Hi, I want to install a heater on Essence my 324 and think the forced air diesel feed heaters sound good. Anyone with ideas about this? They seem to range lots in price also as the van rv crowd grows these are becoming the go to for them. I think that is why there are many options now. I also would need ideas on what size to get for the 30’ boat and some install info. Thanks, Debbie
Deborah Sabo
Essence Nonsuch 324 #103
Wickford, RI
I delivered a 34 ft sailboat to Norfolk from here one January, arriving in a blizzard and it had an Espar unit that I thought was wonderful. Unfortunately, I don’t know the size.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
Hi,
I have a 4kw Webasto forced air diesel heater that keeps my N30U cosy on the rare occasions the crew need it… It has two outlets, one in the cabin and one in the heads/shower. The only possible downside could be the ticking sound from the fuel metering pump. Better sound insulation I will try this winter refit.
Peter Richardson
Non Pareil, Nonsuch 30U,#449
Craignish, W Scotland, UK.
Hi Debbie,
I have also been looking for a diesel heater. There are lots of options ranging from Chinese heaters (a few hundred dollars on Amazon) to something like the high end Wallas heaters which will cost several thousand. The Chinese heaters are very popular for vans, but I am somewhat risk averse, and am dubious about putting a non-marine grade product like this on the boat. Aside from fire hazards, there are carbon monoxide dangers.
At the recent 2025 Vancouver boat show, I was quoted with two options sized for a NS30:
-
Planar / autoterm 4D, about C$2000, including install parts
https://planarheaters.com/product/diesel-air-heater-planar-44d-ha/?srsltid=AfmBOoriLDSTZgN4FPOwYKIXvJDU5IVh1xxTCMgmAjcTBeFZgvcbxLfK -
Wallas Viking Heater - C$4330 , including install parts.
Mike
NS30 #26, Port Moody BC
We have an Espar D5 on our N36. Provides great comfort up here!
Leon King
Cloud Nine, N36
Lewisporte, Newfoundland
My boat has a Espar Airtronic D2, installed in the aft section of port cockpit locker with an exhaust through port side of the transom. It draws diesel from a T-connection near Racor fuel filter near fuel tank. When choosing exhaust location be mindful that the exhaust expels hot gases, so you don’t want it near where someone or something may accidentally touch it. Heated air runs through a 3”(?) flexible hose to a vent fitting under port settee, aft of the fresh water tank.
Also the heater does make some noise when running, so may be disturbing to you and neighboring boats at nighttime. And in certain situations when tied to a dock, the wind may blow diesel exhaust back into the cabin.
Cheers,
Don
’87 NS30U #369 - Breezin’
Vancouver, BC
I have an Espar installed on BIANKA. Came in very handy while living on board in New York City. It was great when sailing in December and early spring. Kept the cabin nice and toasty. But since converting to electric propulsion I no longer carry any diesel and I no longer sail when things start to get too cold.
Mike
BIANKA
1986 30U
Long Island
A few years ago I installed a Planar heater in Chancy. The quality was great, everything fitted Planar were very helpful, their warehouse is in Langley (not far away) and by pure coincidence the family boat was mored in the next slip to Chancy.
The Planar is a Russian product and this was pre Ukraine invasion.
So product excellent / politics, not so much.
Mike, I followed in Paul Miller’s wake. You are welcome to take a peek at what I did anytime.
Mike Jennings.
NS30C 005
Chancy, Port Moody.
No matter the choice installation must be done carefully. A CO detector placed in any closed space where the unit is located and living spaces. A couple living in our neighbourhood passed away on there boat in the marina due to CO poisoning resulting from a faulty diesel heater. Take appropriate precautions.
o
I recently read that heat pumps are replacing resistance heaters in electric cars. They sound good for both heat and A/C in the range of ambient temperatures where most people (Ernest Shackleton excepted) are on their boats.
Does anyone know if this is a viable alternative for boats? It’d seem like if there’s an automotive market there’s a chance of crossover products.
– Bob
Me Gusta
Nonsuch e26U #233
Hi Bob,
Yes, this has been a thing for a very long time in the boat world.
Almost all marine air conditioners have a “reverse” operation which turns them into a heat pump.
Since they’re all water cooled, are you able to extract the heat from the ocean which is much more efficient than heating the air resistively with electricity.
And since water temperature is much more temperate than air, it works in a wider range of climates
Here is what ChatGPT had to say…
Efficiency of Marine Air Conditioner in Heat Pump Mode vs. Electric Resistance Heating
This document compares the efficiency of a marine air conditioner operating in reverse as a heat pump versus electric resistance heating. The efficiency is measured using the Coefficient of Performance (COP).
1. Electric Resistance Heating Efficiency
Electric resistance heaters are nearly 100% efficient, meaning that for every 1 kW of electrical energy input, 1 kW of heat is produced. The COP of electric resistance heating is 1.0.
2. Marine Heat Pump Efficiency
A heat pump extracts heat from seawater and transfers it inside the boat. The efficiency of this process is measured by the Coefficient of Performance (COP):
COP = Heat Output (kW) / Electrical Power Input (kW)
Typical marine heat pumps have a COP of 3 to 4 when operating in seawater at moderate temperatures (50–70°F). This means that for every 1 kW of electrical power consumed, the heat pump can deliver 3 to 4 kW of heat.
3. Efficiency Comparison Example
Heating Method
|
Heat Output (kW per 1 kW Input)
|
COP
|
- | - | - |
Electric Resistance Heating
|
1.0 kW
|
1.0
|
Marine Heat Pump (Typical COP = 3.5)
|
3.5 kW
|
3.5
|
This shows that a heat pump is significantly more efficient than resistance heating, typically delivering 3.5 times more heat per unit of electricity.
4. Impact of Seawater Temperature on Heat Pump Efficiency
The efficiency of a marine heat pump depends on the seawater temperature. As seawater temperature decreases, the COP of the heat pump also decreases. The following table provides estimated COP values at different seawater temperatures.
Seawater Temperature (°F)
|
COP (Heat Pump)
|
Heat Output (kW per 1 kW Input)
|
- | - | - |
32.0
|
1.5
|
1.5
|
37.0
|
1.5
|
1.5
|
42.0
|
2.5
|
2.5
|
47.0
|
2.5
|
2.5
|
52.0
|
3.5
|
3.5
|
57.0
|
3.5
|
3.5
|
62.0
|
4.0
|
4.0
|
67.0
|
4.0
|
4.0
|
72.0
|
4.5
|
4.5
|
77.0
|
4.5
|
4.5
|
Michael Jabara
Hobbes II - 1995 Nonsuch 354
San Rafael, California
Yes. We used to have one some years ago and they are very efficient as they exchange the heat with sea water. And they come with zero CO risk.
You do have to poke a couple of holes in your hull, though only one is below the waterline. Funny, the first time I saw a boat with one I called the owner to tell him his bilge pump was running constantly.
Downside is they need a hefty battery bank if you are going to run them away from shore power.
As Mike said above, I installed a Planar back in 2020 and couldn’t be happier with it. Similar quality to Espar but at about half the cost and much quieter.
HOWEVER unfortunately I can not recommend them since Feb. 2022. Get an Espar.
Paul M
NS30U #211 Sandipier
Cowichan Bay B.C.
Bob,
Interesting line of thought regarding automotive HP packages.
The main difference is that autos use Air-2-Air systems boats would probably lean towards water-2-air.
The AI passage that Michael shared is useful but a couple points are too general to apply to boats.
- The COP chart assumes a specific refrigerant running at a specific pressure. Over the last 5 years residential air-2-air systems have proven that systems can be designed for efficient operation at most temps observed in a particular region. Staying in the sweet spot for efficiency is MUCH easier for a pump’n dump system that makes most sense for boats… assuming you use the right refrigerant. I’d say once current tech is applied a COP of 3 will be a safe assumption in all situations. Don’t forget COP is usually quoted for the compressor the system COP should include the sea water pump and any fans used to distribute the conditioned air. For a system COP of 3, your compressor probably needs to run closer to COP 4
- Folks with older homes, are finding there is more expensive to move to HP systems than just replacing the heat source. The distribution systems in older homes assume heat is provided at a high temp usually 165º F or better. HPs rarely provide heat at more than 125º F, so a lot more surface area is needed to transfer the same BTUs into a living space. The distribution system will take up more space on a boat than the diesel equivalent.
- Using a boat in a cold climate ( if it’s not designed for the conditions ) is a lot like camping. Managing condensation when your inside air temp is 65 and your inner wall surfaces are 40º is difficult. To manage humidity you may need some additional equipment ( air exchanger or dehumidifier ) or to keep the cabin temp much lower than feel comfortable. With a diesel heater, direct vent ( open a window ) may be a viable way to control humidity.
- Energy storage… each gallon of diesel has the equivalent of 35 KWH of electrical energy. Even though your pump’n dump HP has a COP of 3 to compare the cost ( $ and space ), you need to think about the cost and size of a 10 KWH battery for each gallon of diesel you carry assuming you actually need that much reserve. In practice, on Soave my biggest fuel issue is managing fuel age. We’re spoiled into having more abundant energy storage on our boats than we actually need. For a HP you probably need to assume a shore power connection.
On the bright side, I am happy to report that two 800W electric heaters can maintain Soave’s interior at 48º F when the outside temps are in the mid 30º’s F. With the right clothes 48º is comfortable enough for boat chores. Yesterday I removed her waste tank and sponged out her bilge. Besides having very cold hands from the icy bilge water, it wasn’t too bad. A 1200W heat gun makes a dandy hand warmer I was surprised the 15A plug I used at the power station didn’t trip.
Best of all, the power at the boatyard is included in my storage fee so a COP 1 doesn’t bother me. ( I only run the heaters when I am present )
Rob Cohen
s/v SOAVE
NS33 #009
Cedar Point YC
Westport, CT
Number 1 is mainly design considerations which the manufacturer will have already taken into account. They will spec the refrigerant to be used (probably R410A). If you hire or work with a professional dealer/installer they’ll make sure you get the best performance in your boat and location. There’s a place here in San Diego that sells all kinds of these systems for self or professional installation and they are full of more answers than I can ever think of questions to ask.
Maybe/maybe not on Number 2. There is another Nonsuch 33 here in San Diego with one of these systems installed in a cabinet just forward of the dinette. One port blows into the main cabin and one blows into the forward cabin. I’m not sure what the duct size was, but it doesn’t matter because it is all contained within that cabinet. An installation which required running ducts might be more problematic. One 6000/7000 BTU unit I looked at online has a 4" outlet. Some other comments in this thread mention the diesel units requiring 3" ducting. That’s not a huge difference, but might matter in some circumstances. On the other hand, larger ducting reduces back pressure and allows a fan to work easier. Fans draw more current than you might expect, so larger ducts are more electrically efficient.
I suspect that there would be no difference in condensation between HVAC and diesel systems. Neither of them introduce moisture into the air and neither of them remove it.
Yup, you’re going to need a whole shipload of batteries to power an HVAC unit for very long if you are not plugged in to shore power or on a generator. The NS33 I referred to previously also has a generator. Probably for this reason.
I keep looking at these systems and they are tempting. It can get pretty hot in San Diego and AC would be nice. I have a propane heater that keeps the cabin warm in the “winter”, but I do worry about CO and won’t use it at night. Fortunately I sleep better cold, anyway. So for the time being I’ve got more important things to spend my meager boat bucks on.
Debbie was asking about diesel heaters. For cruising or for being at the dock? And do you have a generator? Or are we getting too far afield here?
Regarding holes in hull for heat pump I have a dock neighbor who installed one in his N30U. He teed off and used the head inlet for the below waterline supply. He had some trouble with that setup until he ran the inlet line below the waterline in bilge. Now it works fine. I am thinking of doing the same.
Brian Cayer
Spirit~Wind
N30U 419
Westbrook, Ct.
Hi, I am looking for a heater to cruise. The simpler the better. Debbie
Debbie,
The conversation wandered off topic, and I’m partially responsible. Sorry for that.
The sort answer is… diesel. The model names mentioned earlier in this thread seem to come up often.
Soave had a diesel heater earlier in her life, that I presume served her owners well. The flue vent and space it was installed are ideally suited for any of the diesel units suggested earlier. The heater was centrally located so it was easy to run vents to both the forward cabin and the main salon. Getting a quality install is probably as important as picking the right model.
We’re entering our second season with Soave, and our ambition for cruising exceeded our reality ( so far ). I’m glad we didn’t rush to install a diesel heater. I’m finding plenty of other fun and useful projects.
I use a couple portable electric heaters to take the chill off in our shoulder seasons here in CT, generally April and September. We need shore power for this to work, but it hasn’t limited our enjoyment enough to spring for a diesel heater.
I can send you pictures of the cabinet and flue vent if you are interested. The layout of your 324 is different from Soave, so maybe search for a few 324’s with heaters for install ideas.
Good luck,
Rob
s/v SOAVE
NS33 #009
Cedar Point YC
Westport, CT
Rob, thanks for the information. I went down the ICW last year to Abacos and back. Needed heat at nite in Nov-Jan and then in the shoulder seasons up here in New England. Planning a trip to Canada and will need it then. I will have a professional install but the more I can understand what I want the better the install will be. Where is your machine located? Where vented-air in and exhaust out?. I am thinking put the unit in a lazaret near diesel tank T off of. Vent exhaust out transom. And run hose thru quarter berth to heat. Not sure where air in goes.
Debbie
Essence nonsuch 324
Wickford, RI
Deborah: It would help if we know what boat you had and where you are in your signature. I have a simple propane camping heater I run until bedtime. Works great.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA