I’m going to be moving the furnace from one side of the basement to the other.. I want to connect all of the gas pipe myself since it’s rather basic stuff.. I noticed other HVAC guys who do this all of the time use regular pipe joint compound, however when I questioned my gas guy about it he assured me a differant joint compound was called for.. ? Question one.
I do know they use a non corrosive leak detector which is differant from the normal soap I see used in the field to detect leaks.. I won’t be using the gas at all this summer so I can have the gas company come out and check my connections prior to turning on the gas.. Would it be advisable to use regular liquid soap to check my work, wash it all of and then turn the gas back off and wait for confirmation from the Gas company prior to turning it on in the fall? Question 2
I won’t be using the furnace at all in the future except as a back up. Would it be possible to simply extend the existing gas line , tap off it and run the gas to a couple of small fireplaces? Or will I need to up grade the pipe size (currantly 1 inch)
Replies
Someone should be along with the detailed answer. My brother used a white sealant with teflon in it. Comes in a small plastic jar like other compunds, but is very good for threaded black steel. He called it snot and that is exactly what the drips looked like. When a threaded joint was tightened up, it created a nice bead around the perimeter.
...that's not a mistake, it's rustic
Thing #1, will the distance the gas runs be longer? If yes, you have to check the size tables. Inside the house, gas is under extremely low pressure, like 0.3 PSI, and friction in a long narrow pipe can leave you with not enough getting thru.
In teflon tape, there's special yellow stuff for gas, and white for everything else. If you use the brush-on glop instead, it's all good.
You can find the exact location of leaks with an ordinary dish soap and water mix. That's all you need for the final connections from the valve to the heater.
But for the pipe built into the house, the correct test is to pressurize it with an air compressor, and leave it with a pressure gauge on it to see if it holds. That way you test the whole system conclusively. Crawling around with bubble mix you might miss something. Code says it has to hold 10 PSI for 15 minutes. I left mine with 30 PSI on it overnight.
To do the test, you remove the little cheapo valves at the appliances, and put on caps. Shut off the gas after the meter. Rig a tee with a pressure gauge, ball valve, and air fitting to the system. Pressurize it and shut off the ball valve, note the reading, and come back later to see if it held.
If it holds pressure, you're good to go. If not, pump it up again and go over it with the soapy water to try to find the problem.
-- J.S.
John sprung,
Thanks.. when I move the furnace it's the last gas appliance I will have so I won't have any problem blocking it off and pressure testing..
The distance will go from a foot to twenty feet on a one inch pipe.. If Possible I would like to run an additional three gas fireplaces. if I add all of the pipe length together it will be about 50 to 60 feet.. The fireplaces are a future event, If I need much larger pipe I can either do it now or later..
The gas line into the meter appears to be a copper 3/8ths inch piece,and all the pipe from the meter are 1 inch..
OK, what the table says for 60 ft. of 1" pipe is a maximum of 260 cubic feet per hour. If your gas is a typical 1100 BTU/CuFt, that gives you a total of 286,000 BTU/Hr available. Check with your gas utility to see if 1100 is right. Subtract your furnace from the max to see what you have left for the fireplaces. Out here, 286k would be plenty. But of course I don't know what's typical in sub-freezing climates.
-- J.S.
John Thanks,
Jus looking at new homes under construction it seems like the biggest I see is the one inch I have.. That is for typical stick built homes of 5000 sq.ft. or so.. Next time I speak to the gas company I'll confirm it.. Since I won't be using the furnace except as back up the only real question I'll need to answer is how much gas will the fireplaces consume..