Megaflo-style unvented system and shower goes hot when water used

[crackers1978]

Hi

Sorry if this isn’t the right forum.

I’ve got a megaflo-style unvented hot water cylinder (it’s a Worcester Greenstore SC-210) with a Worcester Greenstar 30Si Compact Combi boiler.

I was specifically told that an unvented system would stop the shower suddenly changing temperature when someone else uses the water.

However, we get it worse than any other house I’ve ever lived in! If someone turns the tap on or flushes the toilet, the shower goes insanely hot.

Does anyone have a solution to this? Is there a particular kind of shower control we should be using? I’ve been looking at the Grohe smart control thermostat which looks very Deleted!

Thanks in advance.

[stoneyboy]

Hi crackers 1978
There are a lot of questions that would need answering, even then it would be difficult to provide a solution remotely.
How does the system operate, is the shower fed directly from the boiler; are there pressure/flow valves in the system; is the existing shower valve thermostatic; are there isolating valves on the shower valve and are they open....etc..........
Suggest you get your installer back to sort out this issue.
Regards S

[crackers1978]

Thanks Stoneyboy.

I’ll do that. My main worry was that there might be different kinds of shower controls for different systems but it doesn’t sound like that’s the case.

[stoneyboy]

Hi crackers1978
Once everything is checked over your problem may well come down to the mains into your house not being not large enough to supply the system installed.
Regards S