DHW Temperature Drastically Fluctiating when CH is on.

[perky416]

Evening all.

Last month i had a new Worcester Bosch Greenstar Compact 32CDI combi installed. I have come to notice that when the CH is on there are drastic fluctuations in the temperature of the hot water when the tap is on. The water temperature is currently set to 46 degrees on the boiler. I tested the fluctuations with the thermocouple on my fluke multimeter. When turning the tap on the cold water naturally comes out the pipe, then the temp goes up to between around 36 and 46 degrees, then back down to around 17 degrees, then up to around 36 degrees, then back down to around 25 degrees, then back up to around 36 degrees before it very slowly climbs into the 40s over the next couple of minutes. The temperature is fine when the CH is off, After the cold has come of the tap I am getting a very constant temperature in the mid 40s.
Surley it cant be normal for the temperature to fluctuate so much? Please could somebody help shed some light on the issue? Should I get on the phone to worcester bosch?

Many thanks.

 

[king of pipes]

set the water temperature to 55 and see what happens then. cheers kop

 

[Scott_D]

Could it be a mixer tap passing?
What did you have before the WB?

 

[perky416]

set the water temperature to 55 and see what happens then. cheers kop

It was originally set to 55 and the same thing was happening. I turned it down when investigating the problem as it was a bit hot having my hand under there before I got the thermocouple under it.

Could it be a mixer tap passing?
What did you have before the WB?

It is a mixer tap in the kitchen, i originally thought this was the problem however when flushing the newly fitted pipes in the bathroom a couple of days ago i noticed the fluctuations, no tap this time just an open pipe, thats what made me realise there is a problem. It was a WB conventional boiler fitted before but i never used it, been in this house a little over a month and the first thing i did was rip out the old system.

Thanks guys.

 

[Riley]

Who fitted it?

 

[ShaunCorbs]

Is this with the tap fully open if so do your tests with the tap only half open

 

[perky416]

Who fitted it?

It was a gas safe engineer.

Is this with the tap fully open if so do your tests with the tap only half open

It was with the tap fully open. I have just tried it half way and the temperature went up to around 48 degrees before dropping all the way to 8 degrees where it sat for a few minutes. I had to open the tap fully to get it to go up again where it then jumped between 32 and 25 degrees a few times before settling at 32.

 

[Riley]

I’d get the fitter back. I assume it’s under warranty?

 

[king of pipes]

Contact worcester it will be under warranty . cheers kop