Kerosene vs diesel

[fred]

Our oil burner was recently converted from diesel to kerosene. Due to a faulty level gauge the tank ran dry. By mistake I threw a couple of gallons of red diesel into the tank. I can get some kerosene from a local filling station. How much kerosene might I need to dilute the red diesel? What damage might burning red diesel do to a kerosene system. ( I wasn't here when the burner was converted but I imagined it only involved changing he injector/nozzle.

Sods law. These problems only occur at the weekend when service isn't available never mind a refill of the tank

[The Natural Philosopher]

They are almost identical. I believe kerosene is slightly lighter and doesn't contain so many additives as red diesel or road diesel. If its a pressure fed boiler rather than a gravity fed AGA etc I shouldn't worry.

You may need a new jet after a year or so on it.

[Martin Brown]

Compared to running the sludgy sediment and junk in the dregs of an oil tank through the injector almost none. Adding enough of it to avoid running dry again before your next oil delivery would be my suggestion.

Also allow it a little time for it to settle again after adding the fuel before firing the boiler again. The injector really doesn't get on with a suspension of fine particles.

I expect red diesel will burn with a slightly sootier flame but not by all that much so I wouldn't be unduly worried about that. Running the main tank dry though is bad for the injector unless you have a secondary feed oil tank like my heating system does.

And just as bad weather and deep snow hampers deliveries too.

[fred]

" a secondary feed oil tank" ? Tell me more. Does it automatically kick in when needed ?

[The Natural Philosopher]

Don't you use a fuel filter?

[Martin Brown]

No. It buffers the main fuel tank by acting as an oil lifter to pump oil from the low bulk tank into a much smaller header tank above the height of the burner. My oil burner is conveniently located in the loft.

The oil lifter is something of a Heath Robinson contraption made in Denmark where having underground fuel tanks is common. The secondary tank provides opportunity for any crud to settle out without ending up by going through the burner jets. Something like this only much older:

More modern systems use a tiger loop to do the lifting.

[John J]

Depending on the model of burner you have the effects could range from sooting up the burner and photocell hourly to barely a noticeable effect. Diesel doesn't ignite as easily as kerosene so expect any conversion to have required change of nozzle to one with a different spray pattern and spray angle together with adjustment of oil pump pressure. Running the tank dry usually results in dragging the crud in the bottom of the tank through into the fuel system. If you have a decent outlet filter at the tank you may get away with replacing the filter element if it's a paper cartridge or cleaning a nylon/metal gauze type. However there's a risk of particulate matter passing on further to the boiler. You may have a secondary filter at the boiler which could need cleaning plus most oil pumps have a strainer in the pump plus the nozzle will have a sintered strainer inlet and a very tiny hole the fuel is pumped through to create the atomised spray for the ignition arc to light. All these could become blocked I'd suggest at least 5 parts kerosene to 1 part red diesel will help to avoid problems with ignition but low temperatures exacerbate the potential for trouble. You should clean out the combustion chamber and flue plates when things are back on an even keel

[Vir Campestris]

I'm confused by this.

The feed pipe to the boiler won't be quite at the bottom of the tank, to stop it sucking up sludge (or water!).

When the oil get to that level it'll start pulling in air instead. Which the pump may not like.

How is the sludge going to get _up_ to the feed pipe?

Andy

[John J]

In practical terms the depth of sludge/water increases slowly over the years. Older steel tanks were installed with a slope so the back end of the tank was slightly lower that the offtake and a desludging valve fitted . A small amount of fuel was drawn from this at service visits. I've seen a lot without the correct slope and a blanking plug instead of the valve. Sludge in the filter and further into the system not at all uncommon.

[Vir Campestris]

That makes sense. But still doesn't explain how running the tank dry will result in sludge in the boiler.

Andy

[Martin Brown]

I guess that some of the crud must be floating on the surface of the fuel and gets sucked in at the last gasp. Whatever the reason it is a bad idea to run the tank dry as it shortens the life of the filters.

Likewise it is as well to allow the oil tank some time to settle after refilling a totally empty tank since that really churns the bottom up!

[The Natural Philosopher]

what happens is that when you add fresh fuel it hits the sludge, and stirs it up instead of hitting the surface of the existing fuel, Ergo for a while there is sludge in the fuel

[fred]

Streuth. High price to pay for peace of mind. I think I'll fit a sight gauge. We had a transmitter device fitted but it was unreliable and I choked at what they charge for a replacement battery. ( couple of pen cells in a length of copper pipe). At present we use a simple dial gauge operated by a float on a length of string. To memory these can stick requiring a few taps to correct then so its back to a dip stick unless someone can offer a better alternative

[Martin Brown]

There was a time when it was the only way to get fuel up to an oil burner that was significantly higher than the fuel tank.

You can find a YouTube on how to swap the battery out on the old Watchman transmitter. Mine works the same way. It was reliable here unless the weather was exceptionally foul when it would sometimes show "r". (for out of range) LED flashes when it is time to reorder oil too.

I'd never go back to a sight gauge. The valve invariably sticks. The ultrasonic level sensors are the way forwards now. The new generation accept a coin cell in the sensor - reviews on Amazon are mixed.

I suspect some of the 1* and 2* reviews are not by competent DIYers.

[The Natural Philosopher]

They are still of limited range but now run off a lithium cell you can buy for less than a quid.

The problem is that replacing them usually results in a watertight seal being badly remade, and that's the end of the unit

( couple

Definitely a case for a raspberry Pi !

The echo sounding bit of the oil gauge works OK. Its the RF link that is unreliable, and the design that puts the battery in the same watertight space as the electronics.