Water differential

6 Jun 2022
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United Kingdom
Hi there, currently doing my bepec sheets for my portfolio and it asks what the water at differential should be in degrees.

The MIs for ideal logic C30 say 35 degrees. Is this just a case of taking the temperature of the hot tap, turning off the boiler and then checking the cold through the hot tap also?

Any help would be appreciated.

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and then checking the cold through the hot tap also?
If you could arrange to get cold water from the hot tap ( by turning off the boiler ) you would have to run enough water to ensure there was no residual heat in the boiler and pipe work.

Or you could measure (1) the temperature of the cold water going into the boiler and (2) the temperature of the hot water coming out of the boiler.
Take temp of cold water coming out cold tap then temp coming out of the hot but the 35 degree rise is dependent on flow 24kw is usually around 10 litres a min ..30kw around 12.5 litres and 40kw around 16 litres . Lower flow rate will result in higher temp rise and higher flow rate a lower temp rise
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If you want to do your own calcs..... LPM @ 35C Temp Rise is Combi HW Output in Kw X 860/60/35. Ie a C30 is 30x860/60/35, 12.29 LPM, as above.
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