baxi duo tec he a puzzling issue with hot / cold water

[julesverne]

Fitted this boiler last month baxi duo tec he a 24. Come back this week to do bathroom refurb in same house. problem is this when you run cold water anywhere in the house. When you turn off the cold water the boiler spring into action for a split second then cycles and then goes back to standby. Is this an issue with sensor in the boiler. Any ideas on this before i call it in to heat team. Im thinking some sensor is sensing a pressure flucuation as you turn boiler off.

 

[Barry98]

call heat time there problem

 

[julesverne]

Just taken the cover off to have a look at the flow sensor. The red light on the sensor comes on for a split second as you turn the sensor off . Is the sensor over sensitive or problem elsewhere im puzzled a bit

 

[diamondgas]

Usual cause is a 'surge' recorded by the sensor due to a 'dead leg' left with a pocket of air in it somewhere on the hot water pipework. Fitting a non-return valve on the hot water outlet will cure it IMHO

 

[Ermintrude]

Was going to say same. Turn water pressure down and it will prove it. It's effectively the boiler picking up water hammer.

 

[MK Heating]

Normally fit a tiny pressure vessel on the cold pipework upto the boiler to cushion the water hammer, and or a non return valve

 

[julesverne]

Thanks guys will fit one in tomorrow

 

[SafeGasInstall]

NRV should be fitted on the cold mains to boiler along with mini exp vessel

 

[diamondgas]

Should NRV be fitted on the cold mains to boiler along with mini exp vessel

That'd do the job and accomodate the tiny amount of expansion should the 'air pocket' be found/removed. They use to fit the mini exp vessels as standard on combi's when they first came out!

 

[phil the bucket]

Could be a hot and cold crossed some where in the house

 

[julesverne]

Just want to say big thanks to everyone NRV on the hot water pipework has cured the issue. Another one for knowledge bank.

I have to say i wouldnt learn half as much as i have if it wasnt for this forum. Big thanks to all