Researching systems

[Dextron]

New member here looking for help figuring out which boiler may be best suited for my useage. I am currently using an oil fired water heater supplying the in-floor heating. This system would remain in place and a wood fired boiler would be plumbed into it. Initially at least I would not be using any storage. One of my first concerns is wood quality. There is a lot of wood available in this area but it is of two main types: driftwood and scrap (meaning wooden pallets for the most part). Which boilers would have the least problems dealing with this?

Thank you.

 

[maple1]

One quick comment: if the driftwood was in salt water, that has been noted as corroding things when burned, and is actually advised against in some boiler manuals. Just one thing to research further. I think any boiler can handle pallets, as long as you can get them cut up & into the firebox. But watch where you dispose of your ashes (nails) - I save my ashes for my icey driveway.

Guess that was more than one comment....

 

[Fred61]

Does the oil fired water heater also supply your domestic hot water? In other words are you circulating potable water through your radiant tubing? That needs to be established before you get advice from the knowledgeable folks on this forum.
BTW welcome to the forum.

 

[Dextron]

maple1:
It is salt water driftwood - right off the beach. That has always been the theory here, that salty wood will corrode the stove and pipes quicker, but I haven't really seen it happening at a noticeable rate. When I built the shop about five years ago I put in a new wood stove. I haven't noticed any unusual corrosion issues with it but I guess this may be hard to measure over the short term. We have had a 1906 Star Estate wood burning cookstove in the house for twelve years now. It is somewhat worn due to it's age but we haven't seen noticeable additional deterioration. Don't get me wrong, I am not saying salt water soaked wood won't cause corrosion issues, I just myself, luckily perhaps, have not seen enough issues to be a problem. Yes burning pallets leaves a lot of hardware in the ashes. We mix our wood ashes into the compost so have taken to screening out the metal because my wife doesn't like it in the flower beds and garden. I didn't think of this, but will nails cause any problems in a boiler? Getting back to the salt issue, will the higher temps in a boiler promote any different chemical reactions if there is much salt?

Fred61:
The existing oil fired water heater only supplies the floor heat. Domestic hot water is an independent system.

 

[BoilerMan]

If I were to buy a $5-10K boiler I'd not burn driftwood in it. The corrosive properties will be 10x worse than in a stove due to the condensation in a boiler during startup. This condensation is basically non-existant in any type of stove dure to low mass and high fireside surface temps....relitivly speaking.

TS

 

[Fred61]

What's the capacity in gallons of your heating water heater? What I'm thinking is to keep it simple and just circulate the water in the oil water heater through your wood boiler and keep all the existing controls for the heating circuits.

 

[BoilerMan]

I'm gonna guess it's a 40gal Bock oil w/h. But thats just a guess...........

TS

 

[Dextron]

Taylor Sutherland:
This could be a lot of money to rot away in a few years so I definitely need to look into it more. Input from anyone that has had experience dealing with a salty environment would be appreciated. At today's fuel price it may be worth it in any case.

Fred61:
That was pretty much my tentative initial plan - leave the existing system as is add heat to it from the wood boiler. I would probably use a heat exchanger between the two systems as I will need run a higher concentration of glycol in the wood boiler system since it will be in an area that won't be heated unless the wood is fired. The existing floor heat only has a strong enough mix to prevent freezing if it is not circulating and areas next to exterior doors get cold.

Taylor Sutherland:
You win a gold star! Bock 32, one of their direct vent models that gets combustion air through the double wall exhaust wall fitting.

 

[Fred61]

Fred61:
That was pretty much my tentative initial plan - leave the existing system as is add heat to it from the wood boiler. I would probably use a heat exchanger between the two systems as I will need run a higher concentration of glycol in the wood boiler system since it will be in an area that won't be heated unless the wood is fired. The existing floor heat only has a strong enough mix to prevent freezing if it is not circulating and areas next to exterior doors get cold

I don't know the particulars of your system. A little more complicated than I was picturing whth the glycol and such but it was just a suggestion. It sounds like you're up to speed on what is needed to accomplish the task.

 

[maple1]

I can't speak from experience on the salt water driftwood - just repeating more or less what I have read here.

I think some boiler manuals state not to use it. I just read mine, and it doesn't mention driftwood at all (I thought it did) - but does advise against oak. Myself - if I had access to a lot of it, and it was seasoned/dried well, and had the experience you seem to have had with no apparent ill affects - I might try it. But it would be quite an expensive gamble if it didn't work out with a new gassifying boiler. I think you can access most boiler manuals on-line, so maybe when you think you've found a boiler you might be interested in, read the manual for it. That doesn't cover chimneys though, just boilers.

 

[mikefrommaine]

Make sure you don't burn any pine driftwood. It will cause a chimney fire, you know.

 

[Fred61]

Salt will also act as a abrasive in the unit which we all know is something we don't need any more of in these fan forced gassers. The abrasion from the ash is already more than we want to deal with.

 

[Dextron]

Most wood stove manuals I have seen warn against using dimensional lumber, driftwood or trash. I suspect all of them would if it had occurred to the manufacturer when they wrote the manual. Since that would eliminate our fuel choices everyone kind of just does what they have to do. Not to get cavalier about it, as there are legitimate reasons why these are not ideal fuels, but I think some of the warning may be manufacturer CYA. We had a chimney fire a couple years ago so I had the occasion to disconnect some of the Metalbestos to see how the inner liner survived. It was gray, not bright and shiny anymore like new stuff, but other than that I didn't find any thin spots, pitting or any other signs of deterioration. The first section over the stove had some warpage on the inside but not bad. As I put my thoughts down in writing I am seeing that I really shouldn't worry about driftwood. I have no doubt it reduces the life of components but I don't think it means complete disintegration in two or three years, I think it is more like reducing total lifespan by 20% or 30%. Thanks guys, that is a load off my mind.

 

[Dextron]

Salt will also act as a abrasive in the unit which we all know is something we don't need any more of in these fan forced gassers. The abrasion from the ash is already more than we want to deal with.

I don't know that it would be an abrasive problem. I have never seen salt on the wood so we are not dealing with even table salt sized particles. My understanding of it is that any salt is what is dissolved in the seawater and enters the wood with the water when it soaks in. I guess if there was a pocket in the wood that filled with seawater and after the water evaporated all the salt could combine into larger crystals but other than that the individual particles are too small to be visible. Interesting. I should gather a bucket of driftwood sawdust, soak it in clean water for a time, press out as much of the water as possible, boil it off and see how much salt there is.

 

[EffectaBoilerUser (USA)]

Welcome to Hearth.com!

Living in Michigan I have not heard of burning driftwood in a wood boiler. I think it would really depend on how much salt was left in the wood after being dried out. Your idea of doing a little experiment to determine the salt content seems like the best way to determine just how much salt is in the wood.

 

[Dextron]

Well, since this hasn't been a severe short term problem, no one has any direct experience indicating immediate issues with boilers, and, when you get right down to it, I don't have much for alternatives to driftwood, why don't we talk about boilers now.
After browsing this forum a bit I see there are a lot more boilers out there than I was finding with my initial web searches. Like most equipment, there seems to be a couple shady operations, some lower end units and then the rest of the systems that all work okay - you just have to find one with the features that work with how you want to use it. It is not that practical for me to get any first hand looks at any so I am hoping the knowledgable folks on here can help me figure out which systems may work best for me.
The existing floor heat is being run with all loops circulating all the time and temperature controlled by setting the water temp with a mixing valve. This has worked very well with using a range from 80 to 95 degrees F and most of the time being between 85 and 90. This presents a fairly constant load to the heat source. Total heat load - I am going to give some rough numbers here so someone may want to double check it. Last winter is a good worst case scenario as we had a nasty cold spell. I used 630 gallons of fuels oil for the year (previous years it has been down around 500). I would estimate 500 of this was for November through April with about 150 of that in January alone. So, five gallons a day is six hours forty minutes of firing for my 100K BTU water heater. The smaller models of most boilers seem to be in this same BTU range so should take a roughly equal amount of run time to provide the same heat. That is worst case, most of the winter it should only be half to two thirds of that. It seems it shouldn't be difficult to obtain enough heat from a wood boiler system, the thing to figure out is how to deliver it evenly over the course of the day. My moderate heat requirement and ability to use relatively low temp water seems to be an ideal situation for using storage. I just really don't want to give up any more shop space than I have to though so let me present another idea. Monday through Friday I would only be firing in the evening as we are all at work or school during the day and I am not comfortable leaving an unattended fire. I am wondering if by setting the floor heat mix 5 or 10 degrees higher when the wood was firing I can put enough extra heat into the house structure to "coast" a while. Also, the water in the wood boiler and the existing water heater together will amount to 80 or 100 gallons that can be used after the fire burns out. Even if all of this doesn't last through the day and the oil has to take over it seems I should still be able to displace well over half of my oil usage.
Everyone feel free to comment. In particular I would like suggestions (and the reasoning behind them) for specific boilers.
Doggone, I didn't realize I wrote so much. Thank you anyone who manages to make it through all this.

 

[mikefrommaine]

I was going to say a stainless steel wood gun might be a good match for the driftwood and lack of storage. But if you don't want unattended fires you might not like leaving it to cycle on and off.

Most come to the conclusion that giving up the space and money for storage is a worthwhile trade.

 

[EffectaBoilerUser (USA)]

I would agree than after the initial sacrificing of space for water storage, all who have installed the storage would have done it no other way.

It certainly is nice to be able to get the 1,000 gallon tanks up to 190-195 on Friday night, leave for the weekend during cold weather and come home Sunday night to a house that has only dropped a few degrees (if any) and know that the propane man did not receive a cent from me.

On a normal cold winter day I am able to burn 100 lbs of wood in my Effecta Lambda 35kW boiler and during a 5 hour burn have the 500,000 plus BTU's that this produced, heat my house, hot tub and hot water for 24 hours or more.

Since you have radiant floor heat you will be able to store more energy in the water batteries as the radiant floor heat does not require water that is nearly as hot as that for baseboard or forced air systems.

 

[Dextron]

Yes, one way or another I need to figure out how to fit in some storage. I have a few ideas and questions on it but I want to narrow down the boiler choices too.

Lambda type units - what are the advantages over conventional units? Any disadvantages?

Do most units have some method of shutting down or idling if the whole system is up to max temp before the wood load burns out? The Wood Gun says it will but do any or all of the brands do this in some way? I would seem that with no storage or even with some smaller amount of storage the smallest boiler that has sufficient output to support the heating load plus some extra to charge storage would be easiest to manage versus something with more output.

What started me looking into wood fired boilers a few weeks ago was seeing an ad from Greenwood in and advertising paper here. Searching forums for information on them there is not a lot about the boiler, mostly complaints about the company having to restart itself. Does anyone here have any experience with one of them? Being built in Washington could save me some shipping costs but I don't want to get something and have problems with both the unit and the manufacturer.

 

[Gasifier]

Dextron. Greenwoods have had problems over the years. Nough said. How tall are the ceilings in your shop? Storage is the way to go. I only have 400 gallons, but would not want to go with anything less. It gives the system more ability. I wish I had three times the storage that I do, but mine works fine the way it is as well. Give us some dimensions of your shop space you can sacrifice. And I take it that is for boiler and tank together. I am thinking of vertical tank(s), that is why ceiling height is needed. Is the shop connected to house? Will you be sending lines underground to house?

 

[Dextron]

Dextron. Greenwoods have had problems over the years. Nough said. How tall are the ceilings in your shop? Storage is the way to go. I only have 400 gallons, but would not want to go with anything less. It gives the system more ability. I wish I had three times the storage that I do, but mine works fine the way it is as well. Give us some dimensions of your shop space you can sacrifice. And I take it that is for boiler and tank together. I am thinking of vertical tank(s), that is why ceiling height is needed. Is the shop connected to house? Will you be sending lines underground to house?

I kind of suspected that about Greenwoods so I'll cross them off the list.

My shop has a 10' ceiling. There is a shelf around the walls down from the ceiling leaving about 8'2" clearance under it. It is only a foot wide and a section could be removed if needed. So looking at some of the storage options out there it shouldn't be much of a problem to put a 300 to 500 gallon vertical tank in one corner. Anything more would take some additional construction, which is a possibility but I really need to finish up the rest of my project here first. The boiler can go where I currently have a wood stove. Looking at the dimensions and layout of several models any of them could be fit in. It may take a little rerouting of the stove pipe but the ceiling is high enough that there is room to work with that. The water heater for the existing floor heat is located in an entryway attached to the side of the house. the entryway roof extends out into the side of the shop roof leaving a covered breezeway between the two. the plan was to run the lines up high along the wall of the shop, through the breezeway and into the entryway to tie into the existing system.

 

[Robby]

Yes, one way or another I need to figure out how to fit in some storage. I have a few ideas and questions on it but I want to narrow down the boiler choices too.

Lambda type units - what are the advantages over conventional units? Any disadvantages?

Do most units have some method of shutting down or idling if the whole system is up to max temp before the wood load burns out? The Wood Gun says it will but do any or all of the brands do this in some way? I would seem that with no storage or even with some smaller amount of storage the smallest boiler that has sufficient output to support the heating load plus some extra to charge storage would be easiest to manage versus something with more output..

I have a unit with O2 sensor(Lambda), all computer controlled and 1200.gal storage. If you load more wood than needed it idles just fine, but I do believe much less efficient doing that. Storage, in my opinion, is the whole secret. LAzy man's system, load, reload if needed, walk away until tomorrow. Longer of course in warmer weather. No learning curve, any kind of wood. I have never tried wet wood, all under 15% (my climate) but from reading this forum it's important.

 

[EffectaBoilerUser (USA)]

Dextron,

Do you have a source for used propane tanks?

In my neck of the woods I have a very good source and am able to get "stubby" 500 gallon propane tanks. After a base ring is welded to these tanks they stand at 8'10". These work very well in rooms with 9-10' tall ceilings. I you can easily join 2 of these tanks together and then enclose them in 1-1/2' tuff R foil faced foam - works great!

See the photos attached to this email

 

[goosegunner]

Brian what is the diameter of the stubbly tank?

What is the length before the ring is added?

gg

 

[EffectaBoilerUser (USA)]

We leave approx. 2" gap between the bottom of the tank and the floor so as to put insulation between the tank and floor.

Thus, this would mean an overall length of 8'8" before adding the base ring. The diameter of these tanks is 41".

A normal 500 gallon tank is 10' long x 37" dia.