On Wed, 09 May 2018 15:12:35 +0100, NY wrote:

"Marland" wrote in message
...
wrote:
Do the suppliers vary the composition of heating oil slightly between
summer and winter?
I wondered perhaps if the neighbours in 2016 got a top up of winter
grade if such a thing exists just before the season changed and that if
it had more aromatics in it we were stuck with it warming up in that
summer.

Almost certainly heating oil is like diesel in that there are
(theoretically) different grades for summer and winter.

However heating oil, unlike diesel in a vehicle, stays in the tank for
many months, so if they filled up with summer oil it may go waxy in the
winter. So heating oil may *all* be winter grade to allow for the worst
case of -20 deg C in a cold winter, even if supplied during the summer.

I've forgotten how long our 1400 litre tank lasted.

For diesel, are there disadvantages with winter diesel (cost; combustion
temperature and hence vehicle performance)? I presume there must be,
otherwise they'd use winter diesel all the time to avoid having to
manage the changeover.

Paraffin (kerosene) is/was used to create a 'winter fuel mix' for diesel
engined vehilcles where up to 25% of the mix was paraffin(kerosene) which
did reduce performance slightly. Unfortunately, because paraffin
(kerosene) isn't available with road duty tax pre-levied, that advice in
diesel engine car(automobile) owner's manuals' of three decades or so
back, became "Up to 25% of unleaded petroleum (gasoline) may be used to
lower the waxing temperature during the winter season." just to stay this
side of "The Law".

So, my guess is that there's no such thing as "summer" and "winter"
grade paraffin (kerosene) or, for that matter, JP4 aviation fuel for
passenger jets routinely flying at altitudes where the air temperature
can be as low as -60 deg C. Otoh, there obviously are summer and winter
grades of DERV which might[1] matter in the case of large tanks of the
stuff used to fuel large emergency standby generators.

[1] A permanent installation of such a diesel powered standby emergency
generator only needs to ensure that the fuel storage tank and pipework is
kept above a minimum temperature which is usually done by the simple
expedient of keeping it indoors alongside of the 100KVA or larger genset
in the generator/boiler room or house. Otherwise for an outside tank,
it's just a matter of insulation and some form of tank heating and
insulated pipe feeds wrapped with heater tape.

The energy costs of keeping 'ordinary' diesel from waxing under very
cold winter conditions in an emergency backup system is chicken feed
compared to all the other running costs of maintaining such a system
serviceable at all times, especially since it removes the question of
when to change from 'summer' to 'winter' grade diesel fuel.

Although a smaller tank of 'winter grade' fuel *might* be maintained as
an emergency startup fuel in case a problem in the temperature
conditioning of the main tankage arises at the worst possible moment,
it's more likely that redundancy in the pipework tape heating system
would be utilised to overcome that very small risk of failure - I'm not
an emergency standby power systems engineer by trade.

--
Johnny B Good