Pressure shower with a combi boiler

[alphonso]

Hello,

Is there anyway of increasing the shower pressure with a combi boiler?
I'm having the old one ripped out, so just using a modern thermostatic control and new un-furred pipes might help things a long a bit.

I imagine you can't use a water pump as there is no cylinder. Any ideas?

[Dr_Gonzo]

AFAIK the flowrate is determined by the boiler itself - although I may be wrong

[ln1234]

Combi boilers usually have a max flow rate capped at 12 litres a minute or something similar, no matter what the incoming flow.

[cjs]

My Combi gives me a very good shower, is the incoming pressure low? how is the cold flow is it fast or just a trickle?

[GreenDog]

cjs said:

My Combi gives me a very good shower, is the incoming pressure low? how is the cold flow is it fast or just a trickle?

Isn't it the cold feed that detemines the actual pressure and the hot just, well warms the water ? Sure I've heard that somewhere before.

[alphonso]

The cold flow is pretty strong. The top floor shower is better than the middle floor (which is the one I'm replacing), so it could be a small pipe bore or old pipes. The pressure should be reasonable when finished, but I wanted to try to make the best of it without changing the boiler as I'm having a cloud shower head installed (as well as a rail shower).

The boiler is a fairly new Worcester junior, possibly too small for the house (4 bed Victorian terrace).

Do you think I'm stuck with what I've got?

[JERRYCO]

Yes your boiler dictates the flow of hot water as Dr Gonzo said. You will have to change your boiler to get a better flow rate. Have you thought about a electric shower?

[Arthur Jackson]

I've never seen a combination boiler yet that has as poor a flow rate as an electric shower........

[andy43]

JERRYCO said:

Yes your boiler dictates the flow of hot water as Dr Gonzo said. You will have to change your boiler to get a better flow rate. Have you thought about a electric shower?

Yup (except the electric shower bit). A high power electric shower is 10kw. A smallish combi is rated double that.

Flow - dependent on pipe sizes, and the rating of the boiler - litres per min for x degrees temp rise. You can really screw it up using push fit plumbing, small bore pipe, or the wrong in-line valves.
Pressure - for a combi, dependent on the water board.

If the shower's bad now, wait until the winter when the incoming mains water is close to freezing!
You need a bigger combi or an alternative solution.