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paulz
Member
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# Posted: 16 Nov 2018 09:37pm - Edited by: paulz
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I'm not using a thermostat with my propane wall heater, just a toggle switch by the bed. I want to use a different toggle switch that lights up when on. The switch has 3 terminals. Top one takes +12v, bottom -12v, middle connects to the +12v when on.
Can I connect the two wires from the heater to the +12v and the middle terminal? See diagram. 12v is not needed for the heater, just connecting the two wires turns it on.
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DaveBell
Moderator
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# Posted: 17 Nov 2018 05:04am - Edited by: DaveBell
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SPDT Toggle Switch
http://www.learningaboutelectronics.com/Articles/Toggle-switch-wiring.php
Set a DVM to DC.
Switch the toogle away from the LED. Connect + Batt straight to a DMV red lead, and - Batt to the pole at the LED and then the center pole to the DMV - black lead. The current flow should light the LED and show 12V on the DVM when toogled towards the LED.
I don't know which side of the LED is Anode and Cathode. So if it doesn't light, reverse the wires.
If this works the way you want, connect the + Batt straight to the heater and the switch center lead to the heater. Now you have circuit on/off, simply.
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DaveBell
Moderator
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# Posted: 17 Nov 2018 05:07am
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You might want to add a fuse in line on the positive side for safety. The heater manufacturer may have a recommended fuse size.
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paulz
Member
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# Posted: 17 Nov 2018 09:30am - Edited by: paulz
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Thanks Dave. SPDT means dual throw I believe? This switch toggles only one way. But I understand your test instructions, and there is connectivity between the + and middle terms when the light is switched on. So it would turn the heater on.
My concern is that the heater wires would also be connected to the + side of the 12v battery but since it would not be connected to the - side it should be ok? Just don't want to hurt the heater controller.
Per the instructions, normal use of this switch is to power a 12v device via the middle terminal.
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toyota_mdt_tech
Member
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# Posted: 17 Nov 2018 01:42pm
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Does the thermostat use 12V?
Maybe a DPST switch, ie will have 2 poles, 4 terminals. Use one pole for the heater, other for a separate 12V circuit that can turn on a lamp.
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paulz
Member
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# Posted: 17 Nov 2018 03:57pm
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The heater doesn't need outside electrical power, i guess it generates enough off propane to activate the gas valve by shorting the two wires. I put my meter on the 2 wires, about .5vdc with the pilot on.
The plot thickens: I connected just the two heater wires to the switch, middle and + terms. Flipped the switch, heater came on as expected. Then I threw caution to the wind and connected a 12v battery to the + and - (outer two) terms. Light came on, heater stayed on. Looking good. Then however, I flipped the switch off and both the heater and light stayed on! Disconected the battery and it turned off. Somehow there is some back feeding going on but I can't get my brain around it. Tried switching the heater wires, reversing the .5v polarity, same thing. Guess I need a DPST.
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toyota_mdt_tech
Member
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# Posted: 17 Nov 2018 05:09pm - Edited by: toyota_mdt_tech
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Yes Paul, with a DPST switch, you will have two separate circuits ie heater and 12V for bulb, and you can add a 12V LED or bulb. Just so you know its on from a quick glance is what i think you are after. Is there a reason you just dont put in a Honeywell round thermostat? Zero power needed.
$40 from Homey Depot.
https://www.homedepot.com/p/Honeywell-Round-Heat-Cool-Thermostat-CT87N/202219050
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paulz
Member
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# Posted: 17 Nov 2018 07:43pm
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Thanks TMT. Maybe a thermostat is the way to go. I got the heater used without one so initially just jumpered the two terminals. Then wired a toggle switch by the bed but I forgot to turn it off one time until it was about 90 degrees in the cabin. So I figured a lighted switch would be good. I'm still a bit nervous about the heater, don't use it while sleeping or when I'm not there, so a lighted switch would tell me for sure if it's on. I'll probably get over the fear, it's really no different than a home wall heater I guess, except for being installed by a duffer
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