Gravity Circuit

skippy5

Hi lads, just looking for your thoughts on how well this gravity circuit will work. I know its not an ideal set up, but still think it will work.

Dtp1979

skippy5 wrote: »

Hi lads, just looking for your thoughts on how well this gravity circuit will work. I know its not an ideal set up, but still think it will work.

It'll work but that depends on the distance of pipework between the stove and the cylinder

skippy5

That should be ok, its about 5 or 6 mtrs across. thanks.

freddyuk

You would be better bringing the return down to the stove same route as the flow. Taking it under the floor will possibly stop the circuit. Can you run the return along from the cylinder then down to the stove?

Dtp1979

freddyuk wrote: »

You would be better bringing the return down to the stove same route as the flow. Taking it under the floor will possibly stop the circuit. Can you run the return along from the cylinder then down to the stove?

As in across the attic then down to the cylinder like the flow?

skippy5

No afraid not, I have 2 doors and a window in the way. The only way across is under the floor and up, even moving the cylinder to the attic is a non runner as I have not got the height.

freddyuk

5 metres horizontal with a dip under the floor up to the stove will not work in my experience.
Someone on another thread who was an expert suggested they had done this but never offered any evidence so I remain very doubtful. The 5 metres horizontal will tend to kill it anyway.

Dtp1979

freddyuk wrote: »

5 metres horizontal with a dip under the floor up to the stove will not work in my experience.
Someone on another thread who was an expert suggested they had done this but never offered any evidence so I remain very doubtful. The 5 metres horizontal will tend to kill it anyway.

Why wouldn't it work as it is in the picture if the distances are ok? I've installed many similar to this and they work perfect.

freddyuk

OK thanks.

shane 007

The return must nit rise up into the attic & take the same route as the flow. That will not work.
As per the sketch, it will work as long as the distance are below 8.0m, but take off 500mm for every elbow & 300mm for every sweeping bend. I would also take off a considerable amount for the drop in the flow from the attic to the cylinder. This would be the concern area on fire start up. The creep circuit will back up their until the flow kicks in to force the return to go, so before that happens, there maybe some pitching. A small heat leak rad would help.

skippy5

shane 007 wrote: »

The return must nit rise up into the attic & take the same route as the flow. That will not work.
As per the sketch, it will work as long as the distance are below 8.0m, but take off 500mm for every elbow & 300mm for every sweeping bend. I would also take off a considerable amount for the drop in the flow from the attic to the cylinder. This would be the concern area on fire start up. The creep circuit will back up their until the flow kicks in to force the return to go, so before that happens, there maybe some pitching. A small heat leak rad would help.

Thanks Shane, there is about 1.3mtr drop to coil flow, is there a guide as to how far it can be dropped before it would cause major issues.

shane 007

skippy5 wrote: »

Thanks Shane, there is about 1.3mtr drop to coil flow, is there a guide as to how far it can be dropped before it would cause major issues.

As I said, it would depend on how many bends & elbows are present along with distance.

skippy5

shane 007 wrote: »

As I said, it would depend on how many bends & elbows are present along with distance.

There are three bends on both the flow and return, two of these are sweeping bends and one elbow. The flow rises up 1.5 mtrs across on a slight rise about 5 mtrs and down 1.5 mtrs to top of coil, the return would be similar. How much can you drop given those dimensions.

shane 007

skippy5 wrote: »

There are three bends on both the flow and return, two of these are sweeping bends and one elbow. The flow rises up 1.5 mtrs across on a slight rise about 5 mtrs and down 1.5 mtrs to top of coil, the return would be similar. How much can you drop given those dimensions.

So already you have nearly 8m of linear pipework, plus bends, so that's an extra 1.1m of bends, totalling nearly 9.0m.
Don't forget there's an elbow at the stove, attic would have minimum 2 & another at the cylinder.
You could try it, but it would probably benefit from a leak dissapator to encourage the gravity circuit to get going. This could be added afterwards.

skippy5

shane 007 wrote: »

So already you have nearly 8m of linear pipework, plus bends, so that's an extra 1.1m of bends, totalling nearly 9.0m.
Don't forget there's an elbow at the stove, attic would have minimum 2 & another at the cylinder.
You could try it, but it would probably benefit from a leak dissapator to encourage the gravity circuit to get going. This could be added afterwards.

Good stuff, I will try that. Thanks Shane