Help with storage plumbing

[leon]

If your determined to make the expansion tank yourself I would be sure to follow the B+G
recommendations for the one inch airtrol valve. IT has to be connected to the bottom tapping in
the tank as illustrated in the tank examples AND the water level in the tank cannot exceed 2/3's
of the horizontal height of the tank as discussed in the drawings and sizing chart.

For the amount of water you have or propose to have in storage you need the next larger airtrol valve being one inch
and a 30 gallon tank AT LEAST for the water volume as you must have a one inch common header pipe that
comes off the tow storage tanks and will be connected to the 45 degree riser that attaches to the one inch airtrol fitting in the horizontal tanks tapping. You can use unions for these connections with no issues.

This is why I suggested the 30 gallon B+G tank and the one inch airtrol for your installation as they are pressure and leak tested and it will work right out of the box with the 1" airtrol fitting. The only thing you need are reducing bushings, pipe strap, pipe plugs and you have to decide if you want the water glass gauge which is a must when filling the system as you will know how much water is in your system if you want to check it as the airtrol valve has no restrictions to flow

 

[warno]

We actually have purpose domed tank ends for expansion tanks that we build for glycol cooling units at work. We pressure test them at 250 PSI. The only reason I would build my tank is if I can't find one that clears my duct work in the attic of my garage. We have a Taco brand expansion tank at work, that a was purchased then not needed, that I can copy fitting locations from.

I think I'm going to avoid the DHW loop for now and focus on the just heating the house. I'll draw up another sketch and see if I'm on the same page with everyone.

 

[warno]

Here's what I'm thinking. Please tell if it's ok or wrong or what to fix.

First I have the OPEN system OWB pushing water to my plate HX. This loop has the boiler protection valve on it.

Then from plate HX to my storage supply manifold. This manifold will be 1.5" pipe reducing at second tank to 1" then reducing again at third tank to 1/2". Correct me if I'm wrong but I think this is called reverse return parallel piping. The return line goes to the third tank at 1.5" then reduces to 1" at the second tank then again to 1/2" at the first tank. So that covers storage.

From my storage supply manifold I'll use a delta T pump to push water 90 feet through underground lines to the house to a manifold in the crawlspace made of 2.5" pipe. This manifold will have 4 ports and then the supply and return to storage. I'll tie into 1 port for my furnace HX then use another port back into the manifold with the return from HX. The 2 remaining ports will remain unused until I figure out what I want to do with my DHW. Then water returns from the manifold back to the storage tanks return piping.

Expansion is going in attic space in garage with fittings in the tops of all three tanks pitched to the final tank then a line ran up to the airtrol fitting.

Again please tell me if I'm getting close or I'm way off.

 

[ewdudley]

Expansion is going in attic space in garage with fittings in the tops of all three tanks pitched to the final tank then a line ran up to the airtrol fitting.

Putting the expansion tank in the attic is ideal (assuming it can't freeze). No need for an airtrol. The airtrol is for separating gas from water flow leaving the boiler. In your design the gas goes to the storage tanks and migrates to the expansion tank with no need for an airtrol.

Note that all volume above the upper supply ports on the storage tanks, and all volume below the lower ports on the storage tanks will be lost for heat storage purposes. In many implementations this can amount to well over a third of potential storage volume being wasted.

But all you need to recover the wasted volume is to run riser tubes up to near the top of the tanks and dip tubes down to near the bottom of the tanks.

 

[warno]

What is the ideal location from top and bottom for the supply and return lines? My drawing is rough but I was thinking 6" down from top and 6" up from bottom. I don't have any experience to back up those measurements it was just an assumption.

Also, if it matters, I was going to build my inlet and outlet pipes to the storage with horizontal holes and end plates on them to act as diffusers to help avoid jetting the water into the tanks.

 

[warno]

Am I on the right track with my new drawing? Should I change anything about it or run it like drawn?

 

[leon]

As EWDudley has said the inlet and outlets location will cause
you to lose water volume as far as reclaiming available heat goes.
installing riser pipes for the suction of the hot water and dip tubes
for the discharge of the cooler return water in each tank will work well.

As for welding in diffuser's that is something that is not required as the water is
not really in any need for diffusion.

You need to worry about being able to drain sediment with three boiler drains
and installing one zinc anode in each tank with three more weldment's for the
zinc anodes in the half way point in each tank.

Why are you using three circulators when you only need one!????????????????????????????
your hot water flow is backwards it needs to enter the tank at the bottom preferably so you can use just "one" circulator pulling the hot water off the top of the three tanks after the steel expansion tank pushing the hot water to the heating load. You can install the external domestic hot water coil anywhere after that and they will not plug as readily as a flat plate heat exchanger as I describe below.


Remove the 3 circulators from your drawing!! The two circulator's that are closest to each other are not going to help you, they will just make more air bubbles and the point of pressure change will be confused and create cavitation issues with the three circulators.

AN external domestic hot water coil would be easier to use and easier to manage as there is nothing obstructing water flow just one in tapping and one out tapping for the boiler water and the domestic
coil will provide 5 gallons per minute of hot water all the time.

The other advantage is the copper coil will not plug for a long time if ever. My external Domestic Hot Water Coil set up delivered hot water for 34 years without plugging and my Keystoker has the same type of coil in the steam chest of the boiler.

 

[warno]

I was thinking the diffusers would slow the water from jetting straight into the tanks and would divert water horizontally.

I didn't draw anything like drains, valves or ect. small parts because I'm just trying to get the flow and plumbing correct. I will have drains and everything in the final install. I don't think I need anode rods in the tanks because they will be pressurized and everything I've read says once the O2 is used up it should be fine.

I'm confused how it only need ONE circ. When I'm running one from boiler to HX, one from HX to storage, and one from storage to house. Right there is 3.

With my storage tanks tied to my expansion tank via fittings in the top air bubbles shouldn't be an issue. Because anything in the lines will be forced to storage then picked up in the expansion header.

I'm wondering if you read my description of the drawing or just looked to the drawing? Like I said in the beginning I'm no artist.



I drew up a quick thought for my tank inlets/outlets. The pipes would run in to an elbow and then up or down to my diffuser. Again the "diffuser" design is an end plate on the pipes then a series of holes drilled into the pipe's side.

 

[leon]

You do not need to have diffusers in the tanks, Large commercial laundries and institutional laundries
have hot water storage tanks do not have them-the hot water goes in and the water goes out to the
end use whether its a large commercial washer or steam ironing system.

You do need the dip tubes and riser tubes WITH NO HOLES.

You need the sacrificial anode rods because of the hot water and its changed chemistry.
You need the anode rods as the anode rods attract any corrosive chemical imbalance
in the water to them and they sacrifice themselves to counter any issues with the water PH
and they become lunch rather than the tank walls.

 

[maple1]

I don't think anode rods are needed in a pressurized system.

 

[leon]

All you need to do is install "one" circulator drawing the hot water water off the header pipe
that is connected to the steel expansion tank.

you can do this with a Tee and two isolation valves for one circulator.

This is exactly how my system is plumbed and it works very very well.

The resistance created by the heating load is the issue for you and
one circulator is plenty for this if you use zone valves for the individual
loads.

My B+G NRF25 circulator has three speeds and the lowest sped is
17 gallons per minute and that would be plenty for your needs and
as it has two higher speeds and you can always increase the
water flow in the heating load.

All you need is one circulator and some proper system design work
and you will be fine.The B+G folks will help you with this simply by asking them.

I want you to succeed not fail. I am not trying to stop your progressing with
your plumbing I am just trying to help you avoid the problems you are making
for yourself in your current drawings.

Your going to have a lot of air bubbles unless you install the circulator in the
header pipe coming off the top of the tanks. The steel expansion tank will
still work fine just like my set up-you need to add a ball valve to shut off the
steel expansion tank too. You need more ball valves preferably 2 at
each tank and several more to shut off the separate heating loads as you
will have to refill the steel expansion tank and drain off the excess water to
create the proper air to water ratio in the steel expansion tank each time.

Most water heaters have sacrificial anode rods so keep that in mind
and they are not that expensive either as they are cheap insurance since
you are building your own tanks from used propain tanks.

 

[warno]

As I said above I will have all the valves I use as needed. I just didn't draw them in.

My supply to house line is coming of my top manifold from my tanks and return to bottom manifold.

If you read my description of my drawing, all my manifolds are over sized. I'm using circs instead of valves. And I did my drawing off of the thought of "primary secondary piping" but using my storage instead of a boiler. My from storage to house runs underground to an oversized manifold(primary loop) where my HX circ. will pull what it needs to heat house on call.(secondary) The return will enter same manifold 6" away where it will mix with some hot supply then head back to the storage tanks return via the initial circ. which for added savings of temp I'm going to run a delta T pump.

 

[warno]

Any other advice for me on the new drawing in post 53?

 

[ewdudley]

Any other advice for me on the new drawing in post 53?

Leaving the plate HX, arrange for piping to convect gently towards storage. Then use a simple aquastat on the pipe leaving the HX to control the HX-to-storage pump according to some minimum temperature so that storage does not get mixed by constant running of the HX-to-storage pump. This will help minimize the temperature of the water entering HX from bottom of storage and will thus maximize the effectiveness of the HX.

The DeltaT pump (or its sensors) should be moved to the house so the sensors can see sooner what's going on with the house manifold. Also it would seem preferable to me to run the storage-to-house ("Delta-T") pump as a setpoint-T pump with outdoor reset. (I assume the storage-to-house pump is not enabled unless there is a furnace call-for-heat.)

 

[warno]

I understand the natural convection part of the HX to storage idea but I'm confused about the aquastat to run the pump through that loop. When should the pump kick on or off? When the water temp in the return to HX is to warm it kicks pump off or the opposite?

Moving the storage to house pump to the house I thought would be ideal from a wiring stand point but I figured that would cause too much line on the suction side of the pump. I figured that might cause issues which is why I drew it in the garage. Is it because it's in a closed loop that it will be fine once it's primed? And yes the storage to house will only run with a call for heat.

I have read about the outdoor reset but I'm confused how they work. Could I get a layman's explanation on them? Please and thank you.

 

[ewdudley]

I understand the natural convection part of the HX to storage idea but I'm confused about the aquastat to run the pump through that loop. When should the pump kick on or off? When the water temp in the return to HX is to warm it kicks pump off or the opposite?

The convection is just to make sure the sensor can see how hot the top of the HX is getting, even if the pump is not pumping.

You don't want the HX-to-storage pump running constantly or else storage will start not-so-hot and will only get good-and-hot at the end of the burn cycle.

When the HX gets hot the pump should run a for a short while and should shut off when the water from the HX cools off a little. This way only hot water goes to the top of storage and you will have hot water available for the water-air-HX, which is important in your design.

 

[ewdudley]

Moving the storage to house pump to the house I thought would be ideal from a wiring stand point but I figured that would cause too much line on the suction side of the pump. I figured that might cause issues which is why I drew it in the garage. Is it because it's in a closed loop that it will be fine once it's primed?

Right. In a closed loop it doesn't matter where the pump is as long as you're not in a situation where "pumping away" is important. What is the elevation change from storage to where the pump would be if it was in the house?

 

[warno]

Right. In a closed loop it doesn't matter where the pump is as long as you're not in a situation where "pumping away" is important. What is the elevation change from storage to where the pump would be if it was in the house?

The plumbing to house will go up the garage wall from the manifold about 2-3 feet Then across the ceiling and drop to the underground line which will be 30" below grade and then it will raise slightly to about 24" below grade in the crawl space. So about 5-6 feet below the supply manifold.

 

[warno]

The convection is just to make sure the sensor can see how hot the top of the HX is getting, even if the pump is not pumping.

You don't want the HX-to-storage pump running constantly or else storage will start not-so-hot and will only get good-and-hot at the end of the burn cycle.

When the HX gets hot the pump should run a for a short while and should shut off when the water from the HX cools off a little. This way only hot water goes to the top of storage and you will have hot water available for the water-air-HX, which is important in your design.

I had to reread it but that makes sense. So put the sensor on the upper line from HX to storage and set the aquastat to cool mode so when it reads hot temps leaving the HX it will pump cool "lower" tank water to cool things down then it goes back to convection mode when it cools down.

 

[warno]

I've posted this same question on another site and someone said that a plate HX may not thermosiphon water. It got me alittle worried about running it that way. It makes sense to not mix the tank water as much as possible but will the HX pull water through just fine convection style.

 

[maple1]

Checked out your drawing in post 53.

The idea of the convection out of the HX (I think) is that it will just convect enough to let the pump control see the heat, and react to it. It likely won't convect much more than that, or won't convect much heat to storage - so the 'other site' feedback on that was right, it won't convect so much that you won't need to pump. As long as there is some uphill slope to it exiting the HX. Like maybe vertical out of it for a short bit to get to & past the pump control sensor, then it can go wherever.

Re. the rest of the drawing - my instinct would likely be to T the expansion tank, in between the HX outlet & the pump inlet. And not the top of tanks. You could put some air vents on top of the tanks to bleed trapped air out. Or just some ball valves you could manually let some air out with. And delete the airtrol. As long as the expansion tank is high up, you shouldn't have air issues since there is no boiler in the sealed part of the system. The higher the better - and maybe also better if you could get it quite far removed from where it is T'd in at to increase the distance air would need to migrate to get from the expansion tank to the system. Like the other side of the garage. As long as the plumbing rises up to it and doesn't have low loops in it. I used an ordinary LP tank for expansion for the first 3 years, sitting on the floor right beside storage. It did OK but did slowly let air into my system over time, I usually needed to bleed one of my zones a couple times a winter, it would airlock. I would still be using that tank if I could have found a high place to put it.

And on the manifold thing - my system has 2 manifolds, supply & return. So my instinct there would be to use 2 manifolds rather than one. And I have just one zone pump, in the house, mounted down low after the return manifold - one dp pump (Alpha) for all of my 5 zones, using the dp pump lets me throttle down my zone flows - the pump will slow itself down to match. The pump will start when any of the zone valves open. And I think with an Alpha, you don't even need to wire it to controls - you can just plug it into a wall outlet and it will sense a zone valve opening and ramp itself up. But I haven't tried that with mine, not sure how good it works in practice. And a big but - a dT pump might work better anyway as you were planning, I have no experience with those either.

Otherwise, what I saw there looks not too bad. From my non-pro & limited experienced view. Which also means that I might have missed something or be out to lunch on something I just said.

 

[warno]

With the expansion on a T fitting will the air flow into the top of the T on its own or will I need an air scoop there? Is it really as simple as a T fitting and nothing else, the pump won't drag air through the fitting?

Everyone keeps saying I shouldn't go with the delta T pump for the storage to house pump. Am I just not understanding what those are for? I was only thinking the delta T would control my return to storage temps to try keeping them as warm as possible.

I just looked through the manual again on the pump I was thinking for storage to house. It says it has setpoint features as well so will this pump work for this location?

Here it is

http://www.supplyhouse.com/Taco-VT2...iciency-Circulator-Less-Flanges-Standard-120V

 

[maple1]

I have no experience with dT pumps so will let someone else answer that one. I do remember some past conversations on whether or not they really did certain things they were advertised to do or not.

There should be no air flowing in your system, or to/from expansion. Only water. As long as it's commissioned properly. Way I did mine, more or less: install a ball valve to isolate expansion from the system, mine was just on the expansion side of the T. (Should also have a drain valve on the expansion tank in case you need to drain it, and a snifter valve on top, & pressure gauge). Before you hook up the expansion tank, close the isolation valve and fill the rest of the system & storage with water (cold fill) to your cold fill psi level (mine was around 8 psi +/-, depends on elevation difference to top of rest of system i.e. in the house). Attach the empty expansion tank. Charge it with air to a couple psi less than the system water pressure. Open the isolation valve. Water will flow up the pipe and ideally into the expansion tank just a bit, until the pressure equalize. Since the system is cold, that is theoretically as close as the air will get to the rest of the system. Then when you heat the system up, more water will flow into expansion - then when it cools off again, water will flow out of expansion but shouldn't drop below the point where it was when cold. It is likely a good idea though to make the expansion tank lots bigger than it 'needs to be' to make sure pressures don't get too high when hot, but also if it's big enough, you don't need to charge it with air - if no precharge, when you open the isolation valve more water will flow into expansion & get the air further away from the system. So to speak. And there will be less chance of air migrating back into the system. Air vents at high points should be good to let air out - tops of storage tanks would be a good spot, air would likely gather there. And piping high spots - any up-down loop can trap air at the top of it and cause an airlock. But also, air trapped at the tops of your storage tank could also serve as additional expansion - as long as the air level didn't get down to the point where it would get into piping. I had that happen to me too once - so I check for air once in a while on top & let it out if there is some there. I haven't had any for quite a while, I swapped out my floor LP expansion tank for a bladder one this fall and that pretty well took care of any air issues.

 

[warno]

I'm planning on an expansion tank of somewhere between 25-40 gallons.

So no air scoops are needed on that T to the expansion? I plan to power prime all the loops when I fill the system so there shouldn't be any air moving around but if some does get in the line will it eventually get picked up into the expansion or bled out the air vents?

As far as a pressure gauge in the system, can it go anywhere or does it go on the expansion tank?

 

[maple1]

They can go anywhere. I think I've got 6 of them scattered around mine. A separate one on the high/air side of expansion will be good for the precharge thing. My 110 gallon expansion was lots for my 660 gallons of storage, likely close to 700 total system.