I was just looking for some thoughts on this. I’m going to be inspecting this house and I was going through the Realtor pictures. I was noticing a really long horizontal run for the furnace and hot water heater venting. Any rules on such a long horizontal run? I’m not sure if they are venting through the wall or the roof. I don’t have much details other then these two pictures.
That pipe surely better not be venting laterally through the wall. That’s only for hi-efficiency PVC pipe with power vents (the furnace in your pic likely is power vented but still needs to vent up, water heater is natural draft and must vent up).
Other folks please chime in… Is there a concern that two gas-fired appliances are sharing the same flue in close proximity to each other, in particular, taking into consideration of the length of relatively horizontal venting that would make it a bit harder to create a good draft? I would make sure that the water heater had no signs of backdraft near the vent hood, regardless. But, I might also turn down the thermostat on the water heater (to ensure it is not fired) and then use a CO meter at the water heater to make sure no exhaust from the furnace is escaping. Thoughts?