Which Heater Is More Efficient?

Question: Could you please address the fuel consumption of forced-air bus heaters vs. the Refleks?

Answer: An accurate comparison of fuel consumption and relative efficiency between the two technologies would require equipment and time we don’t really have at our disposal. However, since both systems burn with an essentially clear exhaust, indicating good efficiency, and diesel fuel has a fixed amount of available heat per unit of volume, I think we can assume that their base efficiency is very close to identical. But the air bus heaters lose a lot of heat through their ducting, as much as 20% in a cold bilge, I’m told, and in addition, more fuel must be burnt—unless the boat is fitted with a wind generator and the breeze is very steady—to replace the electricity used by the bus heaters. Bottom line, I would expect the Refleks to be a clear winner in overall efficiency.

See this post for a general comparison of the Refleks and Eberspacher heaters.

{ 9 comments… add one }

  • Paul December 15, 2013, 11:48 pm

    Having had both heaters installed on our last boat, and spending two winters in Annapolis Md (not much of a winter compared to PEI) I can say that using the espar whilst under way and the Dickinson heater at anchor, works great. However, I may remind everyone that a bulkhead heater also loses a lot of heat out of the chimney.

    I’d have to give the Espar the nod as to which was more efficient. The Dickinson Alaska was rated for 16000 btu and the espar 11000 btu, but the espar definitely “felt” warmer. We had a circulating fan for the dickinson, but it never outperformed the espar.
    We already have one espar for the new boat, and will get a second espar for the second hull too. But if we didn’t have a Cat, we’d also have a dickinson if we had room for the chimney. There’s nothing better than cruising in a cold climate, when it’s cold, as long as I’m warm while doing it.

    Paul from PEI, Canada.

  • Ray Durkee September 21, 2014, 10:18 am

    I am not sure where one would use 75 Ah of electricity with a forced air heater–that sounds really high even for a Webasto or Espar????. I have used a Wallas 30 D for nearly 20 years (I am on my second unit) and the thing uses 10 amp draw at startup for a few minutes, but more like an amp or two once it is running–depending on the setting. I agree that these units are not maintenance free and that it takes some guts to do it yourself, but I have learned over time. Also, I realize that Wallas units are not marketed as heavily as others but I have had very good luck with mine and consider it one of the essentials of cruising life. I even used it during a couple years cruising in Central America—nothing like it to dry the boat and everything in it out. Absolutely essential now that my boat is in Maine in order to take advantage of the great Fall sailing. ScanMarine folks are supberb support folks. The Wallas unit is specifically made for boats and is made in Finland.

  • John Twaalfhoven December 16, 2014, 4:44 pm

    Hello heating experts. Two questions you might be able to help us with regarding a Refleks heating unit. We sailed a new boat from France to the Netherlands late this year. The Refleks comes with a pretty useless manual. I admit every idiot can operate it so a manual should not be needed. Nevertheless we had some issues. First question: instructions say to start the heater on pilot setting. There is no such marking, only high or low. One internet story-telling Skipper sets the pilot to high. Unusual, sounds like a choke on the lawn mower. Could this be correct? Second question: sudden flame out, lots of smoke in the cabin. The boat is known to have an airtight main compartment in case of an emergency. It actually has a full size sealed door. Could it be that openening the door (to the outside) draws air back through the chimney? As you can read, we are guessing…….
    Thanks for any advice.
    Save journeys into 2015

    • Eric Klem December 17, 2014, 9:57 am

      Hi John,

      I worked aboard a boat with a Refleks for a while and I will admit that I never read the manual. We found that our favorite way to light it was to turn the fuel on without lighting it until there was a very small puddle in the middle of the pot and then throw some toilet paper down there to wick up the fuel. We would light this and let it burn for a few minutes. When it was almost out, we would turn on the fuel to the highest setting and it would be lit. After a few minutes, we would dial it back to whatever setting we wanted. I suspect that there are probably better ways to do it than this but once we had something that was reliable and didn’t smoke out the cabin, we stuck with it.

      Having an airtight boat with a heater like this is definitely a problem on some level. Shutting the boat up could create draft issues and be dangerous to those inside. Suddenly opening a hatch would have an effect that is hard to predict as you will get a lot of air movement and the air will have varying concentrations of oxygen and combustion products.


  • Bill Attwood December 17, 2014, 5:04 am

    Hi John,
    The burner control on our Refleks is marked from 1 to 9, and we set it to 1 for lighting. We use a shot of meths to light the burner pot. I made the mistake of using filtered but 6 year old diesel oil at first, and that did lead to problems. Replacing it with new fresh diesel solved the problem, but not before we had to clean out the burner pot – a dirty job. If you put meths into the burner pot, does it light and burn satisfactorily? If it lights and then goes out, this is a sign that there isn´t enough oxygen = the burner pot holes need cleaning out. If the burner pot lights, but produces a lot of smoke and soot, this is a sign that there isn´t enough diesel flowing into the burner pot = clean out the regulator and injection “needle”. I think it unlikely that opening the door would lead to the problems of smoke that you describe, rather the opposite. At home we have a wood-burning stove which does excatly this when we switch on the extractor hood in the kitchen. We have the yacht-type chimney cap on our Refleks, with no additional chimney above deck. Refleks recommend an insulated chimeny pipe above deck for cold conditions, could this be the answer to your problem? If you really can´t solve the problem yourself, a phone call to Refleks in Denmark may be useful. They are very helpful.
    Good luck.

  • Wilson Fitt December 17, 2014, 10:38 am

    We have a diesel fired Dickenson stove, same principle as the Refleks, and once in awhile it would backdraft when the wind was forward of the beam, filling the cabin with smoke. I eventually concluded that the open companionway hatch with dodger over acted like an enormous extraction cowl vent lowering the air pressure in the cabin. The relatively small forward facing dorade vents could not compensate and the result was that the draft in the stove chimney reversed itself. I cured this (mostly) by bringing a 4″ round duct through a bulkhead from the aft end of the boat to a point just below the heater stove where its air intake is. I think it would be more effective if this air supply duct had a little in-line fan to provide positive pressure.

    • Hans December 18, 2014, 11:28 am

      Hi all,
      on my boat i have a Refleks 66MK – the smallest model they make – and i have the same problem with backdraft when the wind comes from port side. After trying various tricks the only cure i found for that is rigging a piece of tarp to shield the chimney cap. The Refleks folks in Denmark also didn’t have a simple solution, they recommended a second pipe parallel to the existing chimney for drawing air from outside and thus being independent of combustion air from inside the cabin. They sent some pictures of such an installation – slight resemblance with a nuclear power plant piping, so i didn’t go for it. Not a real problem once you know what to expect and what to do about it.
      As for lighting i turn the control to full and as soon as the first puddle of diesel appears i turn the control back to low and light the oil with a stove lighter, a waxlike piece that is made especially for the purpose. Doesn’t always work the first time so the trick with the toilet paper is sure worth trying. When the flame starts burning blue and the stove makes cozy bubbling noises i know that i’ve suceeded.
      I wouldn’t want to miss my Refleks for anything. Great stove ! Burns for days and weeks, consumes no electricity, keeps the water kettle hot and needs about 2,5 ltrs./24hrs at low setting.
      Question to Wilson: Isn’t the Dickinson normally fitted out with an electric fan to support draft in difficult conditions ?


      • Nick Kats December 19, 2014, 5:31 pm

        Hi Hans
        My experience is the same as yours. Same Refleks stove, chimney offset to port, dislikes wind from port, shielding with a piece of plywood solves that.
        Next to the Refleks I have a woodstove, chimney offset to right, this also has a problem with wind from starboard, etc.
        Changing the chimney caps dramatically improved both but did not fully solve the problem.

  • John December 18, 2014, 10:39 am

    Hi All,

    Thanks very much for fielding that one. As a long time Espar user I had no clue.


Leave a Comment

Please read our Comment Guidelines before you comment.
If your comment does not display immediately, please contact us
Your e-mail address will not be displayed and we will not send you junk mail.

Get your own avatar like ours.