Flue capy: gas furnace+2 gas HWT heaters
I am being asked to install a 2nd gas-fired HWT in a house that already has a gas furnace and a gas HWT. I would do the plumbing, a gasfitter will hook up the gas and flue. Before calling the gasfitter, I want to figure out if the 2nd gas-fired HWT is a viable option, given the following parameters:
House’s main flue: 6″ round, goes up 1.5 floor through inside masonry chimney.
Combustion Air Supply duct: 4″ round.
Furnace flue: 5″ oval; Furnace input: 108,000BTUH.
Current HWT flue: 3″ round; HWT input: 36,000BTUH.
2nd HWt flue: 3″ round; HWT input: 36,000BTUH.
There must be a formula by which these things can be figured out. If a 2nd gas HWT is not feasible without expensive modifications to the existing flue and combustion air intake, I will take the easy way out and install an electric unit. The owners would prefer gas.
Replies
Bump.
Try JLC
6" flue is pretty darn big, but I don't know for sure. A plumber should know. But what about installing one larger unit? We just had a 75 gallon tank put in, and it isn't too much more $ than a smaller one unit.
How about a power vent model?
The basic formula is set by the National Fuel Gas Code. Different juerisdictions have different implementations.
Also, rise, run and bends in the flues have to be considered.
Check with yopur local code official or heating contractor.
The key to forgiving others is to quit focusing on what they did to you, and start focusing on what God did for you. Max Lucado
Sojourners: Christians for Justice and Peace