The Offshore Voyaging Reference Site

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 Espar normally specify. In heavy weather this will be vulnerable to flooding.

We fabricate a 4′ high chimney by using a standard Espar exhaust through hull, turning a new larger outer part, and welded a 4′ piece of ss pipe on that, and then added a “Charlie Nobel” to the top to stop the rain going down.

We then had a collar turned to go around it at the same hight as the pushpit and attached two braces made of standard Bimini top 1′ tube which I attached to the top of the pulpit.

Note that since we had an isolated ground system on that boat I added plastic ferrules to the braces (just visible in the shot) and a teflon sleeve with a shoulder to the hole through the deck to maintain isolation.

With this setup we could 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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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

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?

Marc Dacey

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!

Robert Andrew

John, in the recent 24V part 2 column you refer to your existing Morgan’s Cloud 12V set up, which includes an 8kw Espar heater and that it keeps the boat toasty even with below freezing outdoor temps. I’ve had a smaller 5kw Espar on my 39ft boat for many years and I’m very happy with it, but I think the maximum temp differential it can manage is about 30 deg F, not enough for “toasty” when freezing outside. Maybe Morgan’s Cloud is well insulated? Excellent analysis of the 24V question.

Bob Andrew