Pumping Over

[bodger67]

My elderly aunt has been told by a plumber that her CH is "pumping over" and that the water in the expansion tank is hot. What does he mean by "pumping over", and is it the cause of the hot expansion tank?

 

[kevplumb]

it means that the hot water from the system is being pumped out of the expansion pipe back into the feed and expansion tank
needs sorting as its letting fresh water into the system

 

[PEDANTICVINDICTIVEMAN]

It will oxygenate the water and rot the heating system from inside out and block everything with sludge, needs sorting.

 

[bodger67]

Thanks, guys.

So why's it happening and is it something a competent DIYer can fix?

 

[kevplumb]

has it just tsarted doingit or is it an ongoing prob

 

[bodger67]

Not sure - they were told by BG that the system has to be power-flushed because the pump packed up twice in a year. They called in another CORGI plumber to do the flushing and it was him who noticed the problem, not BG who get their £17/month for a 3-star contract.

Some of the rads are badly clogged and the plumber is coming back to sort that out, but I don't know whether thats a symptom or a cause.

The system was installed in about 1980 and a new boiler was put in last April. The boiler is kettling a bit but not much, and water does seem to be circulating as all the rads get warm - some more than others.

Is there any reason why BG would be unhappy about a CORGI-registered 3rd party doing the flushing when the system is under a service contract with them?

 

[kevplumb]

Not sure - they were told by BG that the system has to be power-flushed because the pump packed up twice in a year. They called in another CORGI plumber to do the flushing and it was him who noticed the problem, not BG who get their £17/month for a 3-star contract.

Some of the rads are badly clogged and the plumber is coming back to sort that out, but I don't know whether thats a symptom or a cause.

The system was installed in about 1980 and a new boiler was put in last April. The boiler is kettling a bit but not much, and water does seem to be circulating as all the rads get warm - some more than others.

Is there any reason why BG would be unhappy about a CORGI-registered 3rd party doing the flushing when the system is under a service contract with them?

could just be a case of raising the vent pipe /bg unhappy to the tune of app £300 i would think

the sludge etc is a symptom of pumping over could be the system was badly installed and has always had the problem just been noticed

 

[bathjobby]

Bodger67,
From one of my earlier posts re my pumping over problem(a search would have found it for you);

Had the same problem when the pump was on any higher setting than 1, even then I got steam coming out of the expansion pipe into the tank, condensing in the cooler overflow pipe causing it to constantly drip. Have now fixed it and can run pump upto speed 3 without overpumping, 2 fixes but both addressing the same problem;
1) Water level in expansion tank was too high, re-adjusted the float to put water level just above the low pipe feed at the bottom of the tank (because this is an open system, the level of water in the expansion pipe will be the same as that in the tank, therefore, if it is high, it will take very little expansion of the water in the pipe for it to flow into the tank.
2) Expansion pipe into tank was too low, only just about 6 inches above tank before bending through 180 degrees into tank. Same as point 1 above, very little expansion still required before water flowed into tank. Increased the height of this 'bend' so that it is approx 3' above tank before the 180 turn back down to tank.

Sorted it for me, hope it is of some help....

 

[bodger67]

Thanks to all for your responses - helped me understand the problem and reassured here that she wasn't being diddled (by anyone other than BG, that is).

Plumber is fixing it by extending the expansion pipe on the 22nd for a very reasonable £100 including flushing out two more rads.

 

[kevplumb]