Diagnostic Suggestions for Drain Back Valves, Bleed-Back Systems & Snifter Valves for Well or Lake Pipe Freeze Protection & Air Volume Control:

This article describes well piping or lake water supply piping freeze up problem diagnosis: air charge problems on drain back well or lake water systems can cause frozen pipes & water equipoment damage. Here we explain how to diagnose trouble with the snifter valve or drain back valve or the system's air volume control valve.

This article series describes snifter valves and drain-back valve , what they are, how they regulate air in a well water system, how they work with an air volume control, & how these components protect well piping against freezing.

Troubleshooting Frozen Well Pipes on Drain-Back Valve, Dill Valve, & Snifter Valve Systems

How to Test the Snifter Valve

[Click to enlarge any image]

It's easy to check the snifter valve to see if it's working.

1. Turn on the water pump
   
   if it was off. The pump will run until it has pressurized the system and been turned off by the pressure control switch.
2. Open a faucet and drain water pressure
   
   until pressure falls enough to turn on the well pump.
3. Confirm pump turns on:
   
   Since the pump itself is a submersible unit in the well (or under water in a lake) you won't hear the pump run but you can hear the pump relay click to turn it on;
   
   and some pump controls include a "pump on" light.
   
   If you're still baffled, just turn off the pump electrical power and run water until flow is weak at the tap. Then turn the pump on.
   
   You will see a surge in water pressure when the submersible well pump turns on
   
   
4. Then turn off the faucet
5. The water pump will run until
   
   it has re-pressurized the system enough for the pump pressure control switch to turn it off.
6. Repeat this cycle a few times.
   
   At each pump-off cycle water should be draining out of the water piping through the drain back valve and back into the well (or lake). Water draining out of the pipe should draw air into the piping system.
7. When the pump stops and as water is draining out of the pipe system
   
   you should feel a vacuum at the inlet of the snifter valve. Remove the snifter valve cap. When the pump stops put your finger over the valve stem opening. If you don't feel a vacuum the valve is probably not opening as it should.
8. You might also hear air entering the snifter
   
   if the valve is at work.

Four Signs of a Failed Snifter Valve on a Bleed Back Valve Water System

1. Water leaks at the valve
2. No vacuum at the valve inlet when the pump turns off
3. Short cycling well pump
4. Freezing well or lake water supply piping

In our snifter valve photo at above left my finger points to the stem of the snifter valve. Stains on the floor show that there has been leakage at this particular valve.

We have a clue that the snifter valve shown in our photo had not worked for years and was also leaky. Take a look at the floor: you can see the copper stains below the snifter valve and check valve.

How did the owners get away with this leak?

Their well piping was buried at more that eight feet below ground: below the frost line in their area of Northern Minnesota.

So the owners didn't have a problem with freezing well piping.

But they did report a long-standing problem with a water-logged water pressure tank whose well pump short-cycling shenanigans had been dealt-with by manually adding air to the pressure tank at frequent intervals. That solution eventually proved tiresome and unpleasant.

See WATER PUMP SHORT CYCLING.

For this property the owners decided to trash the whole bleed-back system and change out their water pressure tank.

See DRAIN BACK / SNIFTER VALVE CONVERSION to BLADDER-TYPE WATER TANK

How to Test the Air Volume Control

Air volume controls are found only on bladderless water pressure tanks - tanks that do not use an internal bladder tokeep water and air separated.

• On a drain-back water system if the air volume control is working properly you will at least occasionally hear air hissing out of the excesss air release port on the AVC (blue arrow in the photo at left).

Principal Sign of a Failed Air Volume Control on a Bleed Back Valve Water System

• If the air volume control is not working on a drain-back system, because each pump on cycle is pushing a lot of air into the water tank you will ultimately see air spurting out of the building's plumbing fixtures such as faucets. That's because the AVC is not releasing the excess air in the system.
  
  See AIR DISCHARGE at FAUCETS, FIXTURES

Keep in mind that on a drain-back or bleed back water system in which we are emptying water piping of water each time the pump turns off, the job of the air volume control (AVC) is to release excess air from the water pressure tank. This is opposite of the job of AVCs on other water supply systems in which the AVC is supposed to add air to the water pressure tank.

If the AVC is not working properly on a non drain-down water systems you will find the opposite problem: a water-logged pressure tank causing well pump is short cycling.

See WATER PUMP SHORT CYCLING

Watch out: short cycling can still occur on a drain-down (bleed-back) system too, but not because the AVC isn't working.

Rather, if the snifter valve stops admitting air into the piping system OR if the drain-down valve becomes clogged and stops draining water out of the water piping, then because air isn't entering the piping no air is being pushed back up into the bladderless pressure when the pump runs.

Eventually the water tank will become water logged and the well pump or lake pump will cycle on and off rapidly when water is run in the building.

Watch out: On a drain-down / bleed-back water system with either of these problems, because the well piping is not able to drain and not able to fill itself with air at the end of each pump-on cycle, there is also a risk of frozen well or lake water piping.

So if your drain-down system pump is short cycling and your water piping between well (or lake) and the water tank is not buried below the frost line, you may find you have two problems: you had a warning of trouble when the well pump was short cycling, and now you've got frozen pipes too. Darn!

SeeWATER TANK AIR VOLUME CONTROLS for more about AVC devices, the different types of air volume controls, and how these devices are installed, repaired or adjusted.

Air introduced by the snifter valve will protect well piping from freezing? Not if the Snifter Stops Sniffing.

A reader in 2015 noted that the use of a snifter valve on his well system would protect above-frost-line well piping from freezing. We were wrong in our initial reply to the reader when we said that a snifter valve was only for keeping air in the water pressure tank and that it wouldn't prevent well line freezing.

The snifter valve is also referred to in some literature or product descriptions as a drain-back fitting, drain back valve system, or bleed-back valve system or even an air injection system or air volume control system.

It's confusing to have these names spewed about willy-nilly, but they're all talking about the same idea: we combine an air inlet valve and a water drain back valve on well piping along with an air volume control on a bladderless water pressure tank to drain water out of the well piping, inject air into the pressure tank, and protect the well piping (now full of air at the end of each pump cycle) from freezing.

This also explains why people living in warm climates have never heard of these components. We only find these components where water piping between a well and a building or between a lake water source and a building is exposed to freezing.

At DRAIN BACK & SNIFTER VALVE SYSTEM COMPONENTS we sort out the actual differences among drain-back system names & components.

What's going on with drain-back systems & well pipe freeze protection?

The drain back valve (snifter valve) opens when the submersible pump stops and pressure in the well piping drops. At that point a ball inside the snifter valve moves towards the well piping center (away from the outer face or air vent in the valve). This allows air to enter through a small opening in the valve.

With no foot valve or check valve on the bottom of the well piping, admitting air into the vertical well pipe allows water to flow out of the well pipe bottom and back into the well.

The drain back valve and orifice in the well working with the snifter valve who admits air into the well piping extending from just before the water pressure tank down to the piping in the well itself, keeps the well piping air-filled between pump-on cycles.

Allowing the water to drain out of shallow or otherwise frost-exposed water lines between the water source and the building is an effective way to protect those lines from freezing - until something goes wrong and the air injection system fails

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Reader Question: Frozen Well Line troubleshooting & repair: Role of the Drain Back Valve & Snifter Valve in preventing well pipes from freezing

20 Feb 2015 Anonymous said:

FROZEN WELL LINE: I am trying to diagnose why my well line intake has frozen twice in the last year. I have a submersible pump well system and at the inlet end of my air over water pressure tank, I have a check valve installed along with a snifter valve on the inlet side of the check valve.

As I understand it, once the pump completes its cycle and the check valve closes, the snifter valve is supposed to allow air to bleed into the pipe, so the excess water drains back to the well.

For the line to freeze, I suppose the water has not been able to drain bac , or perhaps my check valve is allowing water to leak back to the well slowly and its freezing up? I know I can add a heat trace line to prevent freezing , but I wonder if anyone has suggestions as to what may be faulty in the first place?

This question was originally posted at WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS

Reply:

I think we agree that if well lines are freezing it's usually because they're above the frost line and are remaining full of water for a time when no water is running through the piping.

If your well piping system was relying on a Drain-Back or Dill Valve (mounted on a tee in the well piping) along with a snifter valve (an air admittance valve on a tee at the water tank) along with an air volume control valve (AVC) mounted on the mid-side of the water tank, and if those are no longer working properly then what's needed is to repair or replace the stuck valve.

Drain back valves located on a tee in the well piping can work trouble free for decades but might fail if clogged with crud from the water supply OR the drainback valve might fail if it's located a bit high on the piping in the well and if you're in unusually cold weather that pushes the frost line deeper than usual.

• Check the above-ground snifter valve:
  
  start by checking that the snifter valve (air admittance schrader valve) located right at your pressure tank is working.
  
  Don't forget to check the valve stem cap. If someone replaced a vented valve stem cap with a solid valve cap on a snifter valve, or if the cap is left screwed tightly shut, then the snifter valve can't sniff and it won't admit air into the well piping when it should. A simple fateful twist of a valve stem cap might freeze your well pipes.
• Check for a leaky check valve:
  
  You're right that if the check valve (at the pressure tank base) is leaky, that too could lead to frozen well piping.
  
  This is easier to check. At the end of a pump-on cycle just turn off the water supply to the building right at the pressure tank (on the house side of the tank). That way even slow water use in the house such as a running toilet won't foul up our observations.
  
  Now watch the water tank pressure gauge over 8-24 hours. If the pressure drops, there's a leak somewhere in the tank or well piping system (including that check valve). If pressure stays the same then the check valve is holding.
• Check for a clogged drain-back valve or Dill Valve:
  
  When weather permits you will want to check the drainback valve - no fun as you'll have to pull the well piping. And in some cases you may need to add heating tapes or deepen the well piping run to the building.

Beginning
with WINTERIZE A BUILDING, we describe other approaches to freeze protecting for water piping and supply equipment systems.

On 2020-09-04 by Paul - Snifter valve leaks water when the pump is not running

Can a Stop Check Valve be used instead of or in addition too a check valve on a standard bladerless pressure tank system with snifter and drainback valves that are not functioning to reduce or prevent short cycling of the submersable pump? Do you recommend installing a Stop Check Valve to increase pump life on a domestic well system?

My Snifter valve leaks water when the pump is not running and the pressure tank is empty. Where could the water be coming from? Has my 180 foot deep well gone artisian? I suspect my dainback valve is clogged or stuck closed. Is there anyway to inspect the drainback valve without pulling up the well line? Is there a way to pull up a 1 1/4 inch deep well line by DIY?

On 2020-09-09 by mod) - would a stop check valve cause well pump short-cycling?

Thanks for a helpful question Paul.

I may be missing something here, but a check valve of any type ought to have nothing at all to do with **causing** well pump short cycling issues.

A short cycling well pump is caused by a water-logged pressure tank that has lost its air charge. See details

at WATER PUMP SHORT CYCLING CAUSES

For other readers, from Wikipedia:

A stop-check valve is a check valve with override control to stop flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behavior), it can also be deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure.

 

On 2015-08-02 by Sam - If i put my finger over the snifter valve to deprive of pulling air the vibration stops

I have a submersible pump, 93 feet. With bladderless tank. I recently replaved the pump, ACV, check valve, pressure switch and control box.

The pump runs fine and shuts off at the correct pressure, however once it shuts off the snifter valve pulls up and down rapidly and the pipe down to the pump begins to vibrate.

If i put mu finger over the snifter valve to deprive of pulling air the vibration stops, is this a clogged or bad bleeder valve that is not draining properly?

On 2015-08-02 by (mod) - once pump shuts off the snifter valve pulls up and down rapidly and the pipe down to the pump begins to vibrate.

Good question, Sam, and sorry, but I'm not sure of the answer.

There are essentiallyi two parts to a snifter valve system: the actual snifter valve in the well on the well piping that lets water out and air in to the piping at the end of a pump on cycle, and the air inlet schrader valve (like a tire valve) that is above ground, usually on or close to the water tank or on the piping between the well and the tank.

The valve you're "fingering" is the latter of these two. You could try replacing the valve core stem, but WATCH OUT to use a properly-rated valve core from a plumbing supplier. If you just screwed in an ordinary auto or bike tire valve stem, even if it fits it will be the wrong spring tension and it won't work. The part probably costs less than a dollar. Try that first.

On 2015-08-02 by Sam

Dan,

Thank you for the rapid reply, I replaced the snifter above ground and it still vibrates. i am going to pull up to the bleeder and replace that and see what happens from there. I will post the results.

On 2015-08-02 - by (mod) -

It's a bit of trouble but you may have to replace the bleeder valve in the well. Certainly if I went to the trouble to pull the well piping I'd replace the part as a matter of course.

Question: I think the snifter valve was added to let some air in and aide drainback to the well,

My well line is for sure above the frost line for at least 20 feet. The install is 20 years old, but I am a new owner so I don't have a lot of history, but if the heat line was the only solution,I would have thought it would have been installed by now.. the pipe has some slope, but not much.

I think the snifter valve was added to let some air in and aide drainback to the well, but in extreme cold, maybe its not draining back very quick and freezing? PS: I do have an ACV valve on the pressure tank to regulate air volume in the tank.

Reply:

Generally when we convert from a bladder less steel tank to an internal bladder tank we remove the air inducing snifter valve from the well Line lest the tank become overloaded with air. The air induced by the snifter valve is pushed up into the well line and water tank at subsequent pump on cycles.

On those older system the well line snifter was designed to add air to the tank but required working with not only a suitable AVC but also with an air bleeder valve on the well piping near the pressure tank.

Using a snifter to prevent well line freezing seems unreliable to me. The snifter-induced air cannot guarantee that the portion of a well line subject to freezing will be empty of water.

See SNIFTER & DRAIN BACK VALVES for an explanation of these devices, how they work, where and why they are used on wells with submersible pumps and bladderless water pressure tanks.

Often a shallow well line works well for years without freezing, until in particular we find a very cold winter combined with low snow cover.

I didn't intend to suggest that heat tapes are the only fix, just a common one.

Question: snifter valve air volume control systems can remove iron and sulphur from water?

(Jan 22, 2014) joe said:

Hello I am writing about the snifter valve. If you read your article on why are snifter valve air volume control systems used one it states that the high absorption of air into the system helps oxidize and thus reduce hydrogen sulfide or perhaps iron. But in your last email to me you said it would not. So you have me confused. Thanks for your reply. JOE

Reply:

Thanks so much Joe, I will review these articles and fix that inconsistency.

Honestly, I am sure that I added the statement to which you refer while I was reviewing research about snifter valves, but in replying to your email I simply forgot about it.

You were right, I was mistaken. However we need some clarification:

A snifter valve is only used on deep wells that are operated by a submersible pump AND that feed water into an older-style bladderless expansion tank. The snifter valve, installed in the well piping lets air into the system at each pump on cycle. A companion vent valve installed above ground, close to the pressure tank, or in some cases ON the pressure tank, vents excess air out of the tank to keep the tank's air charge at the proper level.

A water supply system that uses a "captive air" type water pressure tank that incorporates an internal bladder does not need this automatic injection of make-up air, so will not have a snifter valve. In fact when a plumber converts a water supply system from bladderless-tank to internal-bladder tank, s/he needs to also pull the well piping and remove the old snifter valve if one was installed. That is what was going on in my photo series about snifter valves.

So if your water system uses a bladder type tank you wouldn't have a snifter valve installed.

Finally, and here is where we need to do more research, despite the claims of the snifter valve camp, I am doubtful that air injection ALONE will cure a serious sulphur odor in the water supply. More likely we'll need to install a treatment system such as a potassium permanganate "green sand as the plumbers call it" system or a chlorine injection system, combined with filtration, or some equivalent.

Do keep me posted, and thank you VERY much for helping me out with clarity and pointing out an inconsistency on this topic.

Question: to drain the water line I should open the cap on the snifter valve?

(Oct 13, 2014) Ray said:

I recently had a new well installed, drilled w/ a submergible pump. a internal bladder tank was installed .

I was concerned about the water in the tank and water line freezing in the winter , so a sniffer valve was installed on the the check valve.

I was told when shutting the system down for the winter, to open and drain the water tank, and to open the green valve cap on the sniffer/check valve to introduce sir to the system , that would allow the water in the line to drain back into the well. Will this advise work? is their any problem with the sniffer valve installed with an internal bladder water tank? thank You

Reply:

Yes there's a possibility that the advice you were given will work, Ray. But just removing a valve cap won't do it. That cap is supposed to be loose and able to admit air at all times. You shouldn't have to open the snifter valve (found on a check valve usually mounted at the bottom of the water pressure tank) as it should open to admit air on its own - at the end of a pump-on cycle.

If your snifter valve is not working it probably needs a replacement. If you're replacing just the valve stem core don't buy one at your auto parts store - those schrader valves and valve cores operate at different (higher) pressure ranges and are not designed for this application.

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Continue reading at DRAIN BACK & SNIFTER VALVE INSTALLATION / REPLACEMENT or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• AIR DISCHARGE at FAUCETS, FIXTURES
• AIR VOLUME CONTROLS, WATER TANK
• SNIFTER & DRAIN BACK VALVES
  • DRAIN BACK / BLEED BACK VALVE / SNIFTER VALVE PURPOSES
  • DRAIN BACK & SNIFTER VALVE SYSTEM COMPONENTS
  • DRAIN BACK & SNIFTER VALVE OPERATION
  • DRAIN BACK / SNIFTER VALVE TROUBLESHOOTING
  • DRAIN BACK & SNIFTER VALVE INSTALLATION / REPLACEMENT
  • DRAIN BACK / SNIFTER VALVE CONVERSION to BLADDER-TYPE WATER TANK
  • DRAIN BACK / BLEED VALVE / SNIFTER VALVE SUPPLIERS
  • MORRISON WELL SYSTEM FUNCTION & REPAIR
• WATER PUMP SHORT CYCLING CAUSES
• WATER TANK CAPTIVE AIR vs TRADITIONAL WellMate

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