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Relocating water heater - impact on vent size?

1307 Views 10 Replies 2 Participants Last post by  yuri
I currently have a furnace and water heater located next to each other, each with a 3" vent pipe connected with a 6" wye to a 6" horizontal which goes about 6 feet to the chimney. I am remodeling and reducing the size of my mechanical room so the water heater needs to move to the basement, where a new run of 3" vent pipe will connect to the chimney. I am assuming that this means I need to reduce the 6' horizontal run for the furnace down to 3" as well, but being this will be a bit of a pain I figured I'd ask before going through the trouble of replacing it. Is it necessary to get rid of the 6" pipe and install 3" or can I just cap one side of the wye and leave it as is?
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leave it the way it is and cap it is OK. try not to have more than 6 feet of horz pipe to the chimney from the water heater or you may not get enough draft and fumes will spill out. 95% of our water heaters where I am use 4" now for better draft.
actually I may be wrong. I believe that the water heater must enter the chimney above the point where the furnace enters so you cannot go below the furnace entry point. very rare that your case happens but you should check your gas code or local requirments. where do you live and maybe one of our other guys can verify that point.
w/o some pics and being there it is impossible for me and probably the other techs to know 4 sure and at the end of the day it is the local gas inspector and authorities who can red tag it/shut you down plus the insurance company so I have to check out. I imagine some of our other techs may know but some pics may help and once again the local authoritiy/inspectors rule/run the show.
1) where exactly do you live, for the other techs who may know your area

2) you know it is NOT easy to get back into the B vent chimney above the existing tee? cannot just drill a hole in the side of it but must get the proper B vent tee and then shorten one length and probably have to yank it upwards etc etc etc to do it. NOT an easy proposition IMO. B vent chimney tees and fittings are NOT always going to fit each other as one brand/manufacturer may be slightly larger/smaller than the next one so that may be an issue also. I would lean towards an electric water heater or thru the wall type. You are also going to have to move/extend the gas line and you cannot go thru floors with that yellow flex pipe so unless you are a licensed gas fitter or get one to do it your house insurance will likely be void and you can get yourself in one helluva lot of trouble.
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I sounds like you know what you are doing and I cannot see the chimney etc to know all the fine details. One of my cohorts here Beenthere is from PA and has tons of experience so he may chime in later. As long as it is done with proper fittings and to code then the ins co should be happy and then there are no potential liabilities or lawsuits to be dealt with (especially if you go to sell the house later).:yes:
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