Venting two gas appliances in chimney
Ok, let me just get it out of the way that I mainly do new commercial construction, so please bear with me and hopefully help me out here.
As a favor (paid favor), I agreed to have a chimney stack rebuilt in an old house, which has two fireboxes and a furnace. The furnace had been converted to burn gas but they did not line with metal at that time. The same stack also vents a gas water heater, which sits next to the furnace in the basement.
Question: Obviously, the furnace will have to be vented through metal, inside the masonry stack, but what about the water heater, which they have also made vent through the unlined masonry flue? Is the proper thing to do to snake a 3″ metal flue to the water heater in addition to the 6″ for the furnace? Seems like it would get a little congested at the top of the chimney with two caps coming up from the same flue.
Edited 2/11/2009 6:57 pm by Brickie
Replies
If these appliances use B vent, you can tie them together provided the combined line is upsized correctly (i.e. if the furnace is 6" and the WH is 3" you can't simply run 6" all the way up, you need to upsize).
Thanks for your thoughts. It seems to me that there is some controversy concerning the need for the "type b" vent versus a flex aluminum flue. The furnace I might add is a converted oil burner so it is certainly not "high efficiency". I'm mainly wondering what it would be to make that Y connection inside the rough masonry flue.
I'm mainly wondering what it would be to make that Y connection inside the rough masonry flue.
The connection is made just before it enters the masonry.http://www.quittintime.com/ View Image
There should be no controversy. Ask the appliance manufacturer what type of vent material is required. I have very little experience with old equipment, we are always installing new, and there are always clear guidelines. Anyway, if it's B vent, 6 + 3 = 8 if I recall correctly.
Someone more knowledgable will jump in.
Around here it is common to have a gas furnace, 6" or so metal flue pipe, with the 3" HWH vent tapped into it via a T or Y in the basement.
6" pipe continuues into a masonry chimney or up through the roof in a "B-vent", double walled pipe.
Not sure that is legal, code, or whatever - I just see it commonly done.
Installations in service for years without any apparent problems.
Jim