Thermal Expansion Tank instead of....help please

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rafjr64

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Due to the cost of a standard diaphragm tank, I am wanting to use a thermal expansion tank as my pressure tank for my water well. Any reason I cannot do this? Major company offers a pressure tank for $1200 and their thermal expansion tank is half the cost that but made with the same specs (actually higher rated psi on the thermal exp tank). Heard that a lot of people do this. Probably a secret the well industry would like to keep quiet.

Thx in advance,
Rich
 

Reach4

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I expect the thermal expansion tank is much smaller giving a much smaller drawdown. Even if the nominal size were the same, I would not be so confident. Do you have part numbers for comparison?
 

rafjr64

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I expect the thermal expansion tank is much smaller giving a much smaller drawdown. Even if the nominal size were the same, I would not be so confident. Do you have part numbers for comparison?

Well, first off I am replacing two 120ga air over galvanized tanks used for house supply and irrigation.
The expensive WX-350 is the one I cannot afford. The ST-210V is the one I am considering.
Is it true that an old air over galvanized tank can be replaced with a diaphragm tank half the size?
Rookie at all this. Appreicate your time.


pump 13GS10 (1hp)
Well gpm = 18gpm
Depth 51'
Static 21'
1.25" supply pipe
40/60 on the switch
 

Texas Wellman

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What is wrong with the old galv tanks? Be warned that sometimes when you go from a hydropneumatic to a captive air tank it can make the water smell where it did not before.
 

Reach4

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I think your pump may not have been chosen optimally. 13 GPM is a lot, but from that depth I think you would have been better with 3/4 HP. I would have to check the charts to be sure.

Regarding ST-210V, I don't see the hole in your thought, but I have not yet looked at the prices. Maybe check your inbox later.

Is it true that an old air over galvanized tank can be replaced with a diaphragm tank half the size?
No, that is not true -- presuming that you have something that adds air. They got those figures saying what if somebody does not add air, but instead drains the tank of water periodically so the tank starts with atmospheric pressure air. I was shocked when I realized that.
 

rafjr64

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What is wrong with the old galv tanks? Be warned that sometimes when you go from a hydropneumatic to a captive air tank it can make the water smell where it did not before.

A lot of crud at bottom of tanks. Water test at tanks showed lead, aluminum, iron, zinc, manganese. Open drain valve on tanks and it's brown, rusty and ugly. Water test at kitchen sink showed clean. I guess sediment filter and softener are cleaning it fairly well. These tanks have been here quite awhile.

Objective is to get a read on the water I have so I can get a new softener system.
 

rafjr64

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I think your pump may not have been chosen optimally. 13 GPM is a lot, but from that depth I think you would have been better with 3/4 HP. I would have to check the charts to be sure.

Regarding ST-210V, I don't see the hole in your thought, but I have not yet looked at the prices. Maybe check your inbox later.

The previous owner has two 120ga tanks here. I don't know why. Perhaps to irrigate the walnuts and supply the house at same time. Or perhaps to maintain a lot of water storage. The Goulds 13GS10 has a flow range from 4-20gpm.

Anyway, back to the topic at hand. Is there anything functionally different between a well pressure tank and a thermal expansion tank?

both made by Amtrol
both diaphragm style
both made of same construction method
both polyprop lined
both stainless fittings
thermal tank has higher psi rating (makes sense cuz of heat)
thermal tank has 1yr warranty vs. well tank has 7yr warranty (is that also due to heat vs. water usage??)
 

Reach4

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They both have a maximum 150 PSI working pressure spec.
 

PumpMd

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If your standard tanks are not leaking I would keep them, for possible smell problem & the huge drawdowns that these tanks provide. All you have to do is maintain the Precharge in both tanks. Best thing about them is that they have no bladders to go bad, this is why the standard tanks almost last forever but they will eventually rust out.
 

Valveman

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Yeah with that much crud in the water you need to stay away from diaphragm type tanks. All that crud will not have any place to settle and it will come in the house along with extra smell because the water will not get aerated.
 

rafjr64

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If your standard tanks are not leaking I would keep them, for possible smell problem & the huge drawdowns that these tanks provide. All you have to do is maintain the Precharge in both tanks. Best thing about them is that they have no bladders to go bad, this is why the standard tanks almost last forever but they will eventually rust out.

I believe that is what we are witnessing; the tanks are rus
Yeah with that much crud in the water you need to stay away from diaphragm type tanks. All that crud will not have any place to settle and it will come in the house along with extra smell because the water will not get aerated.

I believe the crud is due to the tanks rusting out and any dirt will get filtered by the sediment filter, no?
 
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