[flashheatingand]

The current venting setup on this job is one common vent for an 80% furnace and water heater through a chimney.

I am considering pulling out the existing vent, and running a 4"b-vent for the w/h and the pvc vent for a new furnace. has anyone done this? If so, what are some things that I might want to be aware of?

 

[gene2]

If you are doing a 90% + furnace, I see no problems, done this many times. Just seal the masonry chimney up top to stop draft & rain. Sometimes I leave it open for combustion air though if a one pipe furnace. We usually do two pipe though, but the water heater needs air many times.

 

[flashheatingand]

Thanks Gene, I was concerned about the spacing between the pvc vent and the B-vent. I don't think the heat from the b-vent would "melt" the pvc, but was curious if that might be an issue. I guess if there was a problem, you would have heard about it by now.

Once again, thanks for the input.

 

[coolmen]

all codes apply that 1" clearance from bvent to any cumbustable materials