I'm experiencing a big drop in max water temperature in my shower which seems to reflect the ambient temperature, i.e. it's nice and hot in summer months but drops to luke warm in winter.
The shower is an exposed Triton Thames concentric mixer shower, mains pressure fed. The hot water is supplied via a Greenstar condensing boiler sited in the garage, both are about 5 years old. All pipes are well lagged.
The hot feed pipe feels perfectly hot, almost too hot to touch, and the taps produce good hot water.
I've even tried reducing the pressure on the cold supply to the shower (via a key value) but it seems to make little difference. Could it be something as simple as the fact that the temperature of the cold water supply is that much colder at this time of year?
We live in a very hard water area (Chichester, W.Deleted) so maybe that could have some bearing if mixer values are prone to limescale?