"stevet" wrote in message
...
Hi

I've been helping a friend get her canal boat 'ship shape' and the heating
sytem is most odd, there's a log burner with some sort of back boiler and
pipes that run from one end of the boat to the other, via the radiatoirs.
The pump (a small 12v affair) is at the rear in the engine bay and there is
a loop of pipe that goes up and over before going to the inlet of the pump.
This loop seems to alway get air in it, it does have a bleed valve but it's
a pain to keep having to bleed it. Also you have to bleed it with the pump
off otherwise the pump just sucks more air in.
My question is this, can I put an autmatic vent valve onto this loop,
bearing in mind it's on the inlet side of the pump and only 6in away from
it, or will it just result in more air being sucked into the system. If it's
not a problem then it will make life easier in keeping air out of the
system.

many thanks

STeve



The little rise in the pipe is actually there to catch the air bubbles, before
they get to the pump, and bleed them off. It might actually help to extend the
pipe, that the bleed nipple is on, further up. The extension will catch more
bubbles at a time, and should make it easier to bleed the system of all the
bubbles at one time.

Why does it actually need to be bled frequently anyway?