Drain off Valves

[tosh123]

Hi, go easy on me as this is my first post

I am running the pipe work for a new Combi Boiler Glow-Worm Flexicom cx35, the boiler as you all probably know has it's own drain off valves so what I need to know is do I need to put my own drain valves at the lowest point of the feed and return pipes, even though they are only going to be 300mm max bellow the boiler drain off's.

I will be getting a Gas safe plumber to do the Gas instalation and comishioning side of things

MORE QUESTIONS TO FOLLOW

Quic diagram of what I mean

 

[royalflush]

I would, it will make it a lot easier to drain.

 

[tosh123]

If I do need them can I tee off the 22mm feed and return in 15 mm and run these drain off branches behind the sink, the 15mm lengths will be approx 2 metres long because where the boiler will be positioned the pipework will be behind the dry lining and boxing, or will this cause a problem with air locks etc.

Revised Diagram sad I know but it's an easier way of explaining.

 

[jpm]

If I do need them can I tee off the 22mm feed and return in 15 mm and run these drain off branches behind the sink, the 15mm lengths will be approx 2 metres long because where the boiler will be positioned the pipework will be behind the dry lining and boxing, or will this cause a problem with air locks etc.

Revised Diagram sad I know but it's an easier way of explaining.

1 drain on flow will empty the whole system,anymore is waste of money,time and effort