3/4" gas line needs to be bigger - DIY Chatroom

raymond_anthony · 10-16-2006, 06:31 PM

I had a new furnace put in today. Its a frigidaire 80,000 BTU force hot air unit. I was told by the installer that my gas line (3/4") is not big enough and that the line needs to open up to 1 1/2" after the main. I guess I am confused because main gas line coming up through the ground is only 3/4" so how would opening up to a 1 1/2" pipe increase flow. The main has a T connector on it with one (3/4")line going to another thermopride unit which works fine and the other 3/4" line going to my hot water heater and new furnace. The hot water heater works fine. I have no other appliances using the gas. The gas man said I had 8 something or other coming from the main which is more than enough. Anyone know what is going on here.

majakdragon · 10-16-2006, 07:36 PM

I would call the business that is doing the installation and explain what the gas company said. I have never seen that size line for residential even though I have had the same units running off a 1" main. You don't want to "starve" any appliance for gas but that size sounds pretty large.

raymond_anthony · 10-16-2006, 07:42 PM

I am looking at the notes now and it says 1 1/4" I apologize. My install guys are blaming it on the fact that the plumbers who hooked up my other furnace used 3/4" pipe and tapped off of the existing line. However, the other furnace and appliances arent even on. I feel like im gonna get screwed on this.

#CARRIERMAN · 10-21-2006, 03:27 PM

Hi raymond anthony

Whomever is doing your installation sound like they smoked their crack pipe prior to coming to your house. Ask them to show you a layout of the gas line sizing chart from block. I bet they don't even know what that is. I bet the gas man was talking about 8 inches of gas pressure. For natural gas that is about perfect. I would probably have to reccomend finding someone else to do your plumbing.

Good luck
Rusty

Double A · 10-23-2006, 02:32 AM

I assume we're talking natural gas here. If so, 3/4" will carry a great deal of BTU load, but that all depends on the incoming pressure after the meter. The gas company can tell you what that is. Keep in mind, that they usually use a 2 psig delivery but only 4 ounces of pressure past the meter.

Your local gas code will dictate the size of line required for this new heater. Get a gas fitter or plumber to come out and take a look.

mrairflow · 10-27-2009, 10:14 PM

tell them that if they replace the line and it does not fix the problem you will not be obligated to pay for it see if they still think it is the problem , most of the time if a gas line is to small the heater will still start but not stay lit or have a small flame

Plumber101 · 10-27-2009, 11:01 PM

Quote:

Originally Posted by #CARRIERMAN

Hi raymond anthony

Whomever is doing your installation sound like they smoked their crack pipe prior to coming to your house. Ask them to show you a layout of the gas line sizing chart from block. I bet they don't even know what that is. I bet the gas man was talking about 8 inches of gas pressure. For natural gas that is about perfect. I would probably have to reccomend finding someone else to do your plumbing.

Good luck
Rusty

I'll have to go with Carrierman here. Have this blissful plumber do a lay out and sizing. Also make him have the code book that will have sizing info there. There reaction might give a clue to if he is BS's you for more money/work

beenthere · 10-28-2009, 07:48 AM

Quote:

Originally Posted by Plumber101

I'll have to go with Carrierman here. Have this blissful plumber do a lay out and sizing. Also make him have the code book that will have sizing info there. There reaction might give a clue to if he is BS's you for more money/work

Look at the date of the OP's post.

Hope its resolved after 3 years.

Viper16 · 10-28-2009, 04:34 PM

I sell gas regulators..and trust me if you can get 14" water column of gas to a regulator you can most definitely pass at least 150,000btu/hr of gas out of a 3/4" gas line. Call someone more competent.

beenthere · 10-28-2009, 05:07 PM

How many BTUs is the Thermopride, and how many BTU's is the water hater.
How long of a run is ti from the meter to the water heater, and the new furnace.

Plumber101 · 10-28-2009, 07:45 PM

Quote:

Originally Posted by beenthere

Look at the date of the OP's post.

Hope its resolved after 3 years.

HATE WHEN THA HAPPENS

beenthere · 10-28-2009, 07:59 PM

LOL.. Yea, lots of old post revived recently.