I believe I mentioned testing a new "self-install" kit put out by Webasto.
Here's an update on progress so far. Right now, *no* heater, and winter coming
on. Have to get my butt in gear. :-)

Testing the Webasto Blue Heat Self Install Kit


Part I: Out with the Old, Plan for the New


We've had wonderful service from the old diesel furnace that was installed on
"Indulgence" in 1982. During the last few years, however, the old furnace began
demonstrating that even something very well made and engineered has a finite
life span. We replaced a control unit a year or so ago- and were lucky enough
to find a used part that properly corresponded with some obsolete circuitry. We
could get the original heater to work, most of the time, but it was more
frequently requiring some fiddling and twiddling, (as well as strategically
applied thumping and bumping).

While the old heater may have been built to a high standard in its day, it had
obviously been installed by Quick and Dirty Marine. Mr. Quick had located the
only cold air intake in the pilothouse, while Mr. Dirty ran a very short length
of curving hose to a forward cabin vent. By heating the forward cabin up to
sauna standards, we could count on a lukewarm mid cabin and a slight melting of
icicles aft. Quick and Dirty Marine was more than likely a firm in California,
where heat is less important and "Indulgence" spent most of her early years.

Replacing the diesel furnace was on my "to-do" list, but in the constant
competition between important projects for a limited supply of boat bucks,
those things that refuse to completely and finally die are often assigned a
lower priority than systems that have failed absolutely.

We got a call from Sure Marine in Seattle. Sure Marine is the North American
distributor for Webasto diesel furnaces. "Do you think any of your writers
would be willing to serve as a 'guinea pig'? Webasto has a new, self-install
kit. They have put together all the parts, pieces, and instructions that they
believe an amateur would need to do his or her own heater installation. We need
somebody who would be willing to use it and write up a general report about the
experience, pro or con."

Guinea pig Gould, at your service. This was just the excuse I needed to replace
my very tired furnace. Based on the interior dimensions of "Indulgence", we
determined that the Webasto Air Top 5000 was the proper fit. The Air Top 5000
has a variable heat rating of up to 18,800 BTU/h, (the equivalent of 5.5kW).
The exhausted veteran had been rated at 4.5kW, so we would be enjoying a
greater quantity of heat, and a fresh installation that would hopefully correct
(rather than compound), some of the shortcuts associated with the first heater.


The Air Top 5000 has an ignition system that completely eliminates the old
"igniter plug." I had acquired considerable experience swapping out the igniter
plug on the old furnace, but I won't miss the task on the new. Webasto says the
Air Top 5000 will run about 10 hours on a single gallon of fuel- a statistic
that is near and dear to the heart of all trawler boaters. Although it would
produce more heat, the new Webasto would be slightly more compact than the old
furnace. We ordered the self-install kit just before leaving on our summer
cruise, anticipating it would arrive in early September. I spent the next two
weeks worrying whether I had bitten off more than I should attempt to chew, and
contemplating various installation plans.

During the course of some general reading on the subject, I learned that one of
the most critical considerations for any forced air diesel heat system is
designing a duct system that will permit the most efficient flow of air. My old
furnace duct began curving just a few inches beyond the heater output fitting,
and it would have been much better to have an uninterrupted straight run of at
least several feet to allow the heater to "breathe."
The old heater ran fore and aft, in a five-foot space between the port fuel
tank and the forward bulkhead of the engine room. With almost a foot of space
consumed by the cold air intake fitting, and about two feet by the heater
itself, Quick and Dirty Marine had no choice except to put a sharp bend in the
output hose immediately off the heater. I mentally struggled with the same
space restriction. Even though the Air Top 5000 was several inches shorter than
the old furnace, there was insufficient room to get a straight run of adequate
length if the new furnace were installed exactly where the original had been.

I wanted the new installation to include a duct to carry heat to the aft and
main cabins as well. In the middle of a restless night (during which my mind's
eye ran ductwork hither and yon through the engine room), the painfully obvious
solution occurred to me.

The new Air Top 5000 would be mounted athwartship! This would provide several
feet of uninterrupted ducting to point where it would "Y" back to the forward
heat outlet as well as aft to two new outlets in the main and aft cabins.

Air intake would be somewhat more complex. "Indulgence" has more engine room
ventilation than needed, particularly after converting from a turbo engine to
one that is naturally aspirated. The redundant vents are both on the starboard
side of the boat, safely removed from the furnace exhaust plumbed through a
port through hull. There would be little risk of bringing carbon monoxide
aboard if one of the engine room vents were converted to cold air intake for
the Air Top 5000. Air is introduced to the engine room through 5-inch hoses,
and the hose run from the starboard side to the port side of the boat would be
over 10-feet in length. Such a long run for cold air intake would threaten to
"choke" the heater, and cause it to run less efficiently. The solution will be
to mix internal and external air to the intake side of the furnace. Introducing
some outside air to the system will serve to "pressurize" the cabin, and should
cut down on the jet aircraft noise we never learned to appreciate with the old
heater intake fixed near ear level in the main cabin.

We returned from our summer cruise, ran like crazy to get the following issue
out on time, and them picked up the big cardboard box at Sure Marine. We
unpacked the box to discover an Air Top 5000, a fuel pump, heater controls, a
mounting bracket, an exhaust through hull; an assortment of duct work, bags of
clamps, fittings, screws, and miscellaneous hardware, and, (Glory Be!) an
instruction book.

The old furnace came out much faster than the new Webasto will go in.
Disconnecting the fuel line, the wiring, the ductwork, and unbolting the
furnace from its mounting brackets took less than an hour. I had hoped to reuse
the original exhaust through hull, but as I removed the old furnace it became
obvious the old fitting is too large a diameter for the new exhaust hose. For
fifteen entire seconds I thought about using the old through hull as an
additional engine room vent. In the sixteenth second I realized that the new
exhaust gas through hull will be located somewhere nearby, and that if the old
fitting were left unsealed carbon monoxide would most definitely be wafting
aboard.

As we go to press with this issue, I'm debating whether to use the old through
hull as a combustion air intake port. (I theorize that as there will be CO in
the combustion system downstream from the fuel burn, anyway, there is little
risk in bringing trace amounts aboard in the same, sealed system). I'm also
planning the location of the new exhaust through hull and preparing to locate
the mounting bracket. Reporting progress before finishing the entire job has
its risks, (what if I have to admit a mistake and retrace a step or two?), but
it will allow our readers a more accurate glimpse of the trials and or rewards
associated with a do-it-yourself Webasto installation.