Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers with NON EPA-Certified Models Only => Shaver Furnace => Topic started by: abide on February 15, 2014, 09:11:36 PM
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Hi all,
I posted on this forum early in the season looking for ways to improve the efficiency of my boiler. I found some methods including the damper assembly, additional insulation, Ranco thermostat and a few others. After running it for the last several months there is one universal truth that I had hoped to prove wrong..."You can't polish a turd!" Simply put...There are too many shortcomings on this OWB to overcome. To heat my 2500 square foot home in southern PA I am burning easily 1 cord every 10 days or so. My house is barely able to get past 68 F. I need to feed this monster every 8 hours! The door is so dang small that you can hardly put more than one good chunk in the box before it is rendered inaccessible. The fact that I needed to sink $500 into this machine just to get it running at an unacceptable level is ridiculous. Tonight I am heating with oil again. I simply can not tolerate the idea of wasting more good firewood just to have the vast majority of the heat go right up the chimney! Funny how they claim the 1/2" firebox as a selling point isn't it?? Monday morning I am buying a coal stove. I will be selling the Shaver for $1000 which should buy me enough rice coal to last me through next winter. Sorry for the tone of my post...I am simply tired of being cold and pissed off.
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Sorry to hear about all your troubles. You burn a cord in ten days that's crazy. I have a 2008 165 Shaver with what it came with no updates yet. I heat about 2000sq ft up to 74 degrees F plus DWH with a wheel barrow worth of wood a day when it's -25 F at night and -10F during the day. I'm planning on upgrading the fan and thermostat before next year.
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Sounds like your home needs more insulation. I'm heating a bit more then you are with no problem keeping up. So far this winter I have used about 7 cords since mid October.
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I am sure insulation in my house is some of the issue. Our home is a late 1800's brick farmhouse with 9' ceilings. It does have many upgrades however, including new double pane windows. My indoor boiler temp will only go as high as 135 with the outdoor pushing in 160-170. Of course with the factory design the heat does not get circulated in the water jacket since the supply and return are both stuck behind the firebox. I am really running out of ideas for what I could be doing wrong here and I am very hesitant to sink any more money into this hole. I believe the overall problem is that the design of this particular OWB is incredibly inefficient. The thick firebox impedes heat transfer and has so little area to transfer heat that most of the BTU's go right up the chimney. One thing I will be checking today is for scale buildup on the inside of the tank and firebox.
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As for the heat diff between the front and rear of the unit, my ranco prob is in a well in the rear. On the left front of the stove is the over flow tube. I inserted a long lab thermometer deep in and tilted so the bulb was in the water.The temps were the same.
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I have a PEX thermometer inline with the supply coming off the OWB. Initially when there is a call for heat the dial immediately goes to 170-180. Over the course of a minute or so the temp drops at least 10 degrees below what my Ranco says. I think this is a result of a "pocket" of cooler water being trapped behind the firebox. I will try to conduct your experiment today and see what I come up with. I am scheduling an energy audit tomorrow since it turns out that our local electric company will reimburse me if I implement certain energy saving measures. It should be interesting and hopefully help me prioritize improvements to made throughout the house.
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Abide,
I will be able to talk more later and help out. First few things I have is that the well you have is likely far to short. My buddy had a 3 inch on his Shaver with his ranco and the temp reading was WAY off. We made a 12 inch well and now the temp is right on. What type of pex do you have in the ground, size of your water to water hx, length of pex run, pump you are running, Temp drop from boiler to house and temp drop across heat exchanger? Start by answering those questions and then we can move on. Something is wrong with your delivery system if you can't raise indoor water temps to above 135. Should be able to get within 10 degrees of owb. We can fix these issues. Likely not the owb fault. 1 cord per 10 days is a little excessive. I go through 1 cord every 14 days. So you are not far off, what are you burning in it? That is probably your issue there.
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My dry well is probably 8"-12" deep and is situated a foot from the back and probably a foot in or so. My OWB is configured as follows (in order):
1. Shaver 165
2. Taco 0011
3. 40' 3/4" polybutyl (buried and homemade)
(I have no evidence of water infiltration or large heat loss...snows lays just fine over pipe)
4. 40' 1" PEX (basement)
5. 70 plate heat exchanger
6. Oil fired boiler with 13 gallon water jacket (120,000 BTU)
7. 2" pipe circling basement
8. one or more cast iron radiators in each room (9 total)
House is roughly 2200 sq. feet located in south central PA. 9 foot ceilings with brick exterior. Blown in attic insulation. R13 in walls (maybe). New replacement windows (lots of big windows).
Boiler at temp is 175...temp going into exchanger will be 5 less (this may be due to calibration errors or heat loss in pipe). Oil boiler only gets up to 135 and that is if it is running constantly. I do not know what the OWB return temp is. Outdoor pump is configured to only run when there is a call for heat. I have tried burning everything in this machine (oak mostly...sometimes locust....currently pine). I find the pine gets it up to temp faster than the others however I need to feed it every 4-5 hours and it does not make a good coal bed. The oak seemed to last the longest but still barely made it through the night. I have a suspicion that I may have scale buildup in the heat exchanger and/or water jacket. This will be investigated.
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We'll first off your 3/4 pipe is really not big enough. I would have to look up how many gpms you can move through it efficiently but I think it is around 5 gpm. You said your pump is wired to run only when there is a call for heat but a call for heat where? If your temp in the indoor boiler is only at 135 it is never heating up the indoor boiler up to where it needs to be. I don't know about radiators and the btu outputs at different temps but I know that baseboard puts out around 600 btu per foot at 180 degrees and only 300 at 140 I think. We need to find out what your temp after your hx is and what is the temp when it gets back to the boiler. Also 5 degree loss on that length of run is pretty high heat loss.
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abide, we would like to help out. We can work through your system and find where your problems are if you want to try.
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First of all, RUN THE PUMPS CONSTANTLY, this will allow the oil boiler to heat up, those cast iron rads hold a lot of water and when that returns to the oil boiler it will cool the boiler very fast and your wood boiler loop will suffer from it, do us all a favor and run the loop pumps constantly or you are begging for troubles.
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Thanks everyone for your help...I was also very concerned about the 3/4" pipe. Earlier in the season it was 3/4" the whole way to the hx. To increase the gpm (if ever so slightly) I replaced the basement half of the run with 1". This increased the indoor boiler temp by 5-10 F. Not knowing the remaining lifespan of this boiler it is probably from 2005, I would hate to spend the time and money to replace the underground line. I can easily change the pump over to 24/7 run time though. We are expecting some warm temps in the next few days so it will be hard to do an apples to apples comparison until it gets cold again. I do not know the return temp off the hx. I can hit it with the IR gun but that is hardly accurate. Aside from delaying the heat reaching the hx...what other downsides are there to running the pump constantly?
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We need to know what te temp drop across the heat exchanger is. Also you need to get your indoor boiler all the way up to operating temperature. If you want to run the pump on demand you need to have an aquastat on the boiler that runs it, not the thermostat for the house temp running it. Running 24/7 also circulates water around the water jacket of te owb to help bring the water temp up much easier. Your run to the house is short for piping. I think you could put logster or thermopex in for 500 bucks. You have a decent size pump but you just can't deliver the btus with that 3/4 pipe. Hopefully a dealer didn't suggest that siZe!
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honda,
I am having a hard time understanding how the OWB pump would heat the indoor boiler without the indoor circulator running? My indoor system is just one loop with one circulating pump that only runs when there is a call for heat. I am starting to wonder if my system is designed oddly? I do not know who designed my system. We bought our current house last summer as a foreclosure. To be honest I didn't really even expect the boiler to hold water at first.
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Okay...I was just looking at several drawings online and what I saw was a "wrap around pump" which would continuously circulate the indoor boiler water but not put it through the "loop". I am guessing this is why people encourage me to run the pump 24/7? My configuration lacks this pump. I did not see any drawings that recommend my particular configuration. Is this my problem???
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Yes It is
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I have the same set up with inside boiler. The temp in the house is staying where it needs to be. I don't have a wrap around pump.
Should I install one, even though my temps in the house are good. The only thing I notice is that when the pumps circulate the water from the baseboards, that the temp across the hx drops to about 25 diffs. It comes back up in about 30 sec to a minute. Then runs 10 degree drop across hx. It's the cooler water coming down from the loop.
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Okay...So the way I understand it my lack of a "wrap around pump" is what is causing my internal temps to be so low. If I install a wrap around pump and make sure the outdoor temp is 10 degrees or so more than the internal hi temp limit this should take care of the issue. The next issue is my underperforming underground lines.
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LOGSTOR!
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Lets get your indoor issues figured out and then we can move on.
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very little stoarage at the indoor boiler leads to OWB pump must at least match indoor boiler pump gpm. i doubt the taco 11 can manage that with the restriction of the 3/4 inch underground lines
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Very good point willie.
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First of all, RUN THE PUMPS CONSTANTLY, this will allow the oil boiler to heat up, those cast iron rads hold a lot of water and when that returns to the oil boiler it will cool the boiler very fast and your wood boiler loop will suffer from it, do us all a favor and run the loop pumps constantly or you are begging for troubles.
If the little indoor boiler can keep up with the CI Rads, why can't a much larger OWB keep up? Man I love those old Rads with the bread warmer box.....
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i agree, run the pumps constantly..you may only have low return temps when the nights are very cold..even though your indoor boiler is rated at 120,000 btu, you likely rarely get that demand. if you are sending in 7 gpm you should be able to deliver about 30 btu per square foot and still have decent return temps
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I was on the Shaver website and they illustrate connecting their system up to a pressurized indoor boiler the same way that mine is connected. Of course Central Boiler illustrates using a wrap around pump. Should I disregard Shaver's suggestions?...I think I already know the answer to that.
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Shaver shows an option but that is not the only option. One option doesn't work for every instance.
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I had my energy audit today and it was very eye opening. Basically they try to create a negative indoor pressure of 50 pascals. For my home they were only able to achieve 30 pascals before maxing the fan out. We walked around the inside with the thermal imager and noticed many areas that are pouring in cold air as well as a few wall cavities and one ceiling without insulation. I still don't think my OWB is behaving ideally, however, the house is much less insulated than I initially believed. After a trip to the hardware store I will spend tomorrow sealing some of the larger issues we discovered.
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Abide, I am glad that you did the blower door test and the TIC. Those are very valuable tools to find where your problems are. Hopefully you will be able to seal up all of the areas you found and insulate better. Hopefully you can get us some of the temps we asked for and we can help you on your way to getting things working right!
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I'm not sure what is going on with your wood burner, I can tell you I have a 290 Shaver and it heats my son's house and mine ... Two houses plus our domestic hot water , and has been doing so since 2008/. We have saved a lot of money...........Hope you get it figured out.....It's really not that bad of a stove.