety valves wouldn't ne opening into it anyhow.
All I would be careful about is is the initial high pressure would blast upwards & out the tundish until the pressure drops.

 

[PhoenixServices]

That's what I thought it seemed a very clever way of doing things if it's allowed.

 

[PriestyUK]

Some of the Megaflo drawings show it like this 😀

PAGE 6: http://www.trademate.co.uk/ProductE...Systemfit_Product_Guide_36006064_issue_03.pdf

 

[Ermintrude]

That's the best thing on a megaflow schematic