Moding 120 volt system wiring help

[Jla74]

Hey gang, been reading this site for some time and always been able to get some great information. Thanks.

Now I have found myself with an old Modine 1973 PA75A garage heater and am having trouble finding instruction on wiring it up. It doesn't have a 24v low voltage circuit.

120v valve (2 wire), 120v motor (2 wire), 120v switch (3 wire Red-common, Blue-limit, black-fan) and thermostat.

 

[nadogail]

Google is your friend, contact Modine for installation and operation information.

 

[Jla74]

Tried both of those suggestion with no luck. Modine says they don't schematics for a heater of that age. I have been trying google for two days and can't find anything related to PA75A.

 

[nadogail]

Where are you? If you share your general location a member might offer to help.

Is there an appliance parts or air condition supply wholesaler in your area? They could be a connection to someone who will take on a side job.

In reality, a Gas Unit Heater and a gas clothes dryer will have a lot in common.

Keep in touch.

 

[Jla74]

It's not that I'm not familiar with electricity. I use to do residential wiring for new construction. But I'm not an HVAC expert and am looking for some assistance to ensure i don't connect something incorrect.

What I have so far which I just want to confirm is correct;

Power to thermostat, out of thermostat to hot on gas valve, out of gas valve via com(wht) to limit side of high temp switch, black off high temp to fan, com(red) out of switch to Line common along with the motor common.

I'm assuming the limit switch will open if triggered by high temp and open up the circuit shutting down the gas valve and fan.

 

[nadogail]

First let me post my disclaimers: I have yet to put my hands on a Modine Gas Unit Heater,
I am not an HVAC Tech, I am too far away to volunteer to look at your heater and see what I can figure out.

Having written that, here is what I have to offer. Any book on Gas Dryer repair should have information appropriate to working on your heater.

After all, your heater is similar to a dryer, just without a drum and up off the floor.

Does the heater have power applied to it? If yes. can you make the fan motor run?
If the motor won't run, does it have voltage to the appropriate terminals, If not Why not.

Is gas turned on to the valve? If not turn gas on to the valve,

Does the valve allow gas to the pilot burner?

What kind of ignition does the heater have? If it is a spark, is it sparking? If it is a Hot Element, is there voltage to the element. Those elements crack and look good but without current flow will not heat up. Moving the heater may have made the element crack.

There should be some limit switches to check if the fan is moving air through the heater and you are not in an Over Temperature condition.

Is the thermostat calling for heat?

If all else fails, you can ask you gas utility to preform a Safety Check on your heater.

Good Luck

Keep in touch

 

[Jla74]

Your missing the point here or maybe i was not clear on my question. The heater is sitting on my bench and hasn't been hooked up yet. I am not troubleshooting anything.

I'm simply asking if anyone has a wiring diagram for this simple circuit that I can verify my work against to ensure that when i get it hung and connected the safety systems function per design.

 

[nadogail]

I apologize for my failure to understand your situation.

Because nobody has responded to your request for a schematic, we can assume that you will have to finger it out for yourself.

Good luck. Keep us posted.

 

[bczygan]

Here?
http://www.garagejournal.com/forum/showthread.php?t=313612&showall=1

 

[Jla74]

That's great. the upper left on the computer screen is the one I have been looking for. I can make everything out except the wire colors on the limit. Is that drawing on your PC? if so can you save it as a PDF and email it?

 

[bczygan]

That's great. the upper left on the computer screen is the one I have been looking for. I can make everything out except the wire colors on the limit. Is that drawing on your PC? if so can you save it as a PDF and email it?

Photos are just links to the thread in the first link.

My eyes are bad and I can't make any of it out.

Note how funny it was, that I searched all over the net and found that on GJ, and in a very recent thread too!

Bill

 

[nadogail]

BCZYGAN , you have come through for all of us, thanks