According to Lou :

"rb608" wrote in message
...

I haven't tried it yet, but I keep eyeing a similar redirection. The oil
tank for my home heating is above ground, very near where the dryer vent
exits. On extreme cold days (teens, single digits), water in the tank
will
occasionally freeze up and block the fuel feed. I've been toying with the
idea of extending the vent to encase the tank feed. Hmmm.

It's probably not water in the fuel. All heating oil contains paraffin
(wax) dissolved in it. When the oil get cold, the wax freezes out, blocking
the fuel feed.

Heating oil (and diesel) _is_ essentially "paraffin wax" -
it's just that it's (supposed to be) above its melting point.

In more extreme climates, you have to pay attention, because normal "summer
weight" fuel oils and diesels can freeze at 10-15F. With a result that looks
very much like candle wax. Normal winter weight is usually more like -35F,
but in some cases you need it even lower than that.

I used to work in a refinery lab, and one of the tests we routinely did
was check freeze points on fuel oils and diesel fuels.

The OP may wish to consider discussing with his fuel oil supplier what he's
getting. They should be able to give him the exact specifications. He may
have to pay attention to what the supplier is providing in any particular
season, and judging whether he'll be using the summer weight stuff up before
it gets that cold. Then again, a good supplier should be taking his usage
patterns into consideration when he fills the tank, and not "pushing"
summer weight into the winter.

If the problem recurs this winter, a top up of winter-weight may solve
the problem.

Extending the vent (and/or tenting it with plastic, say) may be a good
solution until you get the situation settled.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.