HELP TARM+1500 GAL. PRESS, STORAGE+OIL BOILER

ALH_4

Could you provide a diagram and/or some photos of the piping on your existing oil boiler?

Diciocco

I recently purchased a used Tarm wood gasifacation boiler, I also found a 1500 gallon tank rated for 60 PSI at 650 degrees. I am haveing a hard time finding a good piping layouts that would include the Tarm boiler the storage Tank and my oil Boiler. I would like to keep it as simple as possible with-out any speacil controls. I currently use zone valves in all of my zones. I plan to keep the burner on the oil boiler unplugged and not use it at all. Any help would be appreciated.

Thanks,

Brian

ALH_4

Alternative Heat Sources

With any pressurized heating tank, make sure you have a proper pressure relief device.

You treat a wood boiler the same as you treat a solar system. The only difference is you are collecting heat from wood instead of the sun. The only "special" control necessary is a differential setpoint control. This control will measure the system return temperature and the storage tank temperature. If the storage tank is warmer than the system return, either a valve or a bypass pump can direct water from the storage tank heat exchanger into the system return.

Obviously I have no idea how your oil boiler is piped or any of the other details of your system. Full outdoor reset on your heating system will maximize the utilization of the wood boiler. In fact, it is almost a necessity. Ideally this would be either an injection-type mixing system or a motorized mixing valve so you can take the oil boiler completely out of the equation when it is not needed.

Tom Blackwell_2

Another consideration is what happens on power failure. If there is any way to do it, pipe the Tarm to the storage tank using minimum 2" pipe with the supply up high and the return run low so that the wood boiler will thermosyphon into the storage tank on power failure.

Eric Johnson

website

There are plenty of Tarm owners with storage tanks and piping ideas here:

http://www.hearth.com/econtent/index.php/forums

Including some Wallies.

Brian_70

Looking for an actual piping diagram with all controlls and valv

I am really looking for an actual diagram with all of the needed controlls and valves. I havn't really found anything that includes the wood boiler, pressurized storage tank and oil boiler combo. I understand I need overheat controll and I have two 80 gal expansion tanks for the 1500 gallon tank. I am not an expert in plumbing and heating, but I am a do it your selfer that is not afriad to tackle any job as long as I can do some research on it first. That being said, I geuss I need something a thrid grader can look at and understand the basic concept.

Brian_70

Existing set-up diagram

This is basicly what I have now. I have an older wood boiler already piped in that I will be replacing with the tarm. I think I need to add an extra circ. on the wood boiler side to circulate through the tank and then draw from the tank with the oil boiler circ.

Brian_70

Any Ideas Guys ?

Any ideas or suggestions ?

hot_rod

my opinion

is it is hard to accomplish all that with just one circulator. I understand the intent to keep piping simple and within what homeowners or installers with miminal experience can handle.

Personally I feel primary secondary piping best covers all the bases. It allows all the various loads and sources to get along.

It really needs some engineering work to be exactly right. You need to identify load calcs, buffer size, temperature requirements, return temperature protection, overheat protection control and piping, control logic, etc.

Not to forget venting, combustion air, expansion and relief sizing, and more.

I wish a simple one, two, or three drawing could cover all those bases, but the system really needs to be built to your application. It could take a bit of time for someone to run all those calculations and put it all down in an understandable format for anyone to understand and install.

I don't think your request is being ignored, but the answer, is a bit more involved than a sentence or two. And a lot more data would be required to even start specing equipment and sizing.

And we haven't even touched on the electrical logic and wiring to bring everything on to the same page.

Just my thoughts.

hr

Brian_72

Maybe I can figure it out ???





Well I consider myself an engineer so I can check that off.

I bought a used Tarm Gassifier 107,000 Btu I bought a 1500 gallon pressure vessel not much I can change there by doing calculations. Return temp protection will do with a mixing valve. Venting: no problem, Combustion Air: No problem, Expansion: two 80 gallon air cushion expansion tanks, Overheat protection: Automag with garvity dump.

As I have said, I am ineterested in piping, controlls and keeping them simple. I appreciate the feedback and concerns about the other details of the set-up. It looks like I am going to have to just dive into it and figure it out as I go, it wouldn't be the first time I have done that.

Thanks,
Brian

ALH_4

Strategy

I don't know if you classify outdoor reset controls as "special", but I think a reset control would be a really good idea to make sure you utilize that wood boiler to its maximum.

Think about it this way. If you have the system supply temperature running at a setpoint, your usable heat capacity in the storage tank is fixed and relatively small. If you need 160°F to the baseboard and you run the storage tank up to 180°F you essentially have 20°F of temperature drop in the storage tank to use for heating. That is approximately 250,000 btu that you can store in the tank.

Let's say it's 30°F outside and your system only needs 140°F supply temperature. You now have twice the capacity in your tank for heating before the oil boiler kicks on to carry the load. You have doubled the amount of heat you can use each time you heat that tank up.

Wood boilers are a big investment and without intelligent controls the benefit is significantly reduced. I would do it with a motorized mixing valve running on outdoor reset and a differential temperature control (tekmar 155 or equal) to switch between the heat sources.

hot_rod

start with some graph

paper and draw out component locations.

How many loads? All the same supply temperature? Will they be zoned with valves or pumps? With pumps determine the gpm flow to size them correctly. then size the piping to the various loadsa nd emitters.

With 107K at 80% efficiency you need to move @ 9 gpm at a 20 degree delta t. You might consider a wider delta t to down size some piping depending on the temperature requirements of the loads.

Pipe sixe could be 1' but larger size for any gravity loops. personally with that boiler stopping should not be a problem, I'd wonder about a gravity over heat zone need. leaky door gaskets are about the only cause of run aways on tight gasification boilers. easy enough to plan some tees should it be needed. possibly the buffer could have some gravity piping?

Determine how and when the buffer comes into the picture. priortize all the loads and dump into the buffer after that.

Is you plan to always have the buffer charged to buy some non burn time, or mainly over temperature protection. That's a lot of volumn for a 90K boiler to keep hot and cover loads.

If it will be maintained then the draw down piping and logic may be different from just over flow parking.

On the drawing include valves for service, draining, and air elimination, also isolation around circulators.

Gauges are nice to see where all the energy is going. Strap on thermistor types work fine and can be moved around easily. www.azel.com has a nice one that captures and shows delta T with the press of a button. A good way to dial in pump speed for best energy exchange.

For me the piping is the easy part. getting the various systems to communicate, control wise is more of a challange. not really an off the shelf control for that unless you are able to write and program a PLC type.

Joe or NoFossil at "the hearth. com" is who I would hire for that task that comes easy to them.

hot rod

Brian_72

Here is my plan so far see pic

Thanks, Andrew I will definitly take your advice and look into the outdoor reset control. Any brand or model suggestion ? Here is a pic of what I have come up with for a piping layout.

The Tarm feed will go directly to the top of the tank and the return will come out the bottom. This will I hope result in minimun mixing so that even if the tank is 120 degree at the bottom the top could be 180 degrees. Feed to the oil boiler will draw for the top of the tank tank. I will put a zone valve with an aquastat that will close if the feed temp to the oil boiler goes below 140 degrees.

See attached pic

Brian_72

Here is what I have so Far see pic

this is my plan so far.

The tarm will feed to the top of the tank and return from the bottom . Hopfully this way there will be minumal mixing so even if the temp at the bottom of the tank is 120 degree the top could still be 180 degrees(instead of the whole tank being 150 degrees. The system will draw from the top of the tank there will be an aquastat with a zone valve that will close when the temp goes below 140 degrees. I will add shut off valves so I can bypass the tank if needed.
see attached pic

hot_rod

one more circ

and some different piping. allows one or both boilers to run, with flow only when they are called on. Loads get priority, wood boiler could be protected with a 140 aquastat on return, or add 3 way thermostatic.

Buffer only gets charged when loop exceeds a setpoint, say 185. Or a differential control could also be used to keep it online. I've seen 4 way valves used to reverse flow through the buffer. My buffer circ runs enough to keep that tank blended and able to be pulled down to 100F or so for radiant floor only use. Also my tank is long and lean and not much temperature difference from top to bottom.

Now you have everything in an orderly fashion, hydraulicly speaking to allow control logic to be added. Double throw relays could be used to priortize functions, PLC's , whatever you are comfortable with.

Expansion tank, fill, relief, etc omitted for clearity. They need to be sized and installed correctly. Add checks on the other side of those P/S take offs also for 100% protection against ghost flow. Conceptual drawing only

hr