If you own a wood stove or a wood burning furnace, you probably understand that wood burning is all about efficiency — the efficiency of your wood fuel, the efficiency of the appliance itself, the efficiency of your flue pipe, etc. You want as much of the heat produced by your furnace or stove as possible not to go to waste.
But even the best wood burning stoves have an efficiency rating of 81% at most. That means in the best-case scenario, nearly 20% of the heat from your wood stove is simply going to waste.
Heat reclaimers were created to rectify this issue, capturing heat that would otherwise be wasted and channeling it back into your home.
But how does a heat reclaimer work?
And what kind of appliances should they be attached to?
At HY-C, we manufacture Magic Heat, a heat reclaimer that’s been around since the 1970s. And we want to share with you just how heat reclaimers work their magic to pump extra heat back into your living space.
By the time you’re through, you’ll know how a heat reclaimer gives you back this extra heat. You’ll also know what kind of wood burning appliances are best for a heat reclaimer, exactly how much recaptured heat one of these appliances helps to save, and how to avoid any dangers that may come along with attaching a heat reclaimer to your flue pipe.
How Does a Stovepipe Heat Reclaimer Work?
One of the most important aspects of a wood burning appliance (whether it’s a stove, a furnace, or a fireplace) is the flue pipe. As wood burns in the firebox, heat, smoke, and other gasses rise through the flue and out of your home.
To install a heat reclaimer, a section of this flue pipe is cut out, and the heat reclaimer is installed in its place.
On the inside of the reclaimer are ten horizontal transfer tubes made of metal. As heat rises through the flue pipe and into the heat reclaimer, those ten tubes are heated up, and a fan on the back of the reclaimer blows that heat out of the tubes and into your home.
The heat reclaimer’s fan is thermostatically controlled and designed to turn on and off based on the temperature of your flue pipe:
- The fan turns on when the pipe is 150°F or hotter
- The fan turns off when the pipe is 120°F or cooler
A heat reclaimer’s fan is positioned only to blow air through the ten heat transfer pipes, not through the flue pipe itself. This prevents smoke from blowing into your home while still allowing heat to filter in.
How Much Heat Does a Heat Reclaimer Recover?
So, how much heat does a heat reclaimer actually circulate back into your house? To answer that question, we’ll have to do some math.
Let’s say you have a wood stove that is 80% efficient.
Now let’s imagine that you burn a log inside of that stove that has 10,000 BTUs of energy in it (a BTU, or British Thermal Unit, is a measurement of a fuel’s heat energy).
Without a heat reclaimer, burning that log inside that wood stove would radiate 8,000 BTUs of heat into your house (80% of 10,000).
Our Magic Heat heat reclaimer, as an example, is capable of recovering up to 30% of the heat energy lost through the flue pipe — in other words, 30% of the 2,000 BTUs lost in the wood stove from our example.
That means in this particular case, a heat reclaimer would recover 600 BTUs of heat energy and send it back into your home.
That may not sound like much, but this example covers just one log. Throughout a cold season, you can expect to burn hundreds of logs in a wood burning appliance. If you burn four cords of wood during the fall and winter — about 3,000 logs — you can recover nearly 2,000,000 BTUs’ worth of energy using a good heat reclaimer.
Which Appliances Can Use a Heat Reclaimer?
The kinds of appliances you can use a heat reclaimer on depend largely on one factor: whether or not they have a flue pipe. Most heat reclaimers are designed to work on appliances with a 6” or 8” flue diameter.
With that in mind, some of the most common heaters to use a heat reclaimer include:
- Wood burning stoves
- Pellet stoves
- Corn stoves
- Wood burning furnaces
- Coal furnaces
Out of these appliances, wood burning stoves in particular utilize heat reclaimers more than any other.
The Dangers of a Heat Reclaimer (and How to Avoid Them)
First and foremost, just like the flue pipe that comes out of your heater, heat reclaimers can get very hot. Touching the appliance — especially the heat transfer tubes — can result in burns and skin damage. So be sure not to touch your heat reclaimer when it’s in use and be sure that any curious kids or pets in your home can’t get near it.
Another concern about heat reclaimers revolves around creosote buildup. Creosote is a byproduct of burning wood with too much moisture in it. It’s highly flammable, so it’s best to avoid creosote buildup in your chimney flue by burning dry, seasoned firewood.
Creosote may also leak out of your heat reclaimer if it’s installed incorrectly, which is very dangerous, as creosote formation on the outside of a wood burning appliance can easily cause a house fire. To prevent this, the crimped end of the heat reclaimer needs to be installed facing downwards toward your heater.
If the crimped end is installed facing upwards, there will be a gap in the flue pipe that creosote could leak from. Installing the crimped end down ensures that creosote stays confined to the inside of the chimney pipe where it can be safely cleaned long after the fire has extinguished.
Should You Get a Heat Reclaimer?
Before now, you may not have known much about heat reclaimers or how they work. At this point, though, you should understand how a heat reclaimer functions, how much heat it saves, and how to avoid any potential dangers they entail.
As to whether or not you should get one for yourself, that depends. If you have a wood stove, a furnace, or any other kind of heater with a flue and you’re interested in recapturing some burned heat to increase the efficiency of your appliance, you may be the perfect candidate for a heat reclaimer.
Just be sure to adhere to the proper instructions when installing your heat reclaimer for maximum safety and efficiency, and follow good burn practices when using your wood burning appliance to keep your heat reclaimer in working order for years to come.
If you’re considering buying a heat reclaimer, Magic Heat — a HY-C product — is a solid model that’s been around since the 1970s. The in-depth review below takes a look at the pros and cons of the Magic Heat to help you decide if getting one is right for you and your heating appliance.