Thread: Rusted fireboxes

I have seen a number of factor built gas fireplaces recently with extensive rusting of the firebox. The recent one was a Heat-n-glow 6000. What would cause this rusting? Is there a limit to the amount of rusting which is acceptable? Who is the best person to review (manufacturer or chimney contractor)?

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Any pics Richard?

Rust to me is a sign of moisture and not something you should have in your fireplace. The appropriate call would be to recommend a level 2 inspection of the fireplace and chimney.

If you do an electronic report and want to recommend chimney inspections, here's a link you can insert. I use it in my reports.

Chimney Inspections

IIRC its a DV gas fireplace. Usual suspects are damper not clipped open at all times, failure to open fully during operation; operation with glass doors open; failure to install, operate, and/or maintain as per manufacturer's instructions, combustion air not from outdoors as specified, or inlet too close to other exhaust vent (such as bathroom/kitchen vaporladden exhaust), exhaust vent not to manufacturer specs (offsets, run length, etc.), uncorrected air shutter adjustment for more than minimum vertical vent run, improper log arrangment, ember material, etc. Doors not properly aligned/door gasket; failure to have inspected, cleaned & serviced annually by qualified service technician - and/or hairy pets/dusty home requiring more frequent cleaning/inspection. Occasional corrosion/paint failure should be addressed by qualified tech a.s.a.p.

Rust sign of improper venting, settings, short cycle (hot) or other operation issue, and/or incomplete combustion/loss of sealed chamber integrity.

Needs full inspection, including combustion analysis, etc. and verification install & function to manufacturer specifications by qualified service technician - removal of corrosion and repaint if necessary again by qualifie service technician.

Need more letters after series 6000 to id model and options. Believe HnG6000 are strictly all horizontal or all vertical venting no dual venting configurations allowed.

Actually, rust is fairly common with gas direct vent fireplaces of all brands and models, esp. when the pilot light is not burned year round. Outdoor moisture enters the vent at standby, cools to dewpoint and condenses. That's one of the reasons we recommend burning pilots year round. The others are to discourage spiders and prolong the life of the thermocouple.

A Direct Vent (DV) fireplace does not have a damper, much less a clamp. It does not have operable doors and thus is essentially immune to pressure regimes less than 25 Pascals WRT indoors.

Yes, the fireplace needs to be inspected but by a Pro qualified to inspect and work on these fireplaces. NFPA 211 does not really address gas direct vents but it geared more towards site built masonry fireplaces and to a lesser degree, factory built fireplaces listed to UL 127 and woodstoves listed to UL 1482 for ex. In the case with a HG 6000, you would want someone with experience with this make and model, who is NFI Certified as a Gas Hearth Specialist, and Certified by HHT to work on their products. A bonus would be if they were also Certified Carbon Monoxide and Combustion Analysts and used to be a quality assurance manager for this mfr. in this region. You know, someone like me! :-) [shameless plug]

FYI, while early DV models had to be ordered as dedicated top or rear vent configurations, HG introduced their TR (top or rear) vent option back in the mid-1990s where you choose on site which way you want to vent it. That system is still in use for most of their std. models including the current HG 6000 series.

Usually, all you need to do is scrub the inside with steel wool then paint with a 1,200F rated paint. They even make special paints for gas fireplace fireboxes. This should be done as part of a routine service call so if you see rusting, its a good sign of lack of proper maintenance.

There are other reasons to have a pro familiar with this type of fireplace inspect and service them:
-inspect for failed glass gasket. Red silicone rubber will fail and has been part of a 'soft recall' by HHT
-test gas pressures
-test wiring connections
-test performance of TC/ TP or electronic ignition
-test for combustible gas leaks
-test for CO spillage
-test safety features
-inspect vent and check for proper clearances to termination and venting configuration
-verify proper fuel useage
-verify venturi setting
-observe burner and operation; verify proper ignition and flame patterns
-clean and adjust pilot prn
-verify clearances to combustibles and facing seal
-review proper operation and maintenance requirements

HTH,
Bob

HTH,
Bob

I wanted to add some vital information from my 19 years experience working on Gas Fireplaces.

The main reason rusting is found in the firebox of a gas fireplaces is from the hydrogen that's found in Natural Gas, When your fireplace is running, the burned natural gas produces corbon monoxide, the hydrogen combines with oxygen in the chamber and creates water vapor, this vapor collects on the glass and the walls of the firebox, it also becomes corrosive with the addition of carbon, turning this water vapor into an oxide, this will eat threw the firebox's paint then will start rusting the metal, the yearly service and clean should have a complete repaint included to keep the fire box's protected. If rusting has already started then a good clean of the rust, and a cover of paint should slow if not stop the rusting.