Electric Baseboard Efficiency?

 I work in a hardware retail store in an area where several hundred people
(from cottage owners to year round residents) live off solar and wind
generated electricity.  I had a question posed to me by one of them and it
has me stumped.  Would replacing a thirty year old 2000 watt electric
baseboard heater with a new 2000 watt baseboard heater be more efficient.
Of course you are still paying for the 2000 watts, but would you be
receiving more radiant heat from it?

I've been asking around and the sales people and electricians say yes.  Any
other comments?

 

I'd say no. They are both 100% efficient.


Maybe, if the new heater had exposed coils or a reflector or insulation
on the side towards the wall, but as you say, they both make 2kW of heat.

Nick

 
Nope.  By definition, electric heat is 100% efficient.  All of the
energy gets converted to heat.  


They're lying or ignorant, possibly both.  Efficiency rating means "how much
of the energy going in is converted to the desired output", and the
remaining is what is lost as waste heat.  Since you're making heat as the
desired output of the device, there is no waste heat.  By definition.

Dave Hinz

 ( see my additions at end... there was no easy way to quote and snip
  and keep this clear )



Dave, you're being a bit too fast here. While you're technically correct
in that the final temperature in the room wll be the same, there *is* a
difference in how people are going to feel.

An electric heater (for that matter, all warm objects) heat up the
surrounding area via those three things we learned back in kindergarten,
namely radiation, convetion, and conduction.

Now eventually all of this (in a sealed room) will stabilize out exactly
the same way, BUT in the process there's a hefty difference.

The electric heater will be providing a big amount of the (initial) output
courtesy of infra red radiation. This not only goes directly via
line-of-sight to the person's skin, making the people feel warmer than the
"air temperature" would suggest, but also does a credible job of bouncing
off the walls and then hitting the people.

So yes, a new and reflective (as opposed to old, dirty, and grimy)
electric heater will make people feel warmer - and sooner. The older one
is dumping more of the (initial) heat directly into the air via
convection, so the people don't get that "radiant" warmth but have to wait
until the air temperature creeps up.

In other words, you'll feel warmer at 65 degrees with a new unit that's
aimed at you (plus a bit of wall bounce) as compared to an older unit.
With the dirty one you have to wait until the air temp gets to 75 or so.

Note that these are very approximate numbers. Actual mileage will vary a
great deal. Cars are closer than they appear in the mirror.

--
_____________________________________________________
Knowledge may be power, but communications is the key
             dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]

 

Given, as snipped above, that the original post asked about replacing
electric baseboard with electric baseboard, and all the electric
baseboard units I've ever met make every effort to be completely
convective in their design, Dave has it exactly correct. The sales
weenies and electricians only make money if they sell you new stuff, and
some are quite happy to lie about what they are selling to get business.

Repacing a convective baseboard with a radiant heater might fit your
argument, but if you put the sort of high temperature refeclting radiant
electric you appear to be discussing in where a baseboard unit was,
you'll probably have a furniture fire in short order - which is one
reason that electric baseboard does not try to take that approach (and
I've seen scorched furniture even with regular electric baseboard, since
it runs a lot hotter than hot water baseboard).

--
Cats, Coffee, Chocolate...vices to live by