piping plan

[Rickard]

Hi Everybody

I've been lurking on this forum for a few months now. There is some great information here. I just bought a Biomax 40 Wood gasification boiler and am working on the best way to install it. I have drawn a piping plan based on the primary secondary model and am looking for some feedback.

http://www.houseneeds.com/shop/heatingproducts/heatu/systemboilermain.asp

Unfortunately I don't have a CAD program

 

[Jersey Bill]

depending on the storage, you should charge the tank from the top, and discharge it from the bottom.

check out the application diagrams on the tekmar site. I found them very helpfull.
http://tekmarcontrols.com/

good luck

 

[Rickard]

Thanks Jersey Bill

 

[ericjeeper]

Nevermind I see the circ pumps

 

[Eric Johnson]

Hi Rickard. Welcome to the Boiler Room. I think you're our first BioMax 40 member. We have a couple of guys with 60s.

 

[Rickard]

I can't wait to get this up and running. I am just hoping my piping plan is on the right track. Any other comments?

Dean

 

[Rickard]

I will add the storage tank next year. I am am planning on using a propane tank or two in a pressurized system. Anyone else have a comment?

Thanks

Dean

 

[Eric Johnson]

It looks good to me, Dean. You will need some sort of low-temp return protection for your BioMax. Some people use another circulator, moving water from the supply to the return below a setpoint, while others use a mixing valve to ensure that water returning to the boiler is above 130 or 140. You need to do something along those lines to protect the boiler.

We have several people using old propane tanks for pressurized storage. There are different ways to pipe the flow through the tank, so you might want to start a thread inquiring about that, or search through some old threads for more info. And, obviously, you'll need a pretty big expansion tank with that much water. There's an excellent thread around here explaining how to rig up a hot water heater vessel for affordable expansion. I'll dig that up later for you if I get the chance.

That's a lot of circs on your drawing. I have circs on all my zones, too, but I don't have nearly that many zones. You might consider using zone valves instead of pumps in some places to save on your electric bill. Again, that's an area where even the pros differ. Either way works--each has its trade-offs. For more information on that, I'd start a dedicated thread.

A few things you might want consider adding (if you haven't already) would be a low water cut-off switch to protect your pumps and boiler, some sort of a heat dump (pumped and gravity fed, if possible) to protect the boiler in a power outage & other overheat situation. Some of this stuff can be added later, but it's easier to put it in from the get-go.

This has all been on-the-job-training for me. I usually figure out how much it's going to cost for all the hardware and how much time it's going to take. Then I double the first number and quadruple the second, and I'm usually in the ballpark.

 

[Sting]

is the air scoop and expansion tank in the correct position

Is there a correct place?

Should there be a dedicated pump on the primary loop?

 

[BrownianHeatingTech]

is the air scoop and expansion tank in the correct position

Is there a correct place?

Should be moved to be between the oil boiler connection and the zone connections.

Should there be a dedicated pump on the primary loop?

In this case, yes. The storage will not be charged by the wood boiler, unless a zone pump happens to be running.

Personally, though, I would add a three-way valve to the wood boiler supply, that can re-direct the water directly to the storage tank.

The pumps on the boilers and storage tank need to be switched around, so they pump into the boiler or tank.

Joe

 

[Rickard]

Hi Sting

I think that each individual zone acts as a pump for the primary loop. I am going with this system because the supply and return piping and manifolds are there now from my present system but I like the Primary Secondary idea and this incorporates both. I can still add heat sources or heatloads easily later on though.

Hi Eric

What is the protection for? I read some things about people putting them in but don't understand their purpose. Does the circulator on the wood boiler not work as a low-temp return? I am guessing that if it is used for over-temp protection then there would have to be two circuits controlling it. One for regular heating and one for temp protection if there were no call for heat when the boiler is still hot. Do I have this right?

I do have a Spirovent air scoop and will get an appropriately sized expansion tank to supplement what I now have.

I already have a low water cut off on my system.

Heat dump? I was under the impression that these boilers will damp themselves down when there is no call for heat. Is there that much time between when the boiler is turned off and when it stops producing heat? I am guessing that the storage tank would act as a heat dump but that will be next year and it wouldn't be gravity fed. I also have one very large baseboard zone (80 ft) that could be used.

I love your cost/time formula. As many times as it goes that way for me I still haven't learned it, though my wife learned it a long time ago.

Thanks much for the help.

Dean

 

[Eric Johnson]

If your return water temps get down to 120, it can create condensation in the firebox (wood side) that mixes with corrosive elements in the firebox and eats away at the steel in the condensation area. Over time (years), the steel can get paper thin, and eventually fail. You want to make sure that the water returning to the boiler is no lower than 140 to prevent this from happening. Something to plan for even if it doesn't make it into your initial install.

If the power goes our or your pump fails and you've got a firebox full of wood and coals, your boiler is probably going to overheat, especially if it's at or near the top of the curve when that happens. When it gets hot enough, your pressure relief valve should pop open and relieve the pressure, but it's a good idea to avoid that if at all possible. A gravity heat dump with a zone valve that opens when the power is cut is one good way to go. You can put a hot water heater vessel above the boiler, which will allow the hot water to convect out of the boiler and into the tank. I have a couple of cast iron radiators in the attic above my boiler serving essentially the same purpose.

I get the impression that most people don't have this kind of gravity heat dump, but I think it's a good idea. Mabye I say that because I have one. I also have a pumped dump zone (greenhouse) that kicks on the pump when the water temp exceeds 200, but it's never come close to activating in my first season.

The low temp return water corrosion protection and the heat dump are separate functions.

 

[Rickard]

Hi Joe

I see my mistake about the storage not charging unless there is a zone pump running. Oops. Why would the three way valve be on the boiler supply side?

Why does it make a difference whether the pump is pushing to or pulling from the boiler or storage?

Thanks

Dean

 

[Rickard]

Thanks Eric

That helps.

Dean

 

[BrownianHeatingTech]

I see my mistake about the storage not charging unless there is a zone pump running. Oops. Why would the three way valve be on the boiler supply side?

So it can divert the water... it either goes out to the primary loop (in the case of heating with the boiler) or gets diverted to the tank (in the case of charging the tank).

Why does it make a difference whether the pump is pushing to or pulling from the boiler or storage?

Because these pumps don't pull. They only push. You want the pump to push through the load. From a hydraulic standpoint, the pump serving the boiler is seeing the boiler as a load, and needs to push water through it.

Joe

 

[rreihart]

I'm no expert. I only know what I've learned here and other forums, but my situation is similar to your's. Here is the plan I went with.

 

[Rickard]

Hi Joe

Sorry, I was thinking "boiler supply side" was supply to the boiler. Of course supply is going to be the same regardless of which way you look at it. Silly me.

Thanks for clearing up the circulator function too.


Hi Rreihart

With your storage tank, the pipe on the far left will change flow direction depending on whether it is charging or discharging right? Also does the oil boiler charge your storage tank?

Here is my updated piping plan. I think it addresses most of the issues.

I will add a 2nd circuit to the wood burner circulator that will work as a heat dump to the storage tank (circulator will run if temp is above a certain point). I am guessing that this would be redundant since I would want it to do the same thing for normal charging of the tank anyway.

The 'mix' (or black) pipe coming off the storage tank will change direction depending on whether it is charging or discharging.
The storage circulator will come on when the storage is discharging.

One thing I am not clear about is what kind of three way valve would be necessary to come off the boiler supply side to the storage tank.

Thanks.

Dean

 

[Rickard]

I guess my big question is, should the 3-way valve coming off the wood boiler supply be a thermic type or should it be a manual mixing type or actuated by some other process?

Dean

 

[BrownianHeatingTech]

I guess my big question is, should the 3-way valve coming off the wood boiler supply be a thermic type or should it be a manual mixing type or actuated by some other process?

The 3-way that charges the tank should be an electric three-way zone valve.

Joe

 

[Rickard]

Hi Joe

So the three way valve would send heat to either the loads or the storage, and not a mix. Is this correct? And what determines the direction? When there is a call for heat from one zone and the wood boiler is on, it will have more heat to throw than the that zone can distribute. I'm not quite understanding this.

Thanks

Dean

 

[BrownianHeatingTech]

So the three way valve would send heat to either the loads or the storage, and not a mix. Is this correct? And what determines the direction? When there is a call for heat from one zone and the wood boiler is on, it will have more heat to throw than the that zone can distribute. I'm not quite understanding this.

Yes, the electric zone valves like that are either one way or the other. They don't send some one way and some the other.

The direction would have to be determined by your control system.

The other option would be to skip that and add a circulator (ie, connect a pipe between the two headers below the zones on your drawing, and insert a circulator just after the Spirovent, to make the loop complete. That way, the boiler can inject water into the loop, and the circulator will move it along to where the storage tank could extract it.

Joe

 

[Tony H]

is the air scoop and expansion tank in the correct position

Is there a correct place?

Should be moved to be between the oil boiler connection and the zone connections.

Joe

What is the reason it needs to be between ther boiler and zones? Also I read somewhere you should have a 12" or so straight run leading into the air scoop is this correct?

Tony

 

[BrownianHeatingTech]

What is the reason it needs to be between ther boiler and zones?

Two reasons - the zone pumps should pump "away" from the expansion tank - and the air scoop should be on the supply side of the boiler so that it gets water flow as much as possible. The scoop can't remove air from water that doesn't pass through it, so it should be located at the point where the most possible water flow will occur.

Also I read somewhere you should have a 12" or so straight run leading into the air scoop is this correct?

18" is the correct number, if using an air scoop. That lets the bubbles move to the top third of the pipe - the air scoops only act on the top third of the pipe, so any bubbles below that would not have a chance of being removed.

Joe