Problem with Inline airgap


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Old 11-17-04, 08:39 PM
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Problem with Inline airgap

I just installed a waterboss mdel 550 and as part of the install used an inline airgap (Gap-a-flo). However, I'm finding that water is flooding out of the airgap during the main backwash cycle. It is fine during the slow brine rinse cycle.

The recommended flow rate for the airgap is upto 7 GPM but they say it has been tested at upto 15GPM (or thereabouts). I am surprised that the softener could be putting out this much out of the drain.

The other possibility is that I used a short stub of 1/2" ID PVC to hook up a barb fitting to the drain line (supposedly 1/2" drain according to the manual although it actually measures more like 5/8"). I know that some flexible lines like for irrigation do not exactly measure upto what they say it is supposed to be - I think 1/2" is not 1/2" actually. I think PEX also has misleading dimensions as I recall.

I am wondering if the reduction to the "real" 1/2" ID from 5/8" is causing this. I will be calling both airgap and waterboss to check the peak flow rates but any insight into this would be useful.
 
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Old 11-18-04, 09:56 AM
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You're seeing the difference between IPS and CTS tubing. IPS 1/2" is closer to 5/8" ID and will allow 1/2" CTS tubing to fit inside it because the ID is used to identify CTS and 1/2" is 5/8" OD.

My guess is that your Gap-A-Flo is not installed straight or your softener doesn't have a DLFC which is hard to believe. Possibly it is the drain the GAF is attached to, that's probably the primary cause and the drain isn't capable of accepting the total flow of the entire backwash and it backs up to overflow.

Gary
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Last edited by Doug Aleshire; 03-11-05 at 07:39 PM.
  #3  
Old 11-18-04, 10:33 AM
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I double checked the GAF and it is installed correctly and pretty much vertical. I think that the drain being the problem is probably correct although I am thinking the problem is with the immidiate drain out of the GAF. The 1/2" line is then expanded to a 2" and the drain from the softener is combined with the WM via a sanitary tee and then coupled to the WM standpipe. The WM works fine so as far as I'm aware the problem is unlikely to be in the standpipe/drain.

I contacted Waterboss and was told that the up-flow cycles were high flow (did not give an exact number but I guess this is down to the water pressure and the drain diameter as well as the flow restriction of the softener).

I am thinking of expanding the drain line out of the GAF from 3/4" to 1" before going to 2". Hopefully 1" will be large enough to support the flow.

I presume DLFC stands for drain line flow control. No sadly there is no such control on the softener to control flow down the drain.
 
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Old 11-18-04, 08:41 PM
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All softeners have a built in and changeable DLFC.

Your standpipe trap may be too close to the drain line connection and filling up due to poor drainage. Or said another way, the stand pipe may not be long/high enough for the flow. If this were mine... I'd tape the air gap and pretend I hadn't.

Gary
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Last edited by Doug Aleshire; 03-11-05 at 07:39 PM.
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Old 11-18-04, 08:51 PM
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Well I guess taping is an option after the inspector leaves

I will try reaming the line with some wire to see if any debris after the install is plugging the line. If not expanding the line seems to be the available option.

As for the standpipe flow capacity - I guess it is a possibility but the WM seems to discharge fine through it and it is a 2" drain with the opening about 5' above the trap (I'm guessing here since I've not opened up the wall but a cleanout is visible at the floor level.)

As for the DLFC - since it does not appear to be an option on the controller would this be a physical control. I certainly cannot see any mention of it in the manual.

Thanks for the input.
 
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Old 11-18-04, 09:07 PM
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The DLFC is internal and won't be mentioned in most softener consumer manuals.

Run a garden hose into the drain for 6-10 minutes and see if it will accept that volume. If so the problem is something else.

Gary
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Last edited by Doug Aleshire; 03-11-05 at 07:39 PM.
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Old 11-18-04, 09:13 PM
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I'm been looking at the manual and yes, I see a mention of it in the assembly diagrams - it is being referred to as .5pm flow control and is housed in the brine valve housing. Not clear if it can be varied or adjusted. Also not clear to me whether it comes into play during the high flow backwash cycle which is the cycle I'm having problems with. The long brine rinse cycle works fine.

Anyway, I'll experiment and see what comes up.
 
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Old 11-18-04, 09:18 PM
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That is the BLFC, not the drain line. You wouldn't change your DLFC, doing so will screw up your softener and cause regeneration problems.

Gary
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Last edited by Doug Aleshire; 03-11-05 at 07:39 PM.
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Old 11-19-04, 10:37 PM
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My initial investigation into this seems to suggest that the airgap cannot handle the high flow rate.

I wonder if I can use another device like a vacuum breaker or check valve. Would there be any issues with using such a device rather than an airgap.
 
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Old 11-23-04, 07:24 AM
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Code says you need an air gap. The GAF works when set up right and operated within it's acceptable gpm range. You don't want any restriction to the drain line flow because that causes the softener incomplete regeneration problems, so no check valve etc..

Gary
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Last edited by Doug Aleshire; 03-11-05 at 07:38 PM.
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Old 11-23-04, 12:33 PM
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I did remove all restrictions on the drain line and this improved the situation but there was water still flooding out. Waterboss says that the high flow backwash cycle can generate upwards of 16 GPM so I think that the GAF is just not compatible with the waterboss. During the regular brine rinse which is low flow (around 3 GPM) it works fine. I thought water softeners did not put out such high flow rates but it seems like it depends on the model. In the case of Waterboss they use the high flow backwash cycle to also flush out the integrated whole house filter so I guess there is a reason for doing this. Due to various restrictions around the standpipe a real airgap or one of the other add on airgaps I've seen for standpipes is not an easy option.

As a final check I removed the GAF and used some copper pipe to make the connection - it works fine in that situation confirming that the problem is the GAF restriction.

I've spoken to the local plumbing inspector about the use of a check valve and they don't have any objection to one being used inplace of an airgap. The one I had in mind is this one - http://www.wattsreg.com/pdf/ES-9DM3_M2.pdf. It suits the purpose as any backflow will discharge (if the second check valve is breached) via the drain to the exterior. The tables on page 2 shows a pressure loss of around 25 PSI at 16 GPM. Assuming a pressure loss of around 5 PSI for the pipe (form the tables) this gives a worst case loss of 30PSI which is a 20PSI margin on the house pressure of 50PSI set by the reg. There will be problems if the system pressure falls below 30 PSI for the high flow backwash but if this were to happen the reg would need replacing.

So this is my current plan to solve this.
 
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Old 11-24-04, 07:38 AM
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Originally Posted by rav12
..... Waterboss says that the high flow backwash cycle can generate upwards of 16 GPM ..... I thought water softeners did not put out such high flow rates ....but it seems like it depends on the model. In the case of Waterboss they use the high flow backwash cycle to also flush out the integrated whole house filter so I guess....

...... I've spoken to the local plumbing inspector about the use of a check valve and they don't have any objection to one being used inplace of an airgap.

So this is my current plan to solve this.
Your plumbing very possibly can't flow 16 gpm!! The person you spoke to at WaterBoss... flat doesn't know what they are talking about; try again and make them prove their statement by asking how to identify your DLFC as a 16 gpm. Ask them how a 1/2" ID drain line carries 16 gpm.... when a 100' of open discharge 3/4" ID copper with 50 psi water pressure barely can!

I've built and serviced a fair number of residential/commercial softeners and heavy mineral filters over the years and the highest DLFC I've ever seen is a 7 gpm. Autotrol, Fleck and Clack don't have any over 7 gpm so what makes WB so special? Someone is missing a "." in their figures somewhere; DLFC usually are stated in tenths of a gallon IE 1.6 2.4 or 7.0 etc..

So I gotta tellya, your plan is based on a guess and incorrect info. The Watts double backflow prevention device (check valve) is going to stop or greatly reduce your softener's drain line flow or possibly cause the tubing to blow off its fittings. Reduced flow to drain ruins your resin and any filter media they have in the filter compartment.

Then tell the plumbing inspector to look up the code on drain lines for potable water softeners and/or filters; an air gap is code everywhere I know of.

Gary
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Last edited by Doug Aleshire; 03-11-05 at 07:38 PM.
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Old 11-24-04, 01:13 PM
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Well, there is only one way to figure out the flow and that is to measure it. I will hook up my pressure/flow gauge and get a proper reading. Anything else would be guesswork. I did not do it until now since I will have to hook up some suitable connectors to go from the 1/2" pipe to garden hose type connectors. If it is under 7gpm I will investigate why the GAF is flooding. If it is high (like 16) then using this is not an option and maybe waterboss has something unique here!

I will do this at the weekend and post back the results.

As for the other points in your post. Cannot comment on the flow capacity of 1/2" ID tubing but I will look at some tables to see what the pressure vs flow rate is. I'm not sure what the pressure drop would be for 16GPM.

Also regarding the check valve - assuming the flow rate is not more than 7GPM (let's say 5 for this example) the additional pressure loss will be 10PSI. If the hoses are securely connected via hose clamps I cannot see why this pressure should blow anything off. It may of course cause issues with the softener itself so this would be a question for waterboss to answer.

Any finally as for the inspector - he is fully aware of the codes (that's his job). Don;t know what it is like in different areas but here the inspectors do recognize that things may not always be posssible by exact codes due to contraints on the project so they usually need to be convinced that the install is going to work - code or not. As in this case - the goal is to prevent backflow - by airgap or other means. At least this is how I see it.
 
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Old 11-26-04, 07:52 AM
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Originally Posted by rav12
Well, there is only one way to figure out the flow and that is to measure it. I will hook up my pressure/flow gauge and get a proper reading. Anything else would be guesswork..... If it is high (like 16) then using this is not an option and maybe waterboss has something unique here!

I will do this at the weekend and post back the results.

Any finally as for the inspector - he is fully aware of the codes (that's his job). Don;t know what it is like in different areas but here the inspectors do recognize....
Simply take the drain line loose and run the water into a bucket for a minute etc. and physically measure the volume you get during backwash. That's one of the ways us softener guys troubleshoot equipment.

I see all this from 17 years experience in the water treatment industry and selling equipment all over the US for the last few years and I've gotta tell ya, I've never heard of a non air gap connection being acceptable anywhere. Plus I know that a double backflow prevention device is going to cause all softeners problems and they should not be used on water treatment equipment drain lines. Plus none of the 4 national plumbing codes call for them on water treatment but they all do call for an air gap.

Gary
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Last edited by Doug Aleshire; 03-11-05 at 07:38 PM.
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Old 11-28-04, 08:40 PM
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OK so you were correct and the person from Waterboss was talking @#&^$^%. I did a flow measurement with the flow gauge as well as the bucket method. The flow gauge read 3 GPM and the bucket method 3.5GPM during the high flow backwash. I also did find the exploded view of the drain line on the waterboss web site and the DLFC is rated at 3.0. I also noticed (which I did not before) that the specifications also say max backwash GPM is 3.0

I did not have time to expoeriemnt with various flow rates through the GAF in isolation but my theory now is that the install is to blame. I used a barb fitting to connect the drain line to the 2" standpipe via a sanitary tee and the barb only measures 0.4" ID so this could be one of the sources of the problem. I also have a horizontal run of around 1' before it empties into the tee - I wonder if this may also be a problem. It is much harder to install it with a vertical fall due to the restrictions around the standpipe but this may be the only solution along with replacing the barb with something else. Perhaphs also expanding the drain line to maybe 3/4" since the GAF has a 3/4" MIP connection.
 
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Old 11-29-04, 06:12 AM
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Now you seem to be going in the right direction. Get the drain line verticle into the GAF and enlarge the drain below the GAF as much as possible. Or if it were mine, I would remove the GAF and stick the drain line into the 2" about 2" and anchor it so it can't get out.

Gary
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Last edited by Doug Aleshire; 03-11-05 at 07:37 PM.
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Old 12-18-04, 06:17 PM
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OK so problem now solved. The fix was to enlarge the drain line to 3/4" and not use any barb connectors that would cause a restriction. Tried it with the install as it is (ie a section with a small downward slope rather than a vertical fall) and it works fine. Actually to prevent any problems after installing (with the GAF flooding indoors) I tried the setup outdoor with a flow gauge connected. It seems like it can flow upto 7 GPM without any problem - could not get it to flow higher (I guess due to the incoming diameter being restricted to 1/2"). Tested with a garden hose conncted to the outside faucet.

It seems like the GAF is likely to have problem with flow of 3GPM or over with a 1/2" outgoing drain line although unfortunately the instructions are not very clear on this. Overall the intructions are a bit vague on exact numbers - saying things like must not have a long run of horzontal drain without any definion of "long".

For anyone thinking of using the GAF for anything at these kind of flow rates - I would suggest not using the 1/2" compression coupling supplied but to use a 3/4" FIP to whatever else is suitable to make the drain connection.

Thanks to Gary for the helpful suggestions.
 
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Old 12-19-04, 10:37 AM
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Thanks for the detailed feedback, very helpful.

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Last edited by Doug Aleshire; 03-11-05 at 07:37 PM.
 

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