Fireplaces, logs, and space heaters. Episode twenty three of the Gas Service Animated series.

First rogue: the gas log set installed in a real wood burning fireplace. The code calls it a decorative appliance, and it borrows everything from the fireplace. The chimney flue has to work, the firebox must be noncombustible, and the log set cannot be run by a thermostat. And the damper can never swing shut over burning logs, so it is fixed open. Here a clamp holds it, per the listing and the manufacturer's instructions.

Two barriers stand between the flames and the living room. A fireplace screen is required with a decorative log set. Glass doors are their own rule. Some appliances are listed to run with the doors open, others closed, and running them the wrong way can upset combustion and overheat the glass. The listing and the instructions decide, every time.

Next, the factory built vented gas fireplace. This one is its own listed appliance with its own venting system, installed to its listing and instructions. If it sits in or against combustible framing, it must be listed for exactly that. Clearances to the mantel and the surround come off the nameplate and the manual. And the direct vent version, which breathes only outdoor air, is the one the code allows in bedrooms and bathrooms.

The floor furnace. A grate in the floor with the heater hanging underneath, still common in older housing. Location is everything. It cannot sit in a doorway, a stairway landing, an aisle, or an exit path. The register keeps at least six inches from the nearest wall, with eighteen inches on two adjoining sides, so nobody is forced to walk across the hot grate. Doors and drapes stay at least twelve inches away. And below, the furnace needs six inches of clearance from the ground, and access for service.

Now the strictest rogue: the unvented room heater. It has no flue. Everything it produces stays in the room, so the safeguards are firm. Every listed unvented heater carries an oxygen depletion safety shutoff. Its pilot burns room air, and if the oxygen level falls, that pilot goes unstable and drops out, closing the gas valve. Unvented heaters are prohibited in bathrooms and bedrooms, with only narrow listed exceptions for small units. And the room itself sets a ceiling: unvented input is limited to twenty Btu per hour for every cubic foot of room volume.

Vented wall furnaces and room heaters live inside or against the wall. In or attached to combustible material, they must be listed for it. The code says a wall furnace must not create a hazard to walls, floors, curtains, furniture, or doors. Its special vent runs up the stud space with firestops at each level, and service panels must come off without touching the building.

Notice the pattern. Every appliance in this gallery lives right where people live: beside the sofa, under bare feet, inside a bedroom wall. So three questions decide every install. Is it listed for exactly this use? Are the nameplate clearances there? And is this the right room, with the right volume and the right air?

So on a service visit, walk the list. Match the rating plate and the listing to how the unit is installed. Confirm the damper or vent state is right for the type. Prove the oxygen depletion shutoff on any unvented heater. Measure clearances with a tape, never by eye. And check the room: volume, combustion air, and no prohibited locations.

The rogues gallery: log sets ride a working fireplace with the damper fixed open. Floor furnaces stay out of walkways. Unvented heaters answer to an oxygen sensor and room volume math. Next episode: two psi systems, higher pressure on purpose.