I'm planning on installing a tankless water heater in my house at the end of my gas line. It's about 50 feet from the gas meter to the house and probably another 50 feet to the end of the pipe. If I have 1" pipe for the first half and 3/4" pipe for the second half, will that provide enough gas to a 199k BTU tankless water heater?

My gas company told me that if needed, I can upgrade my gas supply to 2 PSI from 0.25 PSI, but I'd rather not do that unless absolutely necessary. And even so, if I do upgrade to 2 PSI, I'd need to get a bunch of pressure regulators so that the rest of my appliances in the house still work.

You'll need to do a load calculation. Can you tell us what else is running off the 1" pipe and the 3/4" pipe ?

We have a gas stove, a furnace, and a fireplace (rarely used). The two current water heater tanks are on it but are being replaced by the tankless unit.

i'm guessing 3/4 is too small. even 1 inch inside may not do it.
what is the meter rated for? might need to be bigger than a 250,000 BTU meter.

7" is all you need, IF the pipe sizes are correct for the various distances and appliance loads.

[www.youtube.com]

As packy said...you have to total the btus of all your appliances(even rarely used), and make sure the meter is rated for that many cu/ft.

Try not to nod off watching the video.



Edited 1 times.

A total load determination of all your your gas appliances are required, so that one cold night when everything is cooking, you want to be absolutely sure you have enough gas.

Best Wishes

2 PSI is a lot of gas pressure. People get confused with pressure vs. volume. You can have 11" then an appliance fires and it will drop to 6". As everyone has stated, the best way is to do a total BTU load calc. It also depends how far the gas pipe is running, how many elbows and so on.