After a batch is burned ,and I wake up and check my tank for temps,top and bottom are always equal in temps. Is this common for tanks with so little height, or maybe I'am moving to much water not allowing the water to stratisfy.
1000 gallon horizontal tank owners/stratification question
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jebatty
Minister of Fire
My 1000 gal tank is 19' long and 3' diameter. Stratification is extreme. Failure to stratify or to maintain stratification will relate to flow rate between boiler and tank, flow rate between system and tank, how and where the inlets and outlets are plumbed into the tank. and whether or not the plumbing/flow rate is causing some unusual flow pattern within the tank. My tank is boiler supply injected into the tank about 6" from top and at one end of the tank via an extension tube extending about 24" into the tank which "shoots" the supply hot water across the top of the tank towards the other end. Boiler return is from same end of tank as supply and about 6" up from the bottom. Flow rate between boiler and tank is about 14 gpm. Stratification on charging (no system draw) is extreme.
System draw is from top, middle of the tank, and return is into the middle of the tank via a diptube extending to near bottom of the tank. When system is drawing my tank mixes considerably because 1) flow rate is higher than it needs to be and 2) system draw is mixed down to 100F so system return is quite warm to hot and is being returned to the bottom of the tank. This mixing is no issue for me because I only need 100F supply water anyway and I draw my tank down to about 110-120F before recharging, so boiler still has "cold" water return from bottom of tank.
System draw is from top, middle of the tank, and return is into the middle of the tank via a diptube extending to near bottom of the tank. When system is drawing my tank mixes considerably because 1) flow rate is higher than it needs to be and 2) system draw is mixed down to 100F so system return is quite warm to hot and is being returned to the bottom of the tank. This mixing is no issue for me because I only need 100F supply water anyway and I draw my tank down to about 110-120F before recharging, so boiler still has "cold" water return from bottom of tank.
Nofossil
Moderator Emeritus
For sure I'd look at the flow rate. If you have a baseboard system, then your return temps are going to be pretty high - typically 20
lower that the supply temp, so best case you're only going to see 20 stratification after you've been discharging a while. Slowing down the flow rate can reduce the return temperature at the expense of a slight reduction in baseboard output.
As Jim mentions, if it's plumbed so that returning water 'shoots' across the tank the wrong way (bottom to top) then you'll mix the water more quickly. Slowing down the flow rate might help in this case as well.
lower that the supply temp, so best case you're only going to see 20 stratification after you've been discharging a while. Slowing down the flow rate can reduce the return temperature at the expense of a slight reduction in baseboard output.As Jim mentions, if it's plumbed so that returning water 'shoots' across the tank the wrong way (bottom to top) then you'll mix the water more quickly. Slowing down the flow rate might help in this case as well.
maple1
Minister of Fire
I'd go with flow too - it could be load flow, boiler flow, or a combination.
As long as your tank tappings aren't allowing a short circuit through the tank, that is.
Do you know what your boiler flow is? My loading unit is a 15-58 pump, I'm running it on low speed. Boiler & storage right next to each other, so guessing at 5' of head that would be about 5 gpm. Normal burning I have a 20° deltaT through the boiler, which I think is 'normal'. This summer when playing around with my sidearm, when I had everything opened up to that & also pumping by a 15-58 on low, it would really mess my stratification up. That was mainly because I was getting a low DeltaT with it, so when I replaced that 15-58 with an Alpha & throttled the flow down to 1gpm, it helped a lot with stratification. I've become a big fan of Alphas real quick.
As long as your tank tappings aren't allowing a short circuit through the tank, that is.
Do you know what your boiler flow is? My loading unit is a 15-58 pump, I'm running it on low speed. Boiler & storage right next to each other, so guessing at 5' of head that would be about 5 gpm. Normal burning I have a 20° deltaT through the boiler, which I think is 'normal'. This summer when playing around with my sidearm, when I had everything opened up to that & also pumping by a 15-58 on low, it would really mess my stratification up. That was mainly because I was getting a low DeltaT with it, so when I replaced that 15-58 with an Alpha & throttled the flow down to 1gpm, it helped a lot with stratification. I've become a big fan of Alphas real quick.
Nofossil
Moderator Emeritus
I don't use Alphas, but I do drive my 007 and 15-58 circulators with a variable speed drive that accomplishes the same thing. Sometimes getting the flow right makes all the difference. To see if that helps, you can throttle the flow using any manual valve in the circuit. Not a good long-term solution, but it will show you whether changing flow can help.
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