ultracom sxi f9 fault.

[exbg1]

been to a 30 sxi today f9 fault. book o words says loose conns, iffy pump or faulty pressure sensor. boiler display says 2.4 bar system pressure. seperate pressure gauge reads the same. if i disconnect sensor conn then boiler display says 0 bar. when i re-connect it goes back to 2.4 bar. pump runs & you can hear flow also. anyone tell me where to go next please ?/

 

[petertheplumber12]

Why is pressure so high? it should be about 1 bar when cold, and 2.5bar is too near 3 when it will eject out water to drop pressure. Get pressure down first and see if it make any difference, if too much increase from cold to hot in pressure may need another expansion vessel added.

 

[gazdaz36]

Most of the time the f9 fault is due to a faulty pressure sensor. What should happen is the pump will start and stop for 5 times then it will show an f9 fault. The pressure sensor also acts as a pump proving switch. When the pump kicks in the sensor is looking for a small pressure increase. If it doesn't sense the increase it thinks the pump isn't working. Usually its just due to dirt build up in the sensor. Its better to replace rather than clean, it's not an expensive part

 

[petertheplumber12]

Most of the time the f9 fault is due to a faulty pressure sensor. What should happen is the pump will start and stop for 5 times then it will show an f9 fault. The pressure sensor also acts as a pump proving switch. When the pump kicks in the sensor is looking for a small pressure increase. If it doesn't sense the increase it thinks the pump isn't working. Usually its just due to dirt build up in the sensor. Its better to replace rather than clean, it's not an expensive part

That makes sense gaz, Also the pressure is quite high so a small increase may not show so easily. And if pressure is dropped that may help a bit?