Question about WellMate pressure tank

[ZoneIII]

You folks were so helpful when I had a question previously so I hope you can help with this.

My daughter and son-in-law just bought a house. It's a large house, about 15 years old, with four full baths, a sprinkler system, etc., and it has a big WellMate WM35-WB pressure tank (120 gallons). I've had a well for over 35 years so I know that they have to be maintained but the old owners of the house my daughter bought told them that their pressure tank required no maintenance. I knew that wasn't true so I checked it out. Sure enough, when the tank is de-pressureized, the pressure was only at 20 pounds. (Their cut-in pressure was set to 35 lbs and the cut-off pressure was at 60 pounds. I'll probably adjust the cut-in pressure to 40 pounds.)

Anyway, I brought along a small air storage tank (10 or 12 gallons) that I pumped up with my big compressor so I could increase their pressure, if necessary - which was necessary. When I hooked up my air tank, it took all the air in the tank until it neared 20 pounds, of course, but that only raised the pressure in the tank to 21 pounds. (As you know, with this WellMate tank, the air is in the bladder.) So, my question is, does itsound right that I only raised the pressure one pound with my portable air tank? Could it be that the large volume of the 120 Wellmate tank takes a lot more air to increase the pressure or do you think the bladder is ruptured? (I emailed my son-in-law and told him to let some air out of the air valve and see if any water comes out but he hasn't got back to me yet.)

How long, on average, can you expect an air bladder to last? I think their house is about 15 years old and the tank would be the original tank.

The first question is my most important one but, since I'm here, I have a couple more that I'm curious about:

I was surprised to see that his well pump is on fuses instead of circuit breakers. That's no problem and my own old house is still entirely on fuses but I'm just curious if there is a reason that their newer house would use fuses for the well pump. Is there some advantage of fuses in this application?

Lastly, I've always pressurized my own tanks to 2 pounds below cut-in pressure but I see that WellMate recommends it be set to 4 pounds below cut-in pressure. That's no big deal but I'm just curious about why they recommend that. Is it something about the design of the tank?

Thanks,
Tom

 

[Reach4]

>So, my question is, does I sound right that I only raised the
> pressure one pound with my portable air tank?

Sounds about right. But then there would be the question of the repetablity of your gauge and whether you lost a little air during the process.

>Could it be that the large volume of the 120 Wellmate tank
>takes a lot more air to increase the pressure

yes.

>How long, on average, can you expect an air bladder to last?
>I think their new house is about 15 years old and the tank
>would be the original tank.

I don't know. That WellMate WM35-WB tank has a replacable bladder. It is not cheap. Not trivial swapping out the bladder. But it sounds like that tank has given good service.

>Lastly, I've always pressurized my own tanks to 2 pounds below
> cut-in pressure but I see that WellMate recommends it be set to
>4 pounds below cut-in pressure. That's no big deal but I'm just
>curious about why they recommend that. Is it something about the
>design of the tank?

I doubt it is the design. That extra could compensate for differences in the gauges, but it does not indicate why they recommomend more difference than others. If your gauge at the pressure tank had a lazy hand (tattletale ) it could record if the pressure dropped excessively to indicate that there was too much precharge.

 

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[LLigetfa]

...I emailed my son-in-law and told him to let some air out of the air valve and see if any water comes out...

That test almost never is of value. Most often the air valve is at or near the top so the tank could be 98% waterlogged yet air, not water comes out during the test.

The true test is to measure the drawdown and compare it to published specs.

 

[ZoneIII]

That test almost never is of value. Most often the air valve is at or near the top so the tank could be 98% waterlogged yet air, not water comes out during the test.

Yes, I realize that if no air comes out of the valve, that doesn't prove that the bladder is good. But it would prove that the bladder is bad if water did come out. So one result of the test would be conclusive and one result would be inconclusive. That makes it worth doing. BTW, my son-in-law let some air out and no water was present. That simply means that we still don't know if the bladder is bad, of course.

Someone emailed me with another test to try and my son-in-law is going to do that. If that test comes out O.K., I'll take a larger air tank to his house later this week and see if we can get it up to the proper pressure.

Thanks for the replies, folks! I appreciate it.

If it needs a new bladder, it won't be any problem for me to do it. I've done it before and I work on everything. It's just a PITA. Also, they have a buyer's insurance policy which may cover it if the bladder is ruptured. I'll post what I find out later this week. I'm going out to their house on Wednesday to try to pressure the tank up again but this time I'm taking a larger air tank that also holds more pressure.

 

[LLigetfa]

Yes, I realize that if no air comes out of the valve, that doesn't prove that the bladder is good...

If no air comes out, it would likely mean the air leaked out through a hole in the bladder. Of course the air could have escaped through the valve or the side of the tank or the valve just plain doesn't work.

I still contend that a drawdown test has more value and is very easy to do.

 

[Valveman]

You will wear yourself out making trips with an air tank. It takes several minutes to air up a tank that size when using a good compressor. I have a WM6 I have to air up every 2 or 3 years. It takes a little compressor a few minutes even for that small of a tank (20 gallon). It is buried or I would have already replaced it, just lazy.

 

[Justwater]

when power is off and tank is drained, open a faucet and use a compressor to pump it up to whatever you need. then shake the tank, if its empty you are ok. turn power back on and close faucet.

 

[Reach4]

If it needs a new bladder, it won't be any problem for me to do it. I've done it before and I work on everything. It's just a PITA. Also, they have a buyer's insurance policy which may cover it if the bladder is ruptured. I'll post what I find out later this week. I'm going out to their house on Wednesday to try to pressure the tank up again but this time I'm taking a larger air tank that also holds more pressure.

Wouldn't it be easier to take (or borrow) a 1/2 HP or more compressor? Don't go with one of those vibrating "250 PSI" tire pumps. You need some CFM.

When you work the math, with a 20 gallon tank, you will have a combined volume of 140 gallons that you will end up with 36 PSI air in. The big tank will go up by 16 PSI. 120 * 16 = 1920 PSI-Gallons. (non-standard convenient units. ) of air. To move that much air, the 20 gallon tank would need 1920/20= 96 PSI above 38 PSI for a total of 134 PSI to start.

Now my math or physics maybe off. But if it is, I could be off either side. I welcome somebody to do a better calculation.