Check for Gas pressure?

[onetechyguy]

Hi, I have about 25' of 3/4 line ran out to the front of my detached garage for gas. I need to extend that another 25' to get to the back where I'm going to install me heater. The line is coming off a main 1" tee from the house. I wanted to check to see how much gas pressure I had before I started running pipe to the back of the garage so I bought a 0-30psi gauge from menards. When I hooked it up and turned the gas on it did not move, Is there a specific type of gauge that I am supposed to be using to accurately check gas pressure? This was a round analog gauge. I had a vent free 30,000 btu heater hooked up before so I know there is gas. I need to install a 75,000 heater and want to make sure there is going to be enough gas pressure. Should I have ran 1" out to the garage? Any ideas? Thanks

 

[6768rogues]

After the regulator the gas pressure is too low to measure with the gauge you mentioned. It is measured in inches of water column and if I recall correctly translates to about 4 ounces of pressure. That is much below your gauge's sensitivity range. The low pressure gives a nice blue controlled flame, not a roaring blow torch type of flame.

 

[Andamo]

If you really want to check the pressure, get a 6' length of 1/4'' Tygon tubing and make it into a U shape. Put some water into a small bowl and add some food coloring. Pour this water into one end of the U tube and the water will seek it's own level and the level in the 2 tubes should be directly across from each other. You've just built a manometer.Then where you already have the existing gas tap, and a valve, run some temporary piping to one side of the U tube making sure your connections are all tight. Place the U tube so that it's vertical and slowly turn on the gas valve. One side of the colored water will drop down and then stop with the valve completely open. The difference between the 2 water levels in the U tube is your gas pressure measured in inches of water. Usually on your heater there is a specification called W.C. (water column) that the heater needs to have to operate correctly.

 

[theoldwizard1]

Gas pressure is almost never the problem.

Gas VOLUME can be a problem if the pipe is not big enough.

 

[brihvac]

If you really want to check the pressure, get a 6' length of 1/4'' Tygon tubing and make it into a U shape. Put some water into a small bowl and add some food coloring. Pour this water into one end of the U tube and the water will seek it's own level and the level in the 2 tubes should be directly across from each other. You've just built a manometer.Then where you already have the existing gas tap, and a valve, run some temporary piping to one side of the U tube making sure your connections are all tight. Place the U tube so that it's vertical and slowly turn on the gas valve. One side of the colored water will drop down and then stop with the valve completely open. The difference between the 2 water levels in the U tube is your gas pressure measured in inches of water. Usually on your heater there is a specification called W.C. (water column) that the heater needs to have to operate correctly.

Old School, LOL

Pressure will vary depending on your area. When I set a heater up I usually adjust it to 1/2in WC

 

[onetechyguy]

Thanks guys! I was thinking that was probably not the right gauge to measure it with. My buddy that lives about 15miles from me ran a 3/4 pipe from the front of his existing house to his detached garage about 100' distance and he doesn't have any problems and he has 2 heaters. That is interesting with the diy manometer gauge. I might have to try that! lol

 

[Briguy_123]

Measuring the static pressure (pressure with heater off) will tell you nothing. You need to measure the input pressure at the max firing rate of the heater (75k btu in your case) My Big Max heater requires a minimum of 5 in wc inlet which is very low considering most residential systems run around 12 in wc. The output pressure of the gas valve on my Big Maxx is 4 in wc for altitudes of 0 to 2000 feet.

 

[mitymouse]

Hi, I have about 25' of 3/4 line ran out to the front of my detached garage for gas. I need to extend that another 25' to get to the back where I'm going to install me heater. The line is coming off a main 1" tee from the house. I wanted to check to see how much gas pressure I had before I started running pipe to the back of the garage so I bought a 0-30psi gauge from menards. When I hooked it up and turned the gas on it did not move, Is there a specific type of gauge that I am supposed to be using to accurately check gas pressure? This was a round analog gauge. I had a vent free 30,000 btu heater hooked up before so I know there is gas. I need to install a 75,000 heater and want to make sure there is going to be enough gas pressure. Should I have ran 1" out to the garage? Any ideas? Thanks

Its good you came off of 1 inch for volume,And you distance should be much of a problem for 75,000 btu. however you didnt mention if you used hard pipe or corregated trac pipe/ and the amount of 90s in the pipe. Each 90 is equal to 5 feet of pipe.

 

[39portlander]

I have an Idea, your insurance Co. and local fire dept. would agree to. Have a licensed gas tech. check your work.

Pipeing and install should not be done by weekend worriors. Guy's this is not funny stuff. 3'', 4", 5" manifold?, well can you do a combustion test to see if it's over fired? What are the CO2/O2 readings? If your buying a lb gauge to check inches, your in trouble allready

All gas heating equipment comes with instructions with those little reminders in red ink, be safe out there