Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: big cat on December 04, 2014, 08:52:30 PM
-
I'm beginning to wonder if my NCB-175 is under-sized for my house. I cannot get solid burn times out of my unit. NC specs say that the unit should heat up to 4k sq' and my house is 3k sq' and 15 years old (I also heat domestic hot water). I recently replaced the lines with Logstar and although I'm burning semi-green/seasoned hardwood (4-6 months), I can only get 8 hour burns or so. Some people I talk to get 16, 24+ hour burn times. Was thinking about calling P&M or Central Boiler for some quotes. What do you think?
-
Without knowing what your heat load is, it is hard to say what your problem might be. I can say that 4 to 6 months cut is not dry wood. Dry wood makes all the difference.
I don't burn any wood that hasn't been cut, split and stacked for less than a year. Oak doesn't get burned for 16 months.
I have a P&M BL28-40 that I am going thru my first season with. Learning something every day. Some days frustrating, some days happy. Get to know your boiler, then decide if you need something different. Lot of good info here.
-
Can I ask what is frustrating about your 28-40?
-
Sounds exactly like what's happening to me I only get about 6-7 hrs on mine I just about had enough going today to my local dealer today to ck out the cl6048
-
My firebrick in the bottom fell over and restricted air flow enough that the fire would hardly burn. Had to let it burn down, stand up and space the brick and start all over with a new fire. Turns out, I was shorted 2 firebrick and that caused them to fall over.
-
That sure wood mess up the air flow. Good you found it.
-
First off you really can not use the "will heat blah blah sqft". So let us know what you are trying to heat, what kind of insulation etc. I am going to guess that you have a few issues. First off is that you are very likely on the edge of what you will be able to heat with that size unit and get 12 hour burn times. Second is how is your coal bed look when you reload? You need to have 2-3 inches of coals left when you reload which is very important when you are burning green wood like you are. You can burn green wood like that but your burn times are going to be severely impacted because of howany btus it takes to burn all of the water out of that wood.
-
I am heating a 3k sq' house and DHW. The house is 14 years old and well insulated. My coal bed varies from 4-6+" in depth depending how soon I can get out to it i.e. every 8 or 10 hours, etc. Re: wood - never had a OWB until I bought this house (last November) and am trying to build up my "seasoned" wood piles, however; splitting 30+ chord last year was out of the question.
I've gotten a ton of excellent advice from the folks here and my OWB is certainly running better than last season, but still not getting quality burn times. The previous owner was a "cobb-artist" and I am beginning to think that he chinced out when buying this unit back in 2008.
I was talking to a person today with a Classic OWB brand OWB and he was telling me that he gets snow accumulation on top of his unit. I definitely do not, and when it rains or snows the top of my OWB steams. The previous owner did not have caulking around the stack or water filler (which I fixed) - could the insulation (batt) around my water jacket be shot and this is part of the problem? Maybe consider spray foam to get some better burn times?
-
If previous owner was cheap he may have put in an inferior line set. That would kill your burn times as well. Check temp diff from boiler to house. You may be heating the ground.
-
He said he has logster in the ground. If you still have that much for coals in the box when you reload, why are you reloading so soon? Are your boiler temps dropping at the 8 hour mark? What type of wood are you burning? I burn maple in the shoulder seasons and beach and maple in the colder temps.
-
I think you are going to struggle with burn times until you can burn only seasoned wood. Sounds like you are near the upper end for what that boiler can handle as it is. Depending on the moisture content of what you are burning I would guess it is costing you at least 25% on your burn times maybe more. I would do whatever it takes to get 3 years ahead even if it means paying for a couple pulp loads.
-
That boiler was rated at heating 3000 sq ft. The raised it to 4000 after the design changes in 2009. Also you need to deduct 500 for DHW. The ratings are also for using well seasoned wood and very good insulation. Even then going over 75% of the rating it usually not a good idea. I am guessing the previous owner just used it to lower the gas/oil use and not completely replace it.
The snow melting off the roof can not be compared to a Central Boiler. They have the flue out the back and your stove has a non insulated flue through the roof. The heat that is melting the snow is coming off the chimney pipe above the insulation.
If you are running at 180, I would try dropping the temperature. Those older NC stoves seem to run more efficient down there. Try 160 and see what happens.
-
Thanks guys. Sounds like my assumptions are in the ballpark. I'll drop the temp to 160 and see what happens but sounds like this spring I'll be in the market for a new unit.
With 4-6" of coals the temp starts to drop. I'll tinker a little more. I assume w logstar in the ground and a properly sized unit I should be golden though.
-
So this is typical. I was travelling on business to NYC so I filled the boiler at 6:30 am before I left chock full with hard wood on top of 4" coal bed . Wife calls at 1pm and says the unit is basically out and the house is cold. :bash: Wife restarted the unit.
Home now and I set the temp back to 165 as recommended by RSI and we'll see what I get in the morning.
Question - will dealers install new units in the winter or am I better suited to wait until spring?
Thanks.
-
How much wood is chock full? Length, diameter, how many pieces?
-
I know you are not happy with your boiler, but, before making any big decisions, sit back and relax, have a cold Bud and think thru the whole problem.
I'm not trying to talk you into keeping or getting rid of your current boiler. Talk to a dealer, talk to Slimjim, talk to other owners. You can do it through this website. See if others can help you.
I want you to be happy heating with wood and hope you can fix your problems without spending a lot of money.
A week ago, I wished I had never seen my boiler. Couldn't keep a fire going. Read all I could on this site concerning my model, found others were having similiar problems and found my problems. Now all is good.
-
Thanks for the encouragement Bud Man, I appreciate it. Everyone on this site has been awesome and I learn something everyday by reading the posts here. After reading here, I'm fairly certain that the unit is undersized for our heating demand. I get that I'm not burning 18 month seasoned wood, but I have to believe I should be getting more than 6.5 hour burns.
The load this morning was a combination of oak, maple and elm in 18"lengths, ~8" in diameter, seasoned approximately 6 months. Firebox had 4" of coals and was completely filled and burned to outage within 6.5 hours.
-
I just thought of something, if you are located where you can get coal, I would try getting some and mixing it with the wood. That could be what the previous owner was doing to make it work. I never used coal but if you read up on it here, you will find a lot of posts about how to best load the stove with it. People claim it can make a huge difference on burn times.
Since you already have the pipe in, you should be able to get a new stove installed in the winter but it would depend on the dealer.
-
I'm doing a boiler swap out right now, it's not at all fun with wind blowing and darn cold in northern NH but it is doable.
-
What is house side heating system? Forced air or radiant? Any chance you have in slab radiant that wasn't installed correctly? That sure seems like a lot of wood to use in 6.5 hours. Not sure about where you are but it is not even cold here in Michigan this past week or so.
-
No in-floor heating, just baseboard radiant heat and DHW via a plate exchanger.
-
Any chance you could verify the lines are in fact what the previous owner insist?
-
How many pieces of 8 inch diameter, 18 inches long?
-
fredaddy - lines are not the issue anymore - i replaced the lines this summer with Logstor.
hondaracer - approximately 12 pieces.