Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: Jackman on April 08, 2012, 08:53:37 PM
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I understand that the OWB water does not mix with the indoor oil fired boiler, what I don;t understand is how does the heat exchanger work ..... and does anyone have pics of the heat exchanger?
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I use a flat plate heat exchanger to keep the water separated. I have also used shell and tube heat exchangers in the past and they seem to work well also.
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I understand that the OWB water does not mix with the indoor oil fired boiler, what I don;t understand is how does the heat exchanger work ..... and does anyone have pics of the heat exchanger?
Jackman - My Central Boiler E-classic 1400 is plumbed through the oil furnce. The water line from the OWB comes into the house, through the thermostatic valve and then it enters the oil furnace through the T&P valve. Simply remove the T&P valve, in its place put an iron pipe "T", the T&P valve connects to the "T",then connect the pex from the OWB to the remaining port on the "T". My home computer has pictures of what it looks like. I'll post them to show you how it was done. Roger
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Jackman - Here are the pics I promised to post that shows how my OWB is plumbed through my oil furnace.
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Jackman - Here are the pics I promised to post that shows how my OWB is plumbed through my oil furnace.
I guess I show explain what the pics show. The first one is of the OWB plumbed through the oil furnace. The black thing that's connected to the green pex pipe is the thermostatic valve. Central Boiler insist that it be in place or it'll void the warranty. The second pic shows the how the return is plumbed.
The reason for going through the oil furnace is if the OWB's fire is lost for some reason the oil furnace will take over. Plus, it acts like an early warning system for me. If the fire is lost and the oil furnace takes over I have plenty of time to get to the OWB before I lose any hot coals that may be remaining making the rekindling of the fire much easier. Roger
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It depends on your system if it is a good idea to use a heat exchanger or just plumb direct. If your indoor system is under warranty you would most likely void it completely by depressurizing it.
Also, depending on how it is setup it may cause it to not work quite right.
Plumbing it in direct has some advantages. It will save you about $500 and possibly have one less pump burning electricity.
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It depends on your system if it is a good idea to use a heat exchanger or just plumb direct. If your indoor system is under warranty you would most likely void it completely by depressurizing it.
Also, depending on how it is setup it may cause it to not work quite right.
Plumbing it in direct has some advantages. It will save you about $500 and possibly have one less pump burning electricity.
exactly, also it adds lots of fresh oxygenated water to the boiler, which speeds up the cast iron heat exchanger corrosion in the house boiler, so 8-15 years before they go. You can't use air vents on anything above the OWB water line also. This also voids most pump warranties as well. Its never a good idea to convert a pressurized vessel to an open loop system.
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My OWB was installed professionally by someone contracted by my dealer. I test the water for corrosion and ph level and everything is operating within the guidelines of the CB manual. My CB dealer is well aware of my setup and one would think he would have said something if it at all would void the warranty.
If there is anything I should be questioning my CB dealer with, please, let me know so I can do so. Roger
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When at all possible I would not depressurize a system. Like Hydronix said when you depressurize you will get oxygen into your boiler system. My standard rule of thumb when installing into any type of system is to leave the current system intact as much as possible. There is a reason they are designed to run the way they are, often you can decrease efficiency when you start making changes.
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My CB dealer buddy has installed both ways and has explained to me, there are advantages to both. First of all, you have an open system furnace sitting outside, so there is always oxygen. That is the purpose of the properly maintained corrossion inhibitor, to protect the furnace metal, pumps and all existing compontents in the loop, by driving oxygen out and balancing PH and Nitrite levels. When you use an exchanger you will usually lose 10-15 degrees of water temp in the heat transfer and spend anywhere from $300-$500+ for the exchanger. Yes it is unintrusive and the least distruptive to the existing system. Probably the best way to go if you have old piping or lots of zones and/or pumps in the return line.
By plumbing direct, you eliminate the water heat exchange loss, matching degree for degree in your boiler and save the cost of the exchanger and installation. Pumps need to be moved to the supply side of boiler and if you do have any automatic air bleeders in line, they will need to be locked down. Typically they require at least 10 lbs of pressure or they will allow air into the system and create air lock problems if not closed off. Your piping needs to be tight with no leaks or air locks again could be a problem.
Roger, if your system is running well and plumbed direct, I would not worry about it. You probably saved money and are getting maximum degree for degree heat transfer.
Do your water tests as recommended. I feel I lose less than 1/4 inch of water per year to evaporation, so I rarely need to add water or require additional inhibitor. Never had a corrosion problem in 11 years of owf use either. If you were to run straight water in an open system, yes you would have problems throughout.
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Boilerman, thanks for the reply. I'm glad to know that the installer wasn't pulling a fast one on me.
The first pic shows a ball valve that's closed a bit. When the installer did this, I question why and he said it is to keep the oil furnace system pressurized.
Have a great weekend everyone. The weather looks like motorcycle weather to me so I'll be gone most of the time. Roger
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Any time an "installer" voids another appliances warranty is wrong, I don't care of the heat exchange advantages. Its unethical. If there is a 10-15 degree loss of exchange then he did it wrong. Use the correct HX. All too often OWB design is compromised by the seller or installer for fear of loosing the job because of the increased expense to do the job right. We do many pasteurizers and they require large plate exchangers to maintain temps for health saftey. If thats what is needed to do the job right then this needs to be explained thoroughly to the customer. Instead his oil boiler with a 30 year warranty is void, so too are all the pumps unless they are bronze or stainless. Same goes for the cheap underground supply pipes, cheap it out to get the job. Its sux loosing a job but atleast you know your work is right and your workmanship is covered by your insurance policy and most important your customers interest and investment is covered as well. Insurance does not cover non code compliant work, same as manufacturer's warranties. If you read some boilers I&O manuals they state must be installed by licensed or qualified installer. It always cost more up front to do it the right way, but it saves you soooo much in the long run, not to mention peace of mind. Some of those OWB treatments are not for cast iron boilers, only the manufacturer can tell you this. Just like the boiler seal voids all indoor boiler warranties. I have never seen a well informed customer say , "yes I want to void my boilers warranty by cheaping out on some components." or " well if you just use this much less expensive underground pipe you can save half the money, but you will have to burn twice as much wood, and you might have a soggy puddle in your yard, and your OWB will have a hard time suppling anything over 160* to your house. But you will save lots of money on the pipe". There is nothing cheap about hydronic heating except for long term cost when done right. Anytime somebody does something like this, only gives the wood fuel industry a bad name. The industry needs to protect itself. By the way are there any zones located above the water level of the OWB, like a second floor?
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Hydronix makes some good points. My advice would be to do your homework before doing anything direct without a heat exchange. Just because a outdoor furnace dealer ( who is desperate to sell you a furnace) tells you it can be done without problems doesn't mean you should check with the manufacturer of the indoor boiler to see what the effects would be.
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Hydronix, whats wrong with feeding a 2nd floor with an owh direct plumbed open system?
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http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_10_us.pdf (http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_10_us.pdf)
You can read a good explanation of the effects in this link. Since Caleffi and a few other experts have come across so many simple problems in the OWB world they came out with some nice info and suggestions to help protect the industry. Since the majority of OWB are DIY installed, they should also arm themselves with good info to protect their investment. Anything above the water level can cause boiling, pipe banging, air entering the system from a vacuum or sub atmospheric pressures. Many times the owner/ repair man just reduces the temp because they can't figure out what is going on. There is a chart there with height and pressure changes in the system and vapor pressure & temps to low temp boiling. Plenty of system diagrams for proper design and electronic control wiring. They also have webinars on equipment & design how toos.
This is a perfect example of why the other guy was more expensive, but he should have done a good job explaining why it needs to be done. With the market so tight the last 5+ years, salesmanship and justifying your quote cost is more important than ever. Most OWB customers are going the extra mile to own one of these units and have done "some" research. But all too often they get the majority of their info from one salesman, and have no clue on the important details of safety and performance aspects of the system. How many posts have you read, where they are replacing components or burning way more wood than they should, as a direct result of installation or component issues. Spend it now or spend more later. Sometimes the best customer is a well informed one. Thus understanding why the good guy cost more.
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Any time an "installer" voids another appliances warranty is wrong, I don't care of the heat exchange advantages. Its unethical. If there is a 10-15 degree loss of exchange then he did it wrong. Use the correct HX. All too often OWB design is compromised by the seller or installer for fear of loosing the job because of the increased expense to do the job right. We do many pasteurizers and they require large plate exchangers to maintain temps for health saftey. If thats what is needed to do the job right then this needs to be explained thoroughly to the customer. Instead his oil boiler with a 30 year warranty is void, so too are all the pumps unless they are bronze or stainless. Same goes for the cheap underground supply pipes, cheap it out to get the job. Its sux loosing a job but atleast you know your work is right and your workmanship is covered by your insurance policy and most important your customers interest and investment is covered as well. Insurance does not cover non code compliant work, same as manufacturer's warranties. If you read some boilers I&O manuals they state must be installed by licensed or qualified installer. It always cost more up front to do it the right way, but it saves you soooo much in the long run, not to mention peace of mind. Some of those OWB treatments are not for cast iron boilers, only the manufacturer can tell you this. Just like the boiler seal voids all indoor boiler warranties. I have never seen a well informed customer say , "yes I want to void my boilers warranty by cheaping out on some components." or " well if you just use this much less expensive underground pipe you can save half the money, but you will have to burn twice as much wood, and you might have a soggy puddle in your yard, and your OWB will have a hard time suppling anything over 160* to your house. But you will save lots of money on the pipe". There is nothing cheap about hydronic heating except for long term cost when done right. Anytime somebody does something like this, only gives the wood fuel industry a bad name. The industry needs to protect itself. By the way are there any zones located above the water level of the OWB, like a second floor?
When someone tells me they are a licensed and qualified installer, I generally take their word that they know what they are doing like an auto mechanic.
Now, I want to protect my investment - indoor as well as outdoor - in one of the pics it shows a ball valve being partially closed. The installer said it is to aid in keeping the oil furnace pressurized. Is this incorrect info that the installer gave me? If it is, I'm going after him and report to my dealer of his installer's practices. If you feel it is better that I install a heat exchanger, I'll save my pennies during the down time and have one installed. I just don't know what size I'll need.
As for the underground piping, I went with what Central Boiler sells. I've been told and read that it's the best on the market regarding insulation and durability. It had better be the best at nearly $13.00/ft. 75 feet used.
No zone going to the second floor, yet. Perhaps in very distant future but not now.
Thanks for the link. I'll be doing some reading during my lunch break at work. Roger
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I still believe indoor boilers can be plumbed direct successfully and your installer did not take you for a ride. I'm certainly not saying there is anything wrong with using an exchanger, but am open to the following facts..... There are 1,000's of boilers plumbed direct from various OWF manufacturers. Most show both options in their owners manuals or websites. Roger and I have Central Boiler products. For instance, look at a CB owners manual, CB Brochure or CB Website....CB shows install illustrations for both using Plate Exchangers and Direct Hook ups for boilers. Do you think a company as large as CB other established OWF companies that have been around since the early 1980's would show these diagrams if they were wrong or their customers were having equipment failures? I would doubt it. Most of this negativism I believe is coming from closed pressurized system, old school plumbers (no offense) that don't understand what corrosion inhibitors can do to protect the metal throughout the system and have done so in open systems for years. I also know for a fact you can feed upper level floors with a direct plumbed system and the water will not run over out at the lower OWF as long as no air can enter the loop and the water auto feed valve has been turned off, please read the info I put in my previous thread above. A good example would be to put a straw in a glass of water, put your thumb over the top end, you can lift the straw up with the water in it until it breaks the surface. Only then will it drain out. Many of these "pressurized experts" also state you must use expensive brass pumps because cast iron pumps will fail in an open system. Again my 11 year old 009 Taco standard cast pump is still working fine (knock on wood)
If you still plan to use an exchanger, I would recommend a 5"x12"x50 plate exchanger if your existing indoor boiler is rated at 150,000BTU or less. Which it more than likely is. Again, I believe either install works and is safe with proper corroision inhibitor water treatment in either case and the dealer should probably go over both options and cost differences with the customer, allowing the customer to make the final decision.
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I still believe indoor boilers can be plumbed direct successfully and your installer did not take you for a ride. I'm certainly not saying there is anything wrong with using an exchanger, but am open to the following facts..... There are 1,000's of boilers plumbed direct from various OWF manufacturers. Most show both options in their owners manuals or websites. Roger and I have Central Boiler products. For instance, look at a CB owners manual, CB Brochure or CB Website....CB shows install illustrations for both using Plate Exchangers and Direct Hook ups for boilers. Do you think a company as large as CB other established OWF companies that have been around since the early 1980's would show these diagrams if they were wrong or their customers were having equipment failures? I would doubt it. Most of this negativism I believe is coming from closed pressurized system, old school plumbers (no offense) that don't understand what corrosion inhibitors can do to protect the metal throughout the system and have done so in open systems for years. I also know for a fact you can feed upper level floors with a direct plumbed system and the water will not run over out at the lower OWF as long as no air can enter the loop and the water auto feed valve has been turned off, please read the info I put in my previous thread above. A good example would be to put a straw in a glass of water, put your thumb over the top end, you can lift the straw up with the water in it until it breaks the surface. Only then will it drain out. Many of these "pressurized experts" also state you must use expensive brass pumps because cast iron pumps will fail in an open system. Again my 11 year old 009 Taco standard cast pump is still working fine (knock on wood)
If you still plan to use an exchanger, I would recommend a 5"x12"x50 plate exchanger if your existing indoor boiler is rated at 150,000BTU or less. Which it more than likely is. Again, I believe either install works and is safe with proper corroision inhibitor water treatment in either case and the dealer should probably go over both options and cost differences with the customer, allowing the customer to make the final decision.
I completely agree. It depends on how the indoor system is setup. If you have a brand new expensive indoor boiler I would use a heat exchanger for sure. If it is older and out of warranty probably not. I am not saying it will void the warranty but it will likely not be pleasant trying to get them to cover it.
If you have an indoor system that needs a high water temp to operate correct then connecting direct will work better. You will have a 10+ degree difference across the heat exchanger and that is just the way it is. You can probably get it down to a few degrees by going with a huge heat exchanger. (something like a 10x20 100 plate would likely give almost the same temp on both sides but is $2500 :o)
I hear all the time that you can't run in floor heat systems without it being pressurized but it works fine and I haven't seen any difference in how well it works.
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I still believe indoor boilers can be plumbed direct successfully and your installer did not take you for a ride. I'm certainly not saying there is anything wrong with using an exchanger, but am open to the following facts..... There are 1,000's of boilers plumbed direct from various OWF manufacturers. Most show both options in their owners manuals or websites. Roger and I have Central Boiler products. For instance, look at a CB owners manual, CB Brochure or CB Website....CB shows install illustrations for both using Plate Exchangers and Direct Hook ups for boilers. Do you think a company as large as CB other established OWF companies that have been around since the early 1980's would show these diagrams if they were wrong or their customers were having equipment failures? I would doubt it. Most of this negativism I believe is coming from closed pressurized system, old school plumbers (no offense) that don't understand what corrosion inhibitors can do to protect the metal throughout the system and have done so in open systems for years. I also know for a fact you can feed upper level floors with a direct plumbed system and the water will not run over out at the lower OWF as long as no air can enter the loop and the water auto feed valve has been turned off, please read the info I put in my previous thread above. A good example would be to put a straw in a glass of water, put your thumb over the top end, you can lift the straw up with the water in it until it breaks the surface. Only then will it drain out. Many of these "pressurized experts" also state you must use expensive brass pumps because cast iron pumps will fail in an open system. Again my 11 year old 009 Taco standard cast pump is still working fine (knock on wood)
If you still plan to use an exchanger, I would recommend a 5"x12"x50 plate exchanger if your existing indoor boiler is rated at 150,000BTU or less. Which it more than likely is. Again, I believe either install works and is safe with proper corroision inhibitor water treatment in either case and the dealer should probably go over both options and cost differences with the customer, allowing the customer to make the final decision.
I completely agree. It depends on how the indoor system is setup. If you have a brand new expensive indoor boiler I would use a heat exchanger for sure. If it is older and out of warranty probably not. I am not saying it will void the warranty but it will likely not be pleasant trying to get them to cover it.
If you have an indoor system that needs a high water temp to operate correct then connecting direct will work better. You will have a 10+ degree difference across the heat exchanger and that is just the way it is. You can probably get it down to a few degrees by going with a huge heat exchanger. (something like a 10x20 100 plate would likely give almost the same temp on both sides but is $2500 :o)
I hear all the time that you can't run in floor heat systems without it being pressurized but it works fine and I haven't seen any difference in how well it works.
RSI: My indoor oil furnace was installed in 1993 making it darned near 20 years old. I do not know the length of the warranty so I do not know if it's covered still. Roger
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Just because it says so in the CB manual doesn't make it right or wrong. That is the problem, people see pictures or read it on the net and think its law. It also says to follow all local and state codes, and to check with the other appliances manufacturer suggestions. There is no cast iron boiler on the market that doesn't void warranty if its ran unpressurized and it doesn't matter what CB approved treatment additive is put in. It has to be approved by both manufacturers. It is also boiler code that the vessel maintains a minimum pressure. Anytime a safety device is bypassed or eliminated it violates code. Also if you read the grundfos,B&G,wilo or taco warranty it does not cover cast pumps in open systems. Doesn't mean that they never have covered one, but thats exactly what their policy is. Thus why you see on some OWB part supply sites bronze and Stainless steel options.
No one said running a 2nd floor can't be done, but if you read the link you would see the problems that "could occur". I don't know about you but if any of these things went in on an install without the customer fully understanding the risks and options, then I can confidently say it was an unqualified installer. These are the very things that give them a bad rap. Anyone here check with the insurance policy, if a problem ever did occur and a forensic engineer has to be called out to find the cause, they can and will void or limit the claim loss of the HO policy if these conditions exist. Or they will go after the installer, and you hope he is licensed and insured. If he's not licensed he can't be held liable for his install, he would be treated as a handyman working under HO direction. So if the boiler does rot out and flood an area , hopefully its limited to less than 10,000 in damage. Each policy is different, but I can assure ,if you have State Farm this is their policy. We cleaned one up last year for SFarm and their remediation contractor was ruthless with expenses on the previous installers dime.
As far as that valve being partially closed, that has no effect on the boiler being pressurized. It is either an open loop or its not. All the installer has to say is you were aware, then its a he said/she said deal in court. If it wasn't inspected by the city then your on the hook. And no inspector would approve that. There are 1000's of jobs done without pulling permits and inspections, I guess that makes them all in good working order and done right too.
If you draw a line between plumbers,pressurized experts( licensed boiler installers), and yourself , its not good for anyone. You will always be ahead when you help each other out. Similar to you posting here, to help someone out. If a city official or inspector just dropped by during your install. Will it help you to argue & complain with him or to listen and discuss things so you both understand each other respectfully. Yes I know there are some that there is no talking to, but you'll never know if you don't try.