I noticed at my parents' home that the water pressure was surging every 15 seconds or so with a fixture open. I went downstairs and found that the Amtrol had no precharge. I charged it with a bicycle pump and adjusted pump cut in and cut out to maintain 25 psi at the topmost fixture (a shower head). But I am now worried that I did not use nitrogen or dry air as the Amtrol manual states. Am I risking tank corrosion/explosion/injury?
Is it crazy to recharge a bladder tank with a bicycle pump?
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How do you measure the pressure at a shower head? Anyway, if the pressure at the pressure switch area is about 26 when the pressure switch cuts on, you would set the air precharge 2 PSI lower, or 24.
Now how did the pressure get down to zero? That tank diaphragm may be leaking and be on its last legs.
How do you measure the pressure at a shower head? Anyway, if the pressure at the pressure switch area is about 26 when the pressure switch cuts on, you would set the air precharge 2 PSI lower, or 24.
Now how did the pressure get down to zero? That tank diaphragm may be leaking and be on its last legs.
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Gary Swart
In the Trades
In reply to the original question. The instructions for the Watts thermal expansion tank is to use a bicycle pump. Reason is, the volume of air require is quite small, and a large pump could very easily over inflate and break the bladder. That said, I use my shop air compressor but I was v-e-r-y careful and used very quick, short squeezes on the air valve. Just have to remember the difference in pressure and volume.
Jadnashua
Retired Defense Industry Engineer xxx
Dry air or nitrogen might have a slight advantage, but consider that 'plain' air is mostly nitrogen in the first place. Nitrogen is a slightly larger molecule (N2) verses O2, which is one reason why some prefer it. H2O expands and contracts more with temperature changes, but the real effect is probably noticeable at a track, but in typical real-world use...it's not worth the effort.
The amount of moisture in the air pumped into the tank can promote some rust...but, once all of the O2 is used, up, things cannot continue to rust! Most of the rest of the stuff in 'plain' air are relatively inert, and not likely to cause a problem.
IOW, in an ideal world, yes, it might be best to use nitrogen or dry air (this time of the year in many places, it's already quite dry), but the difference long-term is not likely to be measurable by the average user.
FWIW, to properly adjust the precharge in the tank, you need to shut off the pump, open a valve and let all of the pressure bleed off as the bladder expands. Then, adjust the precharge, then close the valve and turn on the pump...you can't accurately adjust the air pressure with pressurized water on the wet side of the bladder.
The amount of moisture in the air pumped into the tank can promote some rust...but, once all of the O2 is used, up, things cannot continue to rust! Most of the rest of the stuff in 'plain' air are relatively inert, and not likely to cause a problem.
IOW, in an ideal world, yes, it might be best to use nitrogen or dry air (this time of the year in many places, it's already quite dry), but the difference long-term is not likely to be measurable by the average user.
FWIW, to properly adjust the precharge in the tank, you need to shut off the pump, open a valve and let all of the pressure bleed off as the bladder expands. Then, adjust the precharge, then close the valve and turn on the pump...you can't accurately adjust the air pressure with pressurized water on the wet side of the bladder.
Bicycle pump isn't any difference than an electric compressor, except for the larger the tank the more exercise you will get. It could take hours of hard work to air up an 80 gallon diaphragm tank. LOL
Like the others are saying, air doesn't usually get out of a bladder tank unless the bladder is broken. So called "normal cycling" every minute or two will eventually break the bladder, causing the loss of air, and start cycling the pump every few seconds instead. Even "normal cycling" is not good for the pump, then when the bladder breaks and rapid cycling occurs, the pump isn't going to last much longer.
Like the others are saying, air doesn't usually get out of a bladder tank unless the bladder is broken. So called "normal cycling" every minute or two will eventually break the bladder, causing the loss of air, and start cycling the pump every few seconds instead. Even "normal cycling" is not good for the pump, then when the bladder breaks and rapid cycling occurs, the pump isn't going to last much longer.
"How do you measure the pressure at a shower head? "
In this case I just measured the height difference to get the gravity head, then estimated pipe friction loss. I also have a brass 1/2" tee that I can put in behind the shower head, with a pressure gauge on the branch port. But didn't have it with me.
"Anyway, if the pressure at the pressure switch area is about 26 when the pressure switch cuts on, you would set the air precharge 2 PSI lower, or 24."
Ok, yes, I did this, thank you.
"Now how did the pressure get down to zero? That tank diaphragm may be leaking and be on its last legs."
Thank you! I'll check it again (it's been a month or so since I charged it). Amtrol manual had a strong warning about drain plug needing to be air tight. Is it common for it not to be tightly sealed?
In this case I just measured the height difference to get the gravity head, then estimated pipe friction loss. I also have a brass 1/2" tee that I can put in behind the shower head, with a pressure gauge on the branch port. But didn't have it with me.
"Anyway, if the pressure at the pressure switch area is about 26 when the pressure switch cuts on, you would set the air precharge 2 PSI lower, or 24."
Ok, yes, I did this, thank you.
"Now how did the pressure get down to zero? That tank diaphragm may be leaking and be on its last legs."
Thank you! I'll check it again (it's been a month or so since I charged it). Amtrol manual had a strong warning about drain plug needing to be air tight. Is it common for it not to be tightly sealed?
Yes, I did it this way, thank you!
Not common. Those often go years without much air loss. Precharge air pressure can only be measured with the water pressure zero. Otherwise, the air pressure will pretty much match the water pressure. This is not to say there could not be a valve failure. The valve core can be replaced with one made for tires. A little soap bubble solution or spit would let you check for a valve core leak. Don't expect the valve stem to leak. I think it is welded in place.
If you do have a leak inside the tank, even a bad one, you can work around it by adding air periodically. Air contacting water will get dissolved in the water, so it has to be replenished. Once you have established there is a leak, you want a new tank, so you don't have to add air every week. The diaphragm normally separates the air and water, so the air stays for long periods. Well-X-Trol recommends checking annually, and some other makers suggest every 6 months to check.
A compressor on a 44 gallon pressure tank, is much easier than a manual pump. Avoid the "250 PSI" tire pumps they sell.. They tend to be really slow. If you get a compressor to help with such stuff, you want to see a cubic ft/minute spec "Bicycle pumps" can vary in how much air they move.
Jadnashua
Retired Defense Industry Engineer xxx
As important, if not more than the Schrader valve on the tank, is the quality of the cap on the air valve. Better ones have a gasket in there to seal things. Cheaper plastic ones may not have a gasket and rely on the plastic deforming to make the seal...avoid those, even on your car!
The valve core provides the main seal I think. A cap with as seal could be a supplement. There are differing opinions on this.
Plastic valve caps are used by car OEMs and tire places usually. No need to seek out upgrades.
For a pressure tank where you might go years between adding air, a dual seal probably has an advantage. I expect the cap provided with the tank to have the appropriate seal. My Flexcon Challenger has a rigid plastic cap that appears to have a rubber seal.
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Jadnashua
Retired Defense Industry Engineer xxx
True, and metal ones are an expensive mistake if you have a metal stem TPMS in your wheel! But, a quality valve cap does have a gasket in it, whether it's plastic or metal. The plastic OEM ones on my cars do have a rubber gasket in them. They cost a bit more than an all plastic one, but do work better.
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