biasi 24s boiler not giving HW on demand

[abski]

Basically we have had no bother with our Biasi 24s combi boiler for the previous 4yrs, up until a few months ago. Occasionally the boiler would not fire up when the HW tap was turned on, but could turn the CH on and the boiler would fire up instantly therefore giving us HW! This was happening about once every 2 weeks and gradually gotten worse, to the point its a few times a day.
Been told its possily a microswitch,gland or diaphram???
Any help/advise would be greatly appreciated.
Abski

 

[bengasman]

...Occasionally the boiler would not fire up when the HW tap was turned on, but could turn the CH on and the boiler would fire up instantly therefore giving us HW!...

Do you mean that when you open the tap the water stays cold, but when you then call for heat, the water starts warming up?

 

[abski]

Yes, when it calls for hot water the water coming from the tap remains cold, so turning off the tap and calling for CH, the boiler fires up, we then open the tap which then does provide hot water and continues to do so when we turn the CH back off, keeping the tap running when we do. This fault occurs intimitently.
So in a nutshell, turn the tap on, if its cold, turn it off, turn heating on (via stat), turn tap back on and turn stat back down (turning heating off)

 

[bengasman]

When you turn the hot water on, and it works, do your heating pipes get hot?

 

[abski]

When its working fine, the heating pipes do not get hot. Just the pipe going to the tap.

 

[bengasman]

Sounds like a knackered flowswitch.

 

[abski]

Thank you for your help. Its a starting point. Next step source part!

 

[bengasman]

Thank you for your help. Its a starting point. Next step source part!

I think you may want to check before you buy parts.
This involves working on the electrical side of things, so you would need a multimeter.
With some boilers you can safely operate the switch manually, but can't remember for sure if this is one of them.
Tony will know by heart no doubt, may be worth hanging on til he reads this.

 

[abski]

In that case I will take your advise and hang fire for a few more days.
Thanks again

 

[abski]

Going to take previous advice that i may require a flowswitch for my Biasi 24s, as it does not always give hot water on demand. Anyone got any other suggestions?
Would be eternaly grateful for any help.

 

[gaspro1981]

check the dhw diaphragm is not split or worn

 

[JHW]

I have had exactly the same problem. Its still happening although I had the diaphragm that senses the demand for hot water changed. I then had the whole boiler serviced, and it worked for about 2 weeks and has started playing up again. Have tried three Gas safe engineeers and none of them like the Biasi boiler. Only one would even agree to look at it and as I said its still playing up. Getting to the end of my tether, about to throw in the towel and change the boiler.

 

[bengasman]

Might be worth starting a proper thread on this problem, it's not that difficult.

 

[gasbanni]

I have had exactly the same problem. Its still happening although I had the diaphragm that senses the demand for hot water changed. I then had the whole boiler serviced, and it worked for about 2 weeks and has started playing up again. Have tried three Gas safe engineeers and none of them like the Biasi boiler. Only one would even agree to look at it and as I said its still playing up. Getting to the end of my tether, about to throw in the towel and change the boiler.

Probably just the diverter valve that needs servicing ! easy