Need some help here. I am in the midst of remodeling my bathroom, and have noticed how poorly vented my furnace is. The only name or print on the furnace is HW SV-9500. The house is single story, 1600 sq ft. ranch. The furnace is in a small closet with a small hole to the crawl space, and a 10″ or so duct in the ceiling up to the roof.
The flue coming out of the furnace is 4″. It goes up a foot or so to an adjustable elbow that merely offsets it a few inches. It continues up from there for 5 feet at which point it is poorly connected through the floor to a six inch adjustable elbow that connects to another 3 feet or so of 6″ duct that goes through the roof.
All of the duct is single wall galv. no firestop. There are no supports either.
My plan is to replace all of the vent pipe, the 4″ & 6″, with a run of all 4″ double wall flue pipe, add a firestop at the floor, and support the pipe. Is this a good idea?
Do I need the 6″ duct from the ceiling up? The installation is so poor it leads me to believe the installers had no clue what they were doing. I won’t get into how none of the supply ducts are sealed.
Replies
HW SV-9500
Is that identifier on a valve? Google suggests that it's a Honeywell gas valve, made for furnaces.
In general, I'd go with double walled but there are also high heat plastic flues for more direct venting. This is not an area that I'm real familiar with so that's really just my .02 cents.
This post will also serve to bump your thread.
That's not on a valve, but on the front of the furnace. I guess my question boils down to whether or not I need to increase the pipe size like the current setup, or can I run 4" vent from furnace all the way to roof.
Generally speaking, the flue should be the same size as the flue connection on the furnace, all the way up. Increasing it or decreasing it can be done under certain circumstances but only if you know all the rules. Otherwise it can lead to draft problems.
(What kind of bike do you ride?)
What DanH says is right. Whatever is at the top of the furnace is what you continue with or you end up with condensation problems.
You should use the double walled called "B" vent up throughout. With B vent you still have to be 1 inch away from combustibles. What you have is "C" vent and that has to be either 4 or 6 inches away from combustible.
B vent locks into each other but still need a screw to stop themfrom unscrewing. You will need what is called a C to B adapter which makes the connection from the furnace to the B vent.
roger