This is one of our most frequently asked questions!
There are many people that feel they are safe, but here at Pine Tree Heating we DO NOT sell vent free heaters or fireplaces.
Efficiency = percentage of heat from the gas going into the fireplace. 80% efficient means out of 100% gas input into the fireplace, 80% of that gas is used as heat in the house and the remaining 20% of the heat is in the exhaust. Combustion (fire) produces a lot of moisture- up to one quart per hour! Most 90%+ furnaces require an exhaust blower and a condensate pump that move the moisture to a drain. Direct vent fireplaces are as efficient as they can get them without having combustion blowers and drains and other furnace type parts taking up space and reducing the viewing area, and will not work without power. An example of efficiency: 40,000 BTU of gas at 84% is 34,000 BTU as heat and 24% is 5,600 BTU in exhaust.
A direct vented fireplace is a sealed combustion unit. This means that there is glass that is sealed on all sides with a gasket, so no air or moisture comes in or out around the glass. All the air for combustion (the fire) comes from outside and all the exhaust goes outside through two separated parts of a coaxial (pipe within a pipe) chimney/vent. No already warmed air is used from the house, only air from outside. Heat from the fireplace radiates into the house and typically keeps the main furnace from kicking on. Blowers are available for most models. This is the safest and most efficient type of fireplace. The efficiency is under 90% but generally over 70%. Most gas fireplaces that we sell are direct vent and are in the 80 - 86% range. Direct vent is as efficient we can get without having condensate pumps, combustion blowers, pressure switches and condensate drains.
B-vent fireplaces are the next step down in efficiency and safety. There is normally a glass front, but it is not sealed with gasket on all sides, if at all. The air for combustion is used from within the house, and already warmed by your furnace. (it is not important that the air be warm for combustion- I include this fact because, remember, you pay for the gas to heat it the first time also.) This type of fireplace will create a draft on the house, drawing out the already warmed room air to burn in the fire, and out the chimney or vent with the exhaust. The air gets replaces (An open burning fireplace with a gas log in it is typically 20% efficient and makes the furnace run even more.)
In professional terms the INSERT is a fireplace unit that fits inside of an existing wood burning fireplace, whether prefabricated or masonry. An INSERT basically "inserts" into the existing fireplace. The INSERT is smaller but has a large clearance to combustibles, requiring the already present safety clearances of the existing wood burning fireplace. An INSERT can be gas, wood and pellet burning. An INSERT is not safe to install on it's own, with one exception, some pellet units are tested and UL listed to be installed with an additional shroud from the manufacturer, and occasionally are ZERO CLEARANCE.
The ZERO CLEARANCE is a pre-manufacured fireplace that has an extra shroud built on it that reduces the clearance to combustibles (floor underneath is zero clearance- it can sit on wood and be safe) and typically quite minimal to sides of the fireplace unit. These units are unable to be INSERTS. These units are mostly gas and wood burning.
It is ALWAYS best to read the whole installation manual before purchase and if you have further questions, call and ask a professional or contact the manufacturer.
This can be a tricky question! It depends on the manufacturer, the fireplace, stove or insert, the place you want it installed and the fuel type. It is always best to consult the installation manual, manufacturer or professional for what the best practice is for that particular unit before you buy, to be sure you are able to vent it out safely and properly. Each unit may vary, even within the same brand.
Wood Insert: Requires a stainless steel (aluminum will melt) chimney liner through the chimney. There is debate as to how far into the chimney, we always line the chimney to the top- this reduces drafts as well as draw issues. Older models were less efficient and technology was not as advanced as current models, and the days of just inserting the unit without a chimney liner are over.
Gas Insert:There are a couple different lining configurations for direct vent gas inserts. Our preferred way is to line the existing and up to code chimney all the way up for both intake and exhaust. Gas B-vent inserts use a single liner for exhaust, we would line to the top of the chimney with this type as well, however we do prefer to use direct vent inserts for better efficiency.
Pellet Insert: We prefer to line with a bioflex liner to the top of the chimney. Depending on the unit and manufacturer's instructions, it is possible to vent straight through the chimney. If the pellet insert is UL listed as being able to be "built in" as a zero clearance fireplace, with or without a special shroud, you can vent through the wall, up and out the wall or all the way up through the ceiling.
Gas B-Vent Stove: Requires special gas venting straight up through the roof, or up through an existing chimney that is not used for anything else. This is not ideal for basement installations, unless there is an existing chimney.
Gas Direct Vent Stove: Requires special direct vent gas venting. Typically direct vent chimney is coaxial pipe (a pipe within a larger pipe) the inside pipe is where the exhaust exits the fireplace and the exterior pipe is the intake. DV stoves can also be vented through a masonry and sometimes Class A chimney by way of co-linear liners. This type can be vented in several different configurations.
Pellet Stove:Typical installations require "P or L vent" and, depending on the manufacturer's installation guidelines can sometimes go straight out the wall, but more often (because it maintains a bit of natural draft if the power goes out while it is running) up a couple of feet before terminating out the side wall. It can be vented through the roof or with a liner up an existing masonry or class A chimney as well.
Wood Stove:Wood stoves require either masonry or class A (pipe that can reach 2100° F) chimney.
Wood pre-manufacturered zero clearance Fireplace, open or sealed combustion:This type of unit requires air cooled or Class A chimney, depending on the manufacturer's installation guidelines.
Gas B-Vent or Gas Natural Vent Zero Clearance fireplace: These require B-Vent pipe. They also require venting straight up through the roof.
Gas Direct Vent Zero Clearance Fireplace: These units take special direct vent gas venting, the majority use co-axial chimney pipe and can occasionally utilize co-linear liners. Be sure to read the manufacturers installation instructions. Some higher heat output models may require a certain amount of pipe above the unit before it can terminate. These can terminate out the wall or through the roof. The inclusion of a power vent system makes the possibilities virtually endless.
Cracks in the heat exchanger of a furnace are VERY dangerous! They might seem small but they can open up when heated (metal expands with heat, contracts with cool) and let CARBON MONOXIDE into the air that circulates into the house. If your furnace repair person sees cracks have them show you. Most reputable companies will have a camera for viewing them. We have seen cracks that can fit a hand through it when it heats up. Carbon Monoxide is a by-product of gas combustion that, in humans and pets, steal the places in the blood that Oxygen can ride on. If blood cells are a train CO is a gang that steals seats so no one else (Oxygen) can ride the train. It has no taste or smell and is a silent killer. The only way to fix cracks in the heat exchanger is to replace the heat exchanger or the whole furnace.
Changing your furnace filter keeps your furnace running in peak performance and efficiency. The more particles that are in a filter the more plugged it will get, the harder the furnace has to work, driving up electric usage and lowering efficiency. It is similar to trying to drink through a straw with ice on the bottom, you have to work harder and you get less through it. The same goes with heat and your filter. Sometimes when the filter is plugged it can pull the filter into the blower motor and cause damage. Other times it can cause the furnace to over heat and shut down. When the furnace overheats and shuts down without going through the cool down cycle it can cause cracks in the heat exchanger. (see above) If you go too long without a filter you risk plugging the furnace up with dust and dander and causing many more issues that can lead to equipment replacement.