If I add more volume of water to my system (125 gallons) will this give me an extra hour or so of btu's if it is not acting as a seperate storage zone ?
thanks,
Joe
thanks,
Joe
Can someone please answer my dumb question?
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That would be trying to answer what is "X+Y" but you only gave X. What kind of system are you running? Where are you adding this extra 125 gallons?
I have a Econoburn 150 closed loop pressurized system. I plan to add the 125 gallons right at the boiler within the circulation loop before it distributes to the house zones.
125 gallons is about 1000BTU/F. You would need to set this up as a storage loop (see pressurized storage). IF you had a 50F delta (130 operating, 180 storage) you would have 50K BTU stored. For a storage system 125 gallons seems a bit small and you will have to handle the controls for storage versus use. Does it make sense for you - the orginal post says it all - what do you need and what are you trying to achieve.
It can make a lot of sense. I don't have storage but want some. I can't raise my temps a whole lot at one time because I only have a total of 35 gal of water. I can raise my temps 1-2 degrees when it's cold out and by then the water is 130*. Then I need to shut off the furnace, wait a half hour or so and do it again. If I had another 125 gal. I would have 3 times the water to help me get to temps. After I'm up to temps I'm ok.
When I started my 150 without any storage, I found I could overheat easily. Inexperience on fire size was a big reason, but no storage at all was also part of the problem.
I had a spare 60 gallon water heater, so I put that in my loop, and found it helped quite a bit. That extra buffer of volume, as small as it is, slows down my temperature swings, and I'm learning about fire size vs. expected heat load.
I'm more convinced that when I can add about 1000 gallons of pressurized storage to my system I'll see what I've read about dozens of times on this site - I'll have hot, fast, efficient fires, that heat the storage about 10-15 degrees per load.
I'm hoping to find four 250 gallon tanks that I can put in series, mounted vertically, with an insulated framed box around them. (They'll be in my wood room in the basement, next to the boiler, and will have firewood stacked against their box frame.) I keep an eye out on kijiji, at my local propane dealer, and at my junk dealer for used tanks.
I think your storage tank will be a help.
I had a spare 60 gallon water heater, so I put that in my loop, and found it helped quite a bit. That extra buffer of volume, as small as it is, slows down my temperature swings, and I'm learning about fire size vs. expected heat load.
I'm more convinced that when I can add about 1000 gallons of pressurized storage to my system I'll see what I've read about dozens of times on this site - I'll have hot, fast, efficient fires, that heat the storage about 10-15 degrees per load.
I'm hoping to find four 250 gallon tanks that I can put in series, mounted vertically, with an insulated framed box around them. (They'll be in my wood room in the basement, next to the boiler, and will have firewood stacked against their box frame.) I keep an eye out on kijiji, at my local propane dealer, and at my junk dealer for used tanks.
I think your storage tank will be a help.
musclecar joe said:
First of all... not a dumb question... not at all.
Second of all, additional water volume if piped properly and insulated well can increase system efficiency even if the volume is relatively small. No... 125 gallons isn't a great deal of heat storage, and its effects will depend greatly on what the other parameters of your system are. I believe you were asking in an earlier thread about piping up a buffer... to which i mentioned piping it like a hydraulic separator... this would be the simplest way to integrate in my opinion.
the problem you will face is that the econoburn you have has no way of knowing when the fire is out... so when the fire is gone, the fan runs until every last coal is gone... and continually reverse heat exchanges the heat from the boiler jacket into the exhaust... and all the while your circulator pump is still running. I've had some succes with timers in the field to keep this from happening... and it works well enough for a cheap fix, but it's not an exact science. With some experience you could make it work though.
The other issue is that the control on the econoburn does not work well to temper the return water when you're talking about large volumes of storage or buffer. The thermocouple that measures water jacket temperature is about as far away from the return line as you can get... at the very top of the boiler vessel. You could be running 50 degree water into the return on a 180 degree boiler for several minutes before the thermocouple registers a change. It would pay you to add some thermal protection to the boiler in the form of a thermostatic mixing valve or loading unit. This was one of the things we had to add to the manual when I worked for those guys.
cheers
cheers
maplewood said:
Interesting that you have had trouble with overheating... that really shouldn't be a problem with that boiler. The only time I have ever seen one overheat in the field is when the customer neglected to install a barometric damper or if they had the circs wired improperly. The draft control on that boiler doesn't have a good positive or weighted stop on the closed position... just a hanging flapper, so without a barometric damper, draft in the chimney will pull fresh air into the boiler causing inneficient smoldering and overheating. It's a nice idea to install without a damper especially in the event you have a fit of backpuffing where smoke and ash come pouring out of the damper (and every other nook and cranny) but that unit (at least the last version that I installed) has to have a damper for sure. Letting cool air into the chimney at the damper has the effect of building up alot more creosote than without a damper too... not so much on storage installations, but standard installs without storage or buffer. Not a big fan of barometric dampers on any wood equipment unless absolutely necessary... probably more at ease with it on a unit that is hooked to storage though.
cheers.
I was hoping someone else would step up for you musclecar and discuss the physics. What you've described is not storing anything. I'll call it thermal inertia (I just invented that to illustrate what's happening). If you put a heavier flywheel on your truck it will smooth accelerations and momentarily help you going up a hill. But when you want to accelerate that same mass fights you when you try to spin it up. You're not placing excess energy anywhere. Some hybrid cars (maybe all hybrids) instead of throwing energy away via heat thru brakes use electric motors that become generators to slow the car and take that kinetic energy of the car and "move" it to a battery. That's taking energy that would otherwise be thrown away and put somewhere. In our case here.... a thermal battery (big tank) sitting somewhere out of the main loop waiting to collect energy the house can't use at that moment allowing the boiler to burn at peak efficiency. What you're asking is similar to putting 500 lbs in your trunk... will help getting up a hill after coasting, but nothing is free and you're car will work harder towards the top of the hill, i.e. no energy saving... in fact we all know efficiency will go down. Same for you because you've just added a tank with surface area that will "leak" heat which is energy. I can see where adding this buffer may smooth burns, like the flywheel analogy, but bottomline you ain't sticking excess energy anywhere. Sorry. Creating the separate circulation loop to create a true storage device of 125 gallons probably is of little value (too small a battery).... BUT you could. I've read of at least 500 gals on the small systems here. I'm an odd ball here.... still trying to decide if I want storage.
Now my main reason for responding.... what kind of car?
Now my main reason for responding.... what kind of car?
Tennman said:
this flywheel analogy is one of the better ones that i have heard. The only difference is that a "flywheel" on a wood boiler in the form of a buffer will definitely increase efficiency through out the burn... so no, you aren't sticking any excess energy anywhere if used as a buffer unless you consider the increase btu's generated because of an increase in combustion efficiency.
proper insulation is a big deal... a big big deal... and I can't understate the value of having buffers and storage tanks installed inside the living space so that btus lost from the tanks are just added to the heat load of the building.
125 gallons isnt much storage... but if all you need is an extra hour... piping up 125 gallons as storage might make sense... actually, you can use it as both buffer or storage providing you have two different control scenarios available. IF you use that 125 gallons as buffer until the fire is out, and then use it as storage... you can gain some cycle time on a load of wood for sure. Would 250 or 500 gallons be better... probably.
You have to admit that one size just doesnt fit all with these systems. While the conventional wisdom on the forums seems to be that 500 gallons is the bare minimum to be useful... I just have to disagree... just depends on what you want out of the system and what you're budget allows.
Thermal storage is probably the best thing that ever happened to a wood heating system... in my opinion.
cheers
Well... wouldn't ya know it. An expert replies while I was writing. So Piker please explain when adding a buffer is beneficial since that was his original question and I chimed in since the discussion really didn't seem to address his original question of adding water to the main loop. Any disagreement feel free to correct. If there is any benefit I'm not aware of I'd like to know about it because that's a whole lot easier than adding another circulation loop. Glad you joined in.
Tennman said:
Expert is a very strong term... one which should be used cautiously at best, lest it become completely gratuitous. One of the great things about this forum is that there is plenty of information for all of us to learn and to glean from. The day you think you know it all, or the day you think someone else knows it all, is the day you deny yourself the opportunity to expand your mind.
That out of the way... i don't think there's really any major disagreement here. The flywheel analogy is just fantastic.
Where the excess water is at isn't really an issue. Whether it's in the main loop or piped up like a hydro-separator, it can be used as both buffer and storage. Buffer while there is still potential for combustion in the firebox... and storage once the fire has gone out and everything has shut down save for a circulator sending stored heat to the zone(s) from the tank. Basically, it's just an issue of control logic.
In case you haven't noticed... I am a big fan of hydro separation. It's just an elegant way to achieve simplicity in what otherwise can seem to be a complex situation. In this particular scenario, I'd say do away with the control logic of the Econoburn, install a tank as a hydro separator between the boiler and the heating zones... use a loading unit between the boiler and the tank... and a single circulator to feed the main loop to the heating zones. You could actually use the system circulator control on the econoburn to turn on the loading unit once the boiler reaches 150. (You don't really need circulation on cold startup of the boiler... convection inside the vessel will take care of that.) As long as the boiler is above 150 the tank is essentially a buffer... once the boiler drops below 150, the tank automatically becomes storage when the loading unit stops. It's a nice setup actually. Only problem is getting the econoburn to shut the draft fan off once its out of fire since that isn't incorporated into the control.
cheers
I do not have this gasser nor have I ever seen one, but here is my idea anyway for shutting down the fan. Mount a snap disc switch either on the boiler or on the water line wire it in series. in the fan circuit. The fan would only work above a temperature you decide. Parallel to this you wire a hand crank timer, This allows you to override the temp switch for starting fire or any other reason. You can also use this to shut off circ under a pre determined temp. Iwould clamp it to the output pipe and insulate over it. I have used them for circs in the past. You never answered. What kind of car?
The only kind of questions I can answer are dumb ones - some times - and I can't answer this one one so it must not be dumb.
I run a RMND type boiler, with about 15 gal of water (including 75' line to house HX) and the only time I overheat is when the electric goes out.
I still remember my first burning year . . . I thought storage or a buffer or some fancy control or who knows what would 'fix' my problems.
IMHO, you need to figure out why you are overheating first.
Jimbo
I run a RMND type boiler, with about 15 gal of water (including 75' line to house HX) and the only time I overheat is when the electric goes out.
I still remember my first burning year . . . I thought storage or a buffer or some fancy control or who knows what would 'fix' my problems.
IMHO, you need to figure out why you are overheating first.
Jimbo
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