I have a Grant Combi 90 oil boiler. Its about seven years old. We were noticing a drop in temperature at two showers it supplies. I have cleaned out the burner chamber etc and adjusted the blending valve. The water at the taps is hot hot! but the showers remain cool.

I'm beginning to wonder if its a differential pressure thing. Our mains pressure is high. I reduced the stopcock last night and that has improved the situation slightly but you have to run around in the shower to get wet!

Could the fault lie in the plate exchanger?... any other ideas gratefully accepted!

Jim

That sounds more like a shower problem unless it happens when you open several hot taps.

I would be looking at the shower.

Maybe filters or rose needs cleaning.