Hot water temperature

[alison7148]

Having (stupidly) endured months of scalding hot water we have eventually had the thermostat on our hot watertank replaced. However we weren't told what temp to set it at, so showers this morning were luke warm. It is currently at just over 50C. Should I alter the thermostat on our boiler too? (This is currently low as we adjsuted it to try and deal with the v hot water previously). Sorry its a daft question, but I haven't got a clue
Thanks xx

 

[Diyisfun]

It may be that the boiler is set to low for the tank t/stat to do anything.
Try turning the boiler up to 3/4 as its winter.
THe t/stat for the cylinder should be between 60 + 65, is what I have read

 

[alison7148]

Oh ok...have turned up the boiler stat to see what effect that has, then will turn up tank stat too. Thanks xx

 

[alison7148]

Just to clarify - I have set the boiler stat to about 3/4 of the way round the dial. Shall I see if that makes a difference first, before altering the tank thermostat too? The gas engineer left it on around 50C so I was thinking maybe that is where it should be? Just being ultra cautious as i have a young daughter who loves playing with the taps!

 

[Diyisfun]

I think set at 50 it will run cold quickly, but just try it. If the water starts running cold turn it up.

 

[D_Hailsham]

The recommended Hot Water temperature is between 60C and 65C. The reason for the 60C minimum is to prevent the growth of Legionella in the cylinder. The 65C max is to prevent scalding. A typical HW cylinder thermostat has a 8-10C difference betweeen the open and close temperature. So, if you set it to 60C it will heat up to 60C but not come on again until the temp has dropped to about 50C. This is fine as typical bath and shower temperatures are about 30-35C.

The boiler temperature, obviously, has to be greater than the temperature set on the HW cylinder stat. Provided you have a room thermostat controlling the CH side, I would wack the Boiler temp up to max. It will probably never reach max temp, except in the depths of a a very cold winter, as the room thermostat will have shut the boiler down beforehand.

 

[Rob]

Hailsham just curious where you got the figure of 10 degrees?

 

[D_Hailsham]

Hailsham just curious where you got the figure of 10 degrees?

See Honeywell L641 page 2: Differential 10K ( One degree Kelvin = one degree Celsius, but 0K = minus 273 Celsius).

or

Drayton HTS3 Page 2: Differential 8K

 

[Rob]

thanks