Normally those three lines go to:
1) burner box
2) collector box which is what the exhaust fan/inducer attaches to
3) VERY important, it goes to a port on the gas valve. Usually there is a barbed fitting on the side of the valve and the hose goes there. It is supposed to modulate the gas valve pressure if the intake pipe starts to plug with snow or debris. The vacuum in the burner box sucks on the gas valve diaphram and the pressure switch at the same time. Not all furnaces do it that way but if they have a closed burner box they should. If the burners are wide open when you remove the front door then there is no box to hook it up to.
Sounds to me like the previous tech(s) did not know what they were doing and decided to cheat by disconnecting it. That can be dangerous as the switch is getting the wrong vacuum and the gas valve should modulate the pressure for safe and proper combustion.
After 5 posts you can attach pics here. Intro yourself on the home page and get 5 posts. Then post pics of the hoses and burner area.
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1) burner box
2) collector box which is what the exhaust fan/inducer attaches to
3) VERY important, it goes to a port on the gas valve. Usually there is a barbed fitting on the side of the valve and the hose goes there. It is supposed to modulate the gas valve pressure if the intake pipe starts to plug with snow or debris. The vacuum in the burner box sucks on the gas valve diaphram and the pressure switch at the same time. Not all furnaces do it that way but if they have a closed burner box they should. If the burners are wide open when you remove the front door then there is no box to hook it up to.
Sounds to me like the previous tech(s) did not know what they were doing and decided to cheat by disconnecting it. That can be dangerous as the switch is getting the wrong vacuum and the gas valve should modulate the pressure for safe and proper combustion.
After 5 posts you can attach pics here. Intro yourself on the home page and get 5 posts. Then post pics of the hoses and burner area.
Go Advanced>Manage attachments