Water to air exchanger storage

[bowsky64x]

I have been reading about storage fo 2 weeks but can't find the info I need. I have read and fully understand how the simplest storage sticky would operate but that system will not work on my system due to the fact that the load circuit must run at all times so if the house calls for heat the air handler has hot water to work with.
A little info on my system. I have a econoburn 200 that is plumbed with a primary and secondary with 1 inch copper and 1" A PEX. Water runs 400 ft round trip to my house and back to my shop through 2 heat exchangers. It works great and I Have no trouble heating my house and shop wich is over 3000 sq ft. My hope is just like most of us is to have fewer and more intense fires. I have read alot on storage but have found more opinion than fact, more technical wording than real solutions. I know and can appreciate the mathmatical formulas that could help build the perfect system but would like to keep it simple. My system works fine and all I want to do is ad some volume to slow the swing of temps and maybe allow myself some extra time between burns.
First major issue I found is the fact that as great as my econoburn is it isn't smart enough to relize it is out of wood and will continue to run.
Fortunatly I work out of my shop and can monitor my stove at most times.
I would like to see a plumbing design specifically for a system that requires constant flow on the load circuit.
After alot of thinking and reading I feel the best situation for a system that requires constant flow is a storage tank that is plumed in series with the return line after the loads. When the stove is running it is pumping water through the loads wich will take heat if needed and then the water flows thorugh the storage , the storage will soak up any excess btus , obviously more if the loads aren't using heat. the water will always cirulate as long as the water stays above 150 . and when I have my storage charged I can leave my stove on to contrrol the pump but I can use a simple switch on the fan cicuit to shut the draft fan completely off. I realize this isn't the perfect setup but I can't seem to see why it wouldn't work fine.
Please weigh in on this diagrahm and if u got a better idea please share with pics.
Also I want to remove the secondary loop pump from my system and replace it with a mixing valve for boiler protection. What kind of valve are you using that is automatic and works for this purpose.

 

[jebatty]

I think I'm a little dense this morning, but what is the green object by your proposed storage tank? Is it an expansion tank?

Also, I think your circulator has to be located on your supply line before the mixing/return protection valve. It also might be better to locate it on the boiler return line where the water temp is lower, and then it must be located between the valve and the boiler.

First major issue I found is the fact that as great as my econoburn is it isn’t smart enough to relize it is out of wood and will continue to run.

This is pretty easily solved by a manual reset sensor/controller which senses the temperature of the smoke box (the area above the boiler hx tubes before the smoke goes to the flue outlet). On a cold start, reset the controller and it sends power to the draft fan circuitry on the boiler, and the draft fan remains powered while the burn continues. When the exhaust to the flue drops below a setpoint (say, 250F - fire has died out), it shuts power off to the draft fan circuitry. Maybe others have an easier or more elegant solution.

I would like to see a plumbing design specifically for a system that requires constant flow on the load circuit.

If I understand this right, what you are looking for is the "Primary secondary piping for boilers" sticky note. Doesn't this do it for you?

I feel the best situation for a system that requires constant flow is a storage tank that is plumed in series with the return line after the loads. When the stove is running it is pumping water through the loads wich will take heat if needed and then the water flows thorugh the storage , the storage will soak up any excess btus , obviously more if the loads aren’t using heat. the water will always cirulate as long as the water stays above 150 . and when I have my storage charged I can leave my stove on to contrrol the pump but I can use a simple switch on the fan cicuit to shut the draft fan completely off.

Again, doesn't the "Primary secondary piping for boilers" sticky note circuit work for you? I would not put the storage in series with the load; rather, if load return is higher temp than storage, then storage becomes another load circuit to take the extra btu's; but if storage temp is higher than what the load demands, then storage feeds the load; similarly when the boiler is operating so that storage can take the extra btu's the boiler is delivering.

Also I want to remove the secondary loop pump from my system and replace it with a mixing valve for boiler protection. What kind of valve are you using that is automatic and works for this purpose.

I don't quite understand this proposition. I think you need a boiler protection/balancing valve on the boiler if there ever are situations when return water is less than what is recommended for your boiler (140-160F range). Danfoss and Termovar are a couple commonly used.

I hope I am understanding your questions.

 

[bowsky64x]

here is a better diagram

 

[bigburner]

No formulas here, Opinion call it what you want. I use indirect unpressurized storage. {that means big heat exchanger hanging in big open tank} I use a Danfoss 3 way mix valve at the tank. My tank acts like a big battery, the mix valve holds off charging to about 140F and is all open at 157 "I think" or what ever temp t-sat is used. That allows the boiler to reach usable temp without loading storage tank. When load lessens that allows the tank begins to charge. My system is pretty complicated but in a nut shell 150 ft to the shop into a hydraulic separator[200gals] then into the house 300 ft and other building 300 ft. Tank is at the boiler barn. It's 15 ft vertical tank with a 10 ft probe type HX I don't worry about stratification which seams to be the topic of choice here nowadays. This system also has a hydraulic separator [200gals] connected between tank and boiler which has another 3 way valve piped in backwards, lets say which limits the water temp to 180f feeding the pex. The advantage of doing this is to allow for hottest possible storage. Can fire the boiler into the 220F degree range and the tank being 4000 gals it will soak up all the extra horse power. and I have not boiled it yet. Sorry a little of track here. I run circulating pumps 24/7 some loads are in out and some are primary secondary with load activated pumps. what you drew is a simpler version of my system, I would add the 3-way at the tank and if you are using a low mass boiler and I think most people on here are. Put a 3 way at the boiler also. I don't have a boiler protection valve, it sweats so bad in the fall on start up you think it was leaking. It's a large mass boiler 1,200 gallons "can't really shock it" really low water temp could cause condensation in the fire tubes but a valve would not help that any way, that's a firing/load management issue.

 

[sdrobertson]

For the first issue of the econoburn not being smart enough to shut down fast enough when the boiler is out of wood, the simplest solution is to put the boiler on a timer. As you have had the boiler for a while, you probably already kinda know how long a load of wood will last so this will allow you to shut off the draft fans when you think it will be done with the wood supply. This is the way the Garn works. Without adding allot of controls, your idea sounds like it should work to some degree. The more water you have in your system, the more btu's it will hold. With a limit of 150 degrees before you can circulate the water, I would defiantly go with pressurized storage as unpressurized will have a limit of around 170ish. What is your minimum water temp that will heat your house? If it is 150 then your at the point that you must be firing the boiler around the clock. Storage has its limits especially if you need really hot water to run through air handlers that need hot water. 500 gallons of 130 degree water really doesn't help you if your house needs 140 degree water to provide sufficient heat. I would move the planned storage to the supply side to the house. Go from the boiler to the storage, then to the house zone and back to the storage. The boiler when firing would supply 190ish water to the tank so the house zone would also get water this hot. When the boiler is not supplying heat, then your house would still get the hottest water you have in the system.
When I started my system I was circulating water 24 hours to the house also. I needed the water to be around 140ish to provide hot enough water to go through my air handlers. What I found was that I was always mixing the storage when the house was not needing the heat so my return water was hot and eventually I had 2000 gallons of 130 degree water which was useless to me. What I did was replace a regular circulator with a "smart" one that had a sensor that would keep the water at the sensor at a set point. This allowed me to slow down the water depending on the water temp. It took some playing around with it but now I always return water to the tanks at around 110 degrees. If the house is calling for heat, the pump comes on so the water is flowing enough to keep this setpoint of 110 which supplies the inlet of the heat exchanger a water temp of about 150 degrees as I have around 40 degrees drop when the furnace is running. What this provides is my storage has hot water (190ish) at the top while the 110 degree water is at the bottom and this slowly moves up the tank as the hot water is used.
You need to decide how long of period you want to go between firings. If it is just to add a few hours, then some storage may help you get some time. This long rambling was probably clear as mud......should have probably had a couple cups of coffee first :smirk:

 

[kabbott]

I have been reading about storage fo 2 weeks but can't find the info I need. I have read and fully understand how the simplest storage sticky would operate but that system will not work on my system due to the fact that the load circuit must run at all times so if the house calls for heat the air handler has hot water to work with.
.

Should be easy to use a relay that will turn on the load pump whenever the house calls for heat and the fan runs. No reason to run that pump 24/7, lots of reasons
not to. Then you should be able to use the "simplest storage" sticky layout...

Make sure the piping between the boiler and storage can move the full output of the boiler.