Wellmate hydro-pneumatic water pressure tank questions

[robfun]

First time posting here, so go easy on a newbie

Had a plumber in to replace a leaking pressure water switch. (something I'll do myself next time). He told us the bladder in our tank is busted and we need to replace the tank. He pushed air in the top of tank to clear out any sludge and the air was coming out the blow down valve. I’ve done some more reading and I don’t believe he’s correct.

We have model Wellmate UT-150-SQ, which I believe is set up as a hydro-pneumatic tank since there is an air intake (micronizer-like) before the tank and plastic/vinyl tubing running from the top, although it doesn't appear to have an air volume control (AVC) unit attached. The top of the tank also has an air inlet valve, like a standard bike tire valve.
pic attachment link is here:

Questions:
Bladder:
Am i correct that the tank does not have a bladder? I read “One piece, seamless inner shell molded of premium high-density polyethylene which provides impact and corrosion resistance”: http://www.wellmate.com/files/knowledgebase/itemdownload/en/4003265-utseries-specsheet-mr14.pdf

AVC:
From the diagram here http://www.wellmate.com/Files/KnowledgeBase/ItemDownload/en/20198-ut-hp-sp-tanks-install-mr14.pdf
, I expect an AVC unit to be attached to the plastic/vinyl tubing from top of unit. There is no AVC. The piping runs upward and is connected with a T to the discharge lines from our water treatment systems. These lines then run down to sump pit (lines are not submerged). There is currently water in the pipe at top of tank. I’m not sure if the water is coming from the tank or is discharge from the treatment systems. Current setup allows for air to push out with resistance of water in line, but not easily drawn in. Is this okay?

Air Pressure:
What is the correct air pressure inside the tank and how should it be measured in the tank?

• Should the tank be empty (not likely, since no bladder)?
• Should it be full? (if yes, how full? Or does it matter?)
• Should air pressure in tank equal the current water pressure in the tank? Or be 2 psi below like with a bladder tank?
• Right now the water pressure shows 44 psi and the air pressure tank shows 40 psi. Is that okay?

Cut in/out:
The plumber set a 30 differential for the cut in / out. Is 30 / 60 set up okay for the tank? Maybe, not a question that can be easily answered without knowing more specifics.

 

[VAWellDriller]

I've put in a lot of these....this one looks a little different on the top; I think it's just really old.
There is no bladder.
There is an air volume control in the tank connected to the tube coming out. The tube is the vent for excess air in the system.....if the tank is there for sulfur treatment it will burp out a stinky fart every so often, so we run the tube outside or to a location where it doesn't matter if it stinks. In a hydro tank, the air pressure and water pressure are always the same and if you are getting any difference now it is because your gauges are inaccurate.
If working properly, which means there is some device (micronizer, bleed back, or air compressor) the water level would be a little less than half the tank and it would vent out excess air every few days.
The pressure differential is fine, doesn't need to be that much, but if you are happy with your water pressure leave it. The more important thing is to watch the pump cycle and see how long it takes to get from 30-60....like to see a minute or more; the longer the pump cycle the better as far as pump life is concerned.

 

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[LLigetfa]

He pushed air in the top of tank to clear out any sludge and the air was coming out the blow down valve.

Air should also be releasing from the AVC but if he puts the air in faster than the AVC can vent it, it will come out the blow down port. The AVC is a float on the end of a dip tube. It can and does get gummed up with iron and needs to be cleaned periodically. I purchased a spare so that I could soak the old one in Super Iron Out for a few days to clean it.

If your micronizer is still drawing air and the AVC quit venting, you might see air move forward through your plumbing and spit out the taps. Sometimes the air will just collect in the top of a softener or iron filter and get purged when they backwash.

 

[VAWellDriller]

Air should also be releasing from the AVC but if he puts the air in faster than the AVC can vent it, it will come out the blow down port. The AVC is a float on the end of a dip tube. It can and does get gummed up with iron and needs to be cleaned periodically. I purchased a spare so that I could soak the old one in Super Iron Out for a few days to clean it.

If your micronizer is still drawing air and the AVC quit venting, you might see air move forward through your plumbing and spit out the taps. Sometimes the air will just collect in the top of a softener or iron filter and get purged when they backwash.

Sounds like the plumber was doing this with system empty of water....he thought it was a bladder tank and was trying to set pre-charge.....

 

[robfun]

Sounds like the plumber was doing this with system empty of water....he thought it was a bladder tank and was trying to set pre-charge.....

Correct, the blow down valve had been opened and water had finished running out. He checked the air pressure on top of the tank and it read zero, so he thought the bladder had a rip in it. He said there was still water in the tank and so they used an air compressor to inject air into the top of the tank through the bicycle tire type of valve (i forget the correct name) to try and force the water out. That air they pushed in the top was coming out the blow down valve, so he suspected a torn bladder. Said I should replace the tank soon because even though it's working well know, it'll be putting strain on our water pump soon.

 

[VAWellDriller]

Why will it be putting strain on the pump soon? As long as it's not leaking this tank should never need replacement. You may have to work on whatever external air adding device you have and you may need to remove/clean the avc.

 

[LLigetfa]

On my WellMate HP tank, I periodically plug the air line so the AVC cannot vent. Then I inject air through the schrader valve while I purge the line to the iron filter. When the level in the tank drops, a mixture of air and water flushes the iron deposits out of the line. The air/water mixture also creates a violent boiling like action in the iron filter giving the media bed a good shake-up. If your iron filter doesn't have a top basket, then you need to be careful not to move too much air at once or the media will carry up into the valve journals in the head. Don't ask me how I know.

 

[LLigetfa]

You may have to work on whatever external air adding device you have

I keep a spare micronizer too as they are a high maintenance item. They need to be checked often to see if they are still drawing air.

 

[robfun]

Thanks everyone for the replies! I can upload a pic of our setup if that would help. The micronizer device (plumber called it a massey injector) has good suction. Here are a few more questions:

The pressure differential is fine, doesn't need to be that much, but if you are happy with your water pressure leave it. The more important thing is to watch the pump cycle and see how long it takes to get from 30-60....like to see a minute or more; the longer the pump cycle the better as far as pump life is concerned.

Thanks for the insight and input! We're happy with the water pressure. With the current 30/60 setting, pump runs for 25 seconds when I turn off main water valve after cut-in. If I leave the taps open and flowing, the pump runs for 45 seconds. The tank has a max of 75 psi. Should I consider increasing cut out to 70 to extend the pump cycle?

There is an air volume control in the tank connected to the tube coming out. The tube is the vent for excess air in the system.

Do you think it's fine to have the external AVC tube connected to the discharge lines from our water treatment systems? The AVC tube is currently filled with water - is that okay? Does the AVC need to be able to draw air into the tank or only be able to expel it out? If it needs to draw air in, I don't think the current set up will allow it.

I'm wondering if the current setup is in place to capture the expelled air (maybe sulphur smelling) in the line until the water treatment systems discharge. This would cause the sump pump to run, maybe drawing out some of the expelled air.

Otherwise, I can pretty easily disconnect the AVC tubing from the water treatment line and run it down to our sump pit to ensure there is no water in the line. Anyone think that would be a better set up?

Why will it be putting strain on the pump soon? As long as it's not leaking this tank should never need replacement. You may have to work on whatever external air adding device you have and you may need to remove/clean the avc.

The plumber thought it was a bladder tank with a torn bladder with zero air pressure at the top, so he said it would be putting strain on my pump. Now that I know it doesn't have a bladder and is working fine, I know it's not putting strain on the pump. My wording was a bit confusing. Hopefully this clarifies.

 

[LLigetfa]

Air from the AVC tube only discharges mostly air but if the float is in need of servicing, it may also discharge a little water. I run mine down to my sump pit. Odd that yours is full of water.

The position of the float is such that trapped air should be just above the outlet of the tank during normal use meaning not below the kick-in pressure. This supercharges the tank over time. If the pressure were to drop below the kick-in and the AVC cannot discharge the air fast enough, then the air will move forward into the iron filter or softener.

When you drain the tank to zero, you lose that extra amount of air and so the pump cycles will be shorter than normal until your micronizer restores the lost volume of air. After I service my system I always charge the tank with a compressor to regain the supercharge.

 

[robfun]

If I have about 1L of water per week coming out of the AVC, do you suspect I need to replace the AVC or just clean it?

 

[Boycedrilling]

If it was me, I would replace the avc with a new one. Then see if I could clean the old one with CLR.

I have installed one of the Wellmate hydropnuematic tanks. It was on a well that had a naturally occurring gas that was entrained in the water. I ordered an extra AVC at the time, but I haven't had a service call in the 8 or 9 years since I installed it.

 

[Reach4]

Right now the water pressure shows 44 psi and the air pressure tank shows 40 psi. Is that okay?

One minor thing... you probably have a difference in calibration between your air pressure gauge and your water pressure gauge. The air pressure in normal static conditions would be the same as the water pressure at the top of the water in the tank. The water pressure at that point would be only 0.433 PSI lower for each foot that that level is higher than the water pressure gauge. So there is probably an actual difference of less that 2 PSI. It's not a big deal.

 

[robfun]

I've picked up a replacement AVC Model # CH11177 (cost $113 CDN with tax) and am in the middle of trying to replace it.

I can't get the existing AVC to budge. I'm using a slip & lock nut wrench with a 3" capacity, but not having any luck getting it to move. Anyone have any tips to loosen it up? If my wrench had longer sides it would have better grip. Any other better tools out there?

 

[Reach4]

What are you trying to grip onto -- a 1-1/4 hex, or what?

 

[robfun]

I'm trying to grip onto the dark grey part shown in the picture in the first post. It's the top of the AVC that unscrews from the tank. It has a 3" distance from flat side to flat side, which is why my wrench has a 3" capacity.

 

[Reach4]

How about an inverted bench vice, removed from the bench?

 

[robfun]

How about an inverted bench vice, removed from the bench?

My bench vice only has a capacity of 2 - 3/4", which is too small. Even if I did have more capacity, I'm not sure how I'd get leverage to move the bench vice.

 

[robfun]

I picked up some high capacity channel lock pliers and still couldn't get it to budge. Had to have someone hold the tank while I heaved on it.

 

[LLigetfa]

I used a wooden handscrew clamp.