On 28/04/2017 13:54, Graeme wrote:
In message ,
RobertL writes
On Friday, April 28, 2017 at 1:15:20 PM UTC+1, Graeme wrote:

Tried again this morning, and first use of a hot tap results in hot
water arriving much quicker.

Is there a small hot-water leak somewhere? i.e. is hot water being
leaking at some place between the boiler and the tap? This would
dleave a shorter pipe run for the hot water to travel before reaching
the tap

That made me run upstairs to look! No, no leaks. All pipes neatly
capped and not leaking. There were no other changes to any pipes, other
than in the bathroom.

I can think of a possible but highly unlikely explanation:
There are two possible routes through the pipework for the hot water to
reach your tap. The shorter route got air locked when they drained down
the system to cap off pipes in the bathroom. That left the water to find
its way round the longer route. The air lock sorted itself out
overnight, and now the water is taking the shorter route.