Outside Wood Boilers II

[tessiersfarm]

I am in the process of building a wood fired boiler from scratch. I have measured, studied and obsessed over several factory built and a couple of home made units. My boiler will be installed inside my garage and piped underground to the boiler room of my house. I am starting with 2 tanks which I plan to nest into one another to form a full water jacket with a capacity of around 200 gallons of water. I am going to install a pressure relief valve with a pipe directly into the fire box so that if the unit overheats it will dump the water onto the fire. I also plan to install a secondary (freeze plug, if you will) device that will blow out under pressure. I believe my boiler operates at around 6 or 8 psi now so the wood boiler will do the same. My plan is to run a circulator constantly with a normally Open zone valve and a unit heater in the garage and a loop feeding the boiler manifold in the house with a relay so that when the wood boiler is up to temp the LP boiler will not start, and when the house calls for heat it shuts off the garage loop. I have a small blower that will be installed in the front of the unit to force draft when nessesary, and plans to build a by pass damper for loading.

Am I being too ambitous?

I am looking for any suggestions and or experiences to maybe prevent me from making un-nessesary mistakes, and or Ideas to maybe improve my system.

Thanks in advance and again its a pleasure to be part of this group.

[matrob]

I am sure that you have read the previous discussion that I started. Although I feel I burn a lot of wood. I really like my outdoor, and when it goes bad, I will seriously consider building my own. They are fairly simple, and it sounds like you have a good plan. Make sure you give yourself plenty of options for circulating water loops off the back of the boiler. That would allow you to continue heating your garage at the same time as the house calls for heat, if you want. You also never know when you might add another building or have a need for heating another place (hot tub etc.) it. Also, I originally planned on having my boiler(oil, gas or whatnot) set up like yours, but eventually found that having a second thermostat in the house was the easier solution.
I recently looked at some gasification outfits, but found that they would not suit my needs, required more attention and feeding and would be more complex to build, however, hearth.com has some excellent materials on any kind of wood heat you may be interested in.
I will definitely follow this discussion, as I think it will be very informative.
Matt

[Haynes Forest Products]

I think you are creating a problem and the obsessing over ways to fix the problem. First with 200 gallon primary loop you are heating alot of water when you might not need it, plus you will need a bigger expansion tank to cover that much water expansion. If you have a costant low pressure fill with a pressure relief AND a air damper to shut down all oxygen when the water temp get to a critical leval I think you will have that part coverd. Dumping water into a hot firebox can be a big problem. You will warp metal and can cause the chamber to rust out in short order. If your pressure relief developed a small leak like they can you would be dumping water in to the firebox everytime you fired it up. You can get boiler controlers that can do alot of the simple work. B+G and Honeywell both make controlers that can shut down certain zones when heat is a priority and that is what its called a priority zone controler. Most priority zone controllers will shut down the house heat for a max of 30 min. so all heat will make hot water for showers and then the controler will restore the heat to guard against freezing in the house. I think you would be better of with a large storage tank in the basement of the house and heat that and then with a domestic water leg for the house needs. and another loop for home heating that would give you better control.

[halfast tapper]

I was wondering why go with a pressurized system? I have a outside pellet boiler that is a non pressure system. It works great.

[brookledge]

Another issue to check out is the building codes for your area. Putting a wood furnace in a garage is not allowed by some states unless there is a dividing wall. The reason for this is if you bring in a vehicle from the cold and then as the gas expands it will leak out causing gas vapors and then if the concentration is high enough you no longer have a garage.
I know alot of people like to put wood stoves in their garage so if you are going by the book you may want to check it out first and more importantly what would you ins. co say if there was ever a claim.
Keith

[tessiersfarm]

I already have zone valves, priority valves ect on the current system. It has two domestic heat zones, 1 domestic water zone, 1 hot tub zone, and 1 extra zone which would turn into a garage zone wich would also be a dump zone.

With a non pressurized system I would need to go to a heat exchanger and I think it would complicate the system?

I plan to controll the air dampers with electric controlls, the pressure relief would only be an emergency situation and I would be more concerned with an explosion than warped metal. I would think I would notice if the relief was leaking during my daily routine and would just have to replace it if need be. My though process was that the volume of water would act as a buffer if you will to allow the boiler less of a temp differential between supply and return ports.

I was actually looking into the addition of storage tanks in the range of 1000 gallons to allow me to run the boiler more efficiently.

[Fred Henderson]

I am in the process of building a wood fired boiler from scratch. I have measured, studied and obsessed over several factory built and a couple of home made units. My boiler will be installed inside my garage and piped underground to the boiler room of my house. I am starting with 2 tanks which I plan to nest into one another to form a full water jacket with a capacity of around 200 gallons of water. I am going to install a pressure relief valve with a pipe directly into the fire box so that if the unit overheats it will dump the water onto the fire. I also plan to install a secondary (freeze plug, if you will) device that will blow out under pressure. I believe my boiler operates at around 6 or 8 psi now so the wood boiler will do the same. My plan is to run a circulator constantly with a normally Open zone valve and a unit heater in the garage and a loop feeding the boiler manifold in the house with a relay so that when the wood boiler is up to temp the LP boiler will not start, and when the house calls for heat it shuts off the garage loop. I have a small blower that will be installed in the front of the unit to force draft when nessesary, and plans to build a by pass damper for loading.

Am I being too ambitous?

I am looking for any suggestions and or experiences to maybe prevent me from making un-nessesary mistakes, and or Ideas to maybe improve my system.

Thanks in advance and again its a pleasure to be part of this group.





For the saftey of all concerned you best make sure that the tanks you will use are made of boiler plate rated steel.

[Haynes Forest Products]

Heating and maintaining that much water is alot of work. I understand the desire to have a buffer for a more constant heat but I think that 200 gallon yes but 1000 is a small steam locamotive. What will a power outage to to the system and the safty controls. What do you have now and why are you replacing it. When the wife looks around at the boiler I installed for the radiant heat and the snowmelt system under the tiled deck. The ponds and all the little homeade things I show her she shakes her head and says I hope your making a manuel so when your gone I can run this place. Seriously you do have to think about what happens to the system and house if your on vacation and the neighbor is loading the wood and the power goes out and the snow gets deep and they say screw it.

[Jeff E]

I have 2 loops off of my boiler, non pressurized. You can put quite a few heat draws on each loop, if you do them in a logical series.
In the house, the loop starts with the hot water heater, then the heat exchanger in the furnace. the exit temp is only 8 deg. lower than the entry temp when each are calling for heat. I would be very comfortable putting other heat draws on that loop, as they don't drop the water temp that much.
The other loops goes to a home made heater in the sugar house. I cirulate the water through a truck radiator. The tranny cooler side had a leak, so it was junked. I picked it up at a car shop for $5. I built a box around it, put on a thermostat controlled blower behind it an SHAZAM, a super heater for a little $$.
My system has a 300 gallon water jacket, and this provides a few advantages. It takes 5-15 minutes of open damper to bring the water up 10 degrees, when the system calls for more heat. This allows for a pretty clean burn as it can really get cranking in the fire box during that time. It also means there are a lot of stored BTU's in there, so when it shuts down, it can be down for quite a while, saving a lot of wood.

All this to say, I like the higher water storage capacity around the boiler. Not in a remote tank, as that will only loose heat, not collect residual heat from the firebox.
And don't be afraid to put several heat draws on one loop, just do them in a order that has your highest temp need first in line.

[Fred Henderson]

If you build a manifold say 3" in dia and 3 feet long, one for supply and one for return you can put a ciculating pump between the two and pull hot water off that manifold and have no negative effect on any other part of the house.

[Haynes Forest Products]

Fred just described the primary loop in most boiler systems and what I have done on my system. Then I put in a secondary loop that has its own circulator pump and that loop has a tempering valve (ball valve) to give you a pressure differential on the supply side and the return side and I use zone valves for my individual loops with valves to meter the flow for better control when all zones call for heat and the controler will decide if I have enough domestic hot water.

[matrob]

Haynes, you must have a different type of neighbor over in Jacksonport. We would go through hell or highwater over here before giving up on taking care of our neighbors place, and the same holds true when they watch ours. There's a special kind of people over here. A few years back I was reroofing my barn and had lined up about 6 people. On Saturday morning about 14 people showed up, some who I had never met. What a great place to live.

[Haynes Forest Products]

Please dont get me wrong. I think we all have great neighbors. Im just talking about when things go bad and you cant even get your own house in order. I have city water and natural gas so when the poop hits the fan its the elec thats the problem. I think that sometimes when we reinvent the wheel we tend to make things far more work than before so I still like the idea of keeping it simple. I to have helped raise a barn and thawed a pipe and the best of all is free access to 20 acers of maples on pipe lines for helping him tap his trees every year for the fun of it till he passed so we are on the same page. I noticed that you are hiding that little part of heaven your living in.

[Fred Henderson]

We have some Amish family near here and they are good people. A friend of mine wanted to take a vac in the middle of winter and their only source of heat was an outdoor wood boiler. So they ask the Amish man if he would attend it while they were gone for 2 weeks, and he did so. When they return the man left the fire box door open just a bit as he did on his own stove. The boiler got so hot that it melted all the insulation off the internal wiring and boiled out 1/2 of the water. However it did no harm to the water tank. Here is a classic case of someone wanting to be helpful but things went amiss. The boiler was rewired and has worked well all winter.

[tessiersfarm]

my current plan is to shut down all power to the unit at 120 degrees water temp with an aquastat. At 120 degrees the circulator will start to circulate water continuously through the garage loop which will be a normally open zone valve which would circulate naturally in case of power failure. At 140 degrees the relay will turn off the circulator to the LP Boiler which is on a flow valve and will not fire with no water flow, and Turn on the loop from the wood boiler. When the house calls for heat a relay would shut the garage loop off until house was satisfied. At 160 degrees the forced draft fan will start At 180 degrees the forced draft fan will stop. In theory this would allow the boiler to maintain a 160 to 180 degree water temp in the boiler, during which time the house boiler would not run. In a power failure the garage loop would be open to allow natural flow and the draft damper would be shut to choke down the fire. If the wood boiler dropped below 120 degrees all of the controls would shut down and the house boiler would start as normal.

I am currently on a wood stove that will not heat the entire house below 20 degrees. Wood supply is not much of an issue, but I am looking for a fairly simple system I can load two or three times a day and walk away from. I am looking to keep the cost reasonable because if $10,000 was an option I would have a system installed and fire it up. I currently use less than $1000 in fuel a year including kitchen stove and Dryer so The payback on a $10,000 system is not really cost effective.

Thanks Again

[matrob]

Are we assuming the flow of water through the pipes will stop them from freezing up? I have always wondered if this would work. Someday I was planning on performing this experiment. Close the loop coming to the house bypassing the heat exchanger. Let the fire go out and continue circulating the water. I would monitor the temp for a few days with the fire out. Has anyone done this (on purpose)?
Haynes, we definitely have a little piece of heaven, until it turns to mud in April.

[Haynes Forest Products]

Matrob They say moving water wont freeze but I think we have all tested that theory. I think it should say fast moving water wont freeze. If you were to just circulate the water in the system the pump would keep the water warm just from the heat from the pump and friction in the pipes. With the new Pex water lines and the insulation pipe it comes in if its barried far enough down your ok. Why not use the antifreeze thats for radiant heat and not worry about it. With the antifreeze you get better heat transfer,less air in the pipes and pumps wont rust up. If you make your own water jacket type boiler I would opt for antifreeze over the water treatment.

OK you still didnt tell what part of Wisc SO im guessing BELOIT

[tessiersfarm]

I am planning on installing the boiler in my garage which is heated by LP Gas as well. The pipes will be underground but I will bury them 4' to 5' down and insulate them well. I have 8" SDS Pipe that I am going to use as a sleave which will be surrounded by 4" to 6" of ridgid foam. The Insulated Lines will then be pulled through the sleave. I would be surprised if freezing was a problem. I am also planning on intalling the whole thing on a transfer switch so it can be powered from my generator during any power outages.

With Beef Cattle, Poultry, and Meat Rabbits The Boiler is the least of my Vacation Worries. By the way what is a vacation?

[Fred Henderson]

You could also mix in some anti freeze to protect you down to -30 or whatever you feel would work for you.

[tessiersfarm]

when you say mix in antifreeze do you mean like automotive or special boiler anti freeze?

What happens when the fill valve opens, does it eventually dilute it?

[Haynes Forest Products]

DO NOT USE auto antifreeze its differant. They do make special anti for radiant it comes in 5 gallon buckets and you drain the system so it goes in stright. When the system needs to be toped off it will mix and be OK. I use a liquid lifter the cheap Home Depot type and a cordless drill I use a old washing maching hose they have female threads on both ends so you can connect to boiler drain and pump.

[matrob]

Haynes,
I am in Rib Lake. It is northwest of Wausau about 60 miles. A far reach from Beloit.

Boiler Antifreeze is a great idea, but at the prices I have been quoted, there is no way I'll be buying 300 gallons of it. I think it was going to be more than $3.00 a gallon when installed my system.

[Haynes Forest Products]

Matt 300 gallons thats alot of pipe. Is that including a storage tank? I did a 20X36 radiant under cement with a Munchkin boiler and I think the entire system only held 12 gallons. Thats why alot of boiler systems are using the heat exchangers to seperate the outside from the inside. We did a road trip back in 74 and spent the night in Hurley Wisc. What a strange place that was I bet its a great place now but back then it was a depressed looking place. Went up to Ontenogen Mich. for a few fun filled days YIKES they kept calling us OUTSIDERS I think you could do a northern version of Diliverance there.......................................YIKES

[Jeff E]

Glad to know of another northern Wisconsin sapper on here.
I think if we keep this up, it wont be long until NY, PA and Vermont will be looking over there shoulders at the WI maplers coming on strong!

[matrob]

The taylor boiler holds 300 gallons at the firebox, not including pipe.

I would say as you get farther north and farther from urban areas people live "closer to the land". People have always lived on less and don't have the luxuries that others might. But there are so many smart people that have learned how to do things themselves and are great resources.
I moved here from a more urban life 15 years ago and have truly enjoyed the lifestyle and people that I have spent time with. We could never have afforded to have a hobby farm near a bigger city, so this was a perfect fit for us and a good place to raise kids.

Jeff, where are you located?

[Jeff E]

Matt,
We are near Spooner. I had a desire to live up nort' as a 15 yr old, and figured I would have to work down south, and maybe someday have a cabin to retire to.

I was blessed with an opportunity to live and work up here a bit ahead of schedule, moving up in 1987 at the age of 25!!!

Have loved it since, and particularly the people.