Hot and cold radiators.

[derrynoose]

I have no heat in the downstairs CH pipes or radiators but upstairs radiators are warm. From an earlier post I realise that this may be a circulating pump problem, with gravity "feeding" the upstairs radiators. Hot water is passing through the pump beside the boiler in the garage. Is there likely to be a second pump somewhere within the house? Thanks.

[The Builder]

If you're sure that's the circulating pump in the garage, then it's not usual to have another elsewhere, Derry.
You can usually tell if the pump's working by the vibration. Give it a fondle, then switch off to see if you notice any difference.
If it's not going, normal practice is to apply an executive hammer with a few taps to wake it up. Other than that, I guess the pump needs replacing.

[jomifl]

Do you have a 'zone' valve which controls the flow to downstairs and upstairs separately. Although you could have siphonic circulation due to convection it would not be enough to get full heat ouput from the upstairs rads.

[The Builder]

Good point, jom. That could explain it, if the pump is running ok.
Is the boiler a combi?

[derrynoose]

I am rather a novice in this area and no doubt will have to call in an expert! What I called the circulating pump in the garage is a pump to the side of the boiler. There is hot water in the pipe on both sides of the pump before it enters the garage floor on its way to the house. I recollect that when the house was built a lot of pipework was boxed in within a groundfloor toilet so I guess that a second pump or a zone valve could be hidden there. I recall, too, that the "boxing" was done with nails rather than screw nails so a bit of wrecking may have to be done. I like the"executive hammer" idea! That would be a handy solution.Thanks to you both.