Burning Wood in an Outdoor Furnace During Summer?

Burning Wood in an Outdoor Furnace During Summer?

Burning Wood in an Outdoor Furnace During Summer?How to Avoid Damage


If you burn your outdoor wood boiler all summer, do NOT forget this very important operational tip:

Your furnace MUST burn several hours each day in a COMPLETELY DRY mode. How is that achieved? Read on!

All outdoor wood furnaces must be dried out every day. Why? Because wood fuel is very high in moisture. Even the most well-seasoned wood contains about 20% moisture and that is a lot of water.

What happens to all that water? We want it to exit your furnace harmlessly in the form of steam. But that steam coats your entire furnace walls, tubes, door seals, chimney, and your ash with MOISTURE! 

Even if you burn your furnace perfectly every day, you will still produce a LOT of steam that puts a layer of moisture on your entire outdoor wood burning boiler.

This is bad. Moisture is bad for steel. Trust us on this - we won't bore you with the technical reasons, but moisture is just bad for steel.

So HOW can I dry out my outdoor boiler? It's easy! Your boiler MUST burn at least several hours each day with only hot dry coals in it.


Yep, the moisture in wood is burning OUT of the wood during MOST of the burn process. It is ONLY after the wood is burned down to black coals when there is no more moisture left in the wood and it can then burn in a very DRY state.


Every day, you must allow your wood to burn down COMPLETELY to a bed of coals. ONLY THEN CAN YOUR FURNACE DRY OUT!  

So what most people do is they only put enough wood in their furnace so that it will be completely burned down to ashes and only a few coals when they refill.

What is the worst thing to do? Good question!

NEVER "Top Off" your outdoor wood stove with wood fuel. If you go out to check on your wood stove, and it is still half full of wood, DO NOT "Top It Off" with wood...here's why:

When you first fill your furnace with wood fuel, the water in the wood will start to boil off. When your wood is only half-burned, THERE IS STILL a lot of moisture in the wood. If you then add more fresh wood (full of moisture), your furnace NEVER has a chance to dry out. If you always do this, then your furnace walls, tubes, door, and seals will continually be coated with steam, and never have a chance to dry out.

Again, the solution is simple: Please only put enough wood in your furnace so that it will be completely burned down to ashes and only a few coals when you refill.

For more information contact OutdoorBoiler.com. You can also visit our online store if you need any outdoor wood boiler parts and related products!

Operating Furnace FAQs:

  • Am I burning too much wood?

You may be. Is the wood properly seasoned? Have you cleared the firebox? High wood consumption can be caused by a number of factors.

  • Can I leave my Outdoor Wood Burner over the weekend?

You may have someone "feed" your furnace for you or you may lower the thermostat temperature.

  • What are the critical items to operate and maintain my furnace efficiently?

1. Keep water full

2. Manage ash

3. Use water treatment

4. Use seasoned wood

5. Keep fire in the middle of the firebox

6. Clean tubes regularly

  • Why is outdoor boiler water treatment important?

The boiler chemical (corrosion inhibitor) that you would apply to your furnace water coats the inside of the furnace to reduce the effects of corrosion on the metal. 

Click HERE to order our Liquid Armor Water Treatment and other outdoor wood furnace parts. Every gallon of Liquid Armor comes with FREE 2 sample bottles. Then submit your water sample to Outdoor Boiler Lab and get Free Water Test!