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From: Arild Jensen (no email)
Date: Mon Feb 05 2007 - 21:49:40 EST
> -----Original Message-----
> From: Jamie
> Anyone have a preference regards DC heaters? I've heard mixed reports of
> Eberspachers and the like and would really appreciate some live-aboard
views,
> specifically budget vs performance vs reliability (that old chestnut).
REPLY
Both Espar and Webasto use the same control module and both makes have
limited time fan motors.
Typically the fan motors only last 3000 hours.
By comparison a typical 120V AC pump motor will last 10,000 or more than
three times as long.
My suggestion is to have a AC pumps and fans if possibel and either mount in
parallel with th eDC unit or else have a dedicated inverter to power the AC
pumps from the battery. Best bet is a 500Watt or so sine wave inverter.
Yes the sine wave wil give better long life than a MSW inverter driving the
same AC motor.
One of the biggest problems with any of the DC furnaces is their intolerance
to low DC supply voltage.
Its the natuer of the beast that the 3 stage charge wil not kick back in
until the battery has dropped to a low threshold point. Consequently, the
voltage supply to your DC powered furnace fluctuates and you get less than
optimum combustion during the low voltage sessiosn. In addition you should
be aware that many so called DC units require 13.6V to run properly and
even a fully charged battery only delivers 12.^ or one whole volt below
what is required by the equipment.
The ignition controller in particula are prone to mis-firing under low
supply voltage conditions.
Several solutions are available. You can get a DC-DC converter with a
regulated 13.6V output to power your sensitive furnace controller. This
means regardless of what your battery voltage is like the ignition
controller wil maintain decent output.
If you are docked for the winter and have access to steady shorepower you
can also get a battery charger which has a power supply output option. This
is a charger which delivers regulated 13.6V output no matter what the dock
voltage is like even during brownout conditions. Xantrex's True Charge 20
and 40+ chargers have this featuer but so do several other brands.
Read the fine print in the spec section to see if your favourite brand
offers this. Victron Mastervolt and Newmar all offer such chargers.
I have had to tear down and repair both Webasto and Espar DC furnaces. Both
are good. Espar is smaller and thus a bit moore finicky while Webasto is
quick to get open for cleaning. Espar runs more quieter than Webasto but
Webasto has more BTU output in the big size. Aquahot uses a Webasto burner
head. Never had to repair a Hurricane so far.
Hurricane looks like a nice system but seems to be a bit more expensive and
involve more work to service. They also have more of an issue with power
disruption scrambling their controller board. I'm not suer why since all
three companeis have had plenty of tiem to refine their design.
Proheat is a nice system but you are totally on your own if you admit its
installed on a boat. Work like a charm in the trucks and busses I have seen
them installed on. Ditto for one boat installation I did. However if you
need service better take unit to a truck shop and tell em it was in an RV.
<grin> These are almost impossible to self service since you need a
computer to diagnose fault conditions. Dealer cost for a diagnostic tool is
$1500+
My suggestion is to look at a small furnace hydronic system of a brand which
is used for RV or cottage applications.
Get professional help in designing the system. Unless you get it exactly
right, it will be horribly expensive to run compared to using electric
heaters. This is based on having worked for heating contractors, designing
and building my own system in a house (including lots of time spent
optimizing it) and of course doign numerous repairs on boat installations.
Kabola is very expensive! To my surprise the AC version is $1000 cheaper
due to not needing the special converter circuit to run from a battery
supply. Which is why I suggest using a small house hold type furnace and
driving it with a dedicated inverter from your battery. That is if you have
a large boat in cold climates. For smaller boats in more temperate climates
The Espar size is better.
regards
Arild who first learned to fix Webastos while living aboard in frozen
Toronto harbor in -20F winters.
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