combi boiler pressure bouncing only when hot water is being used

[robqqq]

Combi boiler pressure bouncing only when hot water is being used , could this be the diverter valve diaphragm..... cheers Rob

 

[Deleted member 120897]

Is it an Alpha, Ariston, Baxi, Chaffateaux, Ferroli, Halstead, Ideal, Keston, Main, Morco, Navien, Potterton, Ravenheat, Vaillant or Worcester Combi boiler, or one I’ve not mentioned? Perhaps a model number would be wise too.

 

[robqqq]

Is it an Alpha, Ariston, Baxi, Chaffateaux, Ferroli, Halstead, Ideal, Keston, Main, Morco, Navien, Potterton, Ravenheat, Vaillant or Worcester Combi boiler, or one I’ve not mentioned? Perhaps a model number would be wise too.

Hi, that's a lot of boilers 😀, sorry Its a Worcester Bosch 28CDI , I just assumed that all combi boilers worked in a similar way i.e. diverted the water off into another H/E.
I was on the thinking that if the diaphragm had a hole but would it really make the system pressure move so much, its bouncing between 0.5 & 2.5bar its stays constant at 1.5bar when heating the radiators, my other thought was the water to water H/E blocking up , any help would be much appreciated

 

[Deleted member 120897]

Does the pressure stabilise if you turn the tap off?

 

[EvilDrPorkChop]

How's the hot water performance? Sounds like a blocked Plate HEX and kettling to me....

 

[robqqq]

Does the pressure stabilise if you turn the tap off?

Hi , yes

 

[robqqq]

How's the hot water performance? Sounds like a blocked Plate HEX and kettling to me....

Hi, thanks for coming back , hot water coming out the tap is 40 degree C, I think its been hotter , no other issues , no hot water going to the radiators when hot water is on ,

Rob

 

[EvilDrPorkChop]

Blocked plate HEX then i'd say.