Baxi Combi Instant DHW

[plumbbobshan]

Hello, Just a quick one . Baxi Instant 4 years old . DHW fills the kitchen sink no problem, mad hot . Come to fill a bath it a no go . I was going to change the DHW sensor as i had one to hand but thought of asking the question 1st . Any ideas ???????
Regards

 

[payney1974]

If it works ok on your sink i cant see there being a problem with your boiler. Have you checked the flow rate from your bath tap?

 

[plumbbobshan]

hi , Not checked that,the pipe run is only 3m total. But even at the sink the water temp drops off to luke warm once the 1st sink full has gone . Until sunday gone the bath would fill no probs . I told the customer it could be down to very cold mains but he's not happy and said it was colder on saturday ........

 

[wnjswozo]

gas rate it,check flow rate at hot tap on bath

 

[payney1974]

Oh ok, when you drain it down to fit the thermistor I would whip the plate h/ex out and check for a blockage on th ch side, you do this by filling the p h/ex with water then hold vertical and the 2 bottom connections should flow out at the same rate. Does this make sense?

 

[plumbbobshan]

Could the gas rate change itself from sunday to today ?

payney , you say thermistor??? i was changing the DHW sensor green wires . is this a mix up or should i change the thermistor insted ???

 

[payney1974]

I'm not familiar with the baxi instant. But I did mean the dhw sensor / thermistor, if you leave the tap running does the boiler fire go off fire go off?

 

[plumbbobshan]

no the the flame stays the same / hi rate .

 

[payney1974]

So it stays in full rate, hot water runs cold? Is there an issue with div valve ?

 

[plumbbobshan]

Well that was a waste of time . Flow rate good , gas rate good , DHW sensor changed ,2x 2" diaphams changed and ports cleaned out and flushed . NO difference at all .
Like you said payney h/ex is next on the hit list. Its a big ol thing , should be fun to get out . Got to go back as i put cleaner in the system that will need a flush in a few days time.
Just price one up £47+vat is cheap for what it is 21 plate lump !!!!
Its a good job the customer is understanding .

 

[payney1974]

You can sometimes just stick the jet wash through it although i wouldnt do it in this weather as you get wet. But for £47 just bang it in.

 

[plumbbobshan]

watch this space for results .