Forced air diesel heater fuel

[MarkJ68]

I recently bought a Cat-30 and am about to install a forced air heater. The boat has been sitting for quite a while and the diesel in the tank is likely quite old. Will burning this old fuel hurt the new heater or, for that matter, the inboard engine?

Thanks for any help you can send my way!

[CaptTom]

I've heard and read too much about fuel gumming up a diesel heater. The manuals are clear on this. I'd use kerosene or fresh diesel only.

As for the using it in the mains, I'll let someone with more expertise than I answer that. I'm thinking you wouldn't know if there are bugs and/or water in it. Maybe polish it and see what that does to the filters.

[newhaul]

How old is the fuel if the diesel in the tank is less than 10 years old it is just fine for the mains just keep an eye on the water separator and filters for water issues. The fuel for the heater is drawn off the main tank but on its own pickup tube. Will be fine must remember not to install the heater pickup lower than 3/4 way into the fuel tank. ( firstly that keeps you from drawing sediment and water into the heater supply lines. And more important it will leave you with enough fuel for the mains to get to the fuel dock) no joke I have seen it happen to people.

[GordMay]

Greetings and welcome aboard the CF, MarkJ.

[wrwakefield]

Welcome to the forum, Mark.

We have an Espar forced air diesel heater. It runs best on #1 fuel oil [or kerosene or jet fuel, but that costs much more, and we use our heater a lot...]

It doesn't like old diesel, or any additives. Either are just asking for maintenance issues [which will cost you far more than fresh, clean fuel of the correct type.]

While we are frequenting higher latitudes, we keep one of our two fuel tanks dedicated to #1 fuel oil for the heater. We also installed a separate external fuel filter dedicated to the heater- preserving the smaller filter built-in to the heater. This set-up works well for us.

In an emergency, if we run low on #2 diesel for the engine, we can transfer some of the #1 to the engine tank and add something to give it more lubricity. [per our engine manual. e.g., Marvel Mystery Oil.]

If you do this check your engine manual for what, if anything, would be necessary to burn #1.

Best wishes with your new boat and heater.

Cheers! Bill

[Redpcx]

If you can dispose of the fuel at no cost, I suggest you do.
If you don't know how old the fuel is, it could be pretty bad. The cost of filters can exceed the value of the fuel.
Fresh, clean dry fuel is the way to go. Some folks will thank you for the old fuel. Give it away if you can.

[Lepke]

Some people have a tank just for their stove or heater. #1 diesel or home heating oil burns better than #2. Most places I buy fuel have 1, 2, & 3. Whatever you do, a biocide should be added to the tank to kill any organisms. Just changing the fuel will not remove the stuff on the tank bottom. Any decent primary filter should clean the fuel.
Most diesels can burn #1, but it creates more hp and extended running at full throttle can cause heat damage. More so in turbo charged engines.
My current boat had sat 6 years. I burned the exiting diesel after adding a catalyst and biocide w/o problems.

[MarkJ68]

Thanks to everyone for their advice and welcomes. It seems I don't necessarily need to worry about completely removing/replacing the old fuel, but should use additives until the existing fuel is burned off. I also like the tip of not placing the heater fuel line too deeply into the tank to avoid the bottom sludge.

Again, a huge thanks to you all. Enjoy your weekend!

[DeepFrz]

Thanks to everyone for their advice and welcomes. It seems I don't necessarily need to worry about completely removing/replacing the old fuel, but should use additives until the existing fuel is burned off. I also like the tip of not placing the heater fuel line too deeply into the tank to avoid the bottom sludge.

You are setting yourself up for big problems by doing this. Clean the fuel and manually clean the tank and then use additives if you must. However experienced users say don't use additives and use #1 fuel and a clean tank.

[MarkJ68]

Originally Posted by DeepFrz

You are setting yourself up for big problems by doing this. Clean the fuel and manually clean the tank and then use additives if you must. However experienced users say don't use additives and use #1 fuel and a clean tank.

I have to be honest, I'm getting a ton of conflicting information on the subject. I'm also getting a bit worried that I've miss-sized my heater. I originally heard that an Espar D4 would be ideal for my Catalina 30 (in Seattle), but now I'm getting a lot of feedback saying that the D4 is way too large and will encounter problems if mostly running at a lower speed. Don't get me wrong, I greatly appreciate all the input, but trying to decide which advice is the most accurate is proving to be less than easy

[DeepFrz]

I understand the problem with separating the wheat from the chaff but if you have sludge in the bottom of your tank and you don't manually clean it out then sooner or later that sludge is going to get in to your lines, filters, engine, heater.

Today's fuel is not the same as the fuel 10 or 20 yrs ago and deteriorates much more quickly.

I can't comment on the size of your heater but I would use what I had if it were mine. I would also learn how to clean the heater internals and do that on a yearly basis.

[Cheechako]

Having your fuel polished and tank cleaned is always good advice on a new-to-you boat. Then you know what you have and wont be without an engine when you go out on a choppy day and the muck gets churned up in the tank.

[VanIslandGuy]

I'm guessing you have under 80 litres of fuel in the tank?

The cheapest solution may be to try this stuff: Star Tron Tank Cleaner

Let the boat sit for a few days with this in the tanks. Then suck the tank dry and dispose of the fuel. Most automotive repair places will take old fuel for dumping if the marine yard you are at doesn't.

Fill with fresh diesel, proper additives for your area, and have lots of spare fuel filters ready. Be sure to plumb a dedicated diesel fuel filter between your tank and the heater.

For under $100 this eliminates a lot of guess work of will this fuel cause problems or not.