general combi boiler question

[blueteeth]

Hi, could anybody in the know tell me if combi boilers are fitted with a valve or system that limits the amount of hot water it can supply, so even if a shower or tap is demanding to much it will always run as hot as it can. Hope that makes sense the way i explained it.

Its just that im having a lot of bother with my mira excel shower. I fitted a new cartridge and have also had a couple of problems with my combi which scottish gas fix through there homecare. It seems to be that my shower is demanding to much hot water and the combi starts running luke warm. The only way to stop it is to turn the shower down. Any help would be much appreciated as i dont want to phone scottish gas if theres nothing wrong with the boiler but i dont want to get scammed by a plumber who might make up a load of rubbish for a quick buck because its xmas

 

[gas4you]

A lot of combis have a flow restricter in them.

To test to see if it is working ok you need to take the cold mains temp, run hot tap at prescribed flow rate, eg 12 l/m for a 28/30Kw combi, then if the temp rise is at least 35C all is well with the boiler.

 

[blueteeth]

Cheers for the quick reply, its a worcester 24cdi if anybodys wondering

 

[gas4you]

The flow rate for this is around 9-10l/m

 

[blueteeth]

thanks, so would turning the flow down using a stopcock before it went to the shower help? I understand that it would reduce the flow of the shower slightly but it has to beat the amount of messing about i do at the moment to get the temp right.