Cold hot water

[Binnybin]

My son has just moved into a new flat which has an invecta combination boiler controlling the heating and hot water.

Heating is working fine but if you turn the hot tap on the water starts hot, goes cold, starts to get hold then goes cold again and so on.

we have tried adjusting all the temperature settings bit to no avail.

any ideas anybody?

 

[ChrisR]

Never heard of Invecta, neither has the Boiler Efficiency Database!

Problem you describe is usually a build up of scale in the tapwater heat exchanger. Can be boiler side (rust from rads) or tap side (limescale). Either can be treated, with variable outcomes!