Wood Boiler venting.

Leo_10

They have flatplate heat exchangers available for this purpose. Around here no one spends the money for them and often times their system becomes air bound. We get the call that "our" boiler messed up when it is the fault of the wood boiler. A couple of today's boiler companies will not warranty their boiler if attached to an open system.

Leo

Jim Alexander

Vented wood boilers

All wood fired boilers are vented to the atmosphere as delivered. To eliminate the introduction of oxygen to the system I am thinking of closing off the boiler vent and adding an expansion tank to the system. Is this feasible and are there any areas to watch out for?

jp_2

oh boy

you like to build bombs do you?

what happens at full fire when the circulator pump stops pumping?

Jim Alexander

Wood boiler venting

Thanks Leo,
I know the Boiler salesman (Central) does not suggest anything like that but I also know they do sell a flat plate heat exchanger (water to Air).
I am suprised to hear they can be used as an optional vent but I'll sure start investigating it. My major concern was to establish the feasibility and size of an expansion tank needed until the boiler controls shut off the air to the boiler. The boiler salesman says just leave the system unvented and use all copper and Pex piping. Seeing as how the inside of the boiler itself is steel, I think that still allows the possibility of corrosion over time.

Leo_10

If you use

If you use the flat plate heat exchanger it is water to water. The house boiler and the wood boiler water never touches each other. As far as corrosion I am told the wood boiler has chemicals available for this purpose. This way it stays an open system on the wood side and you eliminate the chance of a bomb. A few things to keep in mind, the amount of wood these things use. It isn't cost effective if you have to buy wood. Your neighborhood, if it is crowded may have restrictions on the time of year these units are allowed to be used this may be so in any neighborhood. I am in a crowded neighborhood and the wood stove smoke gets into my house making me walk around looking for the fire. But in the right area they are no problem. One other thing, does the dealer have his own install crew and does he offer service. If not anything he says to get you to buy is suspect in my opinion. As an oil guy I have seen air problems because the dealer said the heat exchanger was not necessary. Plus they don't know or won't tell you about the home boiler warranty being void on the open system.

Leo

Steve Eayrs_2

All wood fired boilers

ARE NOT designed to be atmopheric. Some are designed for pressurized systems. I am sure it would not be advisable to pressurize a non-pressure vessel. Its not rated for pressure and if not blow up on you, at leas void the warranty.

And of course I hope you would also add a T&P valve!


Some wood fired boiler companies (Tarm is one) are pushing installing a large buffer tank. This tank is atmospheric, and can be up to 1500 gal.. or so. The boiler itself may be a pressurized type, but the heat exchanger would be setting down in the big buffer tank. The tank resembles a big hot tub w/ a lid, but not sealed.

If some sales guys is telling you you can pressurize an atmospheric vented boiler, as to see it in print.

steve

Kevin O. Pulver

Amen Steven

The ones that aren't pressure rated aren't "real" boilers are they? I've heard Hot Rod describe them as a "tea kettle hanging over a fire" and in certain areas I've heard they're already outlawed as not burning clean enough.
I'm fortunate to finally have a chance to install a Tarm with 1000 gallon heat storage tank as you described.
Can't wait to see it work. Kevin