Hot Water Vent Pipe

[diynoob]

Where is the supply from the cylinder? Is that coming out of the top of the cylinder? There should also be a vent that should run from there up and over the CWSC.

Given that it's gravity fed primaries then having them venting themselves up to the CWSC isn't really that much of an issue, not a normal approach to join them though (are the returns joined too?). They may be joined as a bypass - is the aga solid fuel or gas? - the concern would be though that they could be shortcutting themselves with both trying to feed both coils.

Yes the top of the cylinder is normal. There is an immersion and there is pipework as you describe - the hot water exits the cylinder at the top and there is a vent there too (leading to the big loft tank). There are no issues with the flow of the hot water out of the taps. Once the HW is heated everything is fine. It's just that it takes forever to heat up so the boiler constantly has to turn itself off waiting for gravity to do it's thing. The aga and boiler are oil.

As many posters have said, a 22mm gravity system is a bad idea. Every engineer that's looked at it says it's crap and needs ripping out so I think everyone is in agreement . Until it can be replaced, are there any other DIY solutions? If I fit a small 100W pump to the HW circuit will that help? Will it cause any problems? Will it send water shooting up the vent into the loft tank?

 

[Madrab]

Will it send water shooting up the vent into the loft tank?

If you pumped the HW primaries the way it's pipe'd just now then yes. You would need to remove the vent pipe from the primaries and just have normal manual/automatic air vent at the top of the primary flow.

You would also need a proper feed and expansion from/to the feed and expansion tank placed at the right position, in relation to the pump if the HW circuit is separate to the CH circuit.

Also not knowing how the internals and how the coils sit complicates things a bit too.

If anything I'd look to see how the CH is pipe'd and if it would be possible to create an S plan on the boiler side.

 

[Hugh Jaleak]

I'm not sure if that Motorised Valve in the HW Primary flow is the best idea either. If this is really a open vented system, you may be sitting on a potential bomb.

I think Madrab has the best idea in the previous post. Perhaps easier to convert the existing HW primaries into the cold feed and vent, then alter the pumped CH side to and S plan system.