Storage Upgrade + Solar option + Biasi

[CMAC]

Hello Folks,
I installed my Biasi 3 wood about 6 weeks ago. It is installed about 45 feet from my oil boiler in a detached garage. My house is about 1800sq ft on slab. 7 years old.
So far the Biasi is doing its job quite well....when I am able to keep the wood fed to it. Burn times are quite short 2-3 hrs when the house requires heat, 4-5 when it doesn't.
I have installed programable T-Stats in the house which work quite well. They are Aube and have a feature which allows you to override the setpoint for 2 hrs then they follow the program. This allows me to use the slab as storage, after I get the Biasi pumping I charge my slab, which in turn throws heat for 4-6 hrs after. Then they fall back to the lower setpoint so my oil boiler stays off after the Biasi is out of wood.
I start the Biasi quite frequently- 1-2/day so its a good thing its easy to bring up to temp.
I am considering a storage tank. From what I have read here at least 800 gals are required. I have not done the the calcs yet.
My questions are:
How long will it take to bring that tank up to 180-200? How long might one expect to draw from these stored BTU's?
The tank construction in general, types, homemade, what companies make good ones?
Exchangers - if homemade tank will 1 coil of copper suffice, I have noticed some have two,? I know this is vague. Some use flate plate exchangers outside of the tank.
Solar option- is it possible to use Solar panels to charge this tank in summer months or is it to large a volume?
I am looking forward to starting this project in the spring/summer. I have a background in PLC's and automation so I will incorporate this in to the system as well as remote monitoring, seems silly but I can't help myself.
Any opinions or personal experiences with the above is greatly appreciated. Pros and cons/misatkes.
Thanks
Cory

 

[steam man]

I haven't had my second cup of coffee yet but I will try and give my overview of what you are trying to do. First-do a good heat loss calculation for your home. You can use this to determine how large a storage tank you can efficiently utilize. With radiant floor heating you can use lower temp loads thus your tank will have a much wider swing in temperature range which gives it more effective storage. I find that since you use your slab for some storage adding a tank may not get you much more ahead though it probably would be more efficient. The other question is whether you boiler is large enough. Could it charge the storage tank and provide heat during a burn cycle? My thought is the boiler should be large enough to provide the current heat load under a fairly cold day while charging the tank. Tank size should provide enough heat to get you through enough time where you willing to start another fire, preferably once a day. Exchangers will depend on whether you have unpressurize or pressurized storage. How many depend on the number of heat sources and number of loads to heat. Integrating solar and other fuel in the same storage tank would probably make the solar much less efficient. It also would take a lot of panels to get a large tank charged. I would go with a DHW setup with separate preheat tank and possibly a DHW preheat coil in the wood boiler storage tank. I suggest you do a lot of reading around the forum. There's a lot here.

I have to get more coffee.

Mike

 

[WoodNotOil]

Which model do you have? From this site it appears they range from 75k-120k btu. With that said, you are probably in the 800-1000 gallon range there anyway. Check out my webpage and nofo's for some info on DIY storage. Both of ours are unpressurized. I don't know of anyone on here with a pressurized storage webpage, but it would be very useful if one of the guys with that type of system would make one. As far as copper coils go, you need a lot of surface area and going with less can defeat the purpose of trying to keep the boiler from idling because it can't transfer all the heat. Most people put two coils in parallel. Length depends on diameter of pipe. Flat plates are another option. There you benefit from a few extra plates as well to ensure you can transfer all the heat. Port sizes also can make a difference. (ie same amount of plates but 3/4" ports vs 1" don't transfer heat at the same rate due to less GPM)

As for solar, if you make the panels it may be feasible, but if you buy expensive ones maybe not. Nofo knows a lot more about that than I do. I know that it collects lower temp water and should probably enter the tank near the middle. Hopefully others will offer more help. Good luck. I love my storage tank!