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Discuss Hot water temp Query in the Water Regulations area at PlumbersForums.net

Good morning everyone,

I would like to know when you run the hot water tap in the bathtub by law/water regulation how hot should the water be set at without mixing any cold water? I used a thermometer today and it came at 45c, should it be higher or is that okay?
I have a combi boiler in the kitchen and it doesn't show you the temperature in numbers but has a dial of 10 dots currently the hot water dial is in the middle (5th dot), any information would be great thank you.
 

townfanjon

Esteemed
Plumber
Gas Engineer
Advent Win
45 degrees out of a combi at this time of year is absolutely fine , bordering on excellent.
 

Stigster

Esteemed
Plumber
The UK Water Regulations state that the hot water should reach 50 degrees centigrade at any outlet within 1 minute of opening the outlet.

Edit to add - That's for stored hot water so I think the other folks advice here is correct as you have instantaneous hot water.
 
Last edited:
Thank you for the reply and it is a 2nd floor flat in the UK (circa 1960) and I got the combi boiler installed in September this year and a new bathroom in October this year. I just wanted to make sure I have the correct temps set for the hot water so that their are no concerns over the water temps, thank you once again.
 
@BobbyJoe as above have said, at this time of year with cold mains slightly lower temperature than warmer months 45°C is normal. Remember a combi boiler will increase cold main water to roughly 35°C higher for hot water demand, obviously in the colder months final result will be a bit lower and warmer a bit higher.
If you had a hot water cylinder instead of a combi, then this should be heated to 60°C but this is irrelevant in your case.
 
Yes as chking said. Reducing the flow rate will produce hotter water. Either crank tap open a little or close incoming main slightly. Remember to reverse in warmer months
 

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