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I will like to know how to wire the 24 volts from the secondary…

Customer Question
I will like to know...
I will like to know how to wire the 24 volts from the secondary side of the transformer to the normally open and Normally closed relay. I know that the 120 volts is staged down to 24 volts for control. And I know that 120 volts is conducted from the door switch to one of the normally open terminals on the relay. Would the common on the 120 go to the door switch also?
Submitted: 8 years ago.Category: HVAC
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Answered in 58 minutes by:
6/25/2010
HVAC Technician: Tim H., HVAC Professional replied 8 years ago
Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3,972
Experience: Experienced in all aspects of HVAC, both residential and commercial.
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Thanks for giving me the opportunity to help! Let me see if I can try to help you. First of all, which relay were you trying to replace? Is this the fan relay (the one that controls the fan?)
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Customer reply replied 8 years ago
This relay is the control relay. The terminals are numbered from 1 to 6. The first two switches are NO., and the other two switches have to be energised to open then, the fan will come on. However, I had the black hot wire that is pigy backed coming from the door switch to one of the terminals on the relay, but the terminal does not show , according to the diagram on the relay, if it is NO or NC. Then, I had the common wire hooked up to the white wire that goes to the heat. May be I shouldn't have done that cause, I am thinking that is why the heat came on with the fan at the same time when I fliped the power switch to "ON", even though the door was open. This is all I could tell you.
HVAC Technician: Tim H., HVAC Professional replied 8 years ago
Are you trying to control the fan only with this relay?
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Customer reply replied 8 years ago
I am trying to wire this relay according to how it is supposed to be wired, so that, it can control the flow of the 24 volts to control when the fan comes on and when it shouldn't. What I am not sure of is that, I don't know if I have to just send 120 volts to the fan motor or through the relay. For your information, this is a furnace with a control board.
HVAC Technician: Tim H., HVAC Professional replied 8 years ago
On a fan relay, you only control the hot side of the 120 volts. In other words, one side comes from the hot side of the 120 volts and the other side goes to high speed hot lead of the blower.
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HVAC Technician: Tim H., HVAC Professional replied 8 years ago

on a fan relay, you only control the hot side of the 120 volts. in other words, one side comes from the hot side of the 120 volts and the other side goes to high speed hot lead of the blower.

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