Pumped Shower

[antoinedecool]

I am about to install one. Gravity fed - cold off tank to valve to twin impeller. the problem is with the hot. I am going to come off the cylinder with a surrey flange but then have to take the pipe up into the roof before going down to the pump. Will this create an inverted u thich will trap air and airlock the pipe. Or can I vent the branch, over the header tank.

 

[Hamiltonandy]

Cannot see you will have problem with air if cold tank higher than pipework. Water under pressure throughout.However whatabout pressure drop in pipes especially hot side. Have you calculated pipe size required?

 

[AnonymousImport]

No I haven't calculated the pipe sizes. I read in Complete DIY that I should run everything in 22mm. Or should I run the cold in 15 to compensate

 

[Hamiltonandy]

Neither will be at mains pressure. Actual pressure is cold tank to pump inlet. I would email manufacturers but personally I would use 22mm on both sides. You could consider the new plastic piping as can take the heat and all push-fit. Costs much more than copper but easier to run round.

 

[AnonymousImport]

I think you need to keep the pipe run below the level of the cold tank. You can't vent it over the tank or you're back to square one and your pump will suck air in from the vent - that's why you use a surrey flange in the first place. I guess you could have a bleed device in the top of the inverted v though.

I was wondering whether a one-way check valve could be used in the vent/overflow line rather than using a surrey flange?