Diesel-fired hot-water heaters are the
most efficient heating system you can in-
stall on a boat. Further, the pipes and hoses
to distribute the hot water are quite small,
usually^3 / 4 inch (DN 20 mm) or a size
smaller. This makes it quite easy to route
the heat through all the tight corners on any
boat. Typical outputs range from around
10,000 Btu for small units up to 200,000 Btu
for very large units. For any serious voyag-
ing cruiser or liveaboard, I almost always
specify diesel-fired hot-water heating. Es-
par and Webasto are two manufacturers of
both hot-air and hydronic central heating
systems for boats.
Diesel-Fired Heater Exhaust
and Intake Air
The diesel exhaust from any diesel central
heater is similar to the dry exhaust from a
diesel engine (see Chapter 7). It’s not quite
as hot at around 800°F (1,470°C), but hot
enough to cause a serious fire if not properly
insulated and to experience cracking
without proper allowance for expansion and
contraction. Review the discussion on dry
exhaust in Chapter 9, and follow the manu-
facturer’s instructions carefully. Unless you
are running the exhaust up a stack, the com-
mon exits are on the hull side or transom.Chapter 15: Air-Conditioning and Heating
Figure 15-13.
Hydronic heater
(Courtesy Espar
Products, Inc.)