I need to replace diesel rubber hose on a a 4 year old Eberspacher D5 6kw heater in my boat - it’s currently fed with a plastic hose (was on the original Eberspacher heater I removed) Can you advise which size I require? Thanks

I'm thinking you may have an Eberspacher D5 Airtronic model heater if it was installed new approx 4 yrs ago. Please can you confirm this assumption? Perhaps if you are unsure of exact model please email a photo of the heater dataplate ( afixing to the heater casing) to sales@butlertechnik.com

We need to learn this info to advise 100% correctly. The standard D5 heater fuel pump has a larger ID fuel hose for the fuel pump inlet compared to the ID for the fuel pump outlet. I recommend you check this visually prior ordering any hose.

For Marine heaters the fuel hose should be ISO 7840 compliant. Please see weblinks below

required for pump to heater - in all circumstances

https://www.butlertechnik.com/item/Eberspacher/Marine-diesel-heater-Fuel-hose-35mm-id-ISO-7840-per-metre/6GV

Required for fuel tank to fuel pump - option of two sizes depending upon specific fuel pump inlet diameter

https://www.butlertechnik.com/item/Eberspacher/Marine-diesel-heater-Fuel-hose-35mm-id-ISO-7840-per-metre/6GV

or larger ID 

https://www.butlertechnik.com/item/Webasto/Eberspacher-Marine-heater-Fuel-hose-5mm-id-ISO-7840-per-mtr-4158400/6IP