A standard efficiency furnace provides 80% annual fuel utilization efficiency (AFUE). These days, 95% AFUE is a common rating among new gas-powered furnaces.So a 95% furnace is more efficient than an 80% furnace. h�bbd``b`*~@��H�� �M@��H���@B}H]��_R� $ This leads to many improperly installed intake and exhaust vents by installers who are unfamiliar with the newer furnaces. A furnace pressure switch is a safety device designed to sense the negative pressure created by the draft inducer at startup. First, check to see if the furnace combustion problem is caused by an obstructed air supply pipe by removing the burner compartment cover. As with a conventional furnace, the pressure switch on a condensing furnace sometimes can fail or get stuck in an open position. To avoid this problem, high efficiency furnace venting requires the use of PVC pipes instead of metal pipes to remove the acidic condensate from your home. When a condensing furnace has a weak flame or will not ignite at all, there are five different conditions you can check for relatively easily, most of them related to venting issues: An obstructed air intake vent pipe in a direct-vent two-pipe system will cause serious combustion problems in a condensing furnace. If the condensate drain is blocked by debris or frozen condensate, or if it simply drains improperly, the pressure switch may open, preventing ignition. Frost accumulation is a common problem with air conditioners and relatively rare on furnaces. I had a new high-efficiency furnace installed in my unheated attic and had the same problem of the furnace not running because the condensate trap had ice in it. A sagging or improperly sloping exhaust vent pipe can collect condensate water and restrict the airflow, resulting in a tripped pressure switch. High-efficiency furnace vent problems High-efficiency furnaces must be vented differently than old furnaces. … What Is a High-Temperature Limit Switch on a Furnace? The minimum upward slope from the furnace is 1/4 inch of rise for every foot of horizontal run. Below you will find some of the most common problems involving PVC intake and exhaust vent pipes and how these installation deficiencies allow the formation of ice to occur. Often, you will see two PVC pipes extending from the furnace through the sidewall or roof of your home—one is the air intake vent, the other the exhaust vent. You can fit a metal screen over the end of the intake vent to prevent future obstructions. Next, check for obstructions such as birds' nests or leaves in the air intake vent, which is generally a PVC pipe that exits through the sidewall of the home. Bob Formisano is a licensed architect and builder with 30 years of experience in the industry. endstream endobj 11 0 obj <> endobj 12 0 obj <> endobj 13 0 obj <>stream Venting for High efficiency Gas Furnaces – Assembly. Introducing "One Thing": A New Video Series. This indicates a direct-vent system. In fact, most homeowners assume frost can't form on a heating appliance due to the warmth it's producing, but it is perfectly possible for the exhaust vent of a high-efficiency furnace … Similar problems have been observed in older homes that have been retrofitted with new high efficiency gas furnaces where the venting has been put through the wall rather than keeping it through the roof." Some furnaces can be adapted for either single-pipe or two-pipe direct-vent installation. In a perfect furnace, the combustion of natural gas would generate only … "A$�d�3�'��{��� bDJ"�RDz�(�D��&{��o���A�0,#_�mz�b��I*�1�D�b�� ̍�Ӂ9=�ʼn %%EOF Another sign of a clogged condensate drain line is if you notice excessive water coming out of the drainage hole of the smaller secondary heat exchanger when the drain line is disconnected. Problems … When a direct-vent system has its air intake and exhaust vents improperly installed on the outside of the home, it can create a problem of "short-circuiting," which allows exhaust gases to flow back into the combustion air intake pipe. Similar to an obstructed air intake pipe, check for obstructions such as nests or leaves, but also check for inadequate sloping of the vent pipe, and make sure the exhaust pipe is supported every 5 feet of its horizontal run. High-efficiency furnaces are being embraced around the world as a cost-effective alternative to more traditional models. How a High-Efficiency Condensing Furnace Differs . �pb���aP�����6��б~1t�J��;���g?���VP�����z�nR�ԉ�S0� ?��� �N�N5����o7�.���o�am���!�h/���t�dH�C��N�0dɲ�������_&-0�C��0Rbj��d�f۫[���M:O��l�i8�wv�K�Ҵ7�ܽ�~�۶�y�����̟藼X%��z��c��L����z�i�hl��p�I���U����"ݘ��߫})l���h�F7�y�H�K���;�2ݏiQ��SR� ���|b����"�h�<3�͸x�6�}n�ya�ʉ��ӗ��YW`Aq�JDqN��3�8�lP�VnTK����&$:A��N=��:�c:��c��e����x� iq�B$+B@�- Br2�����pu$��Ԣ�|_�y��S��4��c���^G�R��!�������w>��+� _n��|�� �oj�މ:�+�ƿp�_ Basic instructions on how to run pvc flue venting on high efficiency furnaces. A high-efficiency or “condensing” furnace can significantly reduce energy consumption in a typical home; however, without a quality installation, the furnace may never deliver its expected energy . 5 Common Problems With High-Efficiency Furnaces Venting in High-Efficiency Furnaces. Energy Star® has found that new furnaces often do not perform to their rated efficiency … 23 0 obj <>/Filter/FlateDecode/ID[<8F4B40C83C188252DBD7AB69298AAC18>]/Index[10 29]/Info 9 0 R/Length 77/Prev 45717/Root 11 0 R/Size 39/Type/XRef/W[1 2 1]>>stream Ignition problems caused by a condensate drain clog may be intermittent. The main difference between a conventional furnace and a condensing furnace is the heat exchanger technology used to extract heat from the combustion process and exhaust the combustion gases. It concentrates on venting problems on the 90% efficient furnace. A. In this type of furnace, 20% of the energy produced by natural gas is expelled as exhaust. For a tutorial that supplements this tutorial and covers issues unique to the high-efficiency gas furnace (90% AFUE and above), read up on troubleshooting a high efficiency condensing furnace. … The result is that air reaching the furnace does not have enough oxygen for proper combustion. … You Need to Make Sure Your Furnace is Venting Properly. High efficiency furnaces with sealed combustion don't have this problem and are a good choice for furnaces that will operate from a sealed attic or crawlspace. Flues Vent Exhaust Gases. ���������=��BX��}���͜��^�>,�gc�q���~߅q�� ��I��F}�� �5��nv�vT���h�Vΰ�K�v�]���j���>8û�EP�� ���=��nKX=Z���[�X��-���l��W�LKSl�:�|�����&�+�i�a�G��dCw�h�Ѿ�G�K[��tX���8�}��x�M��O��"�]u9����_�]>����ا��u If necessary, clean out the vent with a plumber's tool known as a sink auger. We explain the difference between side wall or direct venting for conventional/mid-range efficiency oil or gas burning heaters and side wall vented high efficiency … Since water vapor condenses within the vent pipe, these connections are crucial to ensure proper drainage. While the condensing furnace is different in its design and repair needs, it does have some similarities to a conventional furnace.Like a conventional furnace… h޼�[o�J���>&����-UH\Aj���4��ĕ�{s�}gv Ɓ�UG�����\v?aD����Ex�������. Set the multimeter to ohms (resistance test), then place each multimeter lead on a separate terminal on the pressure switch. They can start and stop as the restricted water flow drains away over time and allows the furnace to cycle back on, but unless the problem is fixed, the symptoms will reappear once the condensate backs up again. ��f�$)"�3^�` �� If you're thinking about encapsulating your crawlspace or insulating your attic with spray foam, consider upgrading to a high efficiency furnace … And if your furnace … These furnaces operate diffe… savings. endstream endobj 14 0 obj <>stream This problem can be avoided by use of a concentric vent kit or by properly installing separate vent pipes using a two-pipe system. I didn’t get much help … This feature makes sure the inducer fan is running and it shuts down furnace ignition if there is not enough airflow to maintain proper combustion. A partially clogged condensate line, or a clog at the condensate collector box near the inducer fan, will often trip the furnace’s pressure switch. Preventing Venting Problems Proper installation and maintenance can prevent furnace shutdown HIGH EFFICIENCY: York recently introduced the TM9Y condensing gas furnace, which … In addition, you should check for cracked or broken hoses running from the pressure switch because this can also cause a tripped switch. The condition of the chimney is a factor because new super-efficient gas furnaces do not vent up the chimney. But some high-efficiency condensing furnaces use a single-pipe vent system, where the combustion air is drawn from the indoor air supply, and a single PVC pipe serves to vent combustion exhaust gases. But if there is an issue or a clog anywhere in the condensate line or drain, water will begin overflowing and leaking from the furnace and onto the floor. High efficiency furnaces offer 90% or more AFUE. It should be a simple choice, right?Well, not really. ��� �a�����F����ȏ��F~"&1,�_l�#��G�x8�� }�;��q�� &�s���0@ If moist fumes aren’t venting out, the moisture will rust the metal there. Something you may have noticed is snow and ice building up around the vents of your high-efficiency furnace. 0 %PDF-1.5 %���� Below, we’ve listed a few problems … Here are some good venting practices. Fixing this problem is probably a job for a qualified HVAC contractor. Another clue could be rust on the grillwork on the front of your furnace. (This is mostly stuff I learned during a training session from IPEX, one of the major manufacturers of plastic piping, with a little of my personal experience and tips) First of all, venting … To test for proper functioning of the furnace pressure switch, you will need a multimeter (voltmeter/ohm-meter). Look in your install manual, most manufacturers will call for the furnace to be installed with a slight forward pitch to allow condensate to drain from the heat exchanger. Conventional – Incorrectly Sized Vent Pipe A conventional furnace (AFUE lower than 90) is equipped with an exhaust vent pipe made of metal (high-efficiency furnaces have PVC vent pipes). endstream endobj startxref This will provide free airflow to the combustion chamber. The … h�b``�f``�e �����Y8�Ÿ���!���a�m�u.��mݑ,=x�D�t2:[@Mh����g�0 �� This one talks about a gas furnace that is giving a pressure switch code. Depending on the installation, a high efficiency furnace will have at least … This heat-extraction processes caused water vapor to condense out of the air, which is drained away through a tube that is usually placed in a floor drain. High-efficiency furnaces are often known as condensing furnaces because they have a second heat exchanger that extracts additional heat from the air that passes through the first heat exchanger. A high-efficiency condensing furnace is a little more complex than a conventional furnace, and troubleshooting is somewhat more complicated since there are more potential problems. F��&�7�G�t@?���IKB���`�j��)Ҥ���_|��]�psw�.�Y�ٳ�⬖��K� d� h��X�r�F}�W�#�EB �Tj���)�ȉͤ*e�H�A�L3�����˜���f�ه��T� z������=���2M�|��~�F�J��Ɣ�3?�S��,៍����7�4��ل���cJ�fp���B ��k1�],B�(ad6��HƼ�߱��� Because the pressure switch senses the accumulation of condensate in the furnace drain pan, the furnace will not operate until the condensate drain has been cleared and the condensate can again flow freely. A clog or problem in the condensate system. Get daily tips and tricks for making your best home. In many cases, the problem is due to ice build-up in the vent pipe, blocking the exhaust flow. Thus, a high-efficiency condensing furnace can be identified by the presence of this drainage tube. �P�FZV�1SuۤY+sP�M�F�G����?�q#�'���ܻ2��/�T���H�=o���?|�5�_=��^?��΍B69rb��^����/�Gw/_>���?���_?~1�{cy�I�8A������H����S������Yxc��^m��ղє6�T�ʚt�l�R����kY6T�����P�I�����T����z$���JYg{*��N3Izݵ�ս�`w���,�`��Ů���˥�@�2�+�H��ne�=ԴI�=e�­�`4rF-L-��X�6jY� ���Ij� ���*u[w�ix�4tFm��˺�m��CZV*{W�+�[~X��n����"��\�8k���u�˪���Vn��I�������. It will ruin the standard venting equipment that is used in conventional gas furnace ventilation systems. At the furnace, disconnect the power leads attached to the pressure switch terminals. � We include for comparison, low temperature side wall vent systems used by high efficiency or condensing boilers, furnaces & water heaters. Balcaen & Sons owner Tom Balcaen says it’s something you should keep an … Most vent icing problems involving high efficiency furnaces are not a direct result of the weather, but an improperly installed venting system. In contrast, modern high-efficiency condensing furnaces exhaust much … This can happen when the air intake and exhaust vents are too close together and the exhaust vent gases—which consist mostly of water vapor, carbon dioxide, and carbon monoxide—are drawn back into the combustion air intake vent. Your high-efficiency furnace has an entire system set up to drain away the condensation it produces. -Slope the drain line … First, set the thermostat to call for heat. … A resistance reading that indicates a larger number or infinity means the pressure switch is faulty and must be replaced. Homeowners are often surprised when their fairly new high-efficiency furnace shuts down unexpectedly in the middle of winter. This tutorial covers the conventional gas furnace (up to 89% AFUE). Traditional gas-fired, forced-air furnaces produce hot combustion exhaust gasses and therefore need metal vent pipes, or chimneys. The most common high-efficiency furnace venting problems are: Drain connections. Ensuring that your high-efficiency furnace … They are vented outdoors horizontally through a wall by a small plastic pipe. When your furnace comes on in the morning, if it is venting into your house rather than outdoors, moisture will condense on the cold glass. The main difference between a conventional furnace and a condensing furnace is the... Weak Flame Caused by … Weak Flame Caused by an Obstructed Intake Air Vent, Weak Flame Caused by Improper Exhaust Gas Recirculation, Failure to Ignite Caused by a Clogged Condensate Drain, Failure to Ignite Caused by Clogged Flue Vent, Failure to Ignite Caused by a Faulty Pressure Switch, Plastic Vent Pipes for High-Efficiency Condensing Furnaces, 8 Common Problems With Conventional Gas Furnaces, Venting a Hot Water Heater: What You Should Know, A Visual Guide to a High-Efficiency Condensing Furnaces, Troubleshooting an Electronic Ignition Furnace That Won't Light, Ventless Gas Fireplaces: What to Know Before You Buy, Easy Winter Preparation Checklist for Your Home, How to Troubleshoot a Gas Furnace That Produces No Heat, 3 Things to Check When Your Furnace Stops Working. If combustion improves when you remove the cover, then the dedicated combustion air supply vent pipe may be obstructed. In addition to the ignition failures common with a conventional furnace, such as a faulty igniter, ignition problems on a condensing furnace may be related to a clogged flue vent condensate line. The pressure switch can also be tripped by an obstructed exhaust flue gas vent pipe. Troubleshooting a High-Efficency Gas Furnace. 38 0 obj <>stream 10 0 obj <> endobj Plugged exterior vents. A modern high-efficiency gas furnace is a computer-controlled wonder that gets the most heat out of every unit of gas it burns. Visually, you can usually identify a condensing furnace because the exhaust gases will exit your home through a relatively small PVC pipe, rather than the large metal exhaust flue found in conventional furnaces. The meter should read 0 or close to 0 (indicating no resistance).