Avoid These 3 Killers When Using Your Outdoor Wood Boiler in the Summer

If you have an outdoor furnace, this applies to you. Period.

Avoiding these three KILLERS will extend the life of your boiler an additional 20 years! (Not doing this may cut the life of your boiler by 75% or more!)

  1. You must follow the “Dry Burn” procedure. See below for the details.
  2. NEVER allow water jacket temps to drop below 140.
  3. NEVER let ASH level build up more than 1-3 inches deep.

First, ASH LEVELS. Remember that dry ash is harmless. But, if ash gets moist, it is caustic and will eat through steel. Deep layers of ash absorb moisture from your firewood, and from the humid summer air.

NOT let your ash get deep in your boiler. I take out a shovel full every day and scrape it completely clean every week.

Second, NEVER allow your water jacket temps to drop below 140. At temps below 140, your boiler will build up creosote, and generate condensation that will destroy your boiler fast.

I once ran a prototype boiler at my home to heat my pool. In just two years, I destroyed the boiler because it always ran below 140 degrees - it was too small to heat my pool! The condensation created so much corrosion that it was a total loss - an expensive but valuable lesson.

Solution: Do not adjust the aquastat below 180 degrees. Add wood daily, but only enough wood to burn for 12-24 hours. And if you are heating a pool with a heavy heating load, call us for special instructions to protect your OWB.

Third, please, please, please ALWAYS use the "Dry Burn" technique.  Please read this carefully:


These are the top three reasons you should “Dry Burn” your Outdoor Boiler every day:

  1. Longer Boiler Life - Condensation inside the boiler kills it. Short life costs money. Long life saves you money!
  2. Less Maintenance – Your time is valuable, isn’t it?
  3. More efficiency=lower cost – get the biggest bang for your fuel!

How do you get a DRY BURN?

As wood burns, the moisture is slowly burned out of the wood. Unfortunately, that moisture is coming out of the wood for most of the burn cycle – it is only at the very END of the burn cycle when the wood is just dry hot coals that all the moisture is out of the wood. This is the DRY BURN state.


Don’t be THAT guy - he thinks he knows everything.

He says: “This doesn’t apply to me!”

Many outdoor boiler owners never allow their boilers to reach this state. They load up their boiler in the morning with a huge load of wood, and by the end of the day, the wood is only half-burned.

This wood has NEVER reached a DRY BURN state and is still giving the inside of your boiler a moisture bath. Then they “TOP OFF” their firebox burn chamber with more moisture-filled wood, adding even more moisture to the process.  This boiler never experiences a DRY BURN.

The solution is simple!  Only load into your firebox the amount of wood needed to get you to your next fill. You want your wood to burn down completely to coals and burn in that DRY BURN state for the last few hours of every wood load.

Don’t be the guy who says this: “This doesn’t apply to me. I only use SEASONED wood! My wood was cut two years ago!” 

What this guy doesn't realize is that even the most seasoned hardwood contains about 20% moisture. That is a lot of moisture, and you gotta deal with it before it deals with you.

  1. Unfortunately, boilers that don’t get a DRY BURN every day, will begin to experience damaging corrosion. The parts of the boiler that are cooler (such as the perimeter of the door) start to show corrosion damage. The ASH will absorb this moisture and if not removed often, will form an acid paste that eats through steel. Steel in the corners can begin to show pitting damage that, if left unchecked, will lead to a leak in your steel.

Dry Burn will extend the life of your boiler, possibly for several decades. Now THAT is worth knowing about!

  1. Also, boilers that don’t get a DRY BURN every day, will require cleaning much more often. This is because the DRY BURN will dry up and burn off accumulated creosote.

Normal creosote forms while normal wood is being burned until it reaches the Dry Burn state. Then in Dry Burn, that creosote dries up and often flakes off. Without a Dry Burn, that creosote builds up thicker and deeper layers.

  1. Finally, the Dry Burn process saves wood! This is because it burns your wood fuel more efficiently and this saves you time and money.


The solution is simple!  Only load into your firebox the amount of wood needed to get you to your next fill. You want your wood to burn down completely to coals and burn in that DRY BURN state for the last few hours of every wood load.

This will dry out all the components that may have become moist from condensation. This will protect your boiler – and your INVESTMENT!


Avoid these THREE boiler KILLERS and keep your boiler healthy, so you can SAVE MONEY and STAY TOASTY WARM AND COMFORTABLE for decades to come!

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