maple1
Minister of Fire
Good point there as well. Mine does cycle. Backup buffer? Something else to add to my long list of things to think about.
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Good point there as well. Mine does cycle. Backup buffer? Something else to add to my long list of things to think about.
Couple of quick thoughts:
The oil boiler looks like the typical three section cast iron, rated ~ 100,000 btu. What would scare me (for you) is if the boiler is oversized by double. The 60 kW FF boiler could heat your house plus two of your neighbor's houses. That's the first question to have answered, is the boiler right sized and does it have the ability to turn down the firing rate for low demand. The manual says it will slow the fan speed for low demand, but the effectiveness of boiler turndown could be zero if you're turning down from 200,000 btu to 125,000 btu and the load is 25,000 btu. Fuel consumption, efficiency, operability will all miss the target area if this is wrong.
The oil boiler you have is perfectly suited to short cycling, firing for five minutes and waiting for twenty minutes, the duty cycle. The cordwood boiler cannot do this. It is always on and putting out heat when firing, for hours, until the fuel load is exhausted. This is to say that a smaller boiler firing longer is indicated compared to a much larger boiler firing for shorter time.
This is what the dealer or installing contractor should do first before buying material or touching the tools, the heat loss calc, then the design and equipment choices will fall out of that. If you truly have a 200k btu load in a normal house, you may want to look at windows, siding, and insulation to get the load to the normal area. If the heat loss calc says the boiler is oversized by double, returning the boiler for the right sized unit would be first on my list.
Over the life of the install, efficiency or lack of, operability, and maintenance issues, will be a far bigger number compared to the initial cost of the install. Good design and implementation will save you the cost of the design fee many times over.
Some of the high efficiency boilers will operate with the flue gas near condensing temp at parts of the cycle (mine does). The masonry chimney will not like condensate and usually a stainless liner is indicated. The manual says regular chimney, but again it depends on the heat extraction and firing rate of the boiler. The liner may be added later if necessary. Condensate will not be a problem when the boiler is ripping into a matched load.
If was bidding that, I would want to add an outdoor reset controller and variable speed injection pump or valve between the tank and the loads even with conventional HW baseboards. Would also add an indirect DHW tank and eliminate the electric DHW. I know my view would add thousands of dollars to the install cost.
The instructions say the changeover from pellet to cordwood is done manually, changing the insert and the pellet chute. As long as you know this and it meets the requirements for automatically running central heat, I would be OK with this and not have a second, backup boiler. That scenario would not work for most customers who are hands off. Also, for the low demand times, do you want to labor to run the big boiler or do you want something that runs in auto with no manual intervention
I have not read all of your thread but I am assuming a normal residential load (~ 2,000 sf) with some insulation and conventional, good quality construction. The only thing I see that scares me is if the boiler is misapplied for the load. A problem like this is easy to fix in design or before construction, but very expensive or impossible to fix after the installation and before discovery of the problem.
The oil boiler looks like the typical three section cast iron, rated ~ 100,000 btu. What would scare me (for you) is if the boiler is oversized by double. The 60 kW FF boiler could heat your house plus two of your neighbor's houses. That's the first question to have answered, is the boiler right sized and does it have the ability to turn down the firing rate for low demand. The manual says it will slow the fan speed for low demand, but the effectiveness of boiler turndown could be zero if you're turning down from 200,000 btu to 125,000 btu and the load is 25,000 btu. Fuel consumption, efficiency, operability will all miss the target area if this is wrong.
The oil boiler you have is perfectly suited to short cycling, firing for five minutes and waiting for twenty minutes, the duty cycle. The cordwood boiler cannot do this. It is always on and putting out heat when firing, for hours, until the fuel load is exhausted. This is to say that a smaller boiler firing longer is indicated compared to a much larger boiler firing for shorter time.
This is what the dealer or installing contractor should do first before buying material or touching the tools, the heat loss calc, then the design and equipment choices will fall out of that. If you truly have a 200k btu load in a normal house, you may want to look at windows, siding, and insulation to get the load to the normal area. If the heat loss calc says the boiler is oversized by double, returning the boiler for the right sized unit would be first on my list.
Over the life of the install, efficiency or lack of, operability, and maintenance issues, will be a far bigger number compared to the initial cost of the install. Good design and implementation will save you the cost of the design fee many times over.
Some of the high efficiency boilers will operate with the flue gas near condensing temp at parts of the cycle (mine does). The masonry chimney will not like condensate and usually a stainless liner is indicated. The manual says regular chimney, but again it depends on the heat extraction and firing rate of the boiler. The liner may be added later if necessary. Condensate will not be a problem when the boiler is ripping into a matched load.
If was bidding that, I would want to add an outdoor reset controller and variable speed injection pump or valve between the tank and the loads even with conventional HW baseboards. Would also add an indirect DHW tank and eliminate the electric DHW. I know my view would add thousands of dollars to the install cost.
The instructions say the changeover from pellet to cordwood is done manually, changing the insert and the pellet chute. As long as you know this and it meets the requirements for automatically running central heat, I would be OK with this and not have a second, backup boiler. That scenario would not work for most customers who are hands off. Also, for the low demand times, do you want to labor to run the big boiler or do you want something that runs in auto with no manual intervention
I have not read all of your thread but I am assuming a normal residential load (~ 2,000 sf) with some insulation and conventional, good quality construction. The only thing I see that scares me is if the boiler is misapplied for the load. A problem like this is easy to fix in design or before construction, but very expensive or impossible to fix after the installation and before discovery of the problem.
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maple1
Minister of Fire
My house is 2600 sqft and the basement is 1400 sqft. O initially thought this unit would be oversized buy the storage would require more btus. I'm order to burn less frequent the 100,000 btuunit they carry won't cut it.
This unit has the ability to burn in a partial load mode. I agree on designing prior to install.
To change from pellet to wood is very simple as well.
This unit has the ability to burn in a partial load mode. I agree on designing prior to install.
To change from pellet to wood is very simple as well.
In order to burn less, you need to increase the overall efficiency of the system. That's the boiler, OA reset, doors, windows, and insulation. That's what the numbers will show. Rightsizing the boiler will increase system efficiency and reduce total fuel consumption.
The larger boiler will burn at a much faster rate, fuel consumption will go up, your labor feeding fuel is more. (It is 2x normal size)
At peak demand times when you can use the excess heat production, maybe you will save some loading cycles with larger loads, but the weather is mostly not at peak demand, and the same number of loading cycles with smaller fuel loads in the right size boiler may meet demand. It seems to be a wash, by guesstimating. It is not every day that you will be saving a loading cycle, but it is every day that you will need to add more fuel because of higher standby and idle losses with the larger boiler.
Many days, demand will be a small quantity, but more fuel will be needed to bring the larger system up to working temp. That is where the problem will be.
I would think the ideal scenario is a 24 hour ride through from the boiler with storage. This gives you a number that can be calculated for the storage tank size. Make one fire a day in the morning for showers and bringing the house temp up. Burn time may be ~ 3 to 4 hours, but burn when the boiler is firing into the house peak load. If you need to add fuel again later in the day, if the system works at max efficiency, the fuel needed will be less.
If you are firing when the house load is at max, you are not using storage too much. Storage is needed because the baseboard loads short cycle, running a little all day, and to absorb the excess boiler output. The larger boiler could require larger storage and larger near boiler piping.
The 30 kW, 100,000 btu boiler is a big boiler. It's a lot of output, especially when it's burning at the design parameters, efficiently, into the normally expected load.
I am certain the big boiler would scare the bidding contractors who know your load by looking at at it for a few seconds, or over the phone. Many, but not all, contractors will hesitate or walk away from a job that indicates problems for them and the customer down the road. If they think the load is in the range of a 30 kW boiler, a customer asking them to install a 60 kW boiler is a huge red flag.
Some additional fuel consumption (labor) would seem to be the only downside to the larger boiler, plus some additional install cost for larger equipment. My predisposition is to specify more expensive materials upfront, but in a way that is reliable and economical over the life of the install.
Rightsizing the equipment takes advantages of the millions of dollars and thousands of man hours that has already been done for you by the factory in the design, engineering, and rating of their equipment. One cannot really ever say that the factory is wrong without showing some numbers or engineering to back it up.
It all goes back to the first question, what is the load, the heat loss calc, then the numbers will show what the fuel consumption will be, how many loading cycles, how much storage is indicated.
The larger boiler will burn at a much faster rate, fuel consumption will go up, your labor feeding fuel is more. (It is 2x normal size)
At peak demand times when you can use the excess heat production, maybe you will save some loading cycles with larger loads, but the weather is mostly not at peak demand, and the same number of loading cycles with smaller fuel loads in the right size boiler may meet demand. It seems to be a wash, by guesstimating. It is not every day that you will be saving a loading cycle, but it is every day that you will need to add more fuel because of higher standby and idle losses with the larger boiler.
Many days, demand will be a small quantity, but more fuel will be needed to bring the larger system up to working temp. That is where the problem will be.
I would think the ideal scenario is a 24 hour ride through from the boiler with storage. This gives you a number that can be calculated for the storage tank size. Make one fire a day in the morning for showers and bringing the house temp up. Burn time may be ~ 3 to 4 hours, but burn when the boiler is firing into the house peak load. If you need to add fuel again later in the day, if the system works at max efficiency, the fuel needed will be less.
If you are firing when the house load is at max, you are not using storage too much. Storage is needed because the baseboard loads short cycle, running a little all day, and to absorb the excess boiler output. The larger boiler could require larger storage and larger near boiler piping.
The 30 kW, 100,000 btu boiler is a big boiler. It's a lot of output, especially when it's burning at the design parameters, efficiently, into the normally expected load.
I am certain the big boiler would scare the bidding contractors who know your load by looking at at it for a few seconds, or over the phone. Many, but not all, contractors will hesitate or walk away from a job that indicates problems for them and the customer down the road. If they think the load is in the range of a 30 kW boiler, a customer asking them to install a 60 kW boiler is a huge red flag.
Some additional fuel consumption (labor) would seem to be the only downside to the larger boiler, plus some additional install cost for larger equipment. My predisposition is to specify more expensive materials upfront, but in a way that is reliable and economical over the life of the install.
Rightsizing the equipment takes advantages of the millions of dollars and thousands of man hours that has already been done for you by the factory in the design, engineering, and rating of their equipment. One cannot really ever say that the factory is wrong without showing some numbers or engineering to back it up.
It all goes back to the first question, what is the load, the heat loss calc, then the numbers will show what the fuel consumption will be, how many loading cycles, how much storage is indicated.
PassionForFire&Water
Minister of Fire
Is 600 gallons adequate for what the OP is aiming for?
600 x 8.35 Lbs/gal = 5,010 Lbs of water
lets assume a usable dT of 185F-140F= 45F
5,010 x 45 = 225,450 BTUs stored in the tank.
If the house needs 50,000 BTU/hr that is 4.5 hours of heat
Unless I miss something, that's not a lot for spending all the money.
PassionForFire&Water
Minister of Fire
PassionForFire&Water
Minister of Fire
Consider the information that was given to you today on this forum of high value!
I assume you paid for the wood boiler already.
If not go for a smaller model, or exchange the bigger for a smaller model. Take the loss if needed!
If yes, see if you can get much more storage.
If more storage is not an option, ....
I don't want to discourage you, but that's were you stand right now.
Good luck.
I assume you paid for the wood boiler already.
If not go for a smaller model, or exchange the bigger for a smaller model. Take the loss if needed!
If yes, see if you can get much more storage.
If more storage is not an option, ....
I don't want to discourage you, but that's were you stand right now.
Good luck.
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maple1
Minister of Fire
I have 660 gallons. Right now I start a burn about this time of day, burn about a load & a half, and call it good. The fire is pretty well out as I'm heading to bed. Repeat. So my storage gets me about 18 hours from the time the fire is done until I light again. In the dead of winter that will increase to about 2.5 loads burned, and I'm looking at about 14 hours. 20 year old 'conventional' construction two story on a windy hilltop.
I would like more storage but haven't figured out how I can fit it in yet. I could likely skip somewhere around 1-2 months of burning days a year if I could increase to where I could skip a day in shoulder seasons or gain an extra day of coasting in summer DHW days. That's quite a bit of fire lighting in the run of a year, and a lot less cold startups.
So 'adequate' is in the eye of the beholder. If I was putting in a 60kw boiler I'd do all I could to get at least 1000 gallons in. So maybe 600 is inadequate? But 600 gallons would likely hold a burns worth of heat, which is what others may aim for - and consider adequate. Also, IMO, as long as storage will hold at least a burn worth of heat, and can coast you to the next day as you want it to, it all but takes boiler sizing for load out of the equation - at least as far as being oversized. I do try to time my burn so that it is ramping up to full burn just as my loads get to calling most (in the evening).
I guess I better go light a fire now.
No-Pro Disclaimer: I am no pro.
My thought is of the unit is undersized and my goal is 1000 gallons of storage, it will only heat to the btus it could put out. it would seem that the 30kw would be right at the maximum limit. With the 60 it would Give me the opportunity to burn less frequent.
One thing I read a lot on hearth is learning your system. Warmer days simply burn pm partial load settings. When it's really cold burn at full capacity.
Just my thought. I emailed the manufacture to ask some of the great questions posed here. This is why this would not be done without all the input I received here
One thing I read a lot on hearth is learning your system. Warmer days simply burn pm partial load settings. When it's really cold burn at full capacity.
Just my thought. I emailed the manufacture to ask some of the great questions posed here. This is why this would not be done without all the input I received here
PassionForFire&Water
Minister of Fire
I honestly didn't track the gallons used. I wasted just under $3000. Sad part my house was still cold.
PassionForFire&Water
Minister of Fire
$3,000 of oil
Lets assume oil is $3.85/gal, what equals around 780 gallons.
Lets also assume you burned all this oil in Nov, Dec, Jan, Feb and March: 5 months
780 gallons x 138,000 BTU/gal = 107,640,000 BTUs over 5 months
or
107,640,000 / 5 months = 21,528,000 BTU/month
or
21,528,000 / 30 days per month = 717,600 BTUs per day
or
over 24 hours = 29,900 BTU/hr
over 12 hours = 59,800 BTU/hr
So, we know that the heat load is somewhere between 30,000 and 60,000 BTU/hr
The peak heat load may be higher then 60,000 BTU/hr
The 50,000 BTU/hr that I used earlier will give 4.5 hours of storage (in 600 gallons)
if you can double the storage to around 1,200 gallons you can store heat for around 9 hours.
This will allow you to go trough the night without firing the wood boiler
If you check how much wood the FF60 holds you can calculate roughly how many time you will need to fire the wood boiler.
When you bring in the efficiency and moisture content, I believe you will end up with between 6,500 and 7,000 BTU/lbs of wood.
Check some topics from Jebatty; he made a lot of good posts on this forum with real world data.
somebody will need to fire the wood boiler.
Depending on the size of the thermal storage this may be 2x per day.
Also key is that you have well seasoned firewood.
Roughly:
if you burn wood pellets, you will save roughly 50% over oil; so $1,500 or 6 to 7 tons of pellets
if you burn cord wood you will save roughly 75% over oil
Payback with wood pellets for a $20,000 install is >13 years
Payback with cord wood is around 7 years
Lets assume oil is $3.85/gal, what equals around 780 gallons.
Lets also assume you burned all this oil in Nov, Dec, Jan, Feb and March: 5 months
780 gallons x 138,000 BTU/gal = 107,640,000 BTUs over 5 months
or
107,640,000 / 5 months = 21,528,000 BTU/month
or
21,528,000 / 30 days per month = 717,600 BTUs per day
or
over 24 hours = 29,900 BTU/hr
over 12 hours = 59,800 BTU/hr
So, we know that the heat load is somewhere between 30,000 and 60,000 BTU/hr
The peak heat load may be higher then 60,000 BTU/hr
The 50,000 BTU/hr that I used earlier will give 4.5 hours of storage (in 600 gallons)
if you can double the storage to around 1,200 gallons you can store heat for around 9 hours.
This will allow you to go trough the night without firing the wood boiler
If you check how much wood the FF60 holds you can calculate roughly how many time you will need to fire the wood boiler.
When you bring in the efficiency and moisture content, I believe you will end up with between 6,500 and 7,000 BTU/lbs of wood.
Check some topics from Jebatty; he made a lot of good posts on this forum with real world data.
somebody will need to fire the wood boiler.
Depending on the size of the thermal storage this may be 2x per day.
Also key is that you have well seasoned firewood.
Roughly:
if you burn wood pellets, you will save roughly 50% over oil; so $1,500 or 6 to 7 tons of pellets
if you burn cord wood you will save roughly 75% over oil
Payback with wood pellets for a $20,000 install is >13 years
Payback with cord wood is around 7 years
The crazy part is I used $3000 but my house was only warm primarily on one zone. If I had every zone heated to 65 It would have been more like $4500. O believe my actual need would ne considerably more.
PassionForFire&Water
Minister of Fire
Maybe you should look first into heat saving improvements: insulation of walls, attic insulation, windows and doors.
This type of investment pays off big time, because cost for heating will only go up.
In MA we have free energy audits.
I'm not sure what information you get out of such an audit, but you get some good info out of it.
For CT:
http://www.cl-p.com/home/saveenergy/rebates/homeenergysolutions.aspx
http://www.ct.gov/opm/lib/opm/pdpd_energy/consumer_faq_home_energy_audit_program.pdf
maple1
Minister of Fire
The 50,000 BTU/hr that I used earlier will give 4.5 hours of storage (in 600 gallons)
if you can double the storage to around 1,200 gallons you can store heat for around 9 hours.
This will allow you to go trough the night without firing the wood boiler
So how, then, am I going minimum 12hrs (assuming coldest day ofthe winter here), and about 18 now (daytime highs of -5°c), without burning, on 660 gallons? I paid attention when insulating & air sealing 18 years ago, but I didn't go beyond conventional practices then. 12" of fiberglass in the attic, 6" in the walls, 2700 sq.ft. in two stories on an open hill top. I never did use just oil for heat, but if I had to I'd estimate it would take at least 1000 gallons to get me through a year. And the house would be colder than it is now.
if you can double the storage to around 1,200 gallons you can store heat for around 9 hours.
This will allow you to go trough the night without firing the wood boiler
So how, then, am I going minimum 12hrs (assuming coldest day ofthe winter here), and about 18 now (daytime highs of -5°c), without burning, on 660 gallons? I paid attention when insulating & air sealing 18 years ago, but I didn't go beyond conventional practices then. 12" of fiberglass in the attic, 6" in the walls, 2700 sq.ft. in two stories on an open hill top. I never did use just oil for heat, but if I had to I'd estimate it would take at least 1000 gallons to get me through a year. And the house would be colder than it is now.
Proud Sub Vet
New Member
For what this is worth... in my prior house (1910 Victorian.. NO insulation, original windows) when our 1940's era single-pipe steam boiler finally croaked, I used Solv it (they seem to service most of CT) - anyway, they were FABULOUS, very knowledgeable and thorough. (We replaced something the size of a Mini Cooper and replaced it with something more along the size of a dishwasher!) I highly recommend them if they are able!
Hate to report, I had a company come out who installed a unit and wanted to charge me $20,000 for the labor on a propane backup which takes one day and the boiler with storage. Seems like that we're trying to hit a home run. 2 guys working 5 days would be $125 hour. That's beyond extremely high for a plumbers labor cost. Bria's Plumbing came in much too high. So the search continues.
Seriously thinking of a Attack and do the install myself.
Seriously thinking of a Attack and do the install myself.
Hey Polo;
Did you ever get a reply from Flexfuel. Were they willing to vouch for, verify, that the 200kW boiler is suitable for your application?
Regarding contractors, they are in general competitive, want to work, and the cost structure is heavily dependent on the expense structure of being in business, which is through the roof. Especially true of small family operations, they work for food and to pay bills. Large operations have larger expense overhead. Lowest cost is for jobs they do a lot of in volume. Anything that looks like it will slow the job down (changes, design errors) gets added to costs.
I still believe a good local guy (heating contractor) can do the job, provided with a detailed buildable design plan. Asking for design/build may be too much for regular guys.
That said, knowing guys from being in business, I did not want anyone touching my house or boiler construction. To get the quality I wanted, which was far above where the market is, I knew I had to do everything myself. I don't recommend it, but it was necessary in my case.
Yes a 200 is ok for my application. The 100 may have been right on the edge. I tried supplying schematics and still increased pricing. I'm getting to the point of selecting another brand. Last time I checked there were only a couple of units I would absolutely stay away from. I love the UL Listed this unit supplies as well as the option to run cord wood and pellets.
Going with the 30kw. After taking the advice and getting the heat calc done. Going with 855 gallons of storage.
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