My son just contacted me with this query about his Rinnai flued gas heater.

"We have been using it a lot more since winter hit and and it has starting turning off quite a lot. It will run for twenty/thirty minutes or so and then shut off. You have to leave it for another five/ten minutes or so before it will start again. Is this something that can be fixed"

Its not a fault I have ever come across on this style of heater so advised him not to use it and call the experts. Went through the perils of carbon monoxide and "waking up dead" to emphasise this. I do know that the heat exchangers on this type can crack and leak.

Just this moment wondered if a blocked flue would cause it to shut down.

Hoping the experienced ones on here could offer advice.