This post is about a dangerous gas water heater vent.
The photo to the right is my water heater. It is a conventional gas water heater. It costs me about $12/month to heat my water.
A standard water heater such as mine is essentially a thermos bottle sitting on top of a gas fireplace. A thermostat is set to get the water to a certain temperature, and a gas burner turns on when that water needs to be heated.
The resulting combustion gases rise up and out through a metal chimney flue on top of the unit, and rise to exit through my roof.
This unit loses a lot of potential energy through that flue. If we were to use all of the hot water in the tank, it would take about an hour to regenerate a new tankful.
A condensing gas water heater is dramatically more efficient.
Instead of venting the combustion gases produced, like the conventional tank does, a condensing unit captures and re-burns that exhaust to heat the water even more.
The circular "chimney" makes the water travel very far, and has a lot of surface area.
As such, more heat is transferred into the water in the tank. It is very efficient.
It is exhausted through a PVC pipe on top of the unit! Plastic does not respond well to heat, so using plastic as the flue means the exhaust has been dramatically cooled as 95%+ of the heat has been recaptured and used to heat water. The resulting exhaust is so cool you could blow dry your hair with it. Not that you would want to...
The recovery rate is very quick, said to be 70%+ of the tank size, and the condensing unit saves money.
See the round, black motor on top of the unit above? That is a powered blower and forces the resulting exhaust gases directly outdoors.
However, on the subject unit in the house I was inspecting the PVC exhaust tubing had become disconnected from the top of the blower motor!
That means that every time the unit heats water and expulses the exhaust gases, a portion of them is entering the house.
Almost certainly the homeowner does not know.
Did the home inspector try to fit the black connector hose back onto the top of the unit?
It seems like every time this home inspector tries to be a Good Samaritan, he gets bitten by Murphy on the behind. Fitting that black connector back onto the top might crack the tubing elsewhere or cause other unforeseen damage. So what he did instead was alert the homeowner immediately.
My recommendation: home inspectors inspect things! In this case I walked around and looked all over the water heater - front to back, and top to bottom. I don't remember the last time I saw this disconnected condition, but I did this inspection! And glad I did. The homeowners, and my clients, are in danger of carbon monoxide poisoning here. This is a serious condition that needs immediate attention!
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560