Gas and Oil Home Heating Furnaces - gas furnace

installing a gas furnace.....

2 questions.

1) instructions say to use ground joint union inside the cabinet. why is this necessary?

2) instructions say to install a drip leg in the supply line as close as possible to the furnace. what's the purpose of this? and how is this supposed to be installed?

thanks

Hello: F. Donger

I moved your question from my gas appliances forum to this heating and cooling forum. In doing so your most likely to get the advice of several professionals experienced in the installation process and requirements.

Basically speaking, you cannot have too many grounds in any appliance with electronic componets. All units attached to the basic heating unit must be grounded and grounded to each other.

Then the entire unit must be grounded to the electrical ground and most likely this unit needs to be grounded to the piping. Why I will never know either.

Gas supply lines are not grounded in my state. Most of the underground lines are PVC plastic lines and they are not grounded.

In fact, all gas lines are not supposed to be grounded. Grounding increases corrosion and rusting of the metal piping. Plastic lines cannot be grounded since the material contains no metal.

I suggest you install the unit exactly as installed and have the final assembly inspected by a licensed heating contractor. Doing so will insure the unit operates and functions correctly. Plus doing so maintains the OEM warranty and meets all local codes.

Knowing exactly what type of unit this is and where it will be installed would help the other professionals in this forum to offer you more accurate and detailed information spefici to the unit.

Resident heating professionals replying within this forum, may have alternate solutions, suggestions, opinions and or test and repair methods. Check back several times for additional replies.

Regards & Good Luck, Web Site Host & Multiple Topic Moderator.
TCB4U2B2B Company Enterprises. Energy Conservation Consultant & Gas Appliance Diagnostics Technician.

# 1 So down the line if you have to replace the gas valve you can take the line apart and put a new valve in


# 2 You put the drip leg and cap down under the T that goes into the furnace that is so any dirt and junk in the gas line or in the gas goes down in that and not into the gas valve

;) ED

thanks Ed,

so, if my gas line is coming up from the basement subfloor, i don't need a drip leg right?

Where the 90o L is for going up make that a T and go up to the furnace. On the bottom of that T put a 8" nipple and a pipe cap. This will keep the junk out. The old gas lines get a rust to them and this is what you get in the lines . So you want this to get in the nipple with the cap and not in you gas valve.
Also when they said a ground union. That was not for electric ground. Some of the old unions had a rubber in them. This one they want is a steel to steel fit;) ED

thanks ed.....i got it...