Baxi 133 noise

[Sureheat]

Hi there im a gas installer ,have a prob on a baxi 133 he plus ,when the hot water is ran after a while once the boiler is starting to get upto a hot temperature it starts making a screeching noise , figure it may be the diverter valve and them o rings again, or poss the pump not circulating enough ,this prob only occurs on hot water heating works fine , water gets hot just the noise starts ,any u guys out there ever come across this one before,dont really want to start changing part after part till i suss it any input will be much appreciated.

 

[baxpoti]

First thought is heat exchanger.

Can you describe the noise any better?

 

[Sureheat]

Noise just starts to get to a screech noise after hot water gets to quite a hot temp ,subsides if u turn down the thermostat therefore the burner cuts down,not sure if it would be heat ex as water is a constant heat not on and off all the time hetaing works fine,u ever had this prob?
its sounds a bit like what u get from the 105e instant off the diverter valve althoug screech isnt as high pitch if u put your ear to flow pipe it almost sounds like it is from there could just be transmitting through pipework though,any ideas baxpoti

 

[tonybhoy]

Old Vokeras (Excel I think) used to make a similar noise which was from the auto bypass,some washer or something in the valve.

 

[baxpoti]

I'd still go with main heat exchanger.
A cheaper option than throwing parts at it, is to try some water softening chemicals, Sentinel X200 or Fernox boiler silencer, give them a few days to work.

 

[Kirk5]

Having hot water noise problem with baxi 133 did you ever find fault