Part 1: Direct-Vent Fireplace Installation Jack Murdock from RMI and Craig Ryans demonstrate how simple it is to have gas appliances and heat in a rural location.
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Project: Modular Mountain Retreat, Episode 8, Part 1See More
First, Bob reviews progress on the interior of the modular home. Steve Roth from Style Solutions demonstrates a new crown molding system that does not require complicated miter cuts. The moldings, which are available in a variety of styles, come pre-finished (painting optional). No special tools are needed to join the molding sections, making it an easy install for weekend handymen. In the great room, a direct vent gas fireplace from Vermont Castings is being installed.
Out on the back deck, Jim Precht and his crew are installing a new Weyerhaeuser ChoiceDek composite deck and railing system. The low-maintenance decking is made from recycled wood and plastic and does not require a stain or finish.
Beautifully sited on wooded acreage with breathtaking views of some of the most beautiful countryside in New England, this Arts and Crafts style bungalow certainly doesn't look factory-built. You'd never know it was a modular home unless Bob took you to the Pennsylvania factory where it was built, almost from start to finish.
The house goes down the assembly line from framing, through wiring and plumbing, all the way to the installation of flooring and priming for paint. The house is trucked to its pre-fabricated foundations on the lot, and start all the finishing touches that will prove that a modular house doesn't have to be a cookie-cutter affair.
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Direct vent exhaust clearance distances for gas fueled appliances:
Table & illustrations of the required space between a direct or side-wall vent for a gas fired heating appliance and building windows, doors, corners, gas meter, air intakes, sidewalks, balconies & decks and other building features.
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.
We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.
Clearance Requirements for Direct Vented Gas AppliancesExhaust Vent Termination Clearance Requirements
In a table below we provide a complete list of required clearance distances between the air intake or combustion gas exhaust vents for direct vented heating appliances.
[Click to enlarge any image]
Highlights of Gas Heater Vent Clearance Distances
Page top Illustration adapted from Thermo Products installation instructions - click to enlarge this or any other image or photo at InspectAPedia. [15]
Colour illustration of direct vent sidewall terminal clearance distances adapted from American Standard Furnace installation instructions that in turn cites ANSI Z223.1/NFPA 54 National Fuel Gas Code for US installations and cites CSA B149.1 Natural Gas and Propane Installation Code for Canadian direct vent gas vent installations.
Notes to the table above
1 Authorities/Sources:
2. For non-direct vent applications such as the side-wall vent appliance shown earlier on this page, the required distance is much greater: 4 feet to the side or below the opening, or 1 foot above the opening.
Typical clearance from an operable window to a direct vented gas appliance vent outlet:
6 inches (15 cm) for appliances up to 10,000 Btu/hr (3 kW), 12 inches (30 cm) for appliances between 10,000 Btu/hr (3 kW) and 100,000 Btu/hr (30 kW), 36 inches (91 cm) for appliances above 100,000 Btu/hr (30 kW)
3. This distance requirement may vary in order to be in accordance with local building codes, the gas supplier, and the equipment manufacturer's own product installation specification
Clearance must be in accordance with local installation codes and the requirements of the gas supplier
3.a. for a gas fireplace exhaust termination cap, 3 feet (91cm) within a height of 15 feet (4.5m) above the meter / regulator assembly
3.b. for a gas fireplace exhaust termination cap, 3 feet (91cm) above - if within 10 feet (3m) horizontally
4. In direct vent applications, this clearance distance must be in compliance with local building codes, the requirements of the fuel gas supplier for the heating appliance in use, and the appliance manufacturer's instructions. For non-direct-vent applications (that is, side wall venting only), the required clearance is 7 feet.
A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwelling and serves both dwellings.
5. This is the author's OPINION based on other clearance distances and standards discussed in the article above.
See CLOTHES DRYER VENT CLEARANCES
Also see CLOTHES DRYER VENTING FAQs
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 impact 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. Direct Vent Terminal Clearances cited in AMERICAN STANDARD GAS FURNACE INSTALLATION MANUAL [PDF] (2008), American Standard Heating & Air Conditioning, that in turn cites:
In accordance with the current CSA B149.1 Natural Gas and Propane Installation Code.
In accordance with the current ANSI Z223.1/NFPA 54 National Fuel Gas Code.
8. Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.
Watch out: there could be other more dangerous conditions: if the air intake vacuum created by the A/C compressor / condenser unit actually draws air or gases out from the nearby direct vent gas heater or from a passive-vented (atmospheric vented) gas fireplace appliance, that increased draft may impact the safe operation of the gas burner, risking dangerous or even fatal carbon monoxide hazards.
Separately, if a different compressor unit design caused the unit's exhaust to blow into the gas heater exhaust vent, that could prevent safe venting of exhaust gases. Where either these conditions are possible I'd increase the clearance distance to 10 feet or 3 meters.
9. This is an excerpt from installation instructions for an example system, the Aerco GF-5050 Innovation Series & ReCon Water Heater Venting and Combustion Air Guide [PDF] retrieved 2017/09/26, original source: http://aerco.com/sites/default/files/document/document/TAG-0043_0Q_GF-5050_INN_RECON%20Venting%20Guide_12-01-16.pdf
Watch out: check with the manufacturer of your heating equipment to determine their recommended clearances between direct vent openings when you are installing multiple direct-vent appliances at the same building.
For help finding the manufacturer of your gas fired equipment see these two links offering both equipment installation and operating manuals and age decoding help:
Also see
Direct Vent Exhaust for Heating Flues: Installation & Inspection
This topic has moved to DIRECT VENT INSTALLATION, SNAFUS & SPECS
Question: what is the maximum allowable length for direct vent gas heater flue & how many elbows can I use?
20917/09/11 Terry said:
I have a Goodman 60,000 BTU high efficiency Direct venting
my fresh air vent is about 3 feet below the window
my exhaust vent I want to move just right around the corner of the house approximately a total distance of about 48 inches
can I do this if not how far to the right of the window and below the window can I be with The exhaust vent thank you
This question and reply were posted originally at DIRECT VENTS / SIDE WALL VENTS
Reply:
You will want to review GAS APPLIANCE DIRECT VENT CLEARANCES Separate Table for Direct Vented Gas Appliances - above on this page.
Where you will find a table of all of the required minimum clearance distances from the vent outlet (or a vent intake) and other building features like windows and doors.
In GENERAL and excerpting from Goodman's GMVC96 Installation and Operation Manual,
The vent termination of a direct vent application must terminate at least 12 inches from any opening through which flue gases may enter a building (door, window, or gravity air inlet).
AND the Installation & Operation Manual for your Goodman heater because there are individual heater model-dependent safety and functional restrictions on how you can extend and route the vent piping between the heater and the exit point: there are constraints on the diameter and length of piping and also on the number and type of bends or elbows that can be used. If you violate these the system may not vent properly and it could be unsafe.
In the Goodman heater manual I use as an example (Watch out: you didn't give your heater model so this our excerpt may not be correct nor safe for you), and using a 60,000 BTUH Goodman MVC96/CVC96 Direct Vent (2 - Pipe) system, the maximum allowable length FOR THAT BTUh example depends on
Assuming use of a 2' or 2 1/2' diameter vent pipe, with 1 elbow the maximum length can be 95 ft. , 2 elbows, 90 ft., and so on, dropping another 5 ft. in length for each elbow up to a maximum of 8 elbows and 60 ft.
The company warns:
Adhere to these instructions to ensure safe and proper furnaceperformance.
The length, diameter, and number of elbows of the vent/flue pipe and combustion air pipe (when applicable) affects the performance of the furnace and must be carefully sized.
All piping must be installed in accordance with local codes and these instructions. - Goodman MVC96/CVC96 Direct Vent manual cited below
You can find the Goodman furnace manual I cite at our list of HVAC manuals provided
at GOODMAN HVAC MANUALS and there you will find contact information for the company so that you can be sure you have the correct instructions and the installation and operation manual for your specific heater.
Watch out: the Goodman furnace direct vent length table given below is adapted from that manual and it might not be correct for your heater and model. Check with your manufacturer or your supplier.
Notes to the table above
Source: GOODMAN TWO STAGE GAS FURNACE CV96 & MVC96 [PDF] Installation & Operating Manual, (Type FSP CATEGORY IV Direct or Non Direct Vent Air Furnace), retrieved 2017/09/11, original source: https :// www.questargas.com/ ForEmployees/ qgcOperationsTraining/Furnaces/ Goodman_GMVC96_Installation.pdf
Watch out: the installation and operation manual used as an example here includes additional vent and vent termination requirements that must be respected for safety and for proper functioning of the heating equipment.
See MANUALS for HEATING SYSTEM CONTROLS for I&O Manuals for other heating equipment brands and models.
Reader Q&A - also see the FAQs series linked-to below
On 2020-01-04 by (mod) - B-vent clearance to combustibles
Cliff help me out if I've misunderstood, but it seems to me that B-vent clearance requirements or gas heater vent clearance requirements that specify distance to nearest combustible are based on possible temperatures involved and thus on the input BTUh of the equipment. Changing a cabinet dimension without changing the BTUh rating ought not innately change the clearance distances.
However a different heater cabinet dimension may actually locate the heater's exhaust vent opening slightly so as to require you to move the routing of the vent / chimney.
On 2020-01-04 1 by Goodman Hacker
@cliff,
'what is the difference between a 80,000 B heater input BTU rating and a 80,000 C heater BTU rating as it applies to your vent length table' The difference between 80,000 B and 80,000 C is the furnace cabinet width. Most residential furnace manufacturers offer 4 cabinet width options being A, B, C, and D widths.
On 2020-01-04 by Goodman Hacker
@Denny,
No Denny, using one pvc vent termination for two appliances is not permissible. If this were an option it would be found in your installation manual and/or ifgc book. Good luck Denny and keep it safe.
On 2019-12-17 by Denny
Will it work and is it OK, to run a 2' PVC furnace vent and a 3' PVC water heater vent out through a common 4' PVC vent through the wall using a Y fitting so there is only one exit through the wall ?
On 2019-12-02 by (mod) -
Robert from the table above on this page we see Distance to each side of centerline extended above a [gas] meter / regulator assembly 4 feet - but electric meters are not sited in the standards that I have found and refer-to here.
Common sense would avoid direct contact or poor detailing that could damage either system (such as gouges, leaks, corrosion)
On 2019-12-02 by Robert
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Is there a minimal distance between the direct vent cap location and an electric meter, or the vertical tube that bring the wire from the roof to the meter ? Minimum distance horizontally from the meter or vertically?
Thanks»!
On 2019-10-05 by cliff
what is the difference between a 80,000 B heater input BTU rating and a 80,000 C heater BTU rating as it applies to your vent length table
On 2019-09-17 by (mod) -
I don't understand the whole situation, Tony but a good place to start is with the brand and model of your gas fireplace. Armed with that information we can take a look into the installation and operation manual for the fireplace to see the minimum clearance distances recommended by the manufacturer.
For example, if you live in a climate where snowfall accumulates, placing the vent where you describe it might put it too close to the ground and subject to being blocked by snowfall- that's unsafe.
On 2019-09-16 by Tony
Can I safely and within code run a 3/4' conduit just under the vinyl siding above a direct fireplace gas vent. The top of the vent is currently 4 inches below the vinyl siding.
On 2019-09-03 by Kevin
Thank you for the info!
On 2019-08-20 by (mod) - minimum clearance from a sidewall direct vent to a neighboring home?
Kevin there's more than one answer - for example are there windows in your home's wall that would make the vent violate that detail?
See all of the vent clearances in the article above. Examples - this isn't the whole list - that could apply to your case include: 12' away from gravity fed air intakes The vent terminal shall be at least 12-inches below, 12-inches horizontally from, or 12-inches above, any door, window, or gravity air inlet into a building. The bottom of the vent terminal shall be located at least 12-inches above grade. Forbidden locations for Gas Heater Direct Vent Terminations
The exhaust vent terminal shall not be located:
over public walkways or over an area where wetting of surfaces by condensate, or water vapor, could create a nuisance or hazard,
near soffit vents, crawl space vents, or other areas where condensate or water vapor could create a nuisance, hazard, or cause property damage, and
where wetting of components by condensate, or water vapor, could be detrimental to the operation of pressure regulators, relief valves, or any other equipment.
14 Inches from Obstructions
The vent terminal shall be installed a minimum of 14-inches from any obstruction
On 2019-08-12 by Kevin
What is the minimum clearance from a sidewall direct vent to a neighboring home? Our houses are fairly close together and I measured 9 1/2’ between my proposed sidewall vent position and our neighbor’s home. All other clearances are fine. Thank you.
On 2019-07-27 by Bill
Thank You!
On 2019-07-27 by (mod) - gas meter clearance to Weber grill
Bill:
Which concern is in your question: 1. grill smoke and exhaust entering the combustion air intake for the water heater? You won't find this explicit in the water heater vent clearances, and the concern varies by type. If your water heater is only venting, that is it's not a condensing heater that also has a combustion air intake, then grill exhaust isn't an issue for the heater and we move on to item 2 below. If your water heater draws combustion air from outside your grill should be located where its smoky exhaust NEVER enters the heater's air intake; grease, soot, smoke can foul the heater's burner and heat exchanger and may make the unit unsafe. While 3 feet may be adequate for some installations, depending on site specifics of buildings, trees, wind, terrain, etc. that could vary. No single answer number would be safe for all conditions. 2. If your concern is heat from the water heater damaging the plastic vent components, the answer may also depend on the size and heat of the Weber grill model. I'd think that three feet would be a bare minimum and even that may not be adequate for large grills. For example a charcoal barbecue grill may be hotter than a small model gas grill. I looked at several Weber Barbecue grill users guides but saw nothing about fire safety clearance distances. You might ask the company for advice. Weber's users guides (find the one for your specific model) are at https://www.weber.com/GB/en/service/user-guides/weber-48602.html Weber contact information: Customer Service Weber UK: +44 (0)203 630 1500 Weber IE: +353 (1)437 2530 Weber USA: 800-446-1071 3. If your concern is for heater exhaust affecting the grill operation, we have no expert data on that concern and it's less likely to be a worry but the same 3 ft. arbitrary guess may be sufficient.
On 2019-07-27 by Bill
How close to the outdoor vent for my gas water heater can i safely use my weber grill?
...
Continue reading at DIRECT VENTS / SIDE WALL VENTS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see GAS APPLIANCE DIRECT VENT CLEARANCE FAQs - questions & answers posted originally on this page.
Or see this
Article Series Contents
Suggested citation for this web page
GAS APPLIANCE DIRECT VENT CLEARANCES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.
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