znake
New Member
Posts: 1
|
Post by znake on Apr 17, 2019 14:40:06 GMT -8
Hello guys, thanks for all this info shared with us. Can someone please help me with info about the bell dimensions of a BBRH? I intend to build a 150 or 200mm BBR with a copper serpentine around the riser to heat up a buffer of 500 liters. So, I could use some help, a link to some topics or any other information. Oh, i almost forgot i need help with the floor secondary air dimensions too. Thank you very much!
|
|
|
Post by peterberg on Apr 17, 2019 23:38:35 GMT -8
|
|
|
Post by coastalrocketeer on Apr 22, 2019 9:56:53 GMT -8
The best place to put your heat exchange coil would be in the bell, I would think... the riser needs to stay hot for clean combustion... and if low mass and well well insulated, a coil around the outside of it would not collect much of the heat from the gas stream passing inside of the riser, and really shouldn’t, if you want clean burning.
A bare coil also does not perform particularly well as an air/flue gas to water heat exchanger, and if one does, with the extreme heat of combustion it is exposed to, one runs into the “boom-squish” hazards of making water exceed 212F/100C in a closed system.
I am doing a directly heated open tank of “buffer water” in the top half of my bell, with water to water heat exchange coils, one of which will be a pressurized thermo-syphon loop to my domestic hot water heater.
Are you planning to have the coil set up to thermo-syphon to the storage tank? Larger diameter pipe (1”) would be advised in this case.
If actively pumped, provisions ought to be made to be able to deal with that pump failing, and cool water entry to the coil stopping, mid burn.
|
|
|
Post by gadget on Apr 22, 2019 12:25:31 GMT -8
I am running 2 coils. One inside the barrel directly above the riser. The other is in a bell. The one in the bell does not add that much heat. Together, they both heat a 55 gallon barrel from 55F to 100F in about 3-4 hours. I have never gone much over 100F. The 55 gallon barrel can transfer the heat to 6 other 55 gallon barrels. I have never gotten them over 85F and that took many hours to get that high.
I have accidentally ran both dry and boiled both coils in separate incidents. My system is "Open" on both ends of the coil. I would also worry about the damage to a dry coil that is mounted above the riser from over heating the copper.
I don't think you will get fast heating action with a coil wrapped around the riser if that is what you are looking for. It will warm the water but not very quickly.
|
|
|
Post by coastalrocketeer on Apr 23, 2019 10:00:16 GMT -8
I am running 2 coils. One inside the barrel directly above the riser. The other is in a bell. The one in the bell does not add that much heat. Together, they both heat a 55 gallon barrel from 55F to 100F in about 3-4 hours. I have never gone much over 100F. The 55 gallon barrel can transfer the heat to 6 other 55 gallon barrels. I have never gotten them over 85F and that took many hours to get that high. I have accidentally ran both dry and boiled both coils in separate incidents. My system is "Open" on both ends of the coil. I would also worry about the damage to a dry coil that is mounted above the riser from over heating the copper. I don't think you will get fast heating action with a coil wrapped around the riser if that is what you are looking for. It will warm the water but not very quickly. Gadget... just to confirm, your system is using 2x3” gutter downspout as exhaust, correct? If that is the correct size, then the fact that you do not boil water in your coils at full fire is likely in large part due to very limited heat output of your core... a 6 or 8” system will run a MUCH higher heat output, and thus increase significantly, the risk of overheating the water inside coil heat exchangers in a hazardous way. Not saying this to criticize your system, or your testimony of your experience with it operating safely, just to point out that heat exchanger sizing and location as well as the amount of heat input to the exchanger are all interrelated, and the hazards of finding out one has erred in design can be catastrophic.
|
|
|
Post by coastalrocketeer on Apr 23, 2019 10:08:59 GMT -8
These hazards of course, being significantly lower with an open system, like yours. :-)
|
|
|
Post by gadget on Apr 23, 2019 13:54:38 GMT -8
I am running 2 coils. One inside the barrel directly above the riser. The other is in a bell. The one in the bell does not add that much heat. Together, they both heat a 55 gallon barrel from 55F to 100F in about 3-4 hours. I have never gone much over 100F. The 55 gallon barrel can transfer the heat to 6 other 55 gallon barrels. I have never gotten them over 85F and that took many hours to get that high. I have accidentally ran both dry and boiled both coils in separate incidents. My system is "Open" on both ends of the coil. I would also worry about the damage to a dry coil that is mounted above the riser from over heating the copper. I don't think you will get fast heating action with a coil wrapped around the riser if that is what you are looking for. It will warm the water but not very quickly. Gadget... just to confirm, your system is using 2x3” gutter downspout as exhaust, correct? If that is the correct size, then the fact that you do not boil water in your coils at full fire is likely in large part due to very limited heat output of your core... a 6 or 8” system will run a MUCH higher heat output, and thus increase significantly, the risk of overheating the water inside coil heat exchangers in a hazardous way. Not saying this to criticize your system, or your testimony of your experience with it operating safely, just to point out that heat exchanger sizing and location as well as the amount of heat input to the exchanger are all interrelated, and the hazards of finding out one has erred in design can be catastrophic. Just to clarify, I would not consider my setup "SAFE". Its just a test heater. Yep, that is my system. It is forced induction so size = output measurements are different. It has been through many different setups but I was running just over 1,000F on top of the barrel when running good fuel and that is with the coil moving heat out and zero insulation anywhere in the system. The other day I had it running on some good dry wood and got the firebrick glowing to an orange color. I try to avoid pine cause it just puts out to much heat and gets to uncomfortable around the barrel. I think if anyone is boiling during a good burn then they need more water flow. The time I did accidentally boil the hot side coil it was just after I had started it from about 40F. It was only a couple of minute into startup before it happened. I don't want anyone to think its no big deal heating water, I could of had some serious problems. Build in your safety nets and have multiple safety features. I'm building a flow sensor to shut off my blower if water flow is lost, as one example. Its just one safety piece of many I will use. Be smart, not dead or burned. And don't do what I do.
|
|