My DIY MEP803 Arctic Heater

[Haoleb]

So let me start out by saying that the objective here was a small heater I can plug in to keep the engine in my 803 warm(ish) when I know it is going to be cold and a good likely hood of power outage. I feel pretty comfortable knowing that the genset will start in cold weather but I do not want to start it when it is very cold if I don't have to. So the options for this are... any number of stick on or magnetic block/oil pan heaters.. but those things all seem pretty cheap and risk of a fire. So I wanted to come up with a better option.

Here is what I came up with. I purchased a 350watt strip heater that comes with the optional finned heat sink. Cost was about $35. I chose this because I believe that 350 watts is about right for an enclosure this size in 0 degree weather and I did not want to have any higher of a wattage than I need because energy is not free!

I originally planned to mount the strip under the engine or somewhere else that is away from anything that might melt or be flammable... but after closer inspection I did not really find any option I liked. But then there- right in a spot away from anything that might burn was the document box on the door. Perfect! I can mount the heater inside of this and it will be completely enclosed in a metal box (fire hazard reasons) and there will be no chance of melting battery cables or hoses... etc. Of course a heater by itself in this box would not do much and it would still get very hot so.. simple.. Just add a fan and make it forced air heater! Because of my job where I repair and sometimes take apart and scrap all kinds of machines I have collected all sorts of spare parts I brought home to use again someday so a lot of them came in to use for this project. The only piece I had to buy was the heater.

Lets begin... First step was I removed the document box off the door so it could be modified.



Next step was I removed the schematic diagram by drilling out the rivets. Have not found a place to reattach this yet but for now it sits in my binder with the TM



Next issue is the heater. I wanted to put it inside of the box but it was just a little too big.. Well the angle grinder made pretty quick work of that and still left me fully functional mounting holes.





So now I proceed to cut a hole for the fan, mount the fan and fan grill with 3/16" rivets. Then I mounted the heater strip with 1/4-20 bolts so that it sits right about in the middle of the box. I also drilled 3 holes in the top to allow air to exhaust out of the box. The fan sucks air into the box where it passes over the heater and out the holes toward the engine. I kind of forgot to take pictures through this part but I also added in a small switch that is actually a circuit breaker rated for 3A (trip around 4.25) with the 350 watt heater and the 15 watt fan this is perfect for circuit protection.



I used about a 6 foot piece of 14AWG SJ cord for the power cord. I have attached it and wired it up in the picture here. The plan is to pass it right through the door and put a plug on it.



Now its got real. I just drilled a hole right into the door. No going back now!



Heater fully installed and wired up! I installed a 90 degree cord grip through the door and put a plug on the other end so I can just plug it in when needed.



You will notice I have also added some sound insulation to the doors as well. The insulation had a metal mylar type surface on it but I added aluminum tape to the surface to help it reflect additional heat. No issues with this foam and the heat even running 12 hours straight.



So I plugged it in to see how it would work! Outside temp is about 10 degrees but in the sun. I have the thermocouple attached to the wiring harness right above the fuel cutoff solenoid. This is the starting internal air temp. I also put some tape over the air intake vents on the front and a blanket over the radiator vent on the top for this experiment.



1 hour after turning on the heater. Inside air temp up to over 50 degrees. The heater box is barely warm to the touch. The fan definitely keeps that heater compartment at a cool temperature.



After around 2.5 hours up to just over 60 degrees. The other thermometer is measuring the surface temperature of the outside of the generator.



I still have it plugged in. I am going to let it run overnight as we are supposed to get below zero tonight and then I will measure the inside air temp in the morning. I would assume by then that the engine will be at the same temperature but I am also going to dip the thermo couple wire into the oil and measure that temperature to see what it is reading. Obviously this is not as efficient as something like a true block heater installed into the coolant jacket but so far it looks pretty promising for my intended uses.

I have calculated at my energy cost of $0.07/KWH it will cost me only about 60 cents to run it for a 24 hour period. Granted that is more than I want to spend to just let it run for 3 months straight when we get our coldest temps but certainly do-able for keeping this running on the days I know it will be very cold.

For those who are interested, The heater strip is a Tempco CSF00519. The fan is a Mechatronics UF12A12-BTHR 120mm fan. Will report back tomorrow with my findings in the morning.

 

[Kenny0]

Good idea and nice work. How about adding a piece of heat resistant insulation inside the box fastened to the door, that should increase its efficiency some. Also using an insulated blanket (like the ones used to cover rapid cure concrete which are weather resistant) to wrap the entire generator.

 

[Haoleb]

Good idea and nice work. How about adding a piece of heat resistant insulation inside the box fastened to the door, that should increase its efficiency some. Also using an insulated blanket (like the ones used to cover rapid cure concrete which are weather resistant) to wrap the entire generator.

I would like to make some kind of waterproof canvas cover customer fitted to the generator. Right now I just keep a tarp over it. Normally it stays inside my garage which never gets below the upper 30's but for this winter I decided to store it outside and let my truck have the nice protected hibernating spot.

So now to report on the overnight results. Outside air temp this morning was just about 0 degrees. I was pleasantly surprised to see that the inside air temp still was maintaining around 60. Just for kicks I gave it a quick start as I would in the summer. No preheat or anything and it started right up like any other day. Overall I would say mission accomplished with the heater. I might add in a high limit cutoff onto the top of the heater box to cut the power in the event the fan dies and it starts getting really hot.




Again showing outside temp and inside air temp.



Measuring oil temperature inside of the sump. Exchanging heat from metal to air back to metal again not very efficient but this way everything in there is one temperature.

 

[robson1015]

Nice work...

 

[Kenny0]

:So now to report on the overnight results. Outside air temp this morning was just about 0 degrees. I was pleasantly surprised to see that the inside air temp still was maintaining around 60. Just for kicks I gave it a quick start as I would in the summer. No preheat or anything and it started right up like any other day. Overall I would say mission accomplished with the heater. I might add in a high limit cutoff onto the top of the heater box to cut the power in the event the fan dies and it starts getting really hot.

Looks like A Success

 

[pjwest03]

I have calculated at my energy cost of $0.07/KWH it will cost me only about 60 cents to run it for a 24 hour period. Granted that is more than I want to spend to just let it run for 3 months straight when we get our coldest temps but certainly do-able for keeping this running on the days I know it will be very cold..

I have used these http://www.thermocube.com/ for years with my diesel tractors.

There is a more advanced option now also http://thepowerbadger.com/

 

[Haoleb]

So another quick update. I added in a high temperature cutout switch for an additional safety measure. I happened to remember just a couple weeks ago I pulled off a thermo-switch from a heatsink I found in the scrap bin. Dug it out and looked up the specs... Perfect! it was a open on rise switch set for 150 degrees F and with 8A current rating.

I got a piece of scrap 1/4" aluminum and mounted the switch to that for some added mass to keep it from switching too quickly for any reason then I drilled the appropriate mounting holes into the document box cover and attached it directly above the heater inside of the box. Now if the fan dies and I loose the forced air cooling it will heat up and cut the power. The switch does self reset and it would turn the heat back on once it reset but I feel pretty confident that this little setup should be pretty safe.

 

[Farmitall]

So another quick update. I added in a high temperature cutout switch for an additional safety measure. I happened to remember just a couple weeks ago I pulled off a thermo-switch from a heatsink I found in the scrap bin. Dug it out and looked up the specs... Perfect! it was a open on rise switch set for 150 degrees F and with 8A current rating.
I got a piece of scrap 1/4" aluminum and mounted the switch to that for some added mass to keep it from switching too quickly for any reason then I drilled the appropriate mounting holes into the document box cover and attached it directly above the heater inside of the box. Now if the fan dies and I loose the forced air cooling it will heat up and cut the power. The switch does self reset and it would turn the heat back on once it reset but I feel pretty confident that this little setup should be pretty safe.

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Nice work!!

You could also tie in a relay connected to a Piezo buzzer that would sound if the high temp cutout activates. The relay would be held closed while power to the heater was present and when it dropped out it would close the terminals to activate a Piezo buzzer.

The buzzer DC circuit could be powered off the battery as it would never draw any current unless it activated so it wouldn't run the battery down at all.

For times when the heater is not being used, just put a toggle switch in series with the DC buzzer circuit to open it so no battery current is drawn.
This would give you an audible alarm to inform you of a heater malfunction.

 

[Kenny0]

So another quick update. I added in a high temperature cutout switch for an additional safety measure. I happened to remember just a couple weeks ago I pulled off a thermo-switch from a heatsink I found in the scrap bin. Dug it out and looked up the specs... Perfect! it was a open on rise switch set for 150 degrees F and with 8A current rating.

I got a piece of scrap 1/4" aluminum and mounted the switch to that for some added mass to keep it from switching too quickly for any reason then I drilled the appropriate mounting holes into the document box cover and attached it directly above the heater inside of the box. Now if the fan dies and I loose the forced air cooling it will heat up and cut the power. The switch does self reset and it would turn the heat back on once it reset but I feel pretty confident that this little setup should be pretty safe.

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I think I would mount the switch on the top of the box instead of the inside and forget the heat sink, the top of the box will act as a heat sink. Mounted as is, it could melt the wires with no air moving. Another way for audio warning would be to hook up a 120 volt buzzer or piezo, one wire to each side of the cutout switch. Cutout switch opens and the buzzer goes off. The smaller current the buzzer or piezo is rated the better. A 0.2 amp or less should be okay. That should keep the heater cool enough without air moving.

 

[Bmxenbrett]

Cool idea! Im suprised that 350w was able to keep the oil that warm.
You should stick your temp probe in my the fuel tank. Gelled fuel is alot more of a deal killer than cold oil.

 

[Haoleb]

Good tips. I did consider adding a relay and making it latch so that if the switch opens it is no longer latched and power would not be re-applied unless a reset button was pressed. I could also add in a warning light on the outside to indicate overtemp but then I could really get carried away adding in thermostats and all kinds of doodads. All of the wiring inside there is 105C rated so it should be ok with the switch opening at 90. This spring when I can move the generator back into the garage I plan on revisiting this a little bit but for now it is just too cold to tinker with it outside.