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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Old heater w/two limit switches, fan, transformer, three

Customer Question

old heater w/two limit switches, fan, transformer, three terminal gas valve, brother replaced the fan but unconnected all wires, i need to know how to rewire it now, thanks for your help
JA: I'll do all I can to help. Is there anything else important you think the HVAC Technician should know?
Customer: no, transformer tested ok,
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the HVAC Technician about your situation and then connect you two.
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

Look and see if there is a label with model number

Customer: replied 1 year ago.
model is 68 200 7, 160,000 btu/hour
Customer: replied 1 year ago.
serial no. 0472 2
Expert:  Tim H. replied 1 year ago.

Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need. Please be patient as many times we work with several customers at once.

Does the unit have a wiring diagram you could upload?

Customer: replied 1 year ago.
if it had a wiring diagram i wouldn't need further information,it has one power in wire(a black, a white, a green) white should go to white on input side of transformer-and white on fan motor, black to one of the thermistor in and out to black in on transformer (?), transformer out one lead to TR(?)on gas valve,other to the other thermisto, thermistor out to gas valve TR-TH(?), and thermistat wires to gas valve TR-TH and gas valve TH ?? any way those are the six elements i need to connect probably not in the right sequence, the sequence is what i need help with, thanks for your help and any input you might have, it is an old unit and has had undoubtedly modifications through its life (changed gas valve, it appears newer than the rest of the unit
Expert:  Tim H. replied 1 year ago.

If you can upload some pics of all the components, I can take a look at them and try and see what I can do. It is tough working with a unit, no wiring diagram, no model number that will help (too old). Since it is a 3 terminal gas valve, I assume unit is standing pilot.

Customer: replied 1 year ago.
pilot works and unit is currently ported for natural gas, i have to travel to the shop to get pictures and no net access at the shop and bro's hour at the shop are irregular
Expert:  Tim H. replied 1 year ago.

OK, well the pics will help me a lot. I've seen almost everything out there in over 20 years in the business and you know what they say, a picture is worth a thousand words!