fuel lines for CDH diesel heater

paulga · Apr 27, 2024

I purchased a 5/32" (4mm) ID rubber hose to connect from the fuel source to the dosing pump, and use as the short joining pieces from the pump to the heater. I just noticed its OD is 6.4mm, so the hose has a very thin wall.

In comparison, the espar 5mm fuel hose for connection from the source to the pump has an OD 11mm, so the wall is about 3 times thick. Their pressure side hose is also very thick: 3.5 ID x 9.5mm OD

Is the Yamakato thin hose good enough for the diesel heater? or should I consider buying the premium hose?

twistedtree · Apr 27, 2024

I think the important things for hose is that it be rated for whatever fluid it's carrying (in this case diesel), and be rated for whatever pressure is involved. There also is a marine rating for fuel hose which I think is USCG A1, and arguably it should meet that too.

If the hose supplied with the heater has a lot thicker wall than the hose you bought, I would be suspicious mostly of it's pressure rating, and also it's rating for diesel. Fuel hoses do tend to be a lot thicker wall for better pretection against external damage.

paulga · Apr 27, 2024

twistedtree said:
I think the important things for hose is that it be rated for whatever fluid it's carrying (in this case diesel), and be rated for whatever pressure is involved. There also is a marine rating for fuel hose which I think is USCG A1, and arguably it should meet that too.

If the hose supplied with the heater has a lot thicker wall than the hose you bought, I would be suspicious mostly of it's pressure rating, and also it's rating for diesel. Fuel hoses do tend to be a lot thicker wall for better pretection against external damage.

the Yamakato line is a "fuel line for small engines/generators" so i thought diesel heater fits into the category. It didn't say A1 standard so I bet it does not meet A1. It will be used inside the bilge, I don't expect any damage from physical abuse.

TJM · Wednesday at 9:52 AM

Hose sizes and ratings can be deceiving. I have seen thin wall hose with higher ratings than thicker wall due to the reinforcing braid within the hose. One thing that makes me sleep better is being able to identify the hose at a later date with its markings on the side being embossed.
FYI, Gas and Diesel fuel ratings may not be the same, always confirm.
All of my hoses are USCG A1 and marked as such. Inspectors love it.

paulga · Wednesday at 10:19 AM

TJM said:
Hose sizes and ratings can be deceiving. I have seen thin wall hose with higher ratings than thicker wall due to the reinforcing braid within the hose. One thing that makes me sleep better is being able to identify the hose at a later date with its markings on the side being embossed.
FYI, Gas and Diesel fuel ratings may not be the same, always confirm.
All of my hoses are USCG A1 and marked as such. Inspectors love it.

the fuel hose in this application is rubber hose 5/32" (4mm) or 3.5mm, i didn't find a type A1 hose in this range

TJM · Wednesday at 4:29 PM

Parker 221FR-5 has 5 mm that meets this spec, USCG A1.

Tomas · Wednesday at 6:17 PM

The ID of the hose is important to the proper metering of fuel to the heater. Whatever hose is used, I think you should match the ID to the heater manufacturers hose ID.

paulga · Wednesday at 6:35 PM

TJM said:
Parker 221FR-5 has 5 mm that meets this spec, USCG A1.

I got from John's video series

Webasto uses 2x5mm hard nylon lines with 4mm rubber joiners
Espar uses 2x4mm lines with 3.5 mm hoses

I understood the espar and webasto here can be switched in letter. The rule is the rubber hose inside need to be a bit narrower than the plastic line

So you see, 5mm rubber hose is too large in either cases

fuel lines for CDH diesel heater

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