wood boiler heat exchanger

hr

indicates they will install larger connection ports, if desired. Something about brackish water conditions? I'm not sure if the passage ways are changed also. a good question for thre HX `pros www.flatplate.com

hot rod

<A HREF="http://www.heatinghelp.com/getListed.cfm?id=144&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"</A>

Mark Evans_3

Wood boiler

Hello everyone,
Last year when I built my house I installed a Peerless pinnacle 140 system by myself which I NEVER could have done without this forum. The answers and knowledge here are incredible. Anyway on to the dilemma. I have decided to install an outdoor wood boiler given the fact that I have 26 acres of woods, a new 1800 sqft garage, and the price of propane. I have everything all set except the hot water plate heat exchanger. My Pinnacle is running 1 1/4 inch supply and return manifolds with a closely spaced T. 3 zones pumping away with taco 007s and 3/4 inch branch circuits, and a 1 inch circuit for DHW. Boiler pump is a Taco 010, on the return. I can not seem to find a reasonably priced Plate Heat Exchanger with 1 1/4 inch connections. My fear is that if I put a HX with 1 inch connections after the boiler pump on the return it will create a bottleneck.( 1 1/4 inch to 1 inch and back to 1 1/4) Would it be better if I could find a way to place the HX in the return manifold before the Tee, and before the pump, so that the Tee would compensate for any volume loss??? My thought is that this arrangement would kind of be the same as say, 1 zone running, with the Tee providing any needed water from the supply side. Also, does anyone know what kind of a temp drop I can expect from a plate heat exchanger with 180 deg. water coming from the wood boiler? Thanks in advance, I know I'm in the right place!!!

Joe Mattiello

Sounds like a great application for the X-pump with two system pumps, and integral heat exchanger. For your reference I attached the catalog data. Additionally, Taco offers heat exchanger only. Contact your local supply house for price, and availability.

hr

The connection size

really doesn't have that much to do with the sizing. If you know the amount of BTU to be moved and the temperatures and flow rates on both sides of the HX then contact a heat exchanger manufacture, like Flat Plate, for a design specfic to your need.

You'd be surprised how many btu's get by 3/4" connections when the delta t's are leveraged.

Robert Bean is a pro at HX sizing. I've seen his clever dual hx arrangements to avoid high cost larger sized FP's

Tony Conner is another HX sizer pro. He sells those beautiful helix wound stainless hxers.

PS e-bay has some incrediable inexpensive hxers from time to time

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

JimGPE_25

Controls?

How does one keep the wood-burner side of the heat exchanger from going to live steam? How does one regulate the heat to get enough heat but not too much? Its not like you can close/modulate the gas valve.

Like olden days with a controlled combusion air inlet based on water temperature?

Just trying to learn somethin'.

hr

A bit of a learning curve, Jim

when it comes to open system wood boilers, or furnaces as they are often called. Most hold large quantities of water to help buffer against steaming. Some have dump overheat methods. Still others have a simple auto refill that just keeps adding water as you steam it away.

A couple days without heat usually is enough to train the owners how to build a fire sized to the load and expected temperatures.

It's a fairly primitive heating devise in all fairness. Basically a pot of water suspended over a camp fire. Add the pollution factor and one really starts to wonder...

Nothing clever marketing can't over-come. Free heat, couldn't afford to be without one, etc, etc.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Mark Evans_3

Wood Boiler

I know the BTU Transfer rate can be regulated by the number of plates on the HX, and that the wood boiler is going to flow 180Deg. water constantly through one side of it. My biggest concern is volume. It seems that due to the very small size of the boiler tank on the pinnacle, it is very sensitive to incoming volume and could steam or run dry if not satisfied. The Closely spaced Tees eliminate this. That is why I would be worried about the HX after the Tees.Maybe I'm paranoid, thats why I'm here. Keep the answers coming, I learn something from every one.

JimGPE_25

Ahhh

Key phrase, "Open system." That makes all the difference.

I have seen people try to add a closed loop to a wood burner, and it gives me the screaming heebees.

Thanks.

Jed_2

Yes, Open Systems, but

I'm hearing about a few systems that are pressurized outdoor wood furnaces. Don't know anything about them, but scares the bjeebies out of me. Are they getting out of control?

Jed

Marty

more t's

If I could draw..... If the boiler is using the close spaced t's why not cut into the return header with another pair of close spaced t's between the last zone and return boiler t? Size a pump for the heat exchanger, add an aquastat so if the wood boiler side of the exchanger is hot the boiler doesnt run or something along those lines. Might be wise to pipe the t's in branch down then loop a thermal trap up to the heat exchanger.

Weezbo

Danger ,Will Robinson DANGER!

"Will ,You. go fire up the boiler" Dr. Smith.

"and ,We will be right here in the underground control room to assist you "

hvacfreak

Superchanger

http://us.tranter.com/phe/superchanger/super.htm

This is the route I'm taking. I have one of these things to finish this fall ( side job ).

They are always very helpful on the large commercial jobs I work on , I'll bet they have something that will be " ideal " for the wood furnace thing. And plate and frame hx's look " cool "....damn the cost.

Joe_76

I have had three closed loops(two homes and a shop) on my wood fired system for ten+ years and install a few every year without problems, you just have to separate the two systems. A quality boiler will almost never produce steam. I say almost because there probably has been times when they have I just have never seen it. The line that I sell shut down tight when the preset water temp is reached. I always use two tees on the return side and pump away from the heat exchanger if the EX is lower than the boiler if not I install the pump at the boiler. I also always install the heat exchanger in the mech room of the home. Some guys are starting to put the heat exchangers at the boiler which I think is a big mistake.

Joe_76

They use an aquastat to close the damper when the temp is reached.

Phil_15

wood boiler

I would recommend reading J. Seigenthaler's article a few years ago on wood fired boilers. He recommends a large insulated heat storage tank. John notes that the most BTUs are extracted from wood by burning it hard and fast. A heat exchanger for transferring this peak BTU wood boiler output would be out of the question. Instead of trying to finely modulate the wood burn rate with electronic damper controls, why not let the wood burn faster (higher efficiency) store the heat, and transfer it over to the closed system over a larger time interval or as needed?
If you already have a heat storage tank in your system, then diregard the above. If not, it would be interesting to compare the two designs (with and without) a heat storage tank.

S Ebels

Exactly

This is the approach recommended by Tarm and also one of the main design features of the Garn unit made by Dectra Ind. Load it up, burn it hot and burn it all.

In a lab test this past spring there were a number of outdoor wood burners tested under identical conditions. IIRC, there were 7 different brands of what you would call typical design. They included about all of the major brands of the "ice shanty" looking wood burners. The actual efficiency numbers were startlingly low ranging from 28% to 41% at best. These are actual lab numbers which are verifiable. In the same test the Garn ran in the 75% range. Let the buyer beware.

Joe_76

I have installed this type of thermal storage for people who are off grid, it really benefits people who can incorporate the storage into their home. Mine was built before I had learned this but I have enough load that the boiler fires at a high rate then the 300+ gallons that is in the boiler is used.

Jed_2

Agreed

It is the only way to leverage the heat source/system requirement approach transfer rates. Forget Flat Plate; but a Turbomax, with high thermal storage, AND a high capacity, high efficiency HX, coupled with some serious flow rates, can and will do the job. Pay back? Well, with a strong back and youth, you might get there.

Jed

hr

I suspect opens systems boil

more often then people know. The Hardy's around here have auto fill systems to handle this. Some one of these days I want to put a water meter on that fill line to see exactly how much steams away. Rookie burners probable steam lot more than experienced burner operators

Some brands like Aquatherm are pressuruzed units. The problem with close systems is at 12 psi water boils at 244. So now you get a pex meltdown at the back of the boiler. Should the pressure rise to 30 psi figure about 274F fluid.

We have all seen pictures of 40 and 50 gallon water heater explosions. Imagine what 150- 200 gallons of super heated liquid would do! Aquatherm ships both a 30 psi relief, and a 210F 75 psi relief. If ever you see those plugged, run far away.

I don't know of any that shut off the air 100% or the fire would die out within 15 minutes or so. Keep in mind the 6" vent hole in the top As such on low load days they will over shot the aquastat settings.

Open units boil, pressurized will absorb up to 210 if T&P equipped, or 30 psi. Even so pex or PAP meltdowns are fairly common with newbies.

Even if you are comfortable with 28-41% efficiencies, it's the pollution that bothers me most. Most country folks burn whatever fits through the door. Grbage, green wood, plastic bottles and bags, etc. Few have garbage collection in rual areas, so either a hole in the back yard, or into the OWF.

Sendhand smoke for the downwinders can be a real drag. Actually don't we all live down wind?

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

ALH_4

Press vs non-press storage

Open storage is a lot cheaper than pressurized storage. Why not store hot water on the non-pressurized side of the system and run that through a heat exchanger to the pressurized side? If you're buying pressurized tanks, 120 gallons of water doesnt store much heat even at an 80-degree usable range.

This is what Tarm is doing from what I understand. Don't they have a cylindrical tank with coils of copper immersed in the non-pressurized fluid? Using water heaters as storage mass is expensive.

-Andrew

Joe_77

Check out www.profab.org (these are the ones I sell) they do shut down 100%, the nice thing about this is if they are burning green wood the fire goes out like you said. I can say that they do not or almost do not boil because I only add water to my system at the end of the season (about five gallons) and I think this is due to the little evap. out the vent.