Is this safe?

Joebif

We want to add or supplement or even remove the use of the propane

heater in this set up. It has propane water heater to service the

radiant heat requirements. The second water tank is used for tempering

only and is being used via gravity so there will never be a time without

water. The heat exchanger in the wood stove is stainless steel. There

are 3 pressure relief valves in the system. The ball valve in next to

the propane heater could allays be left closed and would act as a

storage tank in the summer.  This system is only used for radiant heat

and no domestic water.

LarryC

Are there pictures or drawings posted somewhere?

Joebif,



Are there pictures or drawings posted somewhere?



I am not seeing anything.

Joebif

Image

It did not like the tif format so I changed it to jpg

Joebif

added a mixing valve

I added a mixing valve so the water coming from the solid fuel source will not overheat the radiant supply zones. I may also add a normally open zone valve to a fan coil with a aqua stat so if the solid fuel source gets too hot it will open the zone valve and be able to dump heat in it.  Also if the power fails the zone valve will open and I will not have any high heat problems.



So I guess because no one has said anything that this will work.

kcopp

hold on...

I would not do it. Anytime you stick a "coil" as a hx into a wood stove like that I have concerns. Long of the short of  it you have the makings of a water bomb a PRV is not enough. This is one of the reasons wood boilers are not pressurized. Nice idea.... but risky.

Joebif

Adding the dump zone

What about the added dump zone where any excess heat goes to the fan coil like I said in the last post? If on a normally open valve it will open with no power and when the aquastat gets to 190.



If I start with small fires and test it slowly I should be able to see how fast the temps get to hot correct?



The tempered tank is on a gravity feed to the stove and should never run out of water. The heat exchanger is stainless steel and will not melt. People use these heat exchangers all the time for this.



If this will not work then what will make this safer?  How would you change this to be not under pressure.  It has only 15 PSI set for the system. Put your 2 cents worth into it and let us know.

kcopp

I get it...

Still when you combine heat and pressure you get a tremendous amount of energy... ever see the Watts regulator films of water heater going off like a rocket? Solid fuel is a huge amount of energy hard to regulate too. It not like gas or oil where you can turn off the flame. Wood heat done properly needs a dump zone of 500 gallons of water (or so) a fan coil I don't think will dump off enough heat. Lets see what others think.... ME and Hot Rod have direct experience w/ this set up. kpc

Joebif

500 gallons

That is a lot of gallons. What do you mean and how does this work? Hope the others chime in.

kcopp

Here is a link....

hope this helps a bit.   http://www.woodboilers.com/heat-storage-systems.aspx

Joebif

No storage tank is needed

From the link above in the first paragraph.

"we recommend combining a wood boiler with a water storage tank of

500-1000 gallons. By using this type of thermal storage your wood boiler

will always burn hot and fast – even if your home is not calling for

heat. Instead of smoldering in idle mode when your home is up to

temperature, your wood boiler will continue to burn at maximum

efficiency. The excess heat generated will simply be stored in the water

tank for use later. A certain amount of this idling is acceptable and

if you are only intending to burn wood during the coldest part of the

year, no storage tank is necessary"



I plan on only using this in the coldest part of the year and it is in the greenhouse where the heat will be used all night long and on cloudy days.



I will have 50 gallons in the storage tank I have set up now along with the 50 gallons in the hot water heater.



By the way if I decided to use another storage tank does anyone know of a 200 or 300 gallon tank that can be used that is reasonably priced? Or could I set up 6 55 gallon drums and make them work?

NCPABill

Storage Tank

I'm in the middle of my own install of a wood boiler.  My storage / buffer tank is a 500 gallon propane tank.  I paid $150 for mine, used, but too old for propane.  Designed to hold 200+ pounds.



I have another if your near upstate PA.



Good luck,



Bill

Joebif

Not in your area

I wish I was though.  How are you using the tank? Is it outside? how will you insulate it?

Mark Eatherton

I agree with KCopp...

Don't do it. The quote you reference is based on the fact that ALL wood stove manufacturers have an extraction pump on them. Yours does not, and under normal good burn conditions (intense, hot flames) it WILL kick steam and cause you potential problems.



It is your home, but if you do this, and there is an "issue" that requires your insurance company to become involved, you may very well find your self standing alone. They will not cover your loss.



If it were me, I'd put a pump on it, and I'd put a UPS battery powered device to keep the pump running for as long as it takes to snuff the flames.



Although it appears you have a good handle on the application of pressure relief valves, it doesn't appear as if you have a lot of hydraulic/hydronic experience. Take the advice of the expertise on this board, or not. It is your decision, and you will have to live with it.



Emergency heat rejection loops kick steam almost every time they are deployed and put to use. It is NOT a pretty site, nor anything one wants to be around when it happens during a full out burn process.



Proceed with extreme caution. You are playing with dynamite.





ME

Joebif

Kicking steam

The quote came from something KCoop gave me in the link above.



The manufacturer of the heat exchanger recommends this type of setup with gravity feeding the fuel source. So if they are wrong and have sold thousands of these heat exchangers would they not change their manual to say to add a pump with battery backup? Would they be still selling these if they were blowing up and having all kinds of problems?



This is in a greenhouse so the insurance is not an issue. It might be down the road if I insure it but not right now.



So by putting in a pump and battery back up you feel then that this could work. You also say that I do not have a lot of experience on  hydraulic/hydronic systems.  So what am I missing on the setup? What else can be used?  I asked about the normally open dump zone of a fan coil and it was mentioned that I could use a 500 gallon storage tank. How would this help? How would this be hooked up and used?  I am trying to get the help of this board.



How can I make this safe?  There has to be a way. Not just say do not do this or that but give advise on what you would do to make it as safe as possible.

Joebif

Kicking Steam

The quote came from something KCoop gave me in the link above.



The manufacturer of the heat exchanger recommends this type of setup with gravity feeding the fuel source. So if they are wrong and have sold thousands of these heat exchangers would they not change their manual to say to add a pump with battery backup? Would they be still selling these if they were blowing up and having all kinds of problems?



This is in a greenhouse so the insurance is not an issue. It might be down the road if I insure it but not right now.



So by putting in a pump and battery back up you feel then that this could work. You also say that I do not have a lot of experience on hydraulic/hydronic systems. So what am I missing on the setup? What else can be used? I asked about the normally open dump zone of a fan coil and it was mentioned that I could use a 500 gallon storage tank. How would this help? How would this be hooked up and used? I am trying to get the help of this board.



How can I make this safe? There has to be a way. Not just say do not do this or that but give advise on what you would do to make it as safe as possible.

Mark Eatherton

I can tell you this...

You MUST have a pump to avoid the production of steam, and even that is no guarantee that you will not produce steam. At a minimum, in addition to the use of a UPS and some means of being able to quickly shut down the fire, I would recommend a relief valve at the coil outlet, and NO isolation valves between the tank and the heat source,



The coil manufacturer, who is that? Colmac per chance?



Let me tell you what I've seen a Colmac coil do in a situation where the pump failed under full fire conditions. THe steam that was generated was so forceful that it caused a soft soldered joint to fail on the line serving the wood stove/coil, and the exiting steam drove the 3/4" type K soft copper supply line into the floor joist to the point that it could not be removed. It, to the best of my knowledge, is still a permanent part of the building.



You might not be aware of this, but when a droplet of water is brought up to steam under pressure, when the pressure goes to atmospheric, the droplet of water increases in volume to 1700 times its size. In other words, it goes from droplet to basket ball in the blink of an eye. It is EXTREMELY powerful, and if improperly controlled/relieved will result in catastrophic destruction...



I am sure that the coil manufacturer (if they have a drop of common sense) have LOTS of caveats for the use/misuse of their product and limit their liability to the point that they have none..



The ONLY way I would consider this a "safe" system would be for the heat source hydronics to be a completely open system, not subject to any kind of pressure build up potential. That will require two coils with a pump. One coil in the storage tank, and one in the stove, with a full open vent in between the two coils. Absolutely NO way to generate ANY pressure. This is why most wood stove/boiler manufacturers are an open system. The cost of getting an ASME certification for building pressure vessels is quite intense and very expensive. To say nothing of the insurance premiums connected to the business.



My $0.02 worth. Keep the change.



ME

Joebif

2 manufacturers & confused

http://www.hilkoil.com/



http://thermacoil.com/plumbing.htm



They have no disclaimers on their sites and have sold thousands of these.  There are no sites talking about there bad design or flaws and how they have exploded. If they had problems wouldn't you think someone would be saying this.



I understand what you are saying in the post above. I just don't understand why these 2 companies can then sell these exchangers without any warnings or disclaimers.

Mark Eatherton

It's a free country Joe...

And you can put ANYTHING you want up on the internet, true or not. And you can pretty much DO anything you want to do, until someone gets hurt or worse. Neither of the manufacturers you mentioned have any sort of certifications required by industry standards, like ASME, ANSI and other critical code requirements. One of them says they exceed certain standards, but they do not carry the seal of approval.



You came here seeking advice, and it was given to you. It is your option to take the advice given, or not. Please don't expect anyone with half a mind to endorse something that could be deadly or dangerous. I deal in situations on a daily basis whereby I could cause the death of building occupants with water, electricity, steam, carbon monoxide and other explosive fuels. I have a healthy respect for these things, and know when to say no, and find myself in that position right now. I've given you my best advice (open system).



I also do a lot of forensics work for insurance companies, hence the reasons for my insurance remarks. If you Google "Wood Stove Hot Water Coils" you will find comments both pro and con. Did I mention that I had a wood burning stove at one time that had a copper coil on the outside of the stove that had exploded on me once?



I consider myself extremely lucky to still be on this side of the lawn. Learn from my (our) mistakes, and avoid making the same mistakes we have here.



I wouldn't expect anyone here to endorse your design for fear that it could come back to bite them legally, if something bad were to happen. Even the internet has long arms of the law attached...



Best of luck in your venture. Proceed with extreme caution.



ME



PS, Their warnings are probably a part of the packaging, and by opening the package, you agree to their terms. No insurance company in their right mind would allow them to do so without a lot of caveats.



ME

Joebif

open System

Are there any open system designs then that a DIY can do? Any links that can be recommended that will be safe.



If I were to use a coil in the wood stove what kind of tank can be used and coil to make this an open system and then plumb it to the closed system?

Roland_18

Is this dangerous?

Hi Joebif,

I'll say at the outset that I have no credentials when it comes to things heating related. However, there are others here, who are philanthropists in the true sense of the word. These fine people have gently tried to educate you on the project you propose. I know none of them personally other than reading their posts over the years. Please take a moment and re-read their advice to you. They are trying to save your skin.



As was said earlier, you have the option to experiment to your hearts content. But is this the right way to go? You may eventually find someone who will agree with you though I don't think it will be on this forum.



 I have been smitten many times in my life by what I thought was a perfectly reasonable plan, only to be schooled by reality. If I have learned nothing else, it is to really listen and absorb the wisdom of those who do know the possible downsides of my plan.



Enough of my prattle.

Joebif

That's great

Everybody can say no don't do this or that but then when you ask what to do or how to make it safe no-one helps.  I am not saying that I will do what these manufactures say is okay to do on there websites or in there manuals. All I want to do is do it right and safe that is why I asked and showed the manufacturers drawings that would relate to my setup.



I do not understand then why no-one will say how to do the correct, safe way to do it.



So what you all are saying is no I will not help you do it safe and correct but just do not do it at all.

STEVEusaPA

Joe.......?

Not to pile on, but you've received the best advice you could ask for....and free!  No one says its safe, because no one feels it's safe.  You may not know the people here, but some of the one's who responded are truely the best in the industry with so much experience, and truely care.  Feel free to try your experiment, but sadly no one is going to endorse you...Good Luck

Joebif

Why do I have to keep on hearing this!!

I said that I am not going to do this the original way.  Why do you all have to keep on saying this "it is not safe" instead lets hear how it should be done the correct way in an open loop the safe way.



It like saying to someone who wants to jump out of an airplane.  No its not safe.  Okay what do you have to do to make it safe?  Take a parachute.  maybe 2 parachutes or whatever.



So I know its not safe.



How do you make it safe?  Where can one se how to make an open system.



Please no more of the "its not safe" anymore.



If you are going to give advise on what not to do then give advise on what to do and where you can see , learn and then do it safely.

NH03865

Wrong analogy

Jumping out of an airplane is the wrong analogy.

Let's try a better one.  How do you put the bullet in the gun point it at your head and pull the trigger in a safe manner.

The answer is that there is NO SAFE WAY to do as suggested.

Roland_18

is this safe?

Hi Joe,

I understand your frustration, really. You have an idea to utilize the resources you have at had to flesh out a dream. You want to to maximize the efficency of your chosen heating plant, in this case, a wood burning stove. I think if you had considered using oil or gas as a fuel there would not have been as much of an issue so long as you didn't try to build the boiler yourself. I don't remember the exact post so I'll paraphrase. It is (I think-no expert) difficult to modulate the combustion of a solid fuel, be it wood, coal, paper pellets, corn kernals, etc.

Once a solid fuel gets to combusting, all you can do to control it is restrict the air or pour water on it. With a liquid of gaseous fuel, you can interrupt the combustion with valves to shut off the flow of FUEL. Solid fuel doesn't give you this option.

Given my half-arsed explanation, there may be no SAFE way to accomplish what you want to do. There are limitations to what can be done safely with a solid fuel based system. Consider what you have been told by others here as an opportunity to investigate another way of heating your water SAFELY.

Look at your original post title -Is this safe?- the answer appears to be 'No'. Don't take it as a rejection. It's an oportunity. Ask, people will help you.

Joebif

I am asking

I have asked several times how to make this an open system? Or is the answer still no to the open system. It did not look that way according to ME

kcopp

Lets try this...

again. The only way I see to make it an open set up is to get a boiler that is just thatopen. Lots of water mass and desighned to work that way. You have just a coil there is no way I see to do this. If you try , the coil will evaporate out on you will ruin the coil at best.  You can try whatever you like.... It may work, it may not. Be carefull. As I said before solid fuel can run away fast. Be safe!

Mark Eatherton

An "OPEN" system defined...

An open system can not be pressurized.



In your example, in the piping circuit from the barrel stove coil going to the storage tank with the immersed heat exchanger coil, immediately after the stove coil you will have a full port tee with the side branch facing up. The end of this upward pipe will have to go at least 5' above the highest part of the system served. You will need to increase the size of the pipe to accept the expanding heated water, otherwise expect spillage and a continual need to replenish the water level.



The pump will be place between the vent tee and the tank heat exchanger. There shall be NO isolation valves of ANY sort in this circuit. NONE, ZIP, NADA. Capeche?



All components in this circuit will have to be metal of a non ferrous nature, or stainless steel.



You are going to have to figure out how to snuff the flame on power failure, and how to keep the pump running (UPS) after a power failure to avoid coil stagnation and steam kick.



Here is a link to see some of the coil tank manufacturers.



http://www.google.com/search?q=indirect+dhw+tank&hl=en&client=safari&rls=en&prmd=imvns&source=lnms&tbm=isch&ei=ojB7TrLqMenfiALJ3NSuDw&sa=X&oi=mode_link&ct=mode&cd=2&ved=0CEkQ_AUoAQ&biw=1408&bih=701



ME