PRACTICAL
Fitting a silencer to
a diesel boat heater
H
eaters are a brilliant addition to a
boat – they keep the inside dry
and warm, which prevents mould
and mildew forming, and can extend
your sailing season into the cold and
wet months.
They can, however, be somewhat
antisocial. Unsilenced exhausts give rise to
a roar akin to an idling jet engine, which
has been known to spoil the tranquillity of a
peaceful anchorage. Just to walk down a
pontoon in a Scottish spring or autumn is
to experience what amounts to a
symphony of diesel heaters.
Help is at hand, however. Heater
manufacturers including Eberspächer and
Webasto supply exhaust silencers which
will cut the noise down considerably.
I was a little worried about the state of the
exhaust on my 1992 Eberspacher D1LC
diesel heater, and had never been happy
with the loud roar it made at full chat, so
decided that while replacing it I may as well
add a silencer.
But it’s not quite as simple as you might
assume. The vast majority of diesel heater
exhaust silencers found online are
designed for road vehicles. The marine
ones are much more expensive, currently
costing around £260.
But before you plump for a cheap
silencer off eBay beware: vehicle silencers
are designed to be mounted outside the
vehicle and are not gas tight. Boat
exhausts tend to be in an enclosed locker
that often is linked to the living space – and
Ben Meakins installs a
new silenced exhaust
for his Eberspacher
D1LC diesel heater
the last thing you want is
for exhaust fumes to be
pumped in with your
heated air.
Eberspächer UK’s Peter
Collard has some wise
words for those
considering a quick,
cheap deal online:
‘There is a worrying trend for
people to buy vehicle heating
components and fi t them to their boat
heaters. The vehicle components can be
temptingly cheap but they may come with
a heavy penalty,’ he said.
‘A commonly sought after part is a
silencer for the heater’s exhaust system.
Online they are commonly sold as a
small stainless steel silencer box, but
unfortunately most sellers don’t state
that this particular silencer is not suitable
for marine use.
‘A vehicle heating silencer is designed to
be fi tted beneath a vehicle and do a specifi c
job – to slightly cut down the higher pitched
noises associated with combustion, not
totally silence the exhaust.
The silencer itself is NOT gas tight: it’s
designed to go outside of a vehicle so itdoesn’t need
to be,’ he said.
‘If fi tted in a boat
the heater’s exhaust
gas will be emitted into
the boat while the heater
is running, bringing with it
deadly carbon monoxide.
‘Also, the silencer box is not thermally
insulated. Again, it’s designed to go outside
of a vehicle so doesn’t need to be. If fi tted
into a boat this component will be hot
enough, when the heater is running, to
cause severe injury to anyone touching it
and will be hot enough to melt sails,
dinghies, fenders and anything else that
comes into contact with it. In certain
circumstances this could lead to a fi re.’
The more expensive marine silenced
exhaust, Peter explained, is 2m long and
includes a fl exible silencer 500mm long. It’s
totally gas tight and double lagged. It will be
a lot healthier, safer and maybe a lot
cheaper in the long run. Their new heater
packages come with the silenced exhaust
as standard. So, fully cognisant of the
dangers of automotive silencers, I duly
ordered a proper Eberspächer marine
exhaust kit and set to work...You can fi t a silenced exhaust to all
models of Eberspächer air heaters
ABOVE:
Gas-tight marine
silencer
RIGHT: Automotive
silencer –
dangerous for
marine use