only 45cm between top of HW cylinder and bottom of CWS tank

[jgreer]

I'm about to have a new water pump installed in my flat.

The diagrams from the vendor show a min 1.2 meters distance between the bottom of the Cold Water Storage to the top of the Hot Water Cylinder.

In my one storey flat, it doesn't work this way. There is only a 45cm gap between the bottom of the CWS and the top of the HW cylinder.

There's simply no room to move anything around.

Should I be worried?

 

[croydoncorgi]

Yes.

Probably air will be drawn down the vent pipe when the pump runs.

If it's a shower pump being fitted, make sure the plumber also fits a Surrey or Essex flange to the cylinder. This puts the outlet to the pump lower down, minimising the change of air being drawn in.

First step: get advice from pump manufacturer.

 

[jgreer]

Currently, I can see that happening because the existing pump runs from the top flange. Actually, it runs from a t-joint on the pipe that goes to the top flange... even worse.

My new pump, I intend to have installed with a no stop essex flange from the side of the cylinder. The top flange will only be used for the over flow/vent.

Do I risk having air come into the pump even in that situation because of this 45cm gap?

 

[ChrisR]

Yes but a lot less. Helps if the shower is adjustable- turning it down until it doesn't suck air is at least a possibility.
Word of warning re sucking air, from a flange. DO NOT fit a flange if you intend using an electric immersion heater top mounted. Element could be exposed.