Surely with a longer pipe run more water in the system equals more expansion
and contraction, so the brain, though a little rusty might suggest raising
that pipe to accommodate the expansion?

Brian

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The Sofa of Brian Gaff...

Blind user, so no pictures please!
wrote in message
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Hi all,

We have a fully pumped Oil fired CH. (S Plan I think, 2 separate motorised
valves
one for heating, one for hot water.

I am told the pump is in the return.

Some years ago, we had some alterations (mostly addition of a shower), and
the plumber said the system was pumping over (hadn't seen this before),
and he extended the pipe that goes up in the air (higher) and drops down
into the F&E tank.

Since then I think all has been well.

Fast forward a few years. A boy (didn't look old enough to shave), came
and did some modifications last week. Added some radiators, replaced
another, firred thermostatic valves on all the radiators he'd installed,
replaced the pump.

Announced the system was pumping over, and that if I made sure I always
turned on the hot water at the same time the heating was on, we wouldn't
have any problem (my immediate thought was - what happens when the HW stat
says "no more heat thanks").

Generally, he was rigt, but on one occasion it has pumped over even though
both Heating and HW were on (perhaps as the syslinder stat was no longer
calling for heat).

I noticed after he had left that he had the 3 position Grunfoss pump set
to it's highest head/pressure/speed and I wound it down to "1" , which
according to the stuff on the pump, is lover / slower than "1" on the old
pump. But this made no difference.


Questions............

What might have caused it to start pumping over?

What is the cheapest way to fix it (I really don't want to have him back,
his plumbing of the Radiators was awful! (but I could get the builder who
supplied him to supply another plumber who MAY be better)).

Could the top of the inverted U in the loft be taken even higher (there is
plenty of height up to the ridge)?

Could the system be converted to a sealed system (what MIGHT need to be
replaced? - Boiler (one of the original Wallstars)? Cylinder? Anything
else?

I suppose I could fit a Calor Combi (but there lies MUCH capital expense
and disruption).

Any other suggestions?

TIA

Chris