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| ? for Electric minded ppl..not related to cars. (Page 1/2) |
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maryjane
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DEC 04, 08:23 PM
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I have a torpedo heater 2 yrs old and dual fuel...kerosene or diesel. Brand=Master (made by Pinnacle)
Model is MH-75T-KFA.
Info can be found:
http://masterindustrialprod...M_EN-FR-ES_20151.pdf
(mine does not have the wheels, but that's moot in regards to my problems with it.)
The electrical diagram from the users manual I got with the unit:
It works fine. Has a rotary dial thermostat, with a range from 40 deg F to 100 deg F. This typical pot thermostat is soldered on to a little board.
Thermostat knob is on the far left. There is a green led that illuminates any time the power switch is on.
The heater works great as long as one parameter is met..... 
The ambient temp must be below 47 deg F for the ignitor to come on, motor to turn on and for it to work.
If the temp is below 47degF it works fine, regardless of where I set the thermostat (providing I don't turn it down below 40 deg F ambient temp.)
If ambient temp is below 47 degF and I set the thermostat to 100, it will run till I either rotate the thermostat down or until it runs out of fuel IF the ambient temp is or stays below 47. Once the temp reaches above 47, the unit shuts off, the green light stays on but the unit will not restart. I feel the thermostat is working correctly but whatever tells the PCB what the ambient temp is may not be working right. Boxed in red or yellow in the diagram above are 2 suspects.
In red, is the thermostat limit control, which I would call a thermister and it is mounted just below and behind the fuel nozzle. It's always been my belief that it's job is to protect the unit from extreme temps if too much fuel enters the combustion area, but it may be this is what somehow senses ambient temp as the air is blown into the chamber.?.
The thermostat limit control:
In Yellow, is what the diagram refers to as a 'room sensor'. I can't find anything on it in my research, nor can I locate it on my unit. It appears on the diagram to be outside the PCB, but I haven't found it yet.
Thoughts?
Is there a way to test the thermostat limit control (thermister) ?
Can it be bypassed? (I don't really require a thermostat, as the unit sits in open space on the front porch and is just used to knock the chill off us late at night or early morning as we sit outside and enjoy the Great Outdoors)
I could get a new board for it ($90 + shipping) but if it's one of the other components I'd rather not waste $$. The thermister is only $4 + shipping.[This message has been edited by maryjane (edited 12-04-2019).]
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Boondawg
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DEC 04, 09:53 PM
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I can't help, but I loved the read! 
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WBailey1041
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DEC 04, 10:56 PM
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Does the green led flash?
Constant on?
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theogre
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DEC 04, 11:27 PM
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Red box would kill 120vac so green LED and rest of unit will be off when that is "active."
I think is a "kill switch" for tip over or more likely over temp in the unit. They are very dumb.
Schematic CN2 is connector but maybe installed board has the thermistor on the board.
The sensor could be bad or several things on the board have problems including the temp control pot.
Themistors generally work or not but crap wires etc can make them to read way off. Sim to OP and Coolant gauges in Fiero.
Can't read text in board picture.
Is from a parts store site? Don't trust the picture. Even if correct, Picture may not be an exact match for board you have.
------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave[This message has been edited by theogre (edited 12-04-2019).]
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Blacktree
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DEC 05, 01:39 AM
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This is all just a guess. But here's my thought process.
The Room Sensor appears to be a thermistor that reads the ambient temperature. I'm guessing that's your culprit. According to the schematic, it attaches to electrical connector CN2 on the circuitboard. And the CN2 connector appears to be on the bottom edge of the circuitboard, to the right of the dial knob. Find out where those wires run to, and you'll find the room sensor.
If you have an Ohm meter, you can test the sensor and see how it behaves.
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maryjane
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DEC 05, 11:04 AM
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WBailey1041--the green led is illuminated solid (no flash) anytime the power switch is on, regardless of temp or where the thermostat is set.
The Ogre--Yes, picture of the board is from a parts store website. I will get a good picture today of the actual board on this unit with my dig camera.
I agree that the limit control is usually for overtemp protection. There is a little blurb in the trouble shooting section that says:
"My heater runs for a short period of time then shuts off?
Try turning up your air pressure in 0.5 PSI increments, and try to start again. Also be sure after running a couple minutes that the nose cone is cherry red without any flames coming out. If it is not cherry red, turn up your air pressure 0.5 PSI or until the nose cone glows red. If the heater is running at the correct air pressure and still shutting off, then a slight adjustment to the high temperature switch bracket may be required. Bending the bracket slightly away from the rear of the combustion chamber will decrease the sensitivity of the switch. Always ensure that you never set the pressure higher than the stated setting in the manual."
This might solve an unwanted and premature shutdown, but will not solve the problem of a no start from "cold iron' condition.
This morning, I jumped the thermo limit control by moving it's yellow wire directly to the output side of the switch.. This had no effect.
Blacktree--I too am of the opinion that "room sensor" problem makes sense. I'll have to tear it apart further and see if I can find it..assuming it isn't actually a board component. It would be nice if I had an actual board or unit wiring schematic instead of that pretty limited block wiring diagram but I've looked hard and haven't been able to find one. Propitiatory information I suppose.
Hasn't been all that long ago, I would just do away with that board altogether and wire everything into the switch or a couple of switches. All the old ones had was a switch to power the motor, the high voltage transformer, with wiring going thru a flame sensor, and an anti-tilt switch.
Nowadays, I'm more safety conscious but I do hate that everything you get now has an electronics board that always seem to go out...
.[This message has been edited by maryjane (edited 12-05-2019).]
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cliffw
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DEC 05, 01:26 PM
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Curiosity.
What are you using it for ?
I have one of 'them type heaters. Only used while I am there. You have to be wary of carbon monoxide poisoning. You knew that.
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maryjane
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DEC 05, 03:24 PM
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Cliff...We just use it on the open air front porch as radiant forced air heat for ourselves when we sit out there at night or for me early in the morning while drinking coffee and taking in the new day...and in very low temps in my shop which is already pretty well ventilated thru the eaves but I always open the drive thru overhead door a little and block open the walk in door some as well. In that instance, it was for the dogs to get out of below 20F cold temps and hard N wind. The thermostat came in handy in that, as I set it for 50F.
I believe I have found "room sensor". Coiled up in a wire bundled at the very back of the unit below and slightly behind the fan motor. A little tiny thing. Pics shortly.
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maryjane
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DEC 05, 04:04 PM
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williegoat
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DEC 05, 04:20 PM
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It might be worth a try to clean and re-seat the connector.
I'm sure you have examined the wire for damage.
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