Bus Heater

[Wxx3]

Now that i have my oil worries solved, i wanted to talk about a great success story, the bus heater.

For about $250 the heater heats the entire lower portion of the boat, including the two cabins and two heads.

Not only that, with outside temp around 50 and the pilot house getting downright cold, when I turn on the bus heater, I will actually feel the difference in the pilot house in about an hour.

To the point that I must turn it off.

The best $250 i ever spent.

Should have done it on the first day.

Now, I must talk to Brian at American Diesel, as the engine is running even cooler, so I must change the thermostat.

I have actually turned off the heater, even when i was still cold, because the engine was running too cold, only 160°F vice it's normal 175°

 

[Crusty Chief]

Richard,
I would think a thermostat valve inline to the heater would help. On my Selene, the previous owner removed the valve that uses engine heat to heat the circulation system for the hurricane heater. I'm trying to find a replacement so that while the main is running the heater isn't cycling.
Best of luck.

 

[Al]

Funny story,
I have a one cylinder Yanmar of some date when it was rated at 6 hp. It is in my 18 foot Polsbo skiff. I installed a similar bus heater. Running the engine say at 1400 RPM and turning on the heater to high, wow! the RPM drops and the alternator takes on a real belt slapping strain! All okay though, just jack up the throttle! Enjoy it is nice pilot house heat source. Ours is a "trunk Cabin" configuration.

For running heat in our pocket trawler we use the hot water off the engine through the typical radiator/fan assembly when underway, works well enough even though we are fitted with a 160 degree thermostat.

Our main serious heat is a Wallas dt30 oil furnace, which keeps the boat as warm and ever needed at a very low fuel burn and very stingy on amp draw.
The air flow is directed via vented hose to the major areas requiring heat.

All of this in a 27 foot boat!!

Al-Ketchikan

 

[Xsbank]

Richard, you are probably using too much hot water. You might find if you put a valve inline and "throttle" the hot water you will get as much heat but not cool the engine so much. The bus heater is, after all a radiator. Keep the water in the heater longer to extract more heat before you send it back to the source.

 

[Al]

Ouch!! Damn, I misspoke,my bus heater is electric 12 volt! Sorry, the heater you guys are discussing is the one I have off my engine cooling (hot water) system.

Al-Ketchikan

 

[FF]

You might contemplate a different tap off location for the hot coolant , at the end of the exhaust manifold if its coolant cooled.

If there is a hot section before water is injected in the exhaust , perhaps a few coils of SS tubing and some lagging would help.

We found that a circ pump could be operated after engine shut down for a couple of hours (DD 6-71 3000lbs of iron) , warming the cabin at no cost in fuel or noise.

 

[O C Diver]

Richard, I put 3 bus heaters in my boat (pilothouse, Saloon, and master stateroom) during the refit. The coolant is circulated with a 12 volt pump for solar applications. Each has a 3 speed fan control and a bi-metal thermostat. The plan was to have more heaters in the boat to avoid one area being really hot and the other areas cold. Expect to maintain a modest temperature in the rest of the boat and keep the pilothouse toasty underway.

The problem with your setup is not the engine thermostat which is completely closed when the buss heater is running full output, it's that the bus heater can remove more heat from the engine than the engine can produce at the speed that you are running. There are three solutions. First, increase your speed which will generate more heat from increased fuel burn, and exceed what the buss heater can remove. Second, run the buss heater on a lower fan speed which will reduce the heat output of the heater and maintain the engine temperature. Third (my solution), install in the engine coolant loop a temperature sensor which turns the buss heater blowers on above a set point and off if the coolant drops about 10 degrees below the set point. The temperature sensors are brass 1/8" mpt and available in ten degree increments from 140 to over 200 degrees Fahrenheit. Plan to take my boat South from Chesapeake Bay 1st of the year. Am anticipating a fair amount of use from the buss heaters on the way South.

Buss heater in master stateroom.



Thermostat and fan speed switch.




Ted

 

[Wxx3]

Yes. Good ideas.
Easiest for now will be to just put fan on lowest setting and turn off all together if engine running too cold.

Next winter will be interesting.

Oh and I too have a Wallas 40Dt heater. It's about 80% installed. It will be my March project.

 

[psneeld]

Yes. Good ideas.
Easiest for now will be to just put fan on lowest setting and turn off all together if engine running too cold.

Next winter will be interesting.

Oh and I too have a Wallas 40Dt heater. It's about 80% installed. It will be my March project.

While no expert...we all know who knows them....I would think oil temp is more important than coolant temp.

Might want to check that when operating until jumping through too many hoops.

 

[bayview]

I guess if the heater is in line before the heat exchanger all will be well but I would be concerned if the heater diverted too much coolant from main circulation and caused the thermostat to close. Then parts of the engine might be too hot.

 

[Ski in NC]

I put a bus heater on my rig. Best dang thing since sliced bread. Snow on foredeck and pilot house is 70F.

I too have sucked all the heat out of my motor. Noticed PH getting cooler and looked at engine temp gauge and it had dropped from normal 180 to like 140F. This was running super slow at night with poor vis. And this is an 8.3 liter motor. Amazing how little heat they make at idle. Had to turn the heater to low til I could get some load back on it.

Best location for taps is somewhere on cyl head, this will be highest temp and full pump discharge pressure. Return should go to suction of circ water pump. Thermostat will still control temp unless your heater sucks more heat than engine makes.

Engines have a variety of plumbing methods. Some exhaust manifolds have full coolant flow like Yanmars and I think FL's, but not sure. Other engines like Cummins and 3208's the manifolds are on a bypass loop and you definitely do not want to tap into that without fully understanding the flow.

 

[jleonard]

When I did my repower years ago with the 6BTA Cummins, I had to buy what Cummins called a restrictor when I plumbed in my HW tank. The restrictor was basically a washer pressed into a plumbing fitting to reduce flow.

 

[catalinajack]

Now that i have my oil worries solved, i wanted to talk about a great success story, the bus heater.

For about $250 the heater heats the entire lower portion of the boat, including the two cabins and two heads.

Not only that, with outside temp around 50 and the pilot house getting downright cold, when I turn on the bus heater, I will actually feel the difference in the pilot house in about an hour.

To the point that I must turn it off.

The best $250 i ever spent.

Should have done it on the first day.

Now, I must talk to Brian at American Diesel, as the engine is running even cooler, so I must change the thermostat.

I have actually turned off the heater, even when i was still cold, because the engine was running too cold, only 160°F vice it's normal 175°

So, I am curious about your "normal" 175F operating temp. I recently purchased new thermostats for my FL 120s from Brian. He sent 195F units. My engines generally run at 190F and 197F. And the manual states that 195F is the optimal operating temperature. What am I missing?