Gas fireplace vent too close to air conditioner compressor/condenser unit (C) Gas Fireplace Direct Vent Termination Cap Clearance Distances

  • GAS FIREPLACE VENT CLEARANCE REQUIREMENTS - CONTENTS: required clearance distances for through-wall or side-wall venting exhaust devices for gas fireplaces or gas fireplace heating appliances
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Direct vent chimneys or exhaust for gas fireplaces & gas fireplace inserts:

This article gives typical clearance distance requirements between the termination cap of a gas fireplace or fireplace insert and other building or site features such as windows, doors, other mechanical system components, air intakes, exhausts.

This article series describes side wall vent systems for conventional & mid-range-efficiency heating boilers, furnaces & water heaters. We include for comparison, low temperature side wall vent systems used by high efficiency or condensing boilers, furnaces & water heaters.

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Clearance Distances for the Exterior Vent Termination of a Direct-Vent Gas Fireplace / Heater

Gas fireplace exhaust too close to AC/heat pump compressor/condenser unit (C) InspectApedia AJ

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The clearance distancess shown above and at the top of this page are between the vent termination cap of a gas fireplace and the air inlet side of an A/C or heat pump compressor/condenser. At CLEARANCE DISTANCE, HVAC a reader commented that his building inspector did not accept the safety of this installation. We agreed.

Reviewing manufacturer's installation instructions for a typical gas fireplace direct-vent exhaust termination cover or cap we find that the clearance distances to other building features or mechanical systems are similar but not necessarily identical to the Direct Vent Gas Appliance clearances given in the preceding table. This may be because that a typical gas fireplace heater does not use a power-exhaust vent or also because of different BTUH ranges.

Minimum Clearance Distance Requirements for the Exterior Vent Termination of a Gas Fireplace Heater8

Direct vent gas fireplace exhaust termination item clearance distance Distance required (Canada)1 Distance required (USA)2
Clearance distance from gas vent termination cap to adjacent building   48" 8
Clearance distance to vinyl surfaces such as vinyl siding or vinyl trim   12" 8
Clearance above grade, veranda, porch, deck, or balcony 12" (30 cm) 12" (30 cm)
Clearance to window or door that may be opened 12" (30 cm) 9" (23 cm)8
Clearance to permanently closed window [Note 5] [Note 5]
Vertical clearance to ventilated soffit located above the terminal within a horizontal distance of 2 feet (61cm)
from the center line of the terminal (check with the local code)
18" (46cm) 18" (46cm)
Clearance to unventilated soffit 15" (38cm) 15" (38cm)
Clearance to outside corner: with approved Termination Caps 12" (30cm) 12" (30cm)
Clearance to outside corner: with Manufacturer's Special Termination Cap 6 6" (15cm)6 1-6" (15cm)6, 8
Clearance to inside corner: with approved Termination Caps 12" (30cm) 12" (30cm)
Clearance to inside corner: with Manufacturer's Special Termination Cap 6 6" (15cm)6, 8 1-6" (15cm)6, 8
Clearance to each side of center line extended above [the gas] meter/regulator assembly 36" (90cm)5a [Note 5]
Clearance to [the gas] service regulator vent outlet 36 "(90cm) [Note 5]
Clearance to non-mechanical air supply inlet to building or the combustion air inlet to any other appliance 12" (30cm) 9" (23 cm)
Clearance to a mechanical air supply inlet
3' (91cm) above if within 10' (3m) horizontally
72" (1.8m) 36" (90cm)5b
Clearance above paved sidewalk or a paved driveway located on public property 84" (2.1m)3 [Note 5]
Clearance under balcony, porch, or veranda 12"(30cm)4 [Note 5]

OpinionsOn Additional Recommended Cleareance Distances from a Direct Vent Gas Fireplace Exhaust Opening to other Building Features or Equipment

Distance to an air conditioner or heat pump compressor/condenser unit to the nearest point of a direct vent gas heater or gas fireplace exhaust 24 inches to 6 feet [Note 6]

Notes from the original source cited below:

1. CSA B149.1, Natural Gas and Propane Installation Code

2. ANSI Z223.1/NFPA 54, National Fuel Gas Code

3. A vent shall not terminate directly above a sidewalk or paved driveway which is located between two single family dwellings and serves both dwellings.

4. Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.

5. Clearance in accordance with local installation codes and the requirements of the gas supplier

5.a 3 feet (91cm) within a height of 15 feet (4.5m) above the meter / regulator assembly

5.b 3 feet (91cm) above - if within 10 feet (3m) horizontally

Additional Notes:

6. This is the author's OPINION considering that heat from the gas exhaust vent blowing onto an A/C compressor unit condensing coil could imact the coil's ability to condense refrigerant back to liquid form, affecting the condenser unit's efficiency and life. I'm considering the situation in which the hot gas exhaust blows onto the air intake side of a condensing coil. (Most modern condenser units draw cooling air in from the unit sides and push it out the unit's top). Also see CLEARANCE DISTANCE, HVAC

7. This is a Regency Fireplace Producucts termination cap; other manufacturers may have similar options. See the additional sources below.

8. Watch out: check with the manufacturer of your heater and venting system for specific venting instructions and clearances to combustibles or to other features as these distances may vary from one appliance and manufacturer to another. For example the Travis Industries direct vent clearances include some distances that are different from the tables given above.

DuraVent (and other manufacturers) warn that if a gas appliance, fireplace heater or other heater is not properly installed the system may be unsafe.

A major cause of vent related fires is failure to maintain clearances (air spaces) to combustible materials. It is of utmost importance that double wall direct vent pro be installed only in accordance with these [the manufacturer's] instructions.

Additional sources of direct vent gas fireplace clearance information:

  • DuraVent, "Direct Vent Pro Venting System for Direct Vent Gas Stoves and Fireplaces", M&G Duravent, Inc., Tel: 800-835-4429, Website:, retrieved 2016/04/07, original source:
    Johnson Gas Appliance Company, 520 E. Avenue N.W., Cedar Rapids, IA 52405, Website: or, retrieved 2016/04/07, original source:

    Note: This gas fireplace insert installation manual expects the fireplact to be vented vertically through an existing chimney.
    Venting system must be installed by a Mendota approved person according to Figure 3. pg. 8 with clamps securely in place and all joints leakproof.
  • NAPOLEON® GAS DIRECT-VENT MILLIVOLT SYSTEM INSTALLATION & OPERATION INSTRUCTIONS FOR VENTED GAS FIREPLACE [PDF] for natural gas models GD33NR, GD 24NT, BGD 33NR, BGD34NT, and propane gas models GD33PR, GD 34PT, BGD 33PR, BGD34PT gas fireplaces. (2005) Wolf Steel Ltd., 24 Napoleon Rd., Barrie ON L4M 4Y* Canada Tel: 705-721-1212 Website: Email:
  • Regency Fireplace Products, "P33-4 ZERO CLEARANCE DIRECT VENT GAS FIREPLACE OWNERS & INSTALLATION MANUALl", [PDF] , FPI Fireplace Products International Ltd., retrieved 2016/04/07, original source:
  • R.H. Peterson Co., "REALFYRE PREMIUM GAS LOGS OWNER'S MANUAL" [PDF] Robert H. Peterson Co. 14724 East Proctor Avenue, City of Industry, CA 91746 USA Website:, Tel: 800 332 3973
  • Travis Industries House of Fire, "4415 HO GSR2 (WITH SCREEN) INSTALLATION MANUAL", [PDF], Travis Industries, Inc., 12521 Harbour Reach Dr., Mukilteo WA 98275, USA (2014), retrieved 2016/04/07,original source:

Question: what is the required clearance between adjacent houses & a neighboring direct vent fireplace?

Is there a minimum distance between brick houses in Toronto for venting termination of a fireplace using direct vent? - A.W., 12/30/2012

Reply: 4 feet or local codes

I have not found building code citations that refer to nearby or adjacent buildings when specifying clearances for direct vent fireplaces, though some of the fireplace installation manuals we reviewed specified a minimum of four feet to the nearest separate building.

It seems likely that your local building code inspector would agree that the clearance requirements for the building in which the fireplace is installed would set the minimum acceptable clearances that would then apply also to a nearby or adjacent building.

In other words, if the fireplace vent distances and position relative to your own building windows or doors were LESS THAN those to the windows & doors on the building where the fireplace is installed, and presuming for a moment that the fireplace was installed properly, meeting local building permit and code requirements, then a violation probably exists.

If the fireplace vent distances and position relative to your own building windows and doors is GREATER THAN those to the windows and doors where the fireplace is installed, and presuming for a moment that the fireplace was installed properly, meeting local building permit and code requirements, then a violation probably does not exist.

Take some some sharp photos of the installation that concerns you, or make a sketch and send those along and we may be able to comment further.


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