thermostatic basin mixer question

[pete37a]

hi all

have a quick question for people in the know!!!!

have a thermo basin mixer that when turned on to the cold setting is flowing with a temp of 23-24c
the hot temp is set ok at 42c no problem,
hot temp is coming into tap at 62c
cold temp coming into tap at 18c
now thw client is saying the cold setting should produce no more than 20c
as this tap is for hand washing only surely the 20c temp is for drinking requirements.
as the mixer has a safety shut off on both hot and cold am i right in thinking that even though the tap has a cold setting it still allows a small amout of hot to be blended with the cold thus increasing the temp
because if the hot was shut off the cold would fail safe.
i am 99% sure this is right but could do with a few comments from anyone who knows more than me!!
if this is correct is the 5-6c rise in temp ok ? thoughts???

cheers guys
pete...

 

[snowhead]

What premises, domestic, office block, single factory unit?

Mixed temp should be 34 not 42
Cold incoming is too high at 18, pipework and or tank need lagging,
What's the incoming temp closest to the stop tap

Over 20 (and under 50) is getting into Legionella temperatures.