Gas Furnace/Water Heater Venting

I have a question about how I should write this up. We don’t find a lot of gas furnaces and water heaters in the south. I ran across a gas furnace in a crawl space today. The vent pipe fed into a masonry chimney. In the garage a gas water vent also vented into the side of the chimney above the furnace vent. I believe the two are tied together but can’t confirm because it is behind the masonry. Out of the top of the chimney is a single metal flue.

Any thoughts?

General Notes:

  • All Chimneys and Flues should be inspected and swept on an annual basis with use.
  • It is recommended that a Level 2 Inspection of the chimney / flue be conducted at [FONT=Arial][size=2]this time (prior to closing) in accordance with the NFPA standard.  

I occasionally see double wall class B running the full length of a non-lined masonry chimney which is allowed in this State

I would call out the flex going through the knockout and recommend a better support strap for tht B vent as they are using wire.

Is the vent pipe running downhill?

If it’s vented into the chimney it’s not allowed and the appliances should be checked for spillage. If the pipe is using the chimney as a chase that’s fine but there is often sheetmetal to close off the top of chimney and prevent debris and moisture from getting in.

As far as the flue is concerned you can’t report on what you can’t see. There is either a wye-connector and a metal flue running the length or there is not, but you can’t confirm it either way.

I think the most you could say is, (assuming this is true) “Cannot confirm proper venting of combined furnace and water heater. This is not a common installation in this area of the country and I recommend further evaluation to verify proper venting of gas burning appliances through the chimney.”

And you could also say nothing, or “Chimney flue not fully visible.”

If one owns a CO meter ya can confirm from the roof proper venting:D:D