Thread: Rust under draft hood of water heater

Is this indication of a problem with the water heater or the flue? 11 year old gas fired water heater sharing flue with a 50+ year old gas fired boiler.

Similar Threads:

• range hood
• ABS Flue Pipe on LP Water Heater
• Tankless water heater comment
• Water heater Question
• Reverse plumbing to water heater

Originally Posted by Joe Van Orsdol

Is this indication of a problem with the water heater or the flue? 11 year old gas fired water heater sharing flue with a 50+ year old gas fired boiler.

The "flue" of a gas fired storage type CAT. I water heater is within the jacketed area below the draft hood, and runs inside from the burner area up to just below the draft hood.

From the draft hood is or should be either a VENT connector or Vent to exhaust the products of combustion.

It is an indication of a problem throughout including the boiler and any other devices or restrictions in the area that restrict, move or consume air.

Usual suspects include spillage/backdrafting shared appliance, over heating, incomplete combustion, inproper drafting, blockages, etc. If the boiler is 50 y.o. suspect same of vent connectors/venting. One wonders the venting path, i.e. does it transition to masonry chimney, b-vent to outdoors, etc. elevation, and path.

You give insufficient details of the low efficiency appliances, the area, the venting, nor photo.

Get a qualified technician in to diagnose your myrad issues. This is not a DIY site. I would also suggest a CO monitoring or detection device, although I wouldn't rely upon it as a substitute for a qualified on-site diagnostic testing and inspection of your equipment, combustion air, and venting.

Any pics Joe?

Here you go.

Could very well indicate a potential venting problem as anytime you see rust something bad is going on inside that fuel fired appliance.

The only way to be 100% sure is to perform a complete combustion analysis along with draft interference testing.

The picture is showing rust flakes around the draft hood. I am wondering if the installer just did not clean up after connecting the flue pipes. Many of times I remove the flue pipes from a water heater to install the new heater rust comes out of the flue pipes. I take the old pipes and run a brush through the pipes to get all the loose rust out of the pipes so when I reinstall them I reduce the amount of rust that would get on the top of the new water heater. The rust can be caused by condensation inside the flue pipes.

Now if you verify that its just loose rust flakes and you are worried. You can do a combustion gas analysis as DavidR states. Now if the rust is the top of the water heater rusting out, I defiantly would do a combustion analysis and to see if there is proper draft. Do you see any scorching around the burner opening?