{"id":49,"date":"2023-11-06T16:58:17","date_gmt":"2023-11-06T21:58:17","guid":{"rendered":"https:\/\/opentextbc.ca\/plumbing4b\/?post_type=chapter&#038;p=49"},"modified":"2025-04-22T17:55:07","modified_gmt":"2025-04-22T21:55:07","slug":"describe-methods-providing-gas-appliance","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/plumbing4b\/chapter\/describe-methods-providing-gas-appliance\/","title":{"raw":"Learning Task 1","rendered":"Learning Task 1"},"content":{"raw":"Air consumed by any fuel burning appliances must considered in order to maintain a balanced building. The efficient and safe operation of gas-fired appliances relies on an adequate supply of air over and above that required for building ventilation or make-up air. For all gas appliances, the source environment of the air supply is critical. Combustion air must be free of corrosive chemicals and excessive local atmospheric pressure fluctuations.\r\n\r\nThere are two common methods of delivering the air supply requirement to a gas appliance:\r\n<ul>\r\n \t<li>direct vent systems<\/li>\r\n \t<li>room air systems (non-direct vent)<\/li>\r\n<\/ul>\r\n<h1>Direct vent systems<\/h1>\r\nFor a direct vent system all of the air for the appliance is taken directly from the outside as well as the flue gas is discharge to outdoors. Therefore, direct vent appliance will have no effect on the air balance of the building. Direct vent systems typically have two piping options either concentric coaxial pipe or twin pipe (Figure 1).\r\n\r\n[caption id=\"attachment_274\" align=\"aligncenter\" width=\"844\"]<img class=\"wp-image-274\" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-1-2.png\" alt=\"Two different direct vent appliances. The left appliance has two pipes, one for combustion air to go in and one for exhaust to come out, and the right appliance has one concentric coaxial pipe, where both combustion air goes in and exhaust comes out. \" width=\"844\" height=\"439\" \/> <center>Figure 1. Direct vent appliances<\/center>[\/caption]\r\n\r\nThere are a variety of materials that are used for the venting and air supply piping on direct vent appliances. Some direct vent appliances are designed to use either concentric or twin pipe direct vent options, with the use of the manufacture supplied starter adapter (Figure 2).\r\n\r\n[caption id=\"attachment_275\" align=\"aligncenter\" width=\"748\"]<img class=\"wp-image-275 \" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-2-2.png\" alt=\"\" width=\"748\" height=\"422\" \/> <center>Figure 2. Direct vent starter adapters<\/center>[\/caption]\r\n\r\nDirect vent appliances air supply and exhaust piping system must be sized and installed according to the manufacturer literature and therefore, are not sized by the requirements of the B149.1 Gas code.\r\n\r\nRegardless of the category type, if an appliance utilizes indoor combustion air it is not considered a direct vent appliance. For example some direct vent appliances may also be installed as room air dependent systems (Figure 3), in this case the room air supply needs to conform to the manufacturer\u2019s instructions as well as to the gas code.\r\n\r\n[caption id=\"attachment_276\" align=\"aligncenter\" width=\"438\"]<img class=\"wp-image-276 size-full\" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-3-1.png\" alt=\"A room air dependent direct vent appliance with one short and curved pipe for combustion air to go in and one long pipe for exhaust to come out.\" width=\"438\" height=\"486\" \/> <center>Figure 3. Room air dependent direct vent appliance<\/center>[\/caption]\r\n<h1>Room air systems<\/h1>\r\nNon-direct vent gas appliances draw all of their air supply requirements from the internal room air. The amount of air required will depend on the type of appliance(s) in the room. If an appliance is a natural draft appliance designed to operate with a draft control device, it will require a larger volume of air supply than equipment designed to operate with no draft control device, based on the dilution air requirement (Figure 4).\r\n\r\n[caption id=\"attachment_277\" align=\"aligncenter\" width=\"849\"]<img class=\"wp-image-277 size-full\" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-4-1.png\" alt=\"A labelled diagram of a natural draft appliance. The appliance takes in dilution air, excess air and combustion air (primary and secondary air). The appliance feeds in cool air from the bottom, the cool air is blown upward and is heated by burners as it travels upward before the heated supply air leaves the appliance. The products of combustion leave via a vent in the top. \" width=\"849\" height=\"512\" \/> <center>Figure 4. Room air requirements<\/center>[\/caption]\r\n\r\nIf adequate outside air Is not supplied to the room it will create a negative pressure in the room which will affect the safe operation of the appliances. Depressurization in a building with spillage-susceptible appliances must be limited to \u22120.02 inch w.c. (\u22125 Pa). The outside air is normally brought close to the gas appliance burners via a duct (Figure 5), but a hole in the wall may be used in some instances.\r\n\r\n[caption id=\"attachment_278\" align=\"aligncenter\" width=\"606\"]<img class=\"wp-image-278 size-full\" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-5.png\" alt=\"A labelled diagram of a ducted gas appliance, showing the air supply. Outside air comes into the system through a duct, which provides combustion air, and the discharge terminates beside and above the burner. The return air duct guides cool return air to the system and the hot air supply duct leads the hot air out.\" width=\"606\" height=\"508\" \/> <center>Figure 5. Ducted gas appliance air supply<\/center>[\/caption]\r\n\r\nThe size and location of the duct will be determined by a number of factors including:\r\n<ul>\r\n \t<li>the input of the appliances (Btu\/h)<\/li>\r\n \t<li>type of appliances (draft control device or not)<\/li>\r\n \t<li>building construction<\/li>\r\n<\/ul>\r\nSome loosely constructed buildings with adequate air infiltration and large enough volume, such as a warehouse, may not require an outside opening. In these cases, as the air supply can be provided directly from within the structure with no need for ducts or openings. Even in these instances, the indoor air supply may not be suitable if excessive dust or a corrosive atmospheric condition exists.\r\n\r\nThese methods of using a duct or opening to outside could be referred to as passive air supply compared to a mechanical air supply such as a fan. If a mechanical air supply is used it must be properly sized and interlocked with the appliances to shut-off the gas in the event of an air supply failure. This type of system will require that the gas be reactivated by a manual reset control so that corrective measures are taken by the service technician before the appliance is operated again.\r\n\r\n<img class=\"wp-image-56 alignleft\" src=\"https:\/\/pressbooks.bccampus.ca\/plumbing3e\/wp-content\/uploads\/sites\/1587\/2022\/01\/noun-check-702756.png\" alt=\"\" width=\"50\" height=\"50\" \/>Now complete Self-Test 1 and check your answers.\r\n\r\n&nbsp;\r\n<h1>Self-Test 1<\/h1>\r\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\">Self-Test 1<\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\n[h5p id=\"9\"]\r\n\r\n<\/div>\r\n<\/div>\r\n<h1>Media Attributions<\/h1>\r\n<ul>\r\n \t<li>Figure 1. \"<a href=\"https:\/\/gas-geysers-johannesburg.co.za\/rinnai-technical-page\/\">Direct vent appliances<\/a>\" from Rinnai is used for educational purposes under the basis of fair dealing.<\/li>\r\n \t<li>Figure 2. \"Direct vent starter adapters\" - The source for this image is unknown. It is being used for non-commercial, educational purposes. To receive credit for this image, please reach out to the publisher.<\/li>\r\n \t<li>Figure 3. \"<a href=\"https:\/\/gas-geysers-johannesburg.co.za\/rinnai-technical-page\/\">Room air dependant direct vent appliance<\/a>\" from Rinnai is used for educational purposes under the basis of fair dealing.<\/li>\r\n \t<li>Figure 4. \"Room air requirements\" -\u00a0The source for this image is unknown. It is being used for non-commercial, educational purposes. To receive credit for this image, please reach out to the publisher.<\/li>\r\n \t<li>Figure 5. \"Ducted gas appliance air supply\" -\u00a0The source for this image is unknown. It is being used for non-commercial, educational purposes. To receive credit for this image, please reach out to the publisher.<\/li>\r\n<\/ul>","rendered":"<p>Air consumed by any fuel burning appliances must considered in order to maintain a balanced building. The efficient and safe operation of gas-fired appliances relies on an adequate supply of air over and above that required for building ventilation or make-up air. For all gas appliances, the source environment of the air supply is critical. Combustion air must be free of corrosive chemicals and excessive local atmospheric pressure fluctuations.<\/p>\n<p>There are two common methods of delivering the air supply requirement to a gas appliance:<\/p>\n<ul>\n<li>direct vent systems<\/li>\n<li>room air systems (non-direct vent)<\/li>\n<\/ul>\n<h1>Direct vent systems<\/h1>\n<p>For a direct vent system all of the air for the appliance is taken directly from the outside as well as the flue gas is discharge to outdoors. Therefore, direct vent appliance will have no effect on the air balance of the building. Direct vent systems typically have two piping options either concentric coaxial pipe or twin pipe (Figure 1).<\/p>\n<figure id=\"attachment_274\" aria-describedby=\"caption-attachment-274\" style=\"width: 844px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-274\" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-1-2.png\" alt=\"Two different direct vent appliances. The left appliance has two pipes, one for combustion air to go in and one for exhaust to come out, and the right appliance has one concentric coaxial pipe, where both combustion air goes in and exhaust comes out.\" width=\"844\" height=\"439\" \/><figcaption id=\"caption-attachment-274\" class=\"wp-caption-text\">\n<div style=\"text-align: center;\">Figure 1. Direct vent appliances<\/div>\n<\/figcaption><\/figure>\n<p>There are a variety of materials that are used for the venting and air supply piping on direct vent appliances. Some direct vent appliances are designed to use either concentric or twin pipe direct vent options, with the use of the manufacture supplied starter adapter (Figure 2).<\/p>\n<figure id=\"attachment_275\" aria-describedby=\"caption-attachment-275\" style=\"width: 748px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-275\" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-2-2.png\" alt=\"\" width=\"748\" height=\"422\" srcset=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-2-2.png 776w, https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-2-2-300x169.png 300w, https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-2-2-768x433.png 768w, https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-2-2-65x37.png 65w, https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-2-2-225x127.png 225w, https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-2-2-350x198.png 350w\" sizes=\"auto, (max-width: 748px) 100vw, 748px\" \/><figcaption id=\"caption-attachment-275\" class=\"wp-caption-text\">\n<div style=\"text-align: center;\">Figure 2. Direct vent starter adapters<\/div>\n<\/figcaption><\/figure>\n<p>Direct vent appliances air supply and exhaust piping system must be sized and installed according to the manufacturer literature and therefore, are not sized by the requirements of the B149.1 Gas code.<\/p>\n<p>Regardless of the category type, if an appliance utilizes indoor combustion air it is not considered a direct vent appliance. For example some direct vent appliances may also be installed as room air dependent systems (Figure 3), in this case the room air supply needs to conform to the manufacturer\u2019s instructions as well as to the gas code.<\/p>\n<figure id=\"attachment_276\" aria-describedby=\"caption-attachment-276\" style=\"width: 438px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-276 size-full\" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-3-1.png\" alt=\"A room air dependent direct vent appliance with one short and curved pipe for combustion air to go in and one long pipe for exhaust to come out.\" width=\"438\" height=\"486\" srcset=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-3-1.png 438w, https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-3-1-270x300.png 270w, https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-3-1-65x72.png 65w, https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-3-1-225x250.png 225w, https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-3-1-350x388.png 350w\" sizes=\"auto, (max-width: 438px) 100vw, 438px\" \/><figcaption id=\"caption-attachment-276\" class=\"wp-caption-text\">\n<div style=\"text-align: center;\">Figure 3. Room air dependent direct vent appliance<\/div>\n<\/figcaption><\/figure>\n<h1>Room air systems<\/h1>\n<p>Non-direct vent gas appliances draw all of their air supply requirements from the internal room air. The amount of air required will depend on the type of appliance(s) in the room. If an appliance is a natural draft appliance designed to operate with a draft control device, it will require a larger volume of air supply than equipment designed to operate with no draft control device, based on the dilution air requirement (Figure 4).<\/p>\n<figure id=\"attachment_277\" aria-describedby=\"caption-attachment-277\" style=\"width: 849px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-277 size-full\" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-4-1.png\" alt=\"A labelled diagram of a natural draft appliance. The appliance takes in dilution air, excess air and combustion air (primary and secondary air). The appliance feeds in cool air from the bottom, the cool air is blown upward and is heated by burners as it travels upward before the heated supply air leaves the appliance. The products of combustion leave via a vent in the top.\" width=\"849\" height=\"512\" \/><figcaption id=\"caption-attachment-277\" class=\"wp-caption-text\">\n<div style=\"text-align: center;\">Figure 4. Room air requirements<\/div>\n<\/figcaption><\/figure>\n<p>If adequate outside air Is not supplied to the room it will create a negative pressure in the room which will affect the safe operation of the appliances. Depressurization in a building with spillage-susceptible appliances must be limited to \u22120.02 inch w.c. (\u22125 Pa). The outside air is normally brought close to the gas appliance burners via a duct (Figure 5), but a hole in the wall may be used in some instances.<\/p>\n<figure id=\"attachment_278\" aria-describedby=\"caption-attachment-278\" style=\"width: 606px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-278 size-full\" src=\"https:\/\/opentextbc.ca\/plumbing4b\/wp-content\/uploads\/sites\/441\/2023\/11\/Figure-5.png\" alt=\"A labelled diagram of a ducted gas appliance, showing the air supply. Outside air comes into the system through a duct, which provides combustion air, and the discharge terminates beside and above the burner. The return air duct guides cool return air to the system and the hot air supply duct leads the hot air out.\" width=\"606\" height=\"508\" \/><figcaption id=\"caption-attachment-278\" class=\"wp-caption-text\">\n<div style=\"text-align: center;\">Figure 5. Ducted gas appliance air supply<\/div>\n<\/figcaption><\/figure>\n<p>The size and location of the duct will be determined by a number of factors including:<\/p>\n<ul>\n<li>the input of the appliances (Btu\/h)<\/li>\n<li>type of appliances (draft control device or not)<\/li>\n<li>building construction<\/li>\n<\/ul>\n<p>Some loosely constructed buildings with adequate air infiltration and large enough volume, such as a warehouse, may not require an outside opening. In these cases, as the air supply can be provided directly from within the structure with no need for ducts or openings. Even in these instances, the indoor air supply may not be suitable if excessive dust or a corrosive atmospheric condition exists.<\/p>\n<p>These methods of using a duct or opening to outside could be referred to as passive air supply compared to a mechanical air supply such as a fan. If a mechanical air supply is used it must be properly sized and interlocked with the appliances to shut-off the gas in the event of an air supply failure. This type of system will require that the gas be reactivated by a manual reset control so that corrective measures are taken by the service technician before the appliance is operated again.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-56 alignleft\" src=\"https:\/\/pressbooks.bccampus.ca\/plumbing3e\/wp-content\/uploads\/sites\/1587\/2022\/01\/noun-check-702756.png\" alt=\"\" width=\"50\" height=\"50\" \/>Now complete Self-Test 1 and check your answers.<\/p>\n<p>&nbsp;<\/p>\n<h1>Self-Test 1<\/h1>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\">Self-Test 1<\/p>\n<\/header>\n<div class=\"textbox__content\">\n<div id=\"h5p-9\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-9\" class=\"h5p-iframe\" data-content-id=\"9\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"B4 Self-Test 1\"><\/iframe><\/div>\n<\/div>\n<\/div>\n<\/div>\n<h1>Media Attributions<\/h1>\n<ul>\n<li>Figure 1. &#8220;<a href=\"https:\/\/gas-geysers-johannesburg.co.za\/rinnai-technical-page\/\">Direct vent appliances<\/a>&#8221; from Rinnai is used for educational purposes under the basis of fair dealing.<\/li>\n<li>Figure 2. &#8220;Direct vent starter adapters&#8221; &#8211; The source for this image is unknown. It is being used for non-commercial, educational purposes. To receive credit for this image, please reach out to the publisher.<\/li>\n<li>Figure 3. &#8220;<a href=\"https:\/\/gas-geysers-johannesburg.co.za\/rinnai-technical-page\/\">Room air dependant direct vent appliance<\/a>&#8221; from Rinnai is used for educational purposes under the basis of fair dealing.<\/li>\n<li>Figure 4. &#8220;Room air requirements&#8221; &#8211;\u00a0The source for this image is unknown. It is being used for non-commercial, educational purposes. To receive credit for this image, please reach out to the publisher.<\/li>\n<li>Figure 5. &#8220;Ducted gas appliance air supply&#8221; &#8211;\u00a0The source for this image is unknown. It is being used for non-commercial, educational purposes. To receive credit for this image, please reach out to the publisher.<\/li>\n<\/ul>\n","protected":false},"author":125,"menu_order":1,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"Describe The Methods of Providing Gas Appliance Air Supply","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-49","chapter","type-chapter","status-publish","hentry"],"part":29,"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/pressbooks\/v2\/chapters\/49","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/wp\/v2\/users\/125"}],"version-history":[{"count":13,"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/pressbooks\/v2\/chapters\/49\/revisions"}],"predecessor-version":[{"id":603,"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/pressbooks\/v2\/chapters\/49\/revisions\/603"}],"part":[{"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/pressbooks\/v2\/parts\/29"}],"metadata":[{"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/pressbooks\/v2\/chapters\/49\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/wp\/v2\/media?parent=49"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/pressbooks\/v2\/chapter-type?post=49"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/wp\/v2\/contributor?post=49"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/plumbing4b\/wp-json\/wp\/v2\/license?post=49"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}