Return Fuel Line Tap

[Boondocker]

I have installed an Eberspacher Hydronic S3 D5E CS 12V water/engine heater on my 2021 ecoDiesel Rubicon. Its to supply heat and hot showers for my Alu-Cab camper. I currently have it fueled from a Rotopax tank mounted on the rear door. I have used this successfully on several excursions. I would like to tap into the return diesel line for fuel, as the manufacturer suggests. Their instructions include cutting the return line and trying to suction diesel from the tank. If none flows out, there is a check valve inline, and the project is scrubbed. My questions are, 1)Is anyone knowledgeable about whether this model has a check valve? 2)What is the id of the diesel fuel return line?
This heater is surprisingly efficient, using only a tablespoon or so of diesel for 2 peoples showers.

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[ParatusExpeditions]

Interested in your findings!

 

[Steven_B]

Did you ever get your answers? I’m now curious about tapping the tank for a diesel heater.

 

[Steven_B]

I have installed an Eberspacher Hydronic S3 D5E CS 12V water/engine heater on my 2021 ecoDiesel Rubicon. Its to supply heat and hot showers for my Alu-Cab camper. I currently have it fueled from a Rotopax tank mounted on the rear door. I have used this successfully on several excursions. I would like to tap into the return diesel line for fuel, as the manufacturer suggests. Their instructions include cutting the return line and trying to suction diesel from the tank. If none flows out, there is a check valve inline, and the project is scrubbed. My questions are, 1)Is anyone knowledgeable about whether this model has a check valve? 2)What is the id of the diesel fuel return line?
This heater is surprisingly efficient, using only a tablespoon or so of diesel for 2 peoples showers.

Did you ever successfully tap the fuel tank?

 

[Boondocker]

I haven’t done anything more. I may just keep going with a small tank on the back door of the camper.

 

[Boondocker]

Update. The separate fuel tank is working for heating showers, but not good enough for heating the entire alu-cab camper in cold weather. I plumbed in a radiator/blower for heating the camper when its in the 30’s and below. I used at least a gallon in one night for a toasty warm, no blanket kind of night. I even had one of the tent windows open at least 1/4 of the way. The trap door was left open to circulate the heat. It wouldn’t have been comfortable any warmer. So now it’s back to the fuel line tap to make this practical. The only other way would be to instal my own connection to the fuel tank. That might be the safer method….

 

[fourfa]

watching...

(can't help, but interested in your findings)

 

[Vtur]

How about drilling a hole into the removable fill neck tube, low enough to clear fuel nozzle. Weld on a 90 elbow barb fitting, with one end pointing down toward the tank and run a fuel resistant hose down into the tank. This mod is easily reversible by just capping off the external barb end.

 

[Boondocker]

Sounds like a good idea, but somewhere I read there were 2 flapper valves in that tube, one higher and one lower. I also have read you cant get a tube down there because of the lower one. Is this right or is my memory just messing with me again?

 

[Boondocker]

I’m also trying to find how the gas tank is constructed and what material it’s constructed from. If its just HDPE, I might try to spinweld a small female fitting onto it. This would be a good solution.
I have read some diesel tanks are 2 layer construction, with an inner white lining that is less permeable. Still searching for info.

 

[GoatPowder]

What diameter is the fuel hose you're trying to feed?

My first thought would be to just add a standpipe for a Webasto heater; they're like $20 and you can just cap off the barb if you ever want to remove it.

 

[kevman65]

In answer to your original question about a check valve.

I looked through the parts fiche (allmoparparts.com) and I don't visibly see a check valve anywhere inline on the return side. It is NOT listed as a separate item in the parts list.
This does NOT mean there is not one built into one of the hoses or various connection parts that are in the return.

 

[Cascade253]

Sounds like a good idea, but somewhere I read there were 2 flapper valves in that tube, one higher and one lower. I also have read you cant get a tube down there because of the lower one. Is this right or is my memory just messing with me again?

There's a thread here on the "fill neck mod" that removes the two flappers that are up top. I too am looking for a way to pull fuel out for a diesel heater. Likely going to go with a standpipe type that comes in through the fill neck. But if you figure out tapping into the fuel return I'd be interested.

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