Espar D8 Forced Air Diesel Heater (8KW)

After years of fighting with an unreliable diesel heater, we are very pleased with the Espar heater we installed in 2000. It is one of the bigger ones they make and keeps us toasty in all weather.

One thing we would suggest, though, is not to use the exhaust exit in the hull that they normally specify. In heavy weather this will be very vulnerable to flooding. We had Mike Bowden at Ocean Options, where we bought the heater, fabricate us a 4′ high chimney with a ‘Charlie Nobel’ type top that is braced to the stern rail. With this setup we can use the heater even in very heavy weather at sea—when a wick type heater would almost certainly blow back—which is, after all, when you want to be toasty below. The drawbacks of this type of heater are the substantial electrical use and complexity, but these are balanced by the convenience of just flicking a switch when we want heat, even at sea.

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Meet the Author


John was born and brought up in Bermuda and started sailing as a child, racing locally and offshore before turning to cruising. He has sailed over 100,000 miles, most of it on his McCurdy & Rhodes 56, Morgan's Cloud, including eight ocean races to Bermuda, culminating in winning his class twice in the Newport Bermuda Race. He has skippered a series of voyages in the North Atlantic, the majority of which have been to the high latitudes. John has been helping others go voyaging by sharing his experience for twenty years, first in yachting magazines and, for the last 12 years, as co-editor/publisher of AAC.

5 comments… add one
  • pete Oct 11, 2010, 4:50 pm

    We have a Webasto 3500 and have used it in all weathers and when sailing and must agree with you: flick the switch and 5 mins later we are nice and warm. We sailed from Pontrieux to Morlaix on the Brittany coast in 2006 in F9 with snow storm and -11C outside. Inside in a woolly and a coffee at 25degs C (GREAT).

  • Neil McCubbin Jun 2, 2013, 5:58 pm

    We have had he 5kW Espar since about 1998, first for heating while finishing the boat in Quebec, and since 2008 sailing.
    Only real complaint is that twice it has failed to start. Each time, I took it to an Espar shop where they simply reset the control modue by plugging into their Espar “magic box” which linked to their computer. Cost was trivial, but I was lucky that there was an Espar shop nearby each time.
    They said the problem was “too many restarts” True, we had, due to issues with air in the line from the engine.
    I am considering buying the Espar “magic box” to fix myself, but they cost nearly $500. Does anyone know a better solution?

    • John Jun 3, 2013, 7:48 am

      Hi Neil,

      Sorry I don’t. In fact we sprung for one of the magic boxes for just that reason.

  • Marc Dacey Jun 2, 2013, 10:33 pm

    That very much depends on the size of your boat and the need to keep things warm. If you are in port or on a mooring in cold weather (like all winter long), clearly $500 is pretty minimal for assured, boat-wide heating…just add diesel and enough battery capacity/charge ability to run the sparker and the fans.

    If you are “transient”, however, I really think warming up a single area, like the saloon with a bulkhead diesel heater, can be a better option.

    We have a Mermaid Marine Air heat pump/A-C of 12,0oo BTU performance. It is considerably cheaper to get a second Honda 2000 (the “companion” model) to “kick” the AC March pump (which wants 17 amps to start and then the Marine Air unit and pump “fall back” to a manageable 6 amp draw) than to get an Espar/Webasto unit and to duplicate, as seems necessary, the entire insulated vent setup (I have tried to figure out without success if the existing MMA distribution setup could be Y-valved from a diesel heater).

    A bulkhead diesel heater, if used to keep a central area warm on passage, might make more sense, particularly if you have adequate ventilation to keep condensation to a minimum in the under-heated parts of the boat. If you intend, as do the blog owners, to over-winter in fjords, you’re going to spend multiples of $500 on diesel itself to keep the boat warm, so you might as well go big!

    • John Jun 3, 2013, 7:52 am

      Hi Mark,

      We have a post here on the pros and cons of the various heating options.

      The big benefit of furnaces like the Espar is that you can burn them when offshore, no matter the weather. I can’t tell you the number of boats I have met up north where the crew are freezing their behinds off because the can’t make the bulkhead heater work right at sea or they fear burning themselves or some a piece of gear on the chimney.

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