Thread: Heatilator Direct Vent Gas (Natural) Fireplace

Heatilator Gas Fireplace (Direct Vent) installed in a Basement (sub grade application).

Vent pipe terminates at the rear foundation wall of the home.

After Construction, a Deck was installed......

Thoughts....Suggestions...?

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My first suggestion would be to contact the manufacturer as to the advisability of that location for the combo intake/exhaust. Secondly, I would guess that most inspectors would be concerned about waste gases possibly including carbon monoxide. With a direct vent gas FP, you have controlled combustion which, in theory, releases pretty clean flue gases. In the unlikely event that there is CO produced, it is in open air and will convert to harmless carbon dioxide.

My real concern would be water vapor. That is a byproduct of gas combustion and it may condense on the bottom of the deck. Treated lumber or not, that's not beneficial. However, given the relatively few hours that most fireplaces like this are actually used, it may not be a problem. Used a lot, however, there may be problems such as corroded deck fasteners. This is especially a problem with newer treated lumber used with the wrong type of hardware/fasteners to begin with.

Here is the .pdf from the installation manual with regard to clearances...

Looks to me like your answer is in their installation requirements:
M: Clearance under veranda, porch, deck or balcony - 12 in. (30 cm)
minimum. * Recommended 30 in. (76 cm) for vinyl or plastic.
Only permitted if veranda, porch, deck or balcony is fully open on a
minimum of 2 sides beneath the floor. *

Joseph, item M in that pdf addresses it pretty well. If they still have a problem, they can contact HL Tech Services for ideas. Depending on the unit, they may be able to extend the venting to the edge of the deck and power vent it. As it is, it would appear to fail item M for a 12" clearance. Practically speaking, exhausting 500F+ heat into that homemade grille is asking for a new definition of deck BBQ.

If they need a local resource for repairs, they can contact me or FireSide Hearth & Home up in Limerick, Pa. This is not a warrantied item so it would fall onto the homeowner and contractor who did this.

On a more practical point, this unit will probably experience intermittent deoxygenation and sooting as the deck traps flue gases then recirculates them back into the Fp. The air intake for the Fp is the passageway closer to the house while the exhaust is out at the tip of the trapezoid.

Kevin, I can assure you significant CO and water vapor are produced.

Nice location for that condenser, too!

HTH,
Bob

Thanks Bob

I will pass your name along to the Homeowner.

Bob--
You are certainly more experienced in fireplace tech than I am. However, I still suspect that the main issue is moisture, not heat or CO. The installation docs even reference clearance issues due to condensation. I don't doubt that the temp of the exhaust gases may reach 500 degrees at the intake point of the flue above (and inside) the firebox. However, we know that they cool significantly by the time they reach the exhaust point since they are cooled by the intake air which surrounds the the exhaust flue. If the exhaust gases were this hot, presumably the metal housing would be also...at least, it would be after several minutes of run time. If so, I can't imagine that it would be acceptable (as it is) to install it within reach of people on the deck or patio despite the bilingual warnings in French and English...

Kevin, this is based on 20 yrs of selling and installing HHT gas direct vents with 5 yrs as a factory technical rep. for this mfr. Let me assure you the exhaust temps reach 500+. I agreed with you about the moisture issue and have seen many decks rotted because of this. FYI, rotten wood ignites easier than fresh wood.

Yes, the metal gets that hot. That's why they stamp the word HOT into it!
Bob

Joe,

I'm sure you also wrote up that a/c condenser unit under there.

Also, that metal grille in the opening above that exhaust is going to get "HOT", just like the wood that Bob H. is talking about would. While the metal may not catch fire, it could cause burns when touched. The grille is also resting on wood, which can dry out, rot out, and otherwise become easier to ignite over time (I'm sure Bob H. has that term, I'm drawing a mental blank on that word right now).

Originally Posted by Jerry Peck

...and otherwise become easier to ignite over time (I'm sure Bob H. has that term, I'm drawing a mental blank on that word right now).

I'm not Bob H. and I don't play him on TV. The word is pyrolysis, I believe.

Bob,

Thank you for the help and taking my Inspector's call this morning.

Your number was passed along to the Homeowner. He should be calling you later.

I saw a new home that was vacant had a open house going on, turned on the D.V. fireplace only to catch the birdnest on fire, luckly someone saw the smoke and turned off the unit till the nest was removed, so Check first the vent output for any nests

Originally Posted by Joseph P. Hagarty

Heatilator Gas Fireplace (Direct Vent) installed in a Basement (sub grade application).

Vent pipe terminates at the rear foundation wall of the home.

After Construction, a Deck was installed......

Thoughts....Suggestions...?

Clearance above grade, veranda, porch, deck or
balcony 12 inches

clearance under veranda, porch, deck, or balcony 12", only permitted if veranda, porch, deck, or balcony, is fully open on a minimum of 2 sides beneath the floor

The vent might be okay, I can't tell the clearances. The A/C condenser requires 48" or so clearance though.