"mcslinger" wrote in message
om...
I have a Myson Apollo boiler and a conventional heating and Ho****er
system.

I have recently replaced the pump (myson 53) with a new one
(circulation pumps 53)after it failed but now have the following
problem.

When the system is running a small amount of water is coming out of
the overflow from the small black plastic tank in the loft. I was told
the pump may be set too low so I increased it to the second setting
but this only increased the flow of water so I put it back.

I have had it suggested that the thermostats in the boiler might have
gone and was wondering if anybody could tell me which. I understand
there is one for the return water temperature one for high and one for
low.

I am assuming it will be the return as the problem is still there
wether the boiler is set to high or low.

If anybody could clear this up for me or has another suggestion then I
would be grateful for any information.

First of all do you mean the overflow (which carries water away from the
tank to an open pipe discharging somewhere outside the house where it
is|should be visible?

Or do you mean the vent pipe which is roughly like the crook of a walking
stick and opens over the tank itself?

From the sysmptoms you describe it sounds to me (and everyone else who's
replied to this thread) like the latter. If it is then apart from making
sure the top of the walking-stick section is as high as possible above the
tank and the water level in the tank when cold is only about 2-3", you
should check that the outlet (feed) pipe from the tank and the vent pipe
both join the main pipework close together - less than 6" apart.