Proposed system unpressurized storage

[SteveJ]

I wanted to get opinions on the following layout using the following:

1. Seton W-130 wood boiler
2. Flat plate solar collectors
3. Flat plate heat exchanger
4. Unpressurized 600 gallon storage tank
5. Amtrol heat exchangers submerged in storage tank

The flat plate hx is used to give priority to the zone and then charge the storage tank.

I was wondering is going through the flat plate hx and then through the storage coil would be too much of a temp differential for the wood boiler.

Trying to keep system as simple as possible.

Thanks for any comments,
Steve

 

[antknee2]

Hi Steve
I have a similar setup , and there seems to be a perfect balance of home heating and heat storage happening , all taking place without any fancy controls or intervention on my part , except loading the boiler . Nice and simple design .
Anthony

 

[stonemills3]

Hi. Steve
I have been researching adding storage for this winter, I had wondered whether the heat exchanger out of my Amtrol Wh 41
would work. A Amtrol support guy seems to think they will work and the list price as a replacement part is quite reasonable
when you compare the price of rolling copper tubing into coils.
Doe's anyone have personal experience in using indirect water heater coils in un-presurized storage?

Regards

 

[free75degrees]

what are the pipe dimensions and length in the amtrol hx?

 

[stonemills3]

The tech data shows 20 sq ft with 3/4" supply and return

 

[Nofossil]

Pretty simple, and simple is good.

 

[antknee2]

The Amtrol heat exchanger coils are a twined together 1/2''finned copper tubing design tightly wound and very compact . They have a brass plate flange with about 10 holes drilled to bolt it to the bottom of the tank , great for high output but not easy to service . They have a built in aquastat well about 2 ' long . I collect them for scrap value but never have the heart to cash them in .
Anthony

 

[WoodNotOil]

Steve

If you are worried about the temp differential on the return line, put in a mixing valve like the termovar that Tarm requires. I believe there are other brands of these as well. That gaurantees that the return temp will not do damage to the boiler over time.

Out of curiousity, what type of tank are you planning to use? What kind of coils are you going to use to transfer the heat in the tank?

 

[SteveJ]

Thanks for all the replies...

Instead of using a termovar with a balancing valve as shown at http://www.woodboilers.com/home-heating-equipment.asp, could I use a three way mixing valve like the AM102R-US-1 http://www.nofossil.org/am101mixingvalve.pdf without the balancing valve?

Anthony's setup is very cool but I could not afford three SuperStor 119 https://www.hearth.com/econtent/index.php/forums/viewthread/15633/#171414.

The tank is a home built wood tank with an EPDM liner based on the design at http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Tank.htm with reinforced corners and two straps across the top and bottom.

The HXs are the Amtrol 2700-5000 and two State 9002734 stainless steel that the distributor wanted to unload.

Pictures to come...

 

[SteveJ]

Free standing wood storage tank with EPDM liner.

 

[SteveJ]

Amtrol 2700-5000 heat exchanger as described by Anthony above.

Anthony - do you want to sell any of your collection?

 

[jebatty]

Steve - no problem with your setup, but a question and comment.

1) Why are you isolating all devices from your storage water by using the Amtrol hx's? I isolate my Tarm from my storage with a plate hx because I use an antifreeze mix in the boiler, but not in the storage.

2) Use of the plate hx is an interesting way to give maximum heat priority to the zones if the boiler is "on." On the boiler side, could you eliminate the plate hx by having a T from boiler to zones/tank, and then on the boiler side of the T have a zone valve that opens when the boiler is on and closes when the boiler is off? If zone demand and boiler on, heat would be diverted to zones; if no zone demand all heat to tank; if zone demand and boiler off, tank supplies heat.

The ingenuity on this forum is excellent.

 

[SteveJ]

Jim,

1) me too - I have antifreeze in the boiler and zones and solar loops but just pH treated water in the storage tank. That is why the systems are isolated from the tank. Ideally all the heat sources would be in the same loop requiring no heat exchange but would require more controls - I do not have my TS7260 setup yet. I wanted to have a basic system that could be controlled by a few aquastats and thermostats and then move to the controller phase.

2) I like the idea of the T zone and no flat plate HX. Then the water feed to the wood boiler would be the same as the zones. Is the diagram below what you were thinking? Could use only one coil too and simplifies plumbing. The only issue is the additional zone valve and control necessary. There would be bleed off into the tank but the two pumps should work together to minimize. Very cool Jim - ingenuity at it's best!

I am also attaching a three way zone mixing valve diagram to facilitate only one pump on at a time - but more controls...

What do you think? I vote for Jim's design for now.
Steve

 

[SteveJ]

Upon further review, I see that I have now arrived at nofossil "Simplest Pressurized Storage Solution" https://www.hearth.com/econtent/index.php/forums/viewthread/19086/ for an unpressurized storage solution using submerged coils.

I guess I was thrown off by the title.

The final plumbing layout is shown below. The controls will be as described by nofossil in the "Simplest Pressurized Storage Solution" sticky.

So, I feel pretty good coming full circle and ending up with a design by nofossil.

The backup will initially be a old propane boiler but could be a tankless water heater - (still worried about the limited 40 degree F rise in most tankless - my well water is probably in the 40s).

Comments? Suggestions for improvements?

How to prevent any charging of the storage tank from the backup boiler?
Will the second drawing with the normally open zone valve suffice - closed when backup is on? Still have storage charging when returning from the zones through the tank. How about the third diagram with the 3 way zone valve to prevent any flow through storage when the backup (fossil) is on? Are normally open zone valves more reliable than 3-way zone valves? If so, how about the fourth diagram? There can still be unwanted flow through the boilers whenever just the storage pump is on.

It seems that there is no improving on nofossil's original design...

Thanks again nofossil and Jim and everyone else for the great advice.

Steve

 

[SteveJ]

Okay... sorry about all the diagrams but here is another one...

The "NOT the Simplest Unpressurized Storage Solution using Submerged Coils".

Modes of operation (control details in "Simplest Pressurized Storage Solution"):

1) Heating from Storage
Both normally closed zone valve are closed and there is no flow through the boilers and heat is taken from storage through center coil by storage pump.

2) Heating from Wood Boiler
Normally open zone valve is closed and Seton normally closed zone valve open and storage flow check pump off - so major flow is through zones only.

3) Heating storage from wood boiler
heating zones off storage is charged through left most coil.

4) Heating with oil
Seton is off and normally closed zone valve is closed. Storage pump IFC prevents tank charging. Storage pump is off. Backup zone valve is opened and zones are heated with no tank charging.

Control logic -
1. Storage pump on whenever a demand for heat and both the Seton and Backup zone valves are closed - both high limit switches open
2. Only one pump on at a time
3. Seton zone valve and pump determined by aquastat on Seton boiler supply.
4. Backup zone valve and determined by storage tank aquastat - as described by nofossil
5. Normally open zone valve closed by heat load zone valve high limit switches - as described by nofossil.

So requires different from nofossil's logic for 1 above.

Additional controls and valves - not as simple as before :down:

Let me know what you think,
Steve

 

[in hot water]

Could you use one 3 way zone valve at the top left instead of the two? Also there would not be a way for the Seton to charge the tank and run some heatloads at the same time? For instance a light heat load condition and a fully fired boiler. It might be nice to cover the load and direct additional output to the tank to keep the boiler efficiency up.

Not to sound like a broken record but the primary secondary piping handles ALL of the various options at any time or condition. All zones get exactly the flow (gpm) and temperature they require. I've yet to see any parallel piping arrangement that can cover all of those bases.

The simpler you pipe these systems the less control you have. Sort of like wiring your home with one size breaker and one size of wire

hr

 

[SteveJ]

hr,

Thanks for the advice. I, too, like the primary/secondary but it does not seem to be the most power efficient setup - minimum two circulators running whenever there is a heat demand or source on.

I am off-grid and am willing to sacrifice some heating efficiency for less power consumption.

Any off-grid primary/secondary advice?

Thanks,
Steve

 

[Nofossil]

hr,

Thanks for the advice. I, too, like the primary/secondary but it does not seem to be the most power efficient setup - minimum two circulators running whenever there is a heat demand or source on.

I am off-grid and am willing to sacrifice some heating efficiency for less power consumption.

Any off-grid primary/secondary advice?

Thanks,
Steve

While primary/secondary offers a finer degree of control, it's certainly not necessary. I think it makes more sense when you have a great many heat loads with widely varying flow requirements, or when you have more than one heat source active at a time. A simpler solution that consumes less power is to use zone valves - especially Taco's EBV valves, which consume virtually no power when open. In addition to the zone valves, you need one circulator per heat source, sized to match the heat source. If you look at the plumbing for my system (link in my signature below) that's what I've done. I only ever have one circulator running at a time, and they're all small circulators (Taco 007 or equivalent). There are some new circulators out there that consume even less power.

 

[pybyr]

nofossil (or others) please tell us all more specifics of the more efficient circulators that you mention (URLs if possible). After spending a lot of hours [actually, _weeks_] and thought thinking that there _had_ to be a way that was more _electrically_ efficient than primary/ secondary, I concluded (only after overcoming substantial personal prejudice to the contrary) that primary/secondary is the cat's meow for controllability and future flexibility as I adapt my home space heat and DHW (and gradual renewable inputs) to maximium advantage. BUT I want to try to use the most efficient and durable circulators from the get-go. Thanks

 

[antknee2]

Amtrol 2700-5000 heat exchanger as described by Anthony above.

Anthony - do you want to sell any of your collection?

Hi Steve
If you pay shipping I would have no problem donating one the ultimate off grid system .
Anthony

 

[in hot water]

hr,

Thanks for the advice. I, too, like the primary/secondary but it does not seem to be the most power efficient setup - minimum two circulator running whenever there is a heat demand or source on.

I am off-grid and am willing to sacrifice some heating efficiency for less power consumption.

Any off-grid primary/secondary advice?

Thanks,
Steve

While primary/secondary offers a finer degree of control, it's certainly not necessary. I think it makes more sense when you have a great many heat loads with widely varying flow requirements, or when you have more than one heat source active at a time. A simpler solution that consumes less power is to use zone valves - especially Taco's EBV valves, which consume virtually no power when open. In addition to the zone valves, you need one circulator per heat source, sized to match the heat source. If you look at the plumbing for my system (link in my signature below) that's what I've done. I only ever have one circulator running at a time, and they're all small circulator (Taco 007 or equivalent). There are some new circulator out there that consume even less power.

Your system seems to be evolving nofossil? The drawing on the Sticky above is different than the one at your link? I like the latest version much better. The one on the sticky had some issues in my mind... multiple PONPC with all those expansion tank connections, and pumps in series. It you be nice to see the sticky changed if possible to your latest version.

I thought i saw an even different one with the oil boiler gone and an instantaneous DHW heater in the loop? That takes to oil boiler away from any buffer input, another plus in my hydronic mind. Or am I seeing things? So many post, it hard to keep track of who's on first

Anyways thanks for all the informative posts.

hr

 

[Nofossil]

Your system seems to be evolving nofossil? The drawing on the Sticky above is different than the one at your link? I like the latest version much better. The one on the sticky had some issues in my mind... multiple PONPC with all those expansion tank connections, and pumps in series. It you be nice to see the sticky changed if possible to your latest version.

I thought i saw an even different one with the oil boiler gone and an instantaneous DHW heater in the loop? That takes to oil boiler away from any buffer input, another plus in my hydronic mind. Or am I seeing things? So many post, it hard to keep track of who's on first

Anyways thanks for all the informative posts.

hr

There are two things going on here. My system is indeed evolving - I'm replacing my oil fired boiler with a tankless propane direct vent heater.

The sticky does not represent my system. It's my design for the simplest storage system that I could think of. It uses pressurized storage, where mine is unpressurized. It does not require any kind of additional controller, while mine has a fairly complicated computer based control system.

The sticky is what I would recommend to anyone who wants a simple and straightforward residential system with storage. In a small residential system, the total pressure drop is small enough so that the whole expansion tank vs. circulator location issue doesn't matter. For safety, I like to see an expansion tank immediately adjacent to any large volume of water, though you could certainly use one larger central expansion tank.

More complex applications require more complex plumbing and controls. My goal with the sticky was to show that storage doesn't have to be tremendously complicated.

 

[Nofossil]

nofossil (or others) please tell us all more specifics of the more efficient circulators that you mention (URLs if possible). After spending a lot of hours [actually, _weeks_] and thought thinking that there _had_ to be a way that was more _electrically_ efficient than primary/ secondary, I concluded (only after overcoming substantial personal prejudice to the contrary) that primary/secondary is the cat's meow for controllability and future flexibility as I adapt my home space heat and DHW (and gradual renewable inputs) to maximium advantage. BUT I want to try to use the most efficient and durable circulators from the get-go. Thanks

I've heard discussions about them and I think I remember seeing a link in another thread. I have no personal experience, but it's easy for me to believe that there is more modern technology out there. I think some of the really low power circs are made in Europe - maybe England?

For me at this point, there's no way I could justify the cost and aggravation based on electricity savings alone. However, on a new off-grid system that might be a different story. Perhaps solar system vendors might be likely to import more efficient circulators.....

 

[SteveJ]

How about the attached single pump configuration with eight zone valves and eight valves?

The zone valves allow for zone heating and storage charging based on feedback from thermistors.

The check valves allow more than one zone to be on without causing flow problems.

The three way mixing valve allows the radiant to run at a lower temperature.

Much simpler then primary/secondary :lol:

I figure that even if all eight zone valves are on that it uses less power than another circulator.

The single circulator is a single point of failure and I may plumb another in parallel and have a few spares on hand.

Comments? Suggestions?

Thanks,
Steve