Combi Boiler and Thermostatic Mixer Shower.

I have a Worcester combi boiler and a good water pressure.

the water preasure and flow rate are such that when the upstairs bath hot tap is turned on full the water flow rate is such that once the mini hot resevoir within the boiler is used up the water starts to cool off considerably and the flow rate needs to be backed off to achieve a hot flow again.

My question is this - if i fit a thermostatic mixer shower how does the mechanical mixing in this shower deal with the fact that the hot water temperature into it will drop if it is opened up to full flow or is this something that is going to cause me problems.

do i need to fit some kind of flow regulator or restrictor to the hot inlet that will prevent the shower from drawing too fast from the hot suply that the temperature goes cold and confuses the mixing mechanism...

What boiler is it? Unless its the 440 I would say you have a possible diaphragm/diverter valve fault.

its a heatslave 15/19

i thought it was normal if you ran water through a combi at too high a flow rate the boiler cannot keep up and the resulting temperature drops ???

Didn't realise it was oil. Know nothing about them