Hot Water in Small Expansion tank causing loft to be damp

Hi,

While routing around in my mums attic over xmas, I noticed steam rising from the c/w c/h small expansion tank that is sitting on the larger mains water tank. On closer inspection the water in the tank was hot and it was flowing into the tank is a light but steady trickle flow from a copper pipe. The water was quite hot from the pipe. The steam is rising and soaking into the rafters and felt in the roof and I am concerned that this will cause major problems for my parents with damp rafters. The C/H is a combination of oil and a back boiler. Generally they would have a good fire going most days through the winter and this would heat the rads and they would use the oil initially on cold mornings. I think the problem started to occurr about 2 years ago when the back boiler went and they got a plumber to replace it. Because since then they tell me that if they have a roaring fire, the upstairs rads are roasting hot where as the down stairs are only warm! Any idea why this is happening? Was the plumber they hired a cowboy?

Cheers Ado

Reply to
ado
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Generally

upstairs

It's presumably the expansion pipe from which the hot water is flowing. Often caused by the pump being in the wrong location or too vigerous.

AWEM

Reply to
Andrew Mawson

If the CH pump has 3 speed settings (1, 2 & 3), and it is currently set on the maximum speed (3), try running it slower on the 2 setting. This might fix the pumping over problem. If not, let us know as there are several causes/fixes for pumping over. Regarding the rads, have they been bled of air and balanced?

Reply to
DIY

The other thing is that running in this pumping over state will have quickly resulted in any inhibitor in the system becoming ineffective. When it's fixed, add new inhibitor (ideally after a drain down and refill, but do it anyway even if you aren't going to do the drain down and refill).

Reply to
Andrew Gabriel

It may well do, damp and timber makes for rot unless you are lucky... See if turning the pump down a notch cures the "pump over" if not come back. The tank shouldn't be open anyway a lid will keep normal evaporation in let alone steam due to the fault.

Gravity circulation from the (open fire's?) back boiler will only effectively reach the upstairs rads. How is the interconnection between the oild boiler and back boiler made, ideally there should be neutraliser (commonly made by Dunsley and know as a "Dunsely Neutraliser") so that the back boiler doesn't feed the oil boiler and vice versa. Boilers are quite good a loosing heat from the water and up the flue...

I'm not sure that having a netraliser will help the upstairs/dwonstairs problem though. You need to run the pump and then *definately* have a netraliser and the pump in the CH circuit only. If the oil boiler needs to be pumped, rather than gravity, that will need another pump controlled by the boiler. The Back boiler should (must) be gravity circulation so that a power cut doesn't leave you with a risk of the boiler exploding or getting seriously hot. It also means that you can have heat without mains power.

Reply to
Dave Liquorice

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