cylinder stat accuracy?

[bhm1712]

hi all

after changing to c plan, i set my cylinder stat to 60 degrees. its a honeywell stat and was brand new. I noticed that the water at full temp never seemed to be HOT HOT, just hot, but i could just about hold my hands under it. i measured the temp with a digital thermometer and its only at 50 degrees although the stat is clicking on/off at 60 according to its scale. is it usual for them to be inaccurate like this?

to achieve 60 i have set it to 70 on its scale.

 

[Aquaheat]

Where abouts on the cylinder has the stat been placed and does it have good thermal contact with the cylinder?

Ideally the stat should be placed a third of the way up the cylinder and set to 55C.

A level of inaccuracy will occur but it should not be that great.

All stored water should be kept to at least 65C to prevent bacterial growth.

 

[bhm1712]

it is 1/3 of the way up. i measured the cylinder before installing the stat.

it has good thermal contact with the cylinder, i would have thought if it did not, then the inaccuracy would occur the opposite way, i.e the water inside would be hotter than the stat sensed

 

[Fluffster]

Depending on the lenght of run and insulation you will lose about 5 degrees from tank to outlet.

Pete

 

[bhm1712]

to the outlet in the bathroom its about 1 meter, to the kitchen its about 15 meters

i would have thought the heat loss in 1m was negligible?

 

[D_Hailsham]

after changing to c plan, I set my cylinder stat to 60 degrees. it's a Honeywell stat and was brand new.

The Honeywell L641A has a temperature differential (difference between open and closed) of 10C. They are not designed to be highly accurate, so if you have to set yours to 70C to get a water temperature of 60C at the tap, don't worry. In any case you don't wash in water at 60C, more likely 35-40C. The only reason for storing the water at a higher temperature is to kill Legionella and other nasties; for this you need a temperature about 60C.