I am sorry to hear that you are having trouble with one of our products, diagnosis via e-mail is unfortunately not possible because a physical check / test is needed for the troubleshooting to find out the root cause of a fault.
Alongside this when it comes to gas appliances, we are unable to advise.
Only a competent, gas safe technician should undertake gas repairs.
By giving specific advice, to an untrained individual, Thetford may find itself accountable for any damages direct or indirect resulting from repairs.
We kindly ask you to get in contact with your dealer or one of our Service Centres to ensure a correct and safe resolution to your problem.