Amount of hot water is reducing

[mk2phil]

I've got a gravity H/W system fed by a Potterton Kingfisher boiler. This is set to come on at 5am and go off at 6am. Usually we have plenty of water for 2 showers, but lately the person who gets in for the second shower is not getting any hot water. The amount of time spent in the shower has not increased by the first person either.

Thermostat on tank set to 60C, valve on bottom of return pipe to boiler seems to be working fine.

Any ideas?

 

[cross thread]

try increasing boiler stat setting

 

[Softus]

Alternativley it could be an ailing cylinder stat.