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

Do you have a room stat somewhere and are the radiators in that room fitted with TRVs because you may have a situation where the stat is calling for heat but the TRVs are set below that temperature and are shutting off the flow to the radiators. You should also have at least one radiator with no TRVs usually the choice one is the bathroom radiator this acts as a bypass in a situation where every TRV has shut down.

If you have the above situation a temporary solution is to turn the TRVs in the room with the stat to full on and let the stat control the temperature..

Richard

Hi, we only have TRVs on a few rads,(and it on those near the roomstat and Ive tried setting them to 6 and it hasnt fixed the problem.

On 11/12/2017 17:28, Tricky Dicky wrote:
Do you have a room stat somewhere and are the radiators in that room fitted with TRVs because you may have a situation where the stat is calling for heat but the TRVs are set below that temperature and are shutting off the flow to the radiators. You should also have at least one radiator with no TRVs usually the choice one is the bathroom radiator this acts as a bypass in a situation where every TRV has shut down.

If you have the above situation a temporary solution is to turn the TRVs in the room with the stat to full on and let the stat control the temperature.

Richard

Get a CH engineer to fit a bypass to the system. It does the same job
as leaving a TRV open

Malcolm

On 11/12/2017 16:45, wrote:

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

Had this problem after a replacement boiler was fitted. The cure was to
tee off the vent pipe (the U shaped pipe) Higher up the fed from the
feeder tank than it was. About 6 inches was enough in my case

Malcolm

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

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
wrote in message
...

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

Brian Gaff wrote:

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

Surely the tank accommodates the expansion, and the height of the
overflow just accommodates the pressure differential due to the pump?

--

Roger Hayter

On Tuesday, December 12, 2017 at 9:33:08 AM UTC, Roger Hayter wrote:
Brian Gaff wrote:

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

Surely the tank accommodates the expansion, and the height of the
overflow just accommodates the pressure differential due to the pump?

--

Roger Hayter

Hmmmm,

Some interesting comments. SOME of the new rads are actually replacements (in new positions) for old rads which have been removed), but overall, yes, there is more water in the heating circuit, so perhaps that is the issue as Brian suggests.

How to solve it? I'm not yet sure. As I say, there are plenty of rads still left at the moment without TRVs, so I't's (sadly) not a question of simply fitting a bypass.