Thread: Direct Vent Pipe Clearance to Combustibles - SLP and Direct Vent Pro

I was looking at some Heat n Glo SLP type direct vent pipe (for a gas fireplace / stove) unit. A label on that pipe indicated 3" of clearance from the top, and 1" at the sides and bottom. Simpson's Direct Vent Pro pipe (same 6 & 5/8" size) appears to defer the clearance to combustibles to the Stove / Fireplace manufacture's install instructions, which lists 1" of clearance period. Question is, if Heat n Glo SLP pipe is used on a stove / fireplace which instructions say 1" clearance all the way around, does the HnG SLP's 3" clearance still need to be maintained?

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If you are referring to HGs own proprietary SL pipe and not the only Simpson DV pipe then you use their pipe ONLY on HHT products unless another mfr has specifically tested and listed their unit with that pipe. The listing of that appliance will state the clearances. Anybody can test and list their appliance with anybody elses venting. However, it may have increased clearances from the original application. For instance, some HG units require a 4" clearance off the elbow if it vents off the top and within 3feet of the appliance collar. They actually ship a heat shield with these units to maintain the otherwise 3" clearance.

HTH.

Bob, This is a Lopi Berkshire Green Smart Gas Stove (10K - 30k btu). The local fireplace store (well known and reputable) said that the Heat n glo SLP vent is the type they use for all thier installs of this particular appliance.

The Lopi Berkshire install instructions say 1" clearance. But the vent pipe says 3" above and 1" top and bottom.

Is it your opinion, that because the appliance install instructions are for 1", that the 3" top clearance on the vent pipe can be reduced to 1"?

Also, the area in question is 8ft + away from the appliance collar.

Thanks for your help!

Andrew, I do not see HHT's SLP gas vent pipe listed as approved for use with this Lopi stove so it should not be used. The Simpson DV pipe is fine. The clearances come from the appliance mfr. and not the vent mfr. Simpson clearly states this in their manual for their Pro vent pipe so do not apply someone else's clearances to this appliance.

That Lopi manual leaves a LOT to be desired. Shame because Travis is a good mfr. with a good product but their manual is a dearth of info. Just one example: Lopi states you must use the 'sconce' horizontal termination but show a std. wall cap. The same illustration makes a point to use the 'high wind termination' for vertical terminations yet they forget to clarify it on the horizontal application.

FWIW, I checked on a current production HG Tiara II stove's venting approvals and it lists 5 brands of pipe including their own--all carry a 1" clearance sides and bottom; 1.5" off the top. This is ONLY for this model stove. See each appliance's listed instructions for the applicable clearances.

Examples of what else to check including 1/4 per ft. slope, support every 4ft. horiz., don't pack insulation in firestops, etc.

HTH.
Bob

Just curious, where are you checking to see if HHT's SLP is approved for use with Lopi's Berkshire stove. I do not doubt you, just curious for another resource.

The install instruction says “other Vents may be approved, check with the vent manufacturer”. I have sent messages to both Travis Industries and HHT to get their responses.

As with ANY combustion appliance, your first move should ALWAYS be with the listed instructions that came with that appliance, then the building codes, standards and local ordinances and regulations in that order.

If the listed instructions do not specifically list a component for use with that appliance then you must assume (yes) it is NOT approved unless you later get a written letter from the mfr. that subsequent to the publishing of that manual, that specific model fireplace was later approved for use with the specific component in question, which does happen often. For instance, they'll approve a unit with one horizontal termination and one vertical to get it to market then later complete the tests with several optional terminations and get them listed for use, too. Also, a third party has the right to test and list their product with anybody else's appliance. Travis, for instance has the right to test and list their appliances with their competitor's vent pipe, for example.

To clarify something here: HG *used* to use Simpson Duravent 6x 4 direct vent "SL" pipe. They now roll their own venting at their Heatilator plant but the old Simpson DV pipe is still approved for use with most of their products that take the 6/4 coaxial vent pipe.

Another thing to check is if the use of a sealant is required on the inner section or not. Some brands have such sloppy tolerances that the mfrs specifies a high temperature sealant such as Mil-Pac on the inner joints. If so, you can NOT substitute other high temp. sealants such as furnace cement, stove cement, high temp. RTV silicone or other refractories. In this case, Mil-Pac is specified because it remains pliable and does Not permanently secure the pipes together. It remains soft and pliable allowing the pipes to be disconnected if need be.

I know of a stove shop that used brand A's vent terminations on brand B's vent pipe, which is a no-no. Their incorrect logic was that since Brand B approved the venting from brand A for use on brand B's stoves, they thought the terminations were interchangeable, which they are not. You must stick with the same brand components again, unless the substutute component was specifically tested and listed for use with that pipe on that appliance.

Confused yet?