TheBig1
Deceased RIP
- Nov 27, 2011
- 17,851
- 44,372
- Funster No
- 19,048
- MH
- A class
- Exp
- many many years! since I was a kid
not sure which pump is fitted in your hymer. some are submersed in the tank with integral non return. others have a diaphragm pump with seperate non return valve. either can be fixed by plumbing in a simple non return valve in the pipe near the tank. takes longer to drain the tank and pipes than fitting the valve. dependant on the tank position and access to the pipe its an easy diy job