Is there a Cheaper more basic boiler?

peakbagger

Minister of Fire
Jul 11, 2008
6,176
Northern NH
Pellet stoves have sold very well, so why not small chip boilers? Small chip boilers = pellet stove (replace pellet auger with chip auger) + firebox insulation + boiler coils + circulation pump, right?
If you want to wish and hope and hold your breath until a small residential wood chip boiler magically appears on the market have at it but as we have tried to explain, there are technical issues that make it unlikely that you will see such a product. Effectively many companies started with a clean sheet of paper and tried to design such a device and keep coming to the conclusion that the problem was non uniform fuel. Wood chips vary widely in size, shape, fines and moisture content. When dealing with tons of fuel, size and shape is less important but when dealing with ounces it makes a big difference. Moisture content is pretty much directly related to BTU content and the air fuel ratio is closely related to BTU content. Air fuel ratio is based on pounds not density of fuel. Dealing with all that complexity makes for a expensive complex device. Eventually the light bulb went on to make the fuel more consistent by drying it, grinding it then extruding it into pellets. Once the fuel got consistent, than the cost and complexity comes way down. Froling appears to have gone half way on their large institutional boilers where they supply a clean (no fines) pre-dried, consistent chip size but that means the buyer is beholden to Froling to supply those custom chips. Realistically the pellet market has multiple suppliers of standardized pellets so there is a lot to be said to just go with pellets. Note that as the pellet boiler sizes get larger with more complex controls, the quality of the pellet can get lower than what will work on a residential unit. There are commercial pellets made using a blend of agricultural wastes. There have also been attempts to make pellets out of post consumer waste for large units. Talk to any pellet stove user and their number one complaint it usually fuel quality even with pellets that are claimed to be made to Pellet Fuel Institute standards.
 

monteville

New Member
Nov 23, 2019
67
Dallas
when dealing with ounces it makes a big difference. Moisture content is pretty much directly related to BTU content and the air fuel ratio is closely related to BTU content. Air fuel ratio is based on pounds not density of fuel. Dealing with all that complexity makes for a expensive complex device.
The automotive industry already have mature solutions of fuel/air ratio: MAF sensor + intake air temperature sensor + exhaust O2 sensor + ECU control of throttle and injection. A simple system cost less than $100 if mass produced.

The control algorithm use a short term fuel trim and a long term fuel trim to separately accommodate to fluctuations due to engine operating condition, and refill of the fuel tank.
 

Eureka

Feeling the Heat
Feb 4, 2018
349
NW Wisconsin
Please continue on how this works. What about heat loss in the water as it’s doing it’s job
Might as well skip the stove and just build a fire on the floor using this logic.
 

E Yoder

Minister of Fire
Jan 27, 2017
533
Floyd, VA
If you want to wish and hope and hold your breath until a small residential wood chip boiler magically appears on the market have at it but as we have tried to explain, there are technical issues that make it unlikely that you will see such a product. Effectively many companies started with a clean sheet of paper and tried to design such a device and keep coming to the conclusion that the problem was non uniform fuel. Wood chips vary widely in size, shape, fines and moisture content. When dealing with tons of fuel, size and shape is less important but when dealing with ounces it makes a big difference. Moisture content is pretty much directly related to BTU content and the air fuel ratio is closely related to BTU content. Air fuel ratio is based on pounds not density of fuel. Dealing with all that complexity makes for a expensive complex device. Eventually the light bulb went on to make the fuel more consistent by drying it, grinding it then extruding it into pellets. Once the fuel got consistent, than the cost and complexity comes way down. Froling appears to have gone half way on their large institutional boilers where they supply a clean (no fines) pre-dried, consistent chip size but that means the buyer is beholden to Froling to supply those custom chips. Realistically the pellet market has multiple suppliers of standardized pellets so there is a lot to be said to just go with pellets. Note that as the pellet boiler sizes get larger with more complex controls, the quality of the pellet can get lower than what will work on a residential unit. There are commercial pellets made using a blend of agricultural wastes. There have also been attempts to make pellets out of post consumer waste for large units. Talk to any pellet stove user and their number one complaint it usually fuel quality even with pellets that are claimed to be made to Pellet Fuel Institute standards.
Well said, pellets and chips are very different animals. Chips bridge, catch on each other (they're "fuzzy"), are not uniform density, and have a lot less btu for the same volume (much larger fuel feed and burner needed). It's complicated.
Comparing to gasoline is even more apples to oranges.
 
  • Like
Reactions: sloeffle

peakbagger

Minister of Fire
Jul 11, 2008
6,176
Northern NH
The automotive industry already have mature solutions of fuel/air ratio: MAF sensor + intake air temperature sensor + exhaust O2 sensor + ECU control of throttle and injection. A simple system cost less than $100 if mass produced.

The control algorithm use a short term fuel trim and a long term fuel trim to separately accommodate to fluctuations due to engine operating condition, and refill of the fuel tank.
You are missing a fundamental point or you are just in the mood to argue. Gasoline Diesel Natural Gas and propane are standardized products. Yes there is some tolerance but a pound or volume of any of the four yield a number that closely correlates to set BTU content. When the car first starts its doesnt use most of those goodies you mentioned, its "open loop" and looks up fuel settings based on air flow or some surrogate like MAP or in the old days throttle positions. This works as the internal look up table was mapped based on known btu content for the fuel. Once the engine warms up then it goes into closed loop and starts to look at the various downstream sensors for feedback and tunes the engine to maximize efficiency, performance and minimize emissions. So #1 fuel oil ranges from 137,000 to 131,000 btu./lb (HHV) Yes it varies a bit depending on suppliers but the computer can deal with it. Compare that to wood chips, they can range from negative btu value to 8600 btu/lb for bone dry wood. The reason it can be negative is there is so much water, snow or ice that the fuel value is less than the latent heat of fusion (for snow and ice) and the latent heat of vaporization of the water plus the sensible heat that has to carried along with the process in vapor form until dumped out the stack. Even if it does burn, the flame temp is going to be too low for complete combustion which means less heat output and much higher emissions.

BTW I have on occasion in my career had to work to develop ASME test code packages for biomass power plant performance testing on new state of the art $200 to $400 million dollar plants and even they have a tough time dealing with poor fuel quality. I also tune them up on occasion. So I guess if you think you have better way to do it than the industry I guess its time to spend the retirement fund and design something that will work, meets EPA standards and is economically attractive enough for someone to want to have silo next to their house to hold bulk chips.
 

slowzuki

Minister of Fire
Inefficient? You already own the slab. You would have 0% standby losses. The purpose of the water it to store/buffer the peak output of the boiler when it exceeds the ability of your heating load to take heat.

If you have a big slab in a work shop and you have a minimum room target temp of say 60 F, and you don't mind it getting as high as say 85 F, it will soak up several burn cycles from a boiler no trouble without the boiler going idle. This doesn't work for a house but fine in a workshop/garage.

that is very inefficient...
Water has been proven as the best medium for storing BTU's
 

slowzuki

Minister of Fire
I missed one part of that, also need temp control on the discharge to limit to about 120-140 F going into the slab.

It's not complex, think of what OWB's user do to heat shops using in floor heating. They build a fire in boiler, pump the hot water through the floor when they want the space warmer. That's it. They often have no return protection on the OWB hence the massive rotting fire chamber problems they are plagued with.

If your floor is too small or the loops undersized, you couldn't do this without storage as you would keep kicking your boiler into idling. Properly sized loops though you will have plenty of cold return water and never hit the over temp limits on boiler.

Please continue on how this works. What about heat loss in the water as it’s doing it’s job
 

S.Whiplash

Member
Oct 28, 2012
113
Pellet stoves have sold very well, so why not small chip boilers? Small chip boilers = pellet stove (replace pellet auger with chip auger) + firebox insulation + boiler coils + circulation pump, right?
You are correct, pellet stoves are fairly popular, they cost aprox. $3,000-$5,000. Pellet boilers are far less common, they cost aprox. $10,000-$15,000. Small scale chip boilers can be purchased and imported from European producers such as Heizomat, but they start around $25,000 which makes them an extremely unpopular option for residential home owners. You can get almost anything you want, if you are willing to spend enough money.
 

Brokenstone

Member
Jan 13, 2017
18
indiana
Regarding comparing the slab to water as a thermal reservoir. A slab will lose stored heat much faster. It has much more surface area than a vessel. It is in contact with a colder mass throughout it's greater surface area.
Its not as thermaly dense as water and can store less heat.

A water vessel will store heat longer than a slab will and be able to transfer heat long after a slab is unable to because there is none.
 
Last edited:
  • Like
Reactions: sloeffle

hyfire

Minister of Fire
Aug 3, 2013
718
Ont, Canada
Mbtek makes a non certified boiler, and some people say good things about them for the price, you could buy 3 of them vs a brand name boiler on the market. . I heard customer service is not great, but talked to a few owners, no real complaints just some settings issues. Deliver time is about 2-3 months. Its not a complicated unit and looks simple to clean for the trade off of not being so efficient. 10 year warranty and 5mm thick steel makes them pretty heavy duty.
 

Eureka

Feeling the Heat
Feb 4, 2018
349
NW Wisconsin
A slab does not store heat in any way. It distributes and releases it, constantly, and uncontrollably.
 

Highbeam

Minister of Fire
Dec 28, 2006
18,768
Mt. Rainier Foothills, WA
A slab does not store heat in any way. It distributes and releases it, constantly, and uncontrollably.
I must disagree. As an owner of an insulated 1800 sf slab it absolutely absorbs heat and releases it slowly. There is a huge flywheel effect. Now, is it as good as an insulated 1000 gallon water tank? No. But it is obvious that the thermal mass of a slab is not zero.
 
  • Like
Reactions: Case1030

slowzuki

Minister of Fire
Didn't double check the math but a workable 15 C swing in my 32x24ft slab looked to be same energy as a 40 C swing in a 520 gal tank.

Edit, for example, when I brought my boiler online, it took 2 days continuous firing to bring the return water temperature from the slab up to the target temp.

I must disagree. As an owner of an insulated 1800 sf slab it absolutely absorbs heat and releases it slowly. There is a huge flywheel effect. Now, is it as good as an insulated 1000 gallon water tank? No. But it is obvious that the thermal mass of a slab is not zero.
 
Last edited:

slowzuki

Minister of Fire
They do store heat, a lot of heat, but yes they release it non-stop at a steady and predictable rate into the space. Predictable enough that you can plan a firing schedule around keeping it a reasonably steady temperature. Again, this is not ideal for a house, works fine in a shop.

A slab does not store heat in any way. It distributes and releases it, constantly, and uncontrollably.
 
  • Like
Reactions: maple1

maple1

Minister of Fire
Sep 15, 2011
10,745
Nova Scotia
I must disagree. As an owner of an insulated 1800 sf slab it absolutely absorbs heat and releases it slowly. There is a huge flywheel effect. Now, is it as good as an insulated 1000 gallon water tank? No. But it is obvious that the thermal mass of a slab is not zero.
Agreed.
 

hyfire

Minister of Fire
Aug 3, 2013
718
Ont, Canada
Lets not worry about the slab, I would be more worried about finding a boiler. Go to the mbtek site and start talking to some stove users get some info before you buy anything! Newhoirzonstore has a great selection of european boilers. A froling boiler will be 10-14 k. Or check autom boilers in Quebec about 8-9 k for a csa gassifier.
 

NateB

Feeling the Heat
Mar 5, 2013
293
South Central Pennsylvania
After watching the old tarm video makes. E want one of them But I guessing there are few and far between? And I still should have storage Can storage tanks be added on a closed loop glycol filled system?
Consider an Eko with unpresserized storages from Tom in maine. American solartecnics. You can make your DHW, and supplement your heat. Then in the summer you can dehumidify and cool your garage while heating your DHW with a air source heat pump on your storage.
 

maple1

Minister of Fire
Sep 15, 2011
10,745
Nova Scotia
Lets not worry about the slab, I would be more worried about finding a boiler. Go to the mbtek site and start talking to some stove users get some info before you buy anything! Newhoirzonstore has a great selection of european boilers. A froling boiler will be 10-14 k. Or check autom boilers in Quebec about 8-9 k for a csa gassifier.
Have more info on the autom thing? Google found nothing.
 

S.Whiplash

Member
Oct 28, 2012
113
Pellets cost more than wood ,unless you got a super deal buying them your going to have no cost savings.
That's a bit of a blanket statement, pellets do cost more than wood, but harvesting wood is not free, a significant investment in time and equipment is needed. Directly comparing the cost of wood pellets to fossil fuels per BTU output, they are currently cheaper than oil and propane, but more expensive than N.G.
 
  • Like
Reactions: Highbeam and Bad LP

hyfire

Minister of Fire
Aug 3, 2013
718
Ont, Canada
That's a bit of a blanket statement, pellets do cost more than wood, but harvesting wood is not free, a significant investment in time and equipment is needed. Directly comparing the cost of wood pellets to fossil fuels per BTU output, they are currently cheaper than oil and propane, but more expensive than N.G.
I used to go through 2 bags a day with tax thats $14 worth,. You do a have a point depends what your paying for wood how much is a face cord of wood in equivalent of pellet bags?
 

Bad LP

Minister of Fire
Nov 28, 2014
1,530
Northern Maine
I used to go through 2 bags a day with tax thats $14 worth,. You do a have a point depends what your paying for wood how much is a face cord of wood in equivalent of pellet bags?
Get away from the face cord BS and go to the standard cord of 4x4x8 feet and then run the numbers.
 

Bad LP

Minister of Fire
Nov 28, 2014
1,530
Northern Maine
Comes out to $400 to a cord of wood at 7$ a bag. Wood is around 300 a cord delivered.
I was not seeing that 400 last I noticed in Maine but I honestly don’t know today’s numbers. I was seeing 230-250/pallet and that is close to what my wood guy delivered my last order @ 230/cord. He had to raise his numbers because his permit cost from the paper company went up.