Combi and unvented cylinder

[Jitno123]

Hi everyone

Currently undergoing a loft conversion and my plumber has recommended to get an unvented cylinder installed, I like the idea of it but forgot to ask the plumber will this work with a combi boiler? Is it a simple job or will the boiler need changing? I've got a Baxi Duo Tec 33kw. As the loft conversion is adding another bathroom will defo need a pressurised tank as I will have 1bathroom and 2 shower rooms by the end of it.

Thanks

 

[JohnD]

you can use a cylinder with a combi boiler. the boiler doesn't know or care what the load is.

The incoming water flow and pressure have presumably already been measured.

you might need some larger-diameter pipes.

 

[Jitno123]

Thanks for the reply

The pressure and flow have been tested and seem to be adequate.

Could someone explain how the unvented is installed with the combi? My understanding is that combi is on demand water, so is there a way of converting it so it heats up the water in the cylinder?

Thanks

 

[dilalio]

The unvented cylinder is on the heating flow and return from the combi boiler and is controlled by motorised valve(s), cylinder stat and programmer that diverts heated system water through the cylinder coil when called for. The benefit of using a combi to do this is that you can also use the instant hot water side of the combi to serve certain outlets i.e. Utility sink/ kitchen sink/ cloakroom basin.

 

[Doggit]

You'll also need to split the hot water pipes, so that the new shower gets it's feed from the unvented cylinder.