Expansion pipe problem.

[reeno]

Hi,
Needs some advice please.

My rads only get hot if I place a non return value on expansion pipe in loft by tank.
This should let the water out if it expands
but
will it cause a problem when water cools down and air cannot get in ?

Think maybe my expansion pipe is too close to pump and will be difficult to move.
Are any other gadgets available to fit to expansion pipe
or is this a no no on an open vented system.

Hope I have explained my problem sufficiently any help would be appreciated.

 

[hazetimesfive]

what? is it pumping over then?

 

[reeno]

Thanks for reply.

Not pumping over.

Can hear bit of air being sucked in.

Last night tried a longer expansion pipe
but
did not work.

When expansion vent open pump makes different noise.
Lot quieter when I block vent and water moves around the system.

Also tried pipe from cold feed to expansion pipe (is this called crossing H or something like that).
but
again that did not work just pulled water from cold feed and back round pump.

My pump is on lowest speed.

 

[hazetimesfive]

since this is not a new installation i would say your system is dirty

 

[reeno]

Have flushed system using hose in loft connected to expansion pipe out to drain off downstairs.
open one rad at a time.
Have also took three rads off to clean.

realise this might not be good enough but can not afford a power wash.

Can I leave non return valve on expansion pipe
or
is this asking for trouble.

Got to go to dentist now then work so hopefully can check replies tonight and have another go/

 

[hazetimesfive]

convert it to combined vent + feed, use the open vent as the feed pipe and valve off the old cold feed.

 

[hazetimesfive]

what boiler do you have