How Many Btu’s Can A 3/4″ Pipe Provide?
Posted on | December 19, 2009 | 4 Comments
I am interested in having a tankless water heater installed in my home, but have been told some conflicting information by different people. One tells me my 3/4″ pipe should be ok, others tell me I need to upgrade to 1″ pipe to provide adequate supply. I have a 70Kbtu furnace and a gas range and am looking to install a 120Kbtu water heater. My gas line is 3/4″ and is 25 ft from my meter and has 2 90 degree turns. Should I be OK, or is there a formula I can figure this out with?
Related posts:
- How Many Btu’s Can A 3/4″ Pipe Provide? I am interested in having a tankless water heater installed...
- Can I Install Tank Less Water Heater With Smaller Gas Pipe, Not 3/4″ Pipe Recommended By Manufacturer? I was ready to have tankless water heater installed by...
- $60 Per Foot For Rinnai Vent Pipe? My plumber says the vent pipe for a Rinnai tankless...
- Tankless Vs Converntional Water Heater, Gas Or Electric? I have an electric water heater that is due for...
- I Want To Shut Off My Oil Heat Boiler And Use Electric Radiators For Heat. How Do I Prevent Pipe Freezing? I have a cheap and smelly oil heat boiler. It...
Related posts brought to you by Yet Another Related Posts Plugin.
Comments
4 Responses to “How Many Btu’s Can A 3/4″ Pipe Provide?”
Leave a Reply
December 19th, 2009 @ 1:31 pm
You are not OK. You need a 1 inch distribution line from meter into the house and take off of that furnace at 1/2 inch stove at 1/2 inch and regular water heater at 1/2 inch and this instant water heater at 3/4 inch.
Those are low pressure lines within a house due to safety reasons. The street has high pressure lines and a meter outside your house has a reducing valve to drop the pressure down to Ounces from pounds of pressure. Problem with formulas is they arent that valid because you do not know the inside line pressure in the house and the limits your gas company sets on that pressure.
These sizes above are standard what is used in a newly constructed home today.
Good Luck The Wild plumber
December 19th, 2009 @ 7:18 pm
It will be fine
December 19th, 2009 @ 9:46 pm
You need 1″. Here’s an idea. Do not turn on the stove while the water heater is operating. I’m a genius.
December 20th, 2009 @ 12:42 am
According to the quick reference guide “Code Check Plumbing”, a 3/4″ pipe carrries 250k Btu’s at 20′ and 200k Btu’s at 30′. A 70k furnace, 120k water heater, and typical gas range (65k btu) adds up to 255k btu/hr. So a 3/4″ pipe isn’t big enough if you use your water full out. A typical shower only uses the demand heater at a lower level, so you’re probably just fine if yours has multiple settings, like a Takagi. But if you ever get a clothes dryer you’re in trouble.