Biasi boiler, Hot water problems

12 Apr 2006
Reaction score
United Kingdom
I have a problem with hot water temperature on a BIASI M90.24S combi ,water only luke warm. Central heating is fine, also when boiler fires up, there is a whistling noise.
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Is this something that has only just suddenly happened?

Your model can heat 8 litres per minute to a bit too hot to touch? Are you expecting too much?

What does the temperature scale go up to when you run the hot tap in the bathroom basin?

Do you know anything about the history and in particularly if the system was power flushed when the boiler was fitted? Was the Benchmark Certificate filled in?

Do you have a digital contact thermometer to measure the flow and return temperatures when on DHW mode?

Are the fault indication lights normal ?

Problem has just happenTemperature scale goes up as bathroom tap is opened, know no history of boiler, all fault indication lights are normal, boiler seems to fire up and regulate as normal
I said """What does the temperature scale go up to when you run the hot tap in the bathroom basin?"""

I am quite sure that it goes up but to try to help you I need to have the answers to some questions!

So what does it go up TO ?

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Sorry for delay, If i open hot water tap in bathroom, temperature scale goes upto 65 degrees centigrade, tried this for three minutes, i do not think temp of water from tap is the same as reading on scale. Although boiler seems to be on high fire.
That temperature is not far above normal.

However, I need to know the flow rate. Can you find some way to measure the flow rate ? I need to know the hot water flow rate in litres per minute!

Next thing I want to know is when you are running this hot water demand, what is the gas usage. I want to know how long it takes for the 1 cu. ft. dial on your gas meter to turn ( measured in seconds ). If the meter really does not have this dial then let me know!

Hi, approx flowrate of hot water tap in bathroom, fully opened, is 12 litres per minute, do not have gas meter as mentioned., Thank you, for your help so far.
OK we may be getting somewhere!

Turn on that tap again and adjust the flow rate to 9 litres per minute using the blue tap on the fourth pipe from the left under the boiler.

The boiler should be able to heat this to about 40°C which is just hot enough to keep your hand under but probably too hot for a shower.

If you are still not happy then then on the tap and measure the full reading at start on the metric gas meter for TWO minutes and then read again at the end of the time period and post the two readings.


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