Hot water from Oil central heating escaping through overflow in attic

Gerry1995 · 14-06-2011 6:44pm #1

Turned on the CH after moving hot tank and associated plumbing including heating pipes. Now when Oil burner comes on hot water escapes via the overflow in the attic,any suggestions on how to remedy this please.

Billy Bunting · 14-06-2011 8:50pm

How is the water getting into the tank ?? is there water coming out of the vent pipe ?? (in the attic)

Gerry1995 · 14-06-2011 9:13pm

Sorry, yes hot water from heating vent pipe.

jack of all · 14-06-2011 9:20pm

Not a plumber but sounds like your system is "pumping over" and the easiest way to try and resolve this without major redesign is to extend the length of the vent pipe up to the highest point in the attic space before running it back down to your storage tank. The problem with your system at the moment (apart from the tell tale overflow) is that the constant venting will introduce oxygen into the header tank (promoting corrosion) or in a worst case scenario continued hot water overflow into a plastic tank could cause the tank to fail. Others far more qualified than me should be able to help you here....

decmeister · 14-06-2011 9:21pm

did you lower the tank when you moved it

Billy Bunting · 14-06-2011 9:30pm

Gerry1995 wrote: »

Sorry, yes hot water from heating vent pipe.

Sounds like you have the vent pipe on the positive side of the pump, easiest way to solve this is to combine the cold feed and vent pipe, this is really something a plumber should look at as not all boilers are suitable for a combined feed and vent pipe and pipe sizing is critical.

Gerry1995 · 14-06-2011 10:19pm

Pump is still same side as it was hot cylinder was moved along the pipes. Attach rough diagram if it helps.

Billy Bunting · 14-06-2011 10:35pm

Sorry diagrame doesnt really help. If you move a cylinder then you likely moved the entry point to the system of both the cold feed and vent, that will cause the vent pipe to pump over, normally the feed and vent enter the system within 150mm of each other, if you go beyond this then the vent is under positive presure and will pump over.

Google "Combined cold feed and open vent"

Gerry1995 · 16-06-2011 4:23pm

Thanks to all for advice, having googled "Combined cold feed and open vent" as suggested by Billy I got to http://www.home-heating-systems-and-solutions.com/hydronic-central-heating.html#ans00 , which seemd to have good info well laid out and easily understood. I will do some reading which I hope will help. Many thanks

Hot water from Oil central heating escaping through overflow in attic

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