Running water from expansion pipe when radiators on

[J80FAB]

I have a 29 year old Potterton Netaheat 10-16 MkII which seems to be causing a problem. With the thermostat turned down the water heats up as normal & radiators remain cold. If the thermostat is turned up to heat the radiators this causes the expansion pipe/vent pipe above the feed and expansion tank in the loft to continuously run water (warm or cold) into the expansion tank whether the radiators are warm or not. If however the thermostat is turned down then the running water from the expansion pipe stops

 

[fitz1]

Pumping over. Feed and expansion configuration probably wrong.

 

[wilhelm]

just as well he didnt notice it 29 years ago .

 

[fitz1]

Many people never know that there header tank is working like a radiator.i.e. flowing + returning via feed + expansion.

 

[wilhelm]

ok , j80fab. why were you in the f£kkn loft?

 

[ollski]

Many people never know that there header tank is working like a radiator.i.e. flowing + returning via feed + expansion.

come again?

 

[fitz1]

ollski. u never been in lofts and seen odd shaped plastic header tanks thats been softened by the heating pumping over.But no ones ever noticed ,because it fills back through the drip feed.i.e.circulating.

 

[ollski]

Sorry fitz the way I read your post was that all f&e tanks are constantly circulating

 

[J80FAB]

Pumping over. Feed and expansion configuration probably wrong.

Configuration cannot be wrong ??? Expansion pipe was not directly over F&E tank cover hole. Thus water from pipe ran across the cover & ended up on the ceiling. Had this been going on since central heating installation in 1976 the ceiling would have come down ages ago !

 

[Bahco]

Personally, I would not be spending money repairing a system that is 29 yrs old.
You have had your use out of it and time to renew the lot in my opinion.

Worth considering..............

 

[J80FAB]

Personally, I would not be spending money repairing a system that is 29 yrs old.
You have had your use out of it and time to renew the lot in my opinion.

That is not an option. The boiler works in that it heats the house & provides hot water. There may be a perfectly good reason as to why the pipe is letting water run and this may only cost a small amount to fix.

The system is 'pumping over' but the cause of it in my opinion cannot be an incorrect pipe configuration as stated above.

If materials, parts & knowledge are available then a 'problem' can usually be solved. In this day & age it's all too easy to say if something is old get rid of it

 

[bripl]

good boiler but dangerous if neglected when was the last PROPER service carried out,a simple task for a competent engineer.The problem you have could be a faulty component or system configuration if you do not understand how call in an engineer to rectify/diagnose the problem

 

[fitz1]

partial blockage where drip feed and exp. tee into system.

 

[Bahco]

In this day & age it's all too easy to say if something is old get rid of it

Fair comment.

Only a personal opinion but I feel it is false economy sometimes to keep shelling out on repairs.

Hope you fix it.

 

[J80FAB]

partial blockage where drip feed and exp. tee into system.

Not sure where this would be exactly. If you click on http://www.gasconnect.co.uk/central/conventional.html is the 'teeing' point (t-junction) illustrated as just being under the pump in the central heating diagram ?

The boiler has not been neglected & is in very good condition for its age & usage. The type of servicing I saw carried out by a British Gas engineer a couple of years ago any fool could have done.

'Bripl' rightly points out that an engineer should be able to rectify the problem but finding a decent (& honest ) one isn't easy. After having posted my query on two different sites & received various responses from this one & none from the other then there's no guarantee that even an engineer may pin-point the problem straight away or at all

Whether he fixes it or not in the end he will want some unearthly sum of money which could have gone towards a new CH system False economy indeed !

There is also this http://www.salamander-engineering.co.uk/technicalcentre/faq/faq.htm#pumpover I found which addresses the issue. The only thing in this info which may have any relevance to my CH system is the pump (that's if there's no partial blockage as mentioned by 'fitz1').

I will keep you all posted as an attempt to 'repair' is scheduled for Sunday

Many thanks for all your comments