Question - Feed and Expansion Pipe

[rhubarb1092]

Hi. Few weeks ago I found condensation in my loft. I've been in the house about 18 months and had never noticed it before, although the insulation is dirty and some of the rafters look discoloured (although they seem sound enough) so I suspect it's not the first time this has occurred.

I've done obvious things like plugging holes in the ceiling, replacing spot lights (wrong type) in bathroom with sealed units etc. I also found that there wasn't a lid on the feed/expansion tank, and the water pump was at the maximum setting, which I understand can cause condensation.

Something I have spotted today though is the feed and expansion pipe connects to the flow pipe from the boiler, just before the pump (attached). I've looked in a few manuals and they say the feed should go to the return pipe? Not surprisingly, this pipe gets very hot and I'm thinking that this may be heating the water in the feed tank and causing the condensation? I suspect it's not feeding into the system at the correct place. Any thoughts?

Thanks.

Untitled

• rhubarb1092
• 25 Jan 2009
• 1

 

[leakydave]

Assuming:

a) that you have labelled the pipes correctly, and

b) that the pump is pumping towards the 3-port valve, your current set up is CORRECT:

from boiler: Vent, Feed, Pump, Zone Valve

A tight fitting lid with insulation on top is what you need.

 

[gas4you]

Nothing wrong with your pipe layout. The books you have been reading are obviously out of date with new methods.

Unfortunately there are many books like this out there

 

[rhubarb1092]

Gents - thanks for your replies. That puts my mind at rest.

I take it that it's not unusual for the expansion pipe to get hot a 4-5ft from the junction with the boiler flow pipe?

Thanks again.

 

[nickso]

no, thats fine.

get a new lid on your f+e tank though.

 

[giblets]

Regarding the condensation have you made absolutely sure that the eaves spaces (where the roof timbers join the external wall) have not been stuffed full of insulation? The roof needs to be ventilated and blocking these gaps up will stop that ventilation and lead to severe condensation build-up particularly in the recent very cold weather. You'd be surprised how much moisture a normal household give off.