Upgrading your Existing Fireplace - Glass Doors, improved dampers, Firebacks and Heat Exchangers can help.
Ah, the Fireplace....that icon of luxury and relaxation that represents an escape from the pressures of everyday life. The flickering flames mesmerize and make one forget that most fireplaces add significantly to the cost of home heating! Yes, that big hole in the wall can be responsible for your having to work HARDER to pay your energy bills...and very few folks enjoy higher monthly bills.
Open fireplaces can vary greatly in their efficiency, typically being anywhere from -20% (meaning they lose a lot more heat than they gain) to as much as +10-20% positive.....which indicates that they deliver a small portion of the wood's heat back into your home.
You could certainly convert your fireplace with a fireplace inserted stove, but this can be an expensive proposition (approx. $3,000). Occasional fireplace users also may not want to change the look of their decor with such an installation. There are, however, some less expensive steps you can take to assure you are getting the most from your existing fireplace.
Having a good fireplace grate can increase the efficiency of a fireplace AND make fires easier to start and tend. Some grates are specially designed to make the wood fire radiate better into the room. An example is "The Grate Wall of Fire", which uses clever design to make the glowing part of the logs project heat forward. Note that this type of grate works best with open fires, when a glass door is either not installed or left open during the hottest parts of the fire.
An example of a high quality standard grate can be found in a product called The Self Feeding Fireplace Grate. These grates properly cradle the wood and allow for air to enter from underneath. The rounded design allow the wood to settle toward the middle of the grate, therefore requiring less tending.
Firebacks are upright panels which sit behind the grate and serve a number of purposes. They reflect heat off the rear wall, creating a safer installation and helping to throw heat forward into the living area. The cast iron models are also decorative and can add an heirloom quality look to your fireplace. Some of the highest quality firebacks are produced by the artists at Pennsylvania Firebacks.
Fireplace Heat Exchangers
If you are looking to heat a room or two with your fireplace, a forced air (blower) heat exchanger may be just the ticket. My recommendation is to shop carefully and select a unit which will hold up to the high temperatures and corrosive effects of the fire. Check the warranty carefully as well as the owners manual and manufacturers literature and reputation. I would not recommend the cheap heat exchanger grates commonly sold by home centers and hardware stores - expect to spend $450-$700 for a quality unit. Two brands names which appear well made are The Fireplace Radiator and Stoll Heat Champion.
Another way to improve the efficiency of your fireplace is to limit the available air by the use of glass doors. Using such doors will control the intensity of the fire and slow the rush of heated air up the chimney. These are especially useful when the fire is burning low and you cannot yet close the damper. The idea method of operation for most glass doors is to leave them open when the fire is burning hot and to close them when it is lower and going out.
Most fireplace doors are built using tempered glass which is only good to approx. 600 degrees F. This glass can break due to shock or excess heat if kept closed during hot fires. Some manufacturers offer an upgrade to Ceramic Glass, which is good to 1400 degrees F.
Note: Pre-fab (metal) fireplaces can only be fit with glass doors made by the fireplace manufacturer or approved by another testing authority for such use.
A fireplace damper serves two purposes. It can be adjusted during the course of the fire to allow less airflow up the chimney and therefore less heat loss. It also should provide a relatively tight seal when closed.
Prefab fireplaces have built-in dampers which are often only open-close. These should not be modified or replaced as they are safety tested only in the stock configuration. Masonry fireplace dampers often have problems such as loose fit and missing handles. Cleaning the damper frame and damper can often remove soot, sand and small mortar pieces which stop the damper from proper seal. Replacement parts and handles for many dampers can be ordered through a masonry supply yard or a source such as Whitecaps.
It is my opinion that a decent damper at the fireplace level is best. However, if you have no damper and cannot properly fit one, a number of companies product chimney-top dampers which seal very tightly. They are controlled from inside the fireplace by a stainless cable. Popular brand names are Lyemance, Seal-Tight and Chimalator. Some of these are damper/cap combinations and others are dampers only.
Alternative dampers such as the Fireplace Draft Stopper or the Chimney Balloon can also be effective especially over the off-season or if your fireplace is rarely used.
Outside Air Inlets
A fireplace requires a large quantity of air to burn your wood - air that has already been heated by your conventional heating system. As this air is pulled up the chimney, colder air from outside is pulled into your home through small cracks such as door frames, electrical outlets and other sources. Many pre-fab fireplaces have outside air hookups already built in. If your fireplace is located on an exterior wall, you can inspect the outside structure at the fireplace level for the presence of a small vent which resembles a dryer vent. If you find this vent, then chances are you have outside air installed which can be opened or closed by a small lever inside the fireplace. Consult your owners manual or ask your chimney service professional for proper operation of this valve.
Outside air inlets can also be installed in masonry fireplaces, although such installations are sometimes difficult due to the thickness of brick or lack of an ash dump (which often provide a path to outside air). All in all, most consumers would do better to install a set of quality glass doors and use other methods such as damper control and smaller fires to avoid excess air up the chimney. However, for new installations in tight houses, outside air should be considered.
Fireplace tools add both to the safety and convenience of your fireplace. Having the ability to properly remove the ash, position the logs and rake the embers will also benefit the efficiency of your burning.
After you have taken the proper steps to upgrade your fireplace, you’ll be able to enjoy those flames AND warmth so much more…and, have fewer nasty surprises when the fuel bill arrives.