Thread: Alternative use for a down draft exhaust vent duct

Hi everyone,

I had a client ask me the other day if he could use an existing downdraft vent duct that runs through a concrete slab on grade to route a propane gas line in order to switch from electric cook top to a gas cook top in an island. I was under the impression that he wanted to use it as a pipe chase in stead of a ventilation duct. I later found out that he wanted to use the duct for both uses. I told him that it was unacceptable according to the current municiple code, which is 06 IRC. Was I correct?

Thanks for any feedback.

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Originally Posted by George Hallaron

Hi everyone,

I had a client ask me the other day if he could use an existing downdraft vent duct that runs through a concrete slab on grade to route a propane gas line in order to switch from electric cook top to a gas cook top in an island. I was under the impression that he wanted to use it as a pipe chase in stead of a ventilation duct. I later found out that he wanted to use the duct for both uses. I told him that it was unacceptable according to the current municiple code, which is 06 IRC. Was I correct?

Thanks for any feedback.

You did good!

Honestly I would not want to have an LPG line running under a slab in a chase. If you ever had a leak and with LPG being heavier than air, you would basically have a bomb.

- - - Updated - - -

Scott,

Thanks for the feedback.

As a note of clarification, a gas line under a slab for a habitation is required to be in a chase pipe that is vented to allow the gas from a leak to dissipate away from the structure. There by not building up a gas pocket under the structure. You were right to tell the client that the use he had in mind was unacceptable.

Originally Posted by William Cline

As a note of clarification, a gas line under a slab for a habitation is required to be in a chase pipe that is vented to allow the gas from a leak to dissipate away from the structure. There by not building up a gas pocket under the structure. You were right to tell the client that the use he had in mind was unacceptable.

I have the same situation, but I want to use the existing downdraft vent only for the gas pipeline. Will that still be a problem? Instead of the downdraft vent for exhaust, I plan to install the cooktop hood on the ceiling..