Sidearm questions

[Dune]

I got my long awaited SuperStor yesterday. Turns out it is a SuperStor brand storage tank, not and indirect water heater. After my initial disapointment, I realized I could still use it with a sidearm.

First question, which way should the boiler water flow, with the domstic water (uphill) or against it (downhill)?

Second; My heat loop is 1" pipe. Would it be helpful to have the sidearm be larger (1.5" or 2")?

Third; Would iron pipe be good for the outer pipe?

 

[Dune]

Little help anyone? I did use the search feature and did not find the answers in any of the threads I read.

 

[kabbott]

Boiler flow should be top to bottom, opposite of the DHW gravity flow.
My sidearm is 3/4 inside and 1 1/2 outside, for 1 inch loop 1 1/4 or 1 1/2 should be fine. You can still use 1 inch connections( via reducer or reduced tee)
If you use iron outer pipe you may run into problems with expansion if the inner pipe is a different material, depends on the design I suppose but I think
all copper is easier and not THAT costly so why chance it.

Best thing about a sidearm is it's simplicity....try to keep it simple and it will just quietly do it's job.
There are plenty of post about there construction including my own which is brazed together but they are very easy to do with fittings and soft solder.
I have some pics on here of mine somewhere, search for DIY sidearm.

 

[Dune]

O.K., I found a piece of 1 1/2 copper, next question, can I draw the hot water out of the tee at the high point on the tank? (where the side arm tees in) It seems that under a long draw off, I will be bypassing the tank and the sidearm will not keep up.
There are only three fittings on this tank, all on the side, one ate the bottom, with a drain, one a third of the way from the bottom, and one near the top. If not, I will have to inlet the cold water at the bottom, draw hot water from the next lowest fitting and the top fitting will be just the sidearm and the p/t relief.

Any help greatly apreciated.

Also, if I draw the hot water from the lower third of the tank and feed the cold at the bottom, it seems possible that sometimes I will end up drawing cold water while leaving a two thirds of a tank full of hot water behind.

 

[Duetech]

My side arm is a home made mix of hard copper and iron I see you already have copper so that is fine. Just remember the inner and outer pipe diameters should allow for the actual flow size of your system. Since yours is a one inch system, once built, the displacement of the inner pipe should be small enough to allow the equivilence of a one inch flow through the outer pipe. For instance 1" (id) copper (for the dhw) with 1/16" thick walls has a rough .91 inches of area. 1.5" (id) pipe has a rough 1.77" of area. Subtract .91 from 1.77 and you have .86" of area remaining which means a 1" inner pipe is too big and will restrict the flow and so you should use 3/4" for the inner pipe instead of the 1". Or go to a 2" outer pipe.

Most hot water heaters use a long pipe (drop pipe) to supply cold water to a water heater and a short pipe to siphon/draw hot water out of the top. Your concern of eventually drawing cold water out ot your tank is a valid concern. You should arrange your sidearm so it draws off of the bottom and returns hot water to the top. With your set up I would use 2 T's out of the top. One to tie in the sidearm then extend out to the second T and feed the house demand and extend again for your P/T relief.

 

[Dune]

Thanks Cave. So the cold water should enter at the middle fitting?

 

[Duetech]

Thanks Cave. So the cold water should enter at the middle fitting?

It would work just fine if you built your own drop pipe. That would give good stratificarion and cause the domestic water to exit the top just like a conventional hot water heater.

 

[Dune]

Thanks Cave. So the cold water should enter at the middle fitting?

It would work just fine if you built your own drop pipe. That would give good stratificarion and cause the domestic water to exit the top just like a conventional hot water heater.

With a drop pipe, it seems like I would be sending cold water towards the inlet of the sidearm, so when drawing hot water I might just be pulling cold water through the sidearm.
Am I overthinking this?

 

[Duetech]

My gas hot water heater has a long drop pipe for incoming water and an outlet for hot water. My sidearm is connected to the drain outlet and the pressure relief valve outlet. Cold water coming into the tank is heated a little in the drop pipe by passing through the hot water then it blends with what ever water the turbulence of the flow causes. It takes a while for my tank to run out of hot water. (about as long as it did when it was stricly gas)

If you do not use a drop pipe stratification will help prevent cold water from getting into your dhw supply if the turbulence is too great and or the demand isn't for very long. A short drop pipe will direct the flow downward and away from the hot water outlet and should promote a longer use of the stored hot water. I don't know how big your SuperStor tank is but if it is 40 or 50 gallons it should supply you with ample hot water unless you have a very big demand.

As far as "overthinking"?? If the tank is non returnable you need to look at every aspect to make it function right the first time. You surely don't want a waisted effort. I'm not a pro but I do know that sometimes the best way to turn a good question into a dumb one is by not asking it. The normal hot water tank has one more plumbing outlet than your tank. That is a challenge.

 

[Dune]

It is a challenge. The tank was free so yeah, it is non returnable. The tank is 50 gallons and has 1" ports, so I have room for a drop pipe. I will give that a try. Thanks for your help.

 

[Dune]

O.K., I think I've got it. Cold water getting drawn through the sidearm will get heated on it's way up any how, plus with the one inch port, more water should come out of the tank than through the sidearm anyway. That combined with the fact that I am going to run the tank very hot and mix the hot water anyway means it should work fine. Again, thanks for the help.

 

[Duetech]

Be sure to use plenty of ball valves and a couple of unions on the pipe for the tank so you can back flush the the core of the side arm periodically especially if you don't have soft water. I have to flush mine about once a year.

 

[Dune]

Thanks, I plan to do just that.

 

[Gooserider]

Be sure to use plenty of ball valves and a couple of unions on the pipe for the tank so you can back flush the the core of the side arm periodically especially if you don't have soft water. I have to flush mine about once a year.

There are a couple of neat Webstone brand valves I've seen pointed at that would be really good for flushing the HX - essentially they combine a shutoff and a hose bib - there was a recent thread on cleaning out a flat plate HX that showed them, I think I put it in the "tidbits" sticky - no reason I can see that you couldn't use the same valves on a sidearm...

Gooserider

 

[Dune]

Thanks Goose, I will look into that.