Worcester 24i boiler - limited hot water upstairs

[hlt32]

Hi,

I have a problem where the upstairs shower / bath will not run hot, it starts off a bit hotter than drops to lukewarm.

I had an engineer come over who replaced the electrodes and the heat exchanger plate, but the issue is still there.

When the downstairs shower is on and running on full hot, the upstairs shower water is hotter.

I've tried replacing the thermostatic cartridges in both showers - no improvement.

I tried reducing the mains water pressure a bit to reduce the flow rate - no improvement.

Any suggestions for what to try next?

Thanks in advance for the help.

 

[Johntheo5]

There are a few basic things you can do.

Put the upstairs shower to fully hot & fully open, hold a container under it for exactly 30 secs, measure this with a 1 litre container, X 2 to give the flowrate in LPM, if you have a household thermometer measure the shower temperature, the (my) present mains is 8C, Multipy the flowrate by the difference in temperature between the shower & the mains and divide this by 14.33 to give the shower output in kW.
OR maybe easier, measure both your u/stairs & d/stairs shower flowrates (separately, with only one on), adjust the flowrate to the lowest one, then measure or just feel (if no thermometer) the shower(s) temperatures.

If you want to check the boiler output (Gas Rate) , ensure the boiler DHW temp is set to max, then opening all hot taps fully + showers turned to fully hot, then take a photo of your gas meter, exactly 3 minutest later, to the very second, take another photo. Subtract one reading from the other and X by 198 to give the boiler output in kW, if its running at its rated output of 24kW? then you should get a difference in the gas readings of ~ 0.1212m3.

 

[CountryFan]

I would run the said outlet and feel the flow pipe just in case it’s going down the heating circuit.

 

[Johntheo5]

Strange that the engineer changed the PHEX in view that d/stairs OK but u/stairs not, presume he took a flowtest at least first.