Chinese diesel heater

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8. Be realistic with the length of duct/exhaust. These heaters were designed primarily for the commercial trucking market. They can heat the cab of a truck. Don't expect them to operate efficiently if running 30 feet of heating duct and 10 feet of exhaust tubing.
 
What is a good general rule of thumb for sizing a diesel heater?
 
The short version. Total interior volume in cubic feet X 15 gives the estimated BTU required. Convert between KW and BTU here. Chinese diesel heaters are pretty much 5KW no matter what they claim.


The longer, pre edit, version.


Here's a very detailed discussion of sizing your heater. AMC Cliffy's Which One do I need As you work through the guide near the bottom you'll come to a chart for the area multiplier. I've also seen sources that say to use 15 for the multiplier. I think Sure Marine and others use the 15 multiplier. Where I disagree with this guide is to exclude cabinets, bunks and other built in spaces. Maybe OK for mild winters and occasional uses. But I lived aboard in Seattle for years and went through one of the colder winters for the area. Days of snow on the decks and docks, icy streets, below freezing. Those mentioned closed spaces were cold and affected the comfort of the boat negatively.

Since this is a thread on Chinese diesel heaters they are all rated in KW. You'll need to convert between KW and BTU. Lots of tools on line. Here's one Stoves Online KW to BTU conversion.

Next dig around on You tube about these heaters. Decide which of the contributors you think are knowledgeable and truthful. I came to the conclusion that so call 8 KW Chinese heaters are 5 KW. Not necessarily a problem if you know that going in and if needed install multiple units.

Finally consider your use and acceptable level of comfort. My current boat has an Espar D8LC a true 8 KW, equals 27312 BTU. Indications are it heats a 45' boat well in relatively mild weather, say into the lower 50s at night. That's going to be good enough for our intended use. PNW late spring through early fall. My previous boat at 42 ft had a Hurricane Hydronic rated for 35,000 BTU, equals 10.255 KW. That heater worked very well down into freezing temps. I took advantage of zones which can be a big advantage. On a very cold night I could set the saloon and fwd cabin temps low keeping the aft cabin where we slept warmer. That way the heater didn't have to run as much meaning lower electric consumption during a cold night on the hook. A nice advantage to hydronic heat is it keeps your water heater up when it's running. Also, I don't have enough data yet, but it seems the total electric draw on similar nights was less for the Hurricane that for the Espar.

One more case, my live aboard in Seattle. I put in an air heater no longer available. Marketed as though it were made in Sweden. Here's a press release from 2015 I don't recall which size I purchased. I recall it was not near enough for a 40 ft liveaboard. And it died the 1st winter. It does bear a remarkable resemblance to the Chinese heaters we now see.

A buddy with a 42 ft boat has the Hurricane but rarely uses it for his spring - fall cruising. He's installed a diesel drip heater in the saloon and they are happy with that.

Lots to consider. No simple one size fits all solution. I will say if I were going to heat a 40 - 45 ft boat for cold weather cruising with the currently available Chinese heaters I'd put in two or three. Greater capacity, possibility to set up zones and redundancy. Of course you'd need multiple exhaust ports and fuel supplies.
What is a good general rule of thumb for sizing a diesel heater?
 
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The Chinese knock offs all lie about their specifications. Makes it difficult to size correctly. Best to go bigger.

The problem is that most of these heaters do not shut off when they reach the set temp, they just go to low power. If the heater is oversized, even low power may still be too much for your space. Also, they run at full power for some time during startup and shutdown.
 
I have a German-made Espar D2 on one boat and a Chinese-made Warmtoo heater on another. German heater kit is $1,100 on Amazon and rated at 7.5kw. Chinese heater kit is $100 on Ebay and rated at 8kw. No real difference in heat output (the Germans are probably lying about the rating?) The Espar has a primative thermostat that must sense the heat returning to the unit through the air intake to determine whether to reduce output. That means that one cannot use fresh outside air as the source. The Espar would always see the temperature as whatever the ambient outside temp is and wont turn off. The Warmtoo can use outside air and therefore is great at eliminating condensation and circulating fresh air. The Espar shuts off when the temperature exceeds the thermostat set. To turn on again, it needs to heat up the glow plug (by far the most electricity use). The Warmtoo reduces heat to a minimal about but does not turn off. That is usually reduced enough. If not, we open a window. Much better than having to repeatedly run the ignitor again. The Warmtoo probably uses 1/10th the electricity, which can be an issue on a long-term winter anchorage.

Our boat is the perfect size, although some might call it small. Essentially a Grand Banks 32. The Warmtoo is in the engine room. The ducting has 3 Ys in it. That allows a register in the main cabin (the shortest run closest to the heater), a register in the head, and a register further in the V berth. The main cabin register cannot be shut off. It is important to have one register that can't be shut off so that you can never choke off the airflow. The register in the head is a consession to my wife's occassional need for decadent yachting (one doesn't need heat to do what's required in the head). The register in the V berth is a consession to me as it is my afternoon napping place.

We generally turn our heater off at night, but several years ago we where out on Christmas eve with 27 degree temps and 40 knt winds. That seems to be about the maximum our Warmtoo and Espar can keep up with. But all of this would depend on how insulated/wind proof the vessel. Both of our sliding cabin doors were not windproofed at all (I've since added some weatherstripping). Some of our cabinetry has little openings to the engine room, so again, not exactly windproof. When we do shut the Warmtoo off for the night, it came with a remote fob that allows us to turn on the heat 20 minutes before we get up. One would hope that the Germans have now copied the Chinese on this. If they have, it isn't included in the $1,100 kit on Amazon. Maybe a $300 addition?
 
Is this vevor sold at home Depot the same as warmtoo that you installed?

In an earlier post, boathealer shared his installation journal for a 5kw unit. The exhaust part is 24mm 316L

Does a 8kw model require a larger exhaust through put, i.e. 30mm ? Or is the 24mm still compatible?

I have a German-made Espar D2 on one boat and a Chinese-made Warmtoo heater on another. German heater kit is $1,100 on Amazon and rated at 7.5kw. Chinese heater kit is $100 on Ebay and rated at 8kw. No real difference in heat output (the Germans are probably lying about the rating?) The Espar has a primative thermostat that must sense the heat returning to the unit through the air intake to determine whether to reduce output. That means that one cannot use fresh outside air as the source. The Espar would always see the temperature as whatever the ambient outside temp is and wont turn off. The Warmtoo can use outside air and therefore is great at eliminating condensation and circulating fresh air. The Espar shuts off when the temperature exceeds the thermostat set. To turn on again, it needs to heat up the glow plug (by far the most electricity use). The Warmtoo reduces heat to a minimal about but does not turn off. That is usually reduced enough. If not, we open a window. Much better than having to repeatedly run the ignitor again. The Warmtoo probably uses 1/10th the electricity, which can be an issue on a long-term winter anchorage.

Our boat is the perfect size, although some might call it small. Essentially a Grand Banks 32. The Warmtoo is in the engine room. The ducting has 3 Ys in it. That allows a register in the main cabin (the shortest run closest to the heater), a register in the head, and a register further in the V berth. The main cabin register cannot be shut off. It is important to have one register that can't be shut off so that you can never choke off the airflow. The register in the head is a consession to my wife's occassional need for decadent yachting (one doesn't need heat to do what's required in the head). The register in the V berth is a consession to me as it is my afternoon napping place.

We generally turn our heater off at night, but several years ago we where out on Christmas eve with 27 degree temps and 40 knt winds. That seems to be about the maximum our Warmtoo and Espar can keep up with. But all of this would depend on how insulated/wind proof the vessel. Both of our sliding cabin doors were not windproofed at all (I've since added some weatherstripping). Some of our cabinetry has little openings to the engine room, so again, not exactly windproof. When we do shut the Warmtoo off for the night, it came with a remote fob that allows us to turn on the heat 20 minutes before we get up. One would hope that the Germans have now copied the Chinese on this. If they have, it isn't included in the $1,100 kit on Amazon. Maybe a $300 addition?
 
The problem is that most of these heaters do not shut off when they reach the set temp, they just go to low power. If the heater is oversized, even low power may still be too much for your space. Also, they run at full power for some time during startup and shutdown.

What I have seen with the Chinese heaters is total over blown specifications. One give a way is how much fuel the fuel pump can deliver. I see claims of 8kw but the fuel pump can’t deliver enough fuel to produce 5kw. Some of the 5kw units show fuel pumps that deliver only 2.5kw worth of fuel. My point is expect much lower performance than advertised.
 
I have a German-made Espar D2 on one boat and a Chinese-made Warmtoo heater on another. German heater kit is $1,100 on Amazon and rated at 7.5kw. Chinese heater kit is $100 on Ebay and rated at 8kw. No real difference in heat output (the Germans are probably lying about the rating?) The Espar has a primative thermostat that must sense the heat returning to the unit through the air intake to determine whether to reduce output. That means that one cannot use fresh outside air as the source. The Espar would always see the temperature as whatever the ambient outside temp is and wont turn off. The Warmtoo can use outside air and therefore is great at eliminating condensation and circulating fresh air. The Espar shuts off when the temperature exceeds the thermostat set. To turn on again, it needs to heat up the glow plug (by far the most electricity use). The Warmtoo reduces heat to a minimal about but does not turn off. That is usually reduced enough. If not, we open a window. Much better than having to repeatedly run the ignitor again. The Warmtoo probably uses 1/10th the electricity, which can be an issue on a long-term winter anchorage.

Our boat is the perfect size, although some might call it small. Essentially a Grand Banks 32. The Warmtoo is in the engine room. The ducting has 3 Ys in it. That allows a register in the main cabin (the shortest run closest to the heater), a register in the head, and a register further in the V berth. The main cabin register cannot be shut off. It is important to have one register that can't be shut off so that you can never choke off the airflow. The register in the head is a consession to my wife's occassional need for decadent yachting (one doesn't need heat to do what's required in the head). The register in the V berth is a consession to me as it is my afternoon napping place.

We generally turn our heater off at night, but several years ago we where out on Christmas eve with 27 degree temps and 40 knt winds. That seems to be about the maximum our Warmtoo and Espar can keep up with. But all of this would depend on how insulated/wind proof the vessel. Both of our sliding cabin doors were not windproofed at all (I've since added some weatherstripping). Some of our cabinetry has little openings to the engine room, so again, not exactly windproof. When we do shut the Warmtoo off for the night, it came with a remote fob that allows us to turn on the heat 20 minutes before we get up. One would hope that the Germans have now copied the Chinese on this. If they have, it isn't included in the $1,100 kit on Amazon. Maybe a $300 addition?

The espar d2 is only 2.2 kw, or 7500 btu. If you’re using the inline temp sensor you have probably the most primitive version of the heater. The $1000 kit now gives you a programmable 7 day timer with built in thermostat. Remote thermostats have always been available for those btw.
When the espar reaches temp it goes to low output as well. If that’s still too much after some time it will shut off but it’s rare for that to happen.
Espar has all the options you could ever want, and they did in fact have them first. The Chinese heaters are direct copies of the d2/d4 air heaters.
I certainly can’t knock the price of the Chinese heaters, but I also believe the espar to be superior in quality.
Are they that much better to justify the price? That’s up to you. But my last purchase was an espar hydronic 12. I could have bought Chinese, but I just don’t have confidence it would last for livaboard use like the espar will.
 
I had a planar in the last boat and it gave the option of temp control from external thermo or on the cold air return. With internal cold air circ I found the internal beat the external thermostat
 
What I have seen with the Chinese heaters is total over blown specifications. One give a way is how much fuel the fuel pump can deliver. I see claims of 8kw but the fuel pump can’t deliver enough fuel to produce 5kw. Some of the 5kw units show fuel pumps that deliver only 2.5kw worth of fuel. My point is expect much lower performance than advertised.

This sure seems like a bogus claim. These little heaters use a basic fuel transfer pump (available on Amazon for $12). When they start up, it goes tick tick tick. Then slows to tick, tick, tick. Then they slow to tick . . . tick . . . tick. But when simply connected to 12v power, these little pumps go brrrrrrrrrrr and are rated at about 100 liters per hour (open flow). That's over 25 gallons per hour (138,000 BTU per gallon or 3,450,00 BTU). These little pumps have to be highly regulated inorder to get the production down to 8 or 5kw. 8kw is about 27,000 BTU, so the little tick pumps are regulated down to about 1/10 output when the diesel heater is on high. Because of the requirement of keeping a live flame at idle, they can only go so low, probably still over 1kw.

When I replaced my Webasto, a tick pump was already in place, so I used it and kept the new one that came with my Chinese kit as the spare. Worked fine. Looked to be the same pump and could be. Nothing wrong with Webasto rebranding a Chinese-made pump and charging the extra $250. Or it could be that German law requires it to sell a German-made pump. Good for Germany, if it can convince enough [STRIKE]suckers[/STRIKE] consumers.

Try to find wherever you read that these pumps can't produce 5kw. I'll bet you'll find somebody that doesn't understand them and did a botched install. That's the most likely cause of low performance for any diesel heater.

Check out Amazon for a "Gearzaar Diesel Heater Pump". It's all the same pump: German, Chinese, Russian, 5kw, 8kw, etc. $15. Dang, where's the controversy in that? Maybe I should pick up another spare. I did have one fail once on my John Deere.
 
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...Check out Amazon for a "Gearzaar Diesel Heater Pump". It's all the same pump: German, Chinese, Russian, 5kw, 8kw, etc. $15...

I notice these have "22ML" in the rating. Is that how much fuel is moved per pulse? I don't see anything else listed which might be a flow rate.

One showed "22ML/x1000." Is that a max of 1,000 pulses per minute?
 
Hey Marco,

Smartest move I ever made on our GB was to put a heater vent that blew on the toilet seat, gave me a kitchen pass for several years!
 
Hey Marco,

Smartest move I ever made on our GB was to put a heater vent that blew on the toilet seat, gave me a kitchen pass for several years!

I did the same thing to both heads when I installed our hydronic system. Warm heads in the morning are great.
 
I did the same thing to both heads when I installed our hydronic system. Warm heads in the morning are great.

we have hydronic heated towel racks in each head. wifey loves them...they throw off considerable amounts of heat.
 
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