Things to increase boiler Efficiency

[RobC]

There was a question about how to increase boiler efficiency. Here's the start of a list from easy jobs to more involved.

Clean boiler, including heat exchanger tubes and stove pipe to chimney. Perform every couple of weeks.
Clean blower fan a couple times a year.
Check Barometric Damper for correct draft.

 

[Nofossil]

My candidate for #1:

Figure out how to use short hot fires rather than idling.

 

[Nofossil]

And use dry wood.

 

[Singed Eyebrows]

My flue gas temps were higher than I wanted so I slid a piece of steel step from an industrial ladder in the secondary burn chamber. This forces some of the flame to change to radiant & go into the boiler walls. I don't have a firetube boiler so I couldn't adjust with turbulators. Even if you have firetubes though it should be far easier to throw something in the burn chamber to change some of the convection to radiant, Randy

 

[Nofossil]

My flue gas temps were higher than I wanted so I slid a piece of steel step from an industrial ladder in the secondary burn chamber. This forces some of the flame to change to radiant & go into the boiler walls. I don't have a firetube boiler so I couldn't adjust with turbulators. Even if you have firetubes though it should be far easier to throw something in the burn chamber to change some of the convection to radiant, Randy

The problem is that the environment in the secondary chamber is pretty hostile. I've melted, cracked, vaporized, or eaten away a wide range of materials. Not much can survive for long. I used 1/2" steel plates, and they were badly damaged within a few weeks. Titanium doesn't last at all. Most firebrick turns to gravel. Ceramic tile crumbles. It's just not a nice place.

 

[Chris Hoskin]

number one item, top of the list, by a long shot is DRY WOOD.

 

[NYEDGE]

Making sure that you insulate all pipes with a high grade wrap will reduce heat loss and therefor less wood will be burned.

 

[Singed Eyebrows]

My flue gas temps were higher than I wanted so I slid a piece of steel step from an industrial ladder in the secondary burn chamber. This forces some of the flame to change to radiant & go into the boiler walls. I don't have a firetube boiler so I couldn't adjust with turbulators. Even if you have firetubes though it should be far easier to throw something in the burn chamber to change some of the convection to radiant, Randy

The problem is that the environment in the secondary chamber is pretty hostile. I've melted, cracked, vaporized, or eaten away a wide range of materials. Not much can survive for long. I used 1/2" steel plates, and they were badly damaged within a few weeks. Titanium doesn't last at all. Most firebrick turns to gravel. Ceramic tile crumbles. It's just not a nice place.

I thought of this after posting Nofossil, my boiler has a relatively lazy low velocity flame & does not cause the scaling/descaling that chews up steel. I thought about the Econoburn torch & this would be rough on most anything except probably some Hastelloy type material.//// Works well on mine, probably not for most others though, Randy

 

[pybyr]

Totally agree on dry wood. This year I cut and put up more wood than ever- but got to it later than ever (the Rest of Life intervened), and had a rainy fall, and the difference is immense. I've burned huge amounts of wood and have been needing to run the house cooler than in the last several years despite the ferocious wood consumption.

I just loaded the boiler with some nice small splits of good and dry yellow birch, and it's like running a whole different unit compared to some of the other wood I have been using.

I don't buy the idea that years seasoning is always mandatory, at least if you start with low moisture species such as White Ash and have a sunny and windy drying location, but I can offer proof that efficiency goes down through the floor if your wood is not reasonably dry.

I'm going to try to have a big pallet chainsaw massacre this weekend to re-amass a good quantity of dry wood to see me through the winter, and then, soon, as long as the snow does not get too deep, am going to head into the woods to start laying down trees for next winter's wood.

 

[mikeyny]

DRY WOOD DRY WOOD! Did I say dry wood. I think someone else already said that. Dry wood alone will increase efficiency a great deal no matter what you use it in. YES SOME BOILERS WILL BURN green wood better than others, but you get more efficient burns out of dry wood, although I have to admit I am a bit jealous of those guys with the greenwood boilers that just roll in big green rounds and burn all nite. But then again I dont have all those creosote problems either. Just my 2 and a half cents.
Mike

 

[PassionForFire&Water]

What moisture content are we talking when we say "dry wood"
Is 20% MC considered dry wood ?
Just wondering .. .

 

[steam man]

What moisture content are we talking when we say "dry wood"
Is 20% MC considered dry wood ?
Just wondering .. .

It seems as if 20% for a gassifier is close to the top end for mositure content. I've seen recomendations for 12% on the low end.

 

[heaterman]

#1. Dry wood makes all the difference in the world for good efficiency. You'll be wasting far less heat trying to evaporate the water from the wood and you won't have bearly as much fouling of heat exchanger tubes. Especially if your system does not have storage. MC of 15-20% is good. Pretty difficult to get below that anyhow.

#2. Sufficient storage capacity to hold the btu's generated by an entire load of wood in your boiler. Cycling the fire/gasification process on and off does nothing for efficiency and promotes a dirty burn and dirty heat exchanger which further robs efficiency.

#3. Burn the wood load just as hot as possible to keep temps in the gasification range.

........sounds like I'm describing a Garn.........

 

[jebatty]

It seems as if 20% for a gassifier is close to the top end for mositure content. I’ve seen recomendations for 12% on the low end.

Agree - couldn't quickly spot it in the manual, but recollect that Tarm recommends 10-15%?

 

[Hunderliggur]

The Paxo manual says "The maximum moisture content of the wood used to fuel the boiler should be between 15% and 20%." Also, pump launch temp 170 with 5 hysteresis (hotter upper chamber).

 

[bigburner]

120 degree water this morning verse 145 - this is the difference between standing dead ash verse black walnut cut this spring. [Sold a couple very nice veneer logs, the crops don't cover my taxes any more] My system has to get hot first and then it will burn about any thing, the combustion chamber is 100% refractory. But you can't get it hot on wet wood - I have worked my way into a less desirable section of my wood pile and it shows.

Do any of you guys got picture or video of a gassier [down draft] running on wet wood? All you ever see is the perfect burn! Mine just burns like a bad camp fire.[updraft]

 

[woodsmaster]

The biomass says 15 - 25% but I havn't tried any wood over 17% yet.

 

[Don2222]

Hello

Add 1" thick fiberglass pipe insulation (3 foot sections with Z-Tape for the joints) to your 3/4" heating pipes especially to the indirect water heater if you have one!