Newcomer looking for suggestions/opinions

bab313 · Aug 5, 2014

I've been doing a lot of research on this site and have weighed a lot of options. I have a preliminary design, but would like to get some suggestions from the guys out here that have some great knowledge. Here is my situation:

I have a 3000 sq ft home using baseboard hot water heat in northern NJ. Currently I have an oil fired boiler that I burn anywhere from 600 to 1000 gallons of oil per season, depending on the winter. I have access to free wood, so a wood fired boiler makes sense.

Here is my idea for the design. I'm looking at a Biomass 60 combo with 1000 gallons of storage. I plan to have a coil inside the storage for DHW, that then runs into an electric hotwater heater for use in the summer months. The reason I'm looking at a combo system is because I only have one flue, and I figure this will make the installation take up less space. Also, the oil boiler is 25-30 years old, so using that as a backup may not be the most reliable.

I plan to have this installed in the basement where my current oil boiler is installed. I have a walk-in basement that should allow an easy method for moving wood from outside to the boiler.

Hopefully this sounds reasonable. If anyone has any suggestions or opinions based on their experiences with their systems, I would love to hear them. I'm looking to move out on purchasing everything very soon, so I wanted to get some feedback before moving out on it. Thanks for your help.

brant2000 · Aug 5, 2014

Sounds like a good plan to me. I have a similar setup to what you mention, aside from the fact that my boiler and storage wouldn't hold a candle to the system you are planning out. After heating with it for 3 years now, I have placed an 8' log rack in the basement near the boiler; which provides minimally enough wood to get through the work week without having to trudge outside. Then during the weekend, I'll reload the rack. Just be sure to start working on your wood supply ASAP.

Floydian · Aug 5, 2014

Hello bab13 and Welcome.

What is your current heat distribution setup? Knowing how low of a supply temp you can deliver and still provide the Btu's needed is a key component to figuring how much convenience you will get from storage.

This along with a heat load calculation or a known heat load (BTU/hour) will help optimize your system.

Free wood is great but still takes a lot of time and you've gotta season it well. Period. < 20% MC.

Most combo units don't have the best reputation around here. Search here for more info.

I am sure your plan will work and probably well BUT.....have you considered a pellet boiler? Probably half the cost to heat vs oil, doesn't require much storage (or any, depending) and will require hardly any of your time. All said and done it might cost less to install than the combo unit+storage. Not trying to derail you here, just feel its well worth your time to research this option a little before you buy. Oh and take a good look at Windhager-very nice.

Good luck,
Noah

Pologuy9906 · Aug 5, 2014

I went through the same thing 2 years ago. Finally going with the Woodmaster Flex Fuel 30kw. I read a lot of threads up here. There's tons of information. Keep in mind some are biased because they sell units. So sift through the threads and become knowledgeable. I like the idea of having a unit which happens to be UL listed, easy to switch between pellet and wood amongst others. Rad, read, read.

bab313 · Aug 6, 2014

brant2000 said:
Sounds like a good plan to me. I have a similar setup to what you mention, aside from the fact that my boiler and storage wouldn't hold a candle to the system you are planning out. After heating with it for 3 years now, I have placed an 8' log rack in the basement near the boiler; which provides minimally enough wood to get through the work week without having to trudge outside. Then during the weekend, I'll reload the rack. Just be sure to start working on your wood supply ASAP.

Thanks brant2000. What size system are you using? Sounds like you have the same square footage as me, plus a hot tub. Do you use storage? If so, how much? I don't need to overkill the system if I don't have to, my wallet will thank me for it.

maple1 · Aug 6, 2014

How much would you expect to have to use your oil backup?

Do you have any other fuels in the house? Like propane? Or NG going by?

How old is your oil tank?

If I was getting rid of my existing oil unit, I think I would get rid of the oil tank too & go with something like an electric boiler for backup - or something NG or propane fired if you've already got that. It would eliminate the second chimney issue, free up space, get rid of oil liability potential, & give many more options for a wood unit. Sounds like you are already planning to not use oil for DHW in the summer, and are concerned with the age & reliablity of your existing oil boiler - so I'd follow that path all the way & send the oilman packing. That's what I did.

But the pellet suggestion made above is also something to consider if your local supply situation is good - I think some are even installing Windhagers as their sole heating appliance.

brant2000 · Aug 6, 2014

bab313 said:
Thanks brant2000. What size system are you using? Sounds like you have the same square footage as me, plus a hot tub. Do you use storage? If so, how much? I don't need to overkill the system if I don't have to, my wallet will thank me for it.

Well, the boiler I'm using isn't at all insulated. It provides a lot of radiant heat to the space it's in (basement). Which isn't terrible for me, but is far from ideal. My basement temps run 75-80 most of the time, while the rest of the house is 70-72. I believe the spec's for the unit claim that about 30 MBH of heat goes into the water. Compared to the design rating of the Biomass 60 (205 MBH), this is peanuts. Personally, as long as your home isn't very poorly insulated, you could probably operate just fine with a smaller model. I just two small tanks installed which provide about 120 gallons of storage, which serves more as a buffer than storage. I wish I had more storage, but with the small output from the boiler, it would take me quite a while to charge up 500 or 1,000 gallons.

bab313 · Aug 6, 2014

Is there an easy way to figure out how many BTU/hr I would need? I have last winter's oil use, but that will only give me average BTU/hr. I would think I need to handle the peak load requirements, is that right? I found a detailed calculator on another thread, but it seems more complex than what I would need. I have a two story home, 1500 sq ft per level, basement is unfinished and doesn't need heat, built in 1989 and located in northern NJ. Would the Biomass 40 be sufficient? Should I go with 500 gallons of storage instead of 1000?

bab313 · Aug 6, 2014

maple1 said:
How much would you expect to have to use your oil backup?

Do you have any other fuels in the house? Like propane? Or NG going by?

How old is your oil tank?

If I was getting rid of my existing oil unit, I think I would get rid of the oil tank too & go with something like an electric boiler for backup - or something NG or propane fired if you've already got that. It would eliminate the second chimney issue, free up space, get rid of oil liability potential, & give many more options for a wood unit. Sounds like you are already planning to not use oil for DHW in the summer, and are concerned with the age & reliablity of your existing oil boiler - so I'd follow that path all the way & send the oilman packing. That's what I did.

But the pellet suggestion made above is also something to consider if your local supply situation is good - I think some are even installing Windhagers as their sole heating appliance.

Thanks maple1. This is an interesting idea. I will look into it as well. I don't have NG available, and propane is more than the oil, but an electric backup is not a bad idea.

brant2000 · Aug 6, 2014

bab313 said:
Is there an easy way to figure out how many BTU/hr I would need? I have last winter's oil use, but that will only give me average BTU/hr. I would think I need to handle the peak load requirements, is that right? I found a detailed calculator on another thread, but it seems more complex than what I would need. I have a two story home, 1500 sq ft per level, basement is unfinished and doesn't need heat, built in 1989 and located in northern NJ. Would the Biomass 40 be sufficient? Should I go with 500 gallons of storage instead of 1000?

What size is your existing boiler? That would be a good place to start. It's probably in the ballpark of 120-150 MBH.

bab313 · Aug 6, 2014

brant2000 said:
What size is your existing boiler? That would be a good place to start. It's probably in the ballpark of 120-150 MBH.

My current boiler is 145 MBH. The highest average load I had last year based on oil consumption is 41,500 BTU/hr and that was basically the coldest days of the year. Remembering those days, temps were staying in the 0-20 degree range consistently through day and night. I would think I never really get close to the maximum needed, but I need to back out inefficiencies and the fact that the ratings on the wood boilers is likely under ideal conditions with the best possible wood. If I take the Biomass 40 and reduce by 20%, I'm at 116 MBH. I guess the question is would I ever need more than 116 MBH to heat my home, or will I always have some extra for heating up the storage?

brant2000 · Aug 6, 2014

bab313 said:
My current boiler is 145 MBH. The highest average load I had last year based on oil consumption is 41,500 BTU/hr and that was basically the coldest days of the year. Remembering those days, temps were staying in the 0-20 degree range consistently through day and night. I would think I never really get close to the maximum needed, but I need to back out inefficiencies and the fact that the ratings on the wood boilers is likely under ideal conditions with the best possible wood. If I take the Biomass 40 and reduce by 20%, I'm at 116 MBH. I guess the question is would I ever need more than 116 MBH to heat my home, or will I always have some extra for heating up the storage?

...and take into account the fact that 1,000 (or 500) gallons of storage can provide A LOT of supplemental heat at those times when you may need to shave the peak off of a really cold/windy night. Just make sure you're charged up before heading to bed.

maple1 · Aug 7, 2014

bab313 said:
Thanks maple1. This is an interesting idea. I will look into it as well. I don't have NG available, and propane is more than the oil, but an electric backup is not a bad idea.

If you mean propane is more than oil as a fuel cost, that may be - but I think the cost of the fuel is a much less significant factor to consider when it comes to a backup heating situation, especially if the backup won't be used very much at all. My backup is an electric boiler - but if I had to come up with a non-wood primary heating solution, an electric boiler would likely be my last choice.

Coal Reaper · Aug 7, 2014

600-1000gals/yr for a 3000sqft house in NNJ tells me the house is already pretty well insulated. 41,500 BTU/hr might be a tad low for design temp, but you are likely really close. 500 gallons of storage will probably get you by but you might be happier with 1000. it will be less burns/reloads. try to size your boiler such that a full load of wood will bring your storage tanks from 140* to 200*F.
with the oil boiler being that old i agree to kick it to the curb. the only reason i kept mine was because it and the oil tanks were brand new right before we closed on the house. if you plan to burn wood nearly exclusively, look into electric backup.

bab313 · Aug 7, 2014

Coal Reaper said:
600-1000gals/yr for a 3000sqft house in NNJ tells me the house is already pretty well insulated. 41,500 BTU/hr might be a tad low for design temp, but you are likely really close. 500 gallons of storage will probably get you by but you might be happier with 1000. it will be less burns/reloads. try to size your boiler such that a full load of wood will bring your storage tanks from 140* to 200*F.
with the oil boiler being that old i agree to kick it to the curb. the only reason i kept mine was because it and the oil tanks were brand new right before we closed on the house. if you plan to burn wood nearly exclusively, look into electric backup.

Thanks Coal Reaper for the advice on the one load to charge the tanks. That makes a lot of sense. Do you know how I can figure out how long one load will burn for to determine if it will charge my storage? Also, a range is usually provided for BTU/hr on the boilers, which would be best to use?

Coal Reaper · Aug 7, 2014

Btu per load is the number you are after. You could find it calculating the burn time and multiplying by output. But there can be some variation in the way that btu/hr number is acquired and ultimatly provided to the customer. Better to find out how many pounds of wood will be in a load as btu/# is fixed at 8000 or 8500 or something like that, look it up. So then you have the average density of the wood you plan to typically be burning and the volume of the fire box to figure that out. Dont forget about fudging for air space between splits and the fact that they will be at least 1" shorter than the depth o you firebox. So that will be how many btus are going into the boiler. Multiply by boilers efficiency to get btus going into your system. Then there will by some losses through plumbing. No problem if everything is in the space to be heated. So then you can figure out to what temp rise X gallons will be or how many gallons is appropriate to go from your desired min to max.
Search weighing wood on this forum. There was a number there suggested as a good starting point for temp rise per gallon per pound of wood. 1.5 maybe? Once you get up and running you will learn your system. There is quite a bit of wiggle room with storage.
Have you asked youself this question yet: what is the minimum period of time i want to go between fires? i.e. How long do you want to be able to run on storage at design temp.

maple1 · Aug 8, 2014

Most gassers burn a load of fuel out in about 4 hours. I think.

For what that's worth.

flyingcow · Aug 8, 2014

Here's my experience. I have a 85,000 btu weil mclain oil boiler. Basic insulation(R-19 walls), 2 story/1800 sq/ft house on top of a hill in northern Maine. When it was in the -30/40f temps, the oil boiler basically didn't shut off much. Run at least 45 mins out of every hour. Especially when showers were running. House was able to maintain 70f temp. That told me, the boiler(and distribution) was sized correctly, or at least i think it is. Over-sizing IMO, is not the way to design a heating(or cooling) system. I was burning 1000 gals of oil a yr, on avg. BTW, the -30/40f temps, was maybe 10 days to 2 weeks.

I put in a 30kw unit w/820 gals of storage. Works very well. Got a little lucky, did not do a heat loss calc. I replaced that 1000 gals of oil w/ 6.5 cord of SEASONED wood. Burning closer to 7.5 because we keep house warmer. than we did on oil. IMO a 60kw unit is a bit oversized for what you need.. I found a really good deal on a 60kw unit for my truck garage. That garage I've done a couple of heat load calcs and it looks like a 40kw would be about right. But I couldn't pass on this 60kw unit, but I think I'll put 2000 gals of storage in. That will allow that unit to take a full load an charge the tanks with very little idiling. Just looking for the right deals on the tanks.

Disclaimer----I drive a truck for a living, grain of salt with any info i give.

Coal Reaper · Aug 8, 2014

Yes

maple1 said:
Most gassers burn a load of fuel out in about 4 hours. I think.

For what that's worth.

, with wood on the high end of density. I burn mostly oak, BL, and black birch. Thise will take close to four hours. A laod of tulip poplar is eaten up in less than half that time.

Coal Reaper · Aug 8, 2014

I done what flyingcow did with my 90 kbtu/hr oil cranking most of the time when it was coldest. Its a dirty way to ballpark and i would say only works if you are really paying attention and the OB is close to maxed out. Mine was verified this year when at <10*f the house temp started falling after running on storage for five hours. House would be 3* below setpoint when i got home 12 hours after loading boiler.

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