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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8171
Experience:  Furnace, A/C and heat pump specialist.
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I have 2 janitrol wh-100 heaters. I have not used them for 8

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I have 2 janitrol wh-100 heaters. I have not used them for 8 years. Both are wired to their own thermostats. Neither fan will turn on when it falls below the set temperature.

This is a garage heater isn't it?

Customer: replied 9 months ago.
They are in a 3000 square-foot workshop. I had the same units in a warehouse that I rented years ago and I had somebody install these when I build my workshop.

OK, are you sure these units have a fan that comes on by lowering the thermostat?Most unit heaters just have a fan that comes on after burners ignite to circulate the heat

Customer: replied 9 months ago.
Unless there was a malfunction after I disconnected the gas. I thought the fans kept turning on until I turned off the circuit breaker. (I had stacked pallets of ice melt in front of the thermostats, so I couldn't turn them off.)
Customer: replied 9 months ago.
Can I "heat up" something in the heater to see if I'm developing parts-heifers?
Customer: replied 9 months ago.
That should have been "heat up" something on the unit to see if it will then turn on?

Normally the fans are only on when burners are lit.Tell me how many wires you have at thermostat . If only two wires, touch the wires together and see if we get any response.

Customer: replied 9 months ago.
I was getting "contact" and a clicking up in the unit, when I moved the thermostat, but nothing else.

1. Do you see a wiring diagram you can send me a pic of (I do not have manual on the model)

2. Do you have a volt meter so we can troubleshoot?

3. Did this model have a control board with a light to blink letting us know of a malfunction?

Customer: replied 9 months ago.
1. Attached.
2. Yes
3. No. I think it's too old.

Lest make sure the limit shows continuity with wires removed.

Then with thermostat calling for heat check for 24v between 24v common and 24v Hot from thermostat.

Customer: replied 9 months ago.
I have headed home and watch daughter so my wife can head to work. Will you be available tomorrow during the day?


Customer: replied 9 months ago.
Thanks. I'll respond tomorrow when I get back in.

Sounds good.

Customer: replied 9 months ago.
Let me know when you start for the day. I'll be back in front of the heaters in 15 min.

I am here. Lets check to make sure the limit is closed with wires disconnected. If so turn thermostat to call for heat and let me know if we get 24v to the valve

Customer: replied 9 months ago.
I am now getting no clicking in the unit when the thermostat is activated "up" or "down." I have checked the connections in both units and they are correct. I have 110 running to the fan switch on he left (I believe) and nothing at the motor switch. Pic attached. This might be more efficient if you don't mind calling.

Sorry for the delay.Got called away right after I replied. Can you bypass the fan switch to see if we get power to motor?

Customer: replied 9 months ago.
I can get the fan to run by direct connecting it to the incoming power. Is that what were asking?

I mean close the circuit below to fan by bypassing fan switch to see if motor will run

Customer: replied 9 months ago.
the fan turn on when I brushed the two connections of the thermocoupler (?) on the left

OK lets do this.jump the wires at the thermostat together and see if we get 24v at gas valve.

Customer: replied 9 months ago.
Sorry about that, I had an unexpected delivery. No voltage btwn TR/TH after jumping the thermostat.

How about 24 at the TR terminals on valve?

Customer: replied 9 months ago.
Nothing from TR/TR.

Hmm we may have a bad transformer. Don't these come directly from transformer? And how about 120 into transformer?

Customer: replied 9 months ago.
New transformer. That was my first guess because It looked so bad. Good power into the transformer which is hot because I forgot to unjump the thermostat

Let me know if the transformer fixes you up.

Customer: replied 9 months ago.
Sorry for the confusion. I have already replaced the transformer.

I see.So you have a new transformer but it has 120 in but nothing out?

Customer: replied 9 months ago.
I guess neither one of us read the schematic correctly. I have AC not DC coming out of the transformer. So testing it with DC didn't work. I have 120ac NOT 24dc between TR and TR at the valve.
Customer: replied 9 months ago.
Wait, is this the wrong transformer?

I only see one transformer on diagram. Power comes into transformer. Thermostat calls for gas valve to open , burners come on ands once temp is reached limit to fan closes signaling fan on from what I can tell.

Customer: replied 9 months ago.
This is the new one

WE only need 24v output but this should be fine.Anywhere between 24 and 28 is acceptable.Is the transformer not sending 25v out?

Customer: replied 9 months ago.
Battery must have been dying or it was dropped too many times. Borrowed a meter from next door.
24 at thermostat
0 btwn TH/TR
24 out of transformer

TR and TR at valve 24V?

Customer: replied 9 months ago.

OK jumping the thermostat wires should make valve open.

Customer: replied 9 months ago.
I thought I just did this. Are you saying TR/TH at the valve should be 24?

24V common goes to one TR terminal. 24V hot goes to other TR terminal.

One thermostat wire should connect to each TH.

When thermostat is raised or jumped the circuit should flow back to TH at valve giving us 24v between TR and TH See below.

Customer: replied 9 months ago.
I now have:
24 TH (top) to TH bottom
24 TR (top) to TH bottom

Gas valve should be clicking and opening. If not the solenoid on the valve may be defective

Customer: replied 9 months ago.
Something is clicking. I want to get some telephone wire and stretch it from the thermostat over to where the heater is a touch them together and see if the noises coming from the valve

OK. Make sure gas supply is on also.

Customer: replied 9 months ago.
Gas supply is OFF. The gas company said to make sure that the unit is "functional" before they came out.

Appears it should be functional once you have gas. If the valve is clicking, that means it is opening.

I think if we get gas it will work. Here is what should happen. Thermostat calls for heat,gas valve opens, burners light and heat chamber,when warm blower is energized.

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