Backflow Preventer Leak

Reply

  #1  
Old 03-08-15, 07:47 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
Backflow Preventer Leak

Hi All-
Early last week I had my heating technician replace a Aquasmart 7600 control with a Honeywell on my Buderus G115. The high limit of the new control was set to 190, while the previous control was set to 180. After replacement, I noticed a very very small amount of water, like a few drops a day, leaking from the vent of the Backflow Preventer. From my reading of the posts on this forum, the vents are designed to drip or spit when the pressure in your heating systems exceeds the pressure from the water flow into your house.

Is this dripping normal for the operation of this boiler? I am thinking maybe the increase in the upper limit has resulted in the slight drip...which is once again only a few drops a day.

Thank you.
 
Sponsored Links
  #2  
Old 03-08-15, 08:00 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
For starters, whether or not the increased temp is responsible for the dripping, turn it down to 180F. There's no reason to have to increase the high limit setting.

No, the increased temp is not likely causing the drip in the backflow preventer.

No, it's not 'normal' for the BFP to drip, but it does happen fairly often.

Did the tech do anything else to the boiler while he was there? Anything that required water to be fed into the system, such as bleeding, purging, etc...?
 
  #3  
Old 03-08-15, 08:03 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
Yes. I believe the system was purged to install the new control. There was some water on my basement floor after the tech left.

Why should the high limit be brought down to 180? Is it bad for the system?
Thank you.
 
  #4  
Old 03-08-15, 08:14 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
There was no need to purge anything to install the new control. Must have been some other reason he messed with the water

Here's what has probably happened to the BFP...

Since the water line to the boiler RARELY has any water flowing through it, 'crud' builds up in that line. When water IS flowed, that crud breaks loose and can foul check valves by the crud getting under the valve seat.

The chances are pretty good that if it's only a couple drops a day that it will stop dripping by itself. Give it some time and monitor it. If it's still dripping in a couple weeks, or if it gets worse, it's an easy thing to change... when the weather finally warms up and you don't need the heat anymore... although, if you have valves before and after the BFP and pressure reducing valve, it could be done at any time.

Why should the high limit be brought down to 180? Is it bad for the system?
No, it's not necessarily 'bad' for the system. But why heat the water any hotter than it needs to be to heat the home? The old setting of 180F never gave insufficient heat, did it?

Turn it down and maybe save a little money on fuel.
 
  #5  
Old 03-08-15, 08:22 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
Thank you NJ!

I'll monitor it for a few weeks and have the tech come out if it continues.

Actually we did have some trouble warming a few of our rooms at the old high limit setting on the AquaSmart.

On a side note, I went through 3 AquaSmart controls in 3 years. Beckett needs to fix their product!
 
  #6  
Old 03-08-15, 08:40 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
Actually we did have some trouble warming a few of our rooms at the old high limit setting on the AquaSmart.
Are you sure that it's not because it has been SUPER cold this winter?

I went through 3 AquaSmart controls in 3 years. Beckett needs to fix their product!
Are you sure it's the control and not something wrong with the installation?

Why not switch to something like the HydroStat product?
 
  #7  
Old 03-08-15, 08:46 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
The rooms have been real cold since we moved in to the house 3 years ago and replaced the boiler. It was nearly impossible to get the rooms over 65 degrees during the winter. Being a first time homeowner, I didn't question it. The house is a small ranch built in the 50s; I think the issue stems from the design of the heating system...boiler excluded.

As for the control, I have spoken to reps at Beckett, who confirmed that they are having issues with the temp sensors on the Aquasmart. They told me they are trying to fix the issue with the next release of the product. The two heating technicians I spoke to last week told me they are replacing them like crazy and refuse to install them.
 
  #8  
Old 03-08-15, 09:06 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
refuse to install them.
Then why didn't they steer you to a different product then?

I think the issue stems from the design of the heating system...boiler excluded.
It may well be.

When the heating system was designed, they should have done a room by room heat loss estimate.

With this information, they would have known how many feet of baseboard to install in each room.

Baseboard is rated at so many BTU OUTPUT per FOOT at 180F . That number is typically right around 550 BTUH per FOOT.

So, if a room has say 5500 BTUH of heat loss on the coldest day of the year, they would have had to install TEN FEET of baseboard to meet that loss.

If the heat loss is higher than the installed baseboard, the room will get cold...

Have you popped the covers on the baseboards and vacuumed the dust out? If not, you should, you will be amazed at how much more heat comes out of them.
 
  #9  
Old 03-08-15, 09:15 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 52,531
Received 327 Votes on 306 Posts
It takes a little cold weather to find the rooms where they undersized the radiators.

Also, in addition to carefully cleaning the dust off the fins.... make sure the air flow door is open. Many people don't realize you can adjust that door to tailor each rooms heat level.
 
  #10  
Old 03-08-15, 09:22 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
Yet another issue to consider...

If the rooms have WTW carpeting and the carpeting is obstructing the air inlet on the bottom of the baseboards it will GREATLY cut down on the heat output.

Additionally, furniture against the baseboards will also obstruct the airflow through them.
 
  #11  
Old 03-08-15, 09:28 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
Regarding the steering to a different control product...

Beckett didn't have a recommendation and I didn't really question my heating techs recommendation of the Honeywell. At some point a homeowner has to trust the contractor...right? Both contractors I spoke to said that unless you want an outdoor reset, there is nothing on the Market that they consider reliable that has the load adjustment technology .

As for the fins and heating system....

I think some of the issue with the heating of the rooms was related to the Aquasmart and its economizing feature. It took to long to get the boiler to a temp that could adequately warm all the rooms.

I think I will turn the high limit on the boiler down to 180 when my wife isn't looking...she is enjoying the comfort of the higher limit since I pay the bills.

The fins are cleaned yearly..there are no obstructions in front of the baseboards.
 
  #12  
Old 03-08-15, 09:46 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
Ohhhh... you DID get a different control! I was under impression that they replaced with same.

That's fine... Honeywell is as good as any.

there is nothing on the Market that they consider reliable that has the load adjustment technology .
You could educate them!

PEX - Radiant Heat - Radiant Heating - Plumbing Supplies - SupplyHouse.com

I think I will turn the high limit on the boiler down to 180 when my wife isn't looking...she is enjoying the comfort of the higher limit since I pay the bills.
She won't notice the difference!
 
  #13  
Old 03-15-15, 05:53 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
Hi again,
So it's been a little more than two weeks since my relatively new boiler's backflow preventer started dripping post the replacement of its control. Once again, the amount of water that is coming out of the vent is very low, maybe 4 or 5 drops a day (it hasn't gotten worse). I called the heating tech who did the job. He told me that it is not unusual for this to happen when new water is added into the system (the well was replaced) and that a lot of people simply seal the vent to stop the dripping. He did say however that he would replace the BFP if I would like. So here are a few questions...

If I don't get it fixed, is there a risk that I will find a lake in my basement someday or will this be something that will just be a nuisance (ie it will just drip like it does today)?

If I wanted to get the BFP fixed, do you think the heating tech should pick up some of the tab related to fixing it since the dripping started after he swapped controls?

Thanks again!
 
  #14  
Old 03-15-15, 09:04 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
He told me that it is not unusual for this to happen when new water is added into the system
That's true, and it very often takes out the pressure reducing valve as well. It goes back to that 'crud' that builds up in the line. Those components just sit there unused, sometimes for decades... no water flowing... when you DO flow water, that crud breaks loose and fouls the valve seats.

a lot of people simply seal the vent to stop the dripping
Yes, that happens... it ain't right, but that's the way it goes.

Truth is that the likelihood of anything 'bad' happening by this practice is pretty slim. Your city water pressure would have to drop below the pressure of the boiler, the check valve in your pressure reducing valve would have to fail, and also TWO of the THREE check valves in the backflow preventer would also have to fail. Pretty slim chance, eh?

As long as there is a valve upstream of the BFP, it's about a ten minute job to replace that part. No soldering, just wrenches.

It's about a $40 part. Why not replace it?

is there a risk that I will find a lake in my basement someday or will this be something that will just be a nuisance (ie it will just drip like it does today)?
Most likely it will remain as is. As with anything in life, there's no 100% certainty.

If I wanted to get the BFP fixed, do you think the heating tech should pick up some of the tab related to fixing it since the dripping started after he swapped controls?
No, I don't think so. It wasn't his 'fault'. He didn't do anything wrong. It's just the way it goes... with plumbing, any kind of plumbing, it's always something... you touch one thing, and you better be prepared to touch them all.
 
  #15  
Old 03-29-15, 08:00 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
NJTrooper et al-

The drip continues....

This week I had the BFP replaced and the dripping out of the vent appeared to immediately stop. Unfortunately, this morning I found some droplets of water below the vent. The dripping coincided with my wife using the domestic cold water for laundry. Putting "two and two" together, I stopped her laundry cycle to see if the dripping occurs when cold water is being used. So I put on the cold water in the tub...which resulted in a slight drip (4 or 5 drips). The boiler was at 170 degrees when I ran the test.

So the saga continues. I am really not sure where to go from here. Do you think the drip is a result of low water pressure when the water is being used and the boiler is warm? Should I replace the BFP again? Could there be something else going on?

Any help would be appreciated.
 

Last edited by kgalligano; 03-29-15 at 08:49 AM.
  #16  
Old 03-29-15, 08:47 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
Are you on city water?

Did the guy FLUSH THE LINE before he installed the new valve? (It's very important to do so!)
 
  #17  
Old 03-29-15, 08:52 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
I am on city water. I don't know if he flushed the line. I updated my post below slightly. The vent also leaks when the boiler is not on but is hot (170) and the tub is on.

The crazy thing is that I checked for dripping all week and had no issues until this morning when the wife did the laundry.

How would you proceed?

Thank you again.
 
  #18  
Old 03-29-15, 09:07 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
Do you think the drip is a result of low water pressure when the water is being used and the boiler is warm?
I suppose it's possible... but do you notice low pressure when filling tub, etc?

Should I replace the BFP again?
Not if YOU have to pay for it! Your guy should warrant his work... he didn't 'fix' the problem.

Could there be something else going on?
Can't think of anything except an actual defective BFP, or your guy not flushing the line and crud got into the valve again.

It IS possible for 'intermittent' discharge to occur if there is any 'water hammer' occurring on the domestic side of the valve because this 'jerks' the check valves and they may 'spit' a few drops. Quick closing valves such as those on a washing machine or dishwasher can cause water hammer. There's a bit about this in the documentation for the BFP from Watts, and it is also mentioned here in this thread:

http://www.doityourself.com/forum/bo...ater-line.html

Scroll down to posts 19 and 20 for some graphics that help us 'visual thinkers' understand how the BFP is supposed to work.
 
  #19  
Old 03-29-15, 09:26 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
I haven't noticed a big change in water pressure...but then again I don't really pay a lot of attention to it.

How would you play it from here? Should I wait a few days to see if it continues or should I get the tech to come back asap to fix it?

Or should I just leave it, given the low likelihood of the valve 100% failing (i.e. it will always drip but never be a flood hazard given the bfp design).
 
  #20  
Old 03-29-15, 06:16 PM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
So I let the boiler cool down to 120F and turned on the cold water in the tub. There was no leaking from the BFP.

Once I cranked up the heat in the house, and got the boiler up to 170ish and then turned on the cold water in the tub, the drip started again.

Argh! All this for a shotty Beckett control. I hope its just a faulty bfp. Money doesn't grow on trees
 
  #21  
Old 03-29-15, 06:24 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
What's the pressure in the boiler COLD... and then HOT ?
 
  #22  
Old 03-30-15, 02:35 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
Its 21 PSI at the high limit. Ill check the low when it cools; what should it be at? I am starting to think your original hypothesis about either a faulty part or the piping not being flushed is the issue.
 
  #23  
Old 03-30-15, 05:14 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
21 HOT is ok... it should be around 12-15 PSI when cold.
 
  #24  
Old 03-30-15, 06:28 AM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
The heating tech came out again to look at the drip from the BFP. I showed him that the dripping coincided with the use of the cold water in the tub or the washing machine. Since he had never seen a situation like this before, he called in the owner. The owner was perplexed as well. In the end they switched out the BFP and the dripping stopped. They also told me if I have any additional issues, they are going to call Watts.

So I'll be on the look out for more dripping...hopefully the part was just faulty.
 
  #25  
Old 03-30-15, 07:36 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
Did he flush the line?.....................................
 
  #26  
Old 03-30-15, 03:11 PM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
Well the BFP preventer is still dripping. I am kind of at the give up point. The BFP now looks to drip not when domestic water from the tub is turned on, but when it is turned off.

About the flush...To be honest, I don't know. I let him in the house and he swapped the parts. I can call and ask. He did say the first BFP that was replaced had gunk on it; the last one was clean.

Once again the dripping started when the tech replaced my Beckett aquasmart control with a honeywell.

So should I continue this saga and call another contractor or should I accept the fact the BFP will drip a few drops and plug it? I know I asked this question before, but what is the likelihood me of coming home to a pool in my basement one day on a 1 (low) to 10 (high) scale? Will the drip get worse or most likely stay the same?

NJT- I appreciate your help. I am just running out of patience and would like to avoid cutting another check if possible.
 
  #27  
Old 03-30-15, 04:15 PM
Member
Join Date: Oct 2008
Location: USA
Posts: 2,876
Received 5 Votes on 5 Posts
I suspect that the pressure at the supply side of the backflow preventer is dropping below the boiler pressure during transients. If so, the problem isn't the backflow preventer, but rather the piping between the backflow preventer and wherever the transient is being induced - possibly a clogged pipe.
 
  #28  
Old 03-30-15, 04:21 PM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
An update to post the below...

I decided to call the outfit that completes my annual tune up (not the folks I have been dealing with) and told him my story. He said that if the BFP was replaced 3 times and the dripping occurs post large scale domestic water use , that the issue is most likely NOT boiler related. Instead he believes that the drip is most likely related to the pressure of water entering the house being too high. He told me that he would recommend just putting a bucket under the valve, and as long as the dripping is minor, don't sweat it. If the drip gets worse, he told me to call the Town to test the pressure.

Thoughts?
 
  #29  
Old 03-30-15, 04:41 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
You could test the pressure yourself easily and not too much $$ .. maybe 10-12 bucks.

Watts 3/4 in. Plastic Water Pressure Test Gauge-DP IWTG - The Home Depot

Thing is though... the water pressure would have to be VERY high to cause that to leak. Look at the graphic and you'll see that the higher the pressure, the harder it pushes on that diaphragm, and the more it will not want to leak.

It's never been a boiler related thing actually. Although you did say that you only noticed it when the boiler was hot...

That BFP is on the domestic side of the pressure reducing valve and the boiler pressure shouldn't really affect it... there's usually a check valve in the pressure reducing valve as well.

I'm not going to commit to saying that you won't be faced with a flood... but the odds are very low that you will have that problem.
 
  #30  
Old 03-30-15, 04:42 PM
Member
Join Date: Oct 2008
Location: USA
Posts: 2,876
Received 5 Votes on 5 Posts
he believes that the drip is most likely related to the pressure of water entering the house being too high.
I don't know how that could be. If you (or they) believe it, then call the water department.
 
  #31  
Old 03-30-15, 04:55 PM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
I am going to call the Town tomorrow. He specifically said something could be stuck where the water enters the house and that the combination of turning on and off high use domestic cold water outlets and the slightly above average pressure (or did he say lower, I worked a 12 hour day today...sorry) results in a pressure fluctuation that cause the slight drip. Or in other words there is something clogging the pipe somewhere before water hits the BFP , which I believe is what gilmorrie suggested the problem to be (I think; I am not a professional heating tech).

I don't think I mentioned this in the previous post, but the dripping is only a handful of drops a day and occurs primarily when the tub or washer are turned on (or off from) full crank cold . Most of the time the water doesn't collect, just evaporates.

On another note, I found this great video on how BFPs work.

http://m.youtube.com/watch?v=N0wU4SWrE74

It mentions how water hammers possibly from washing machines, can cause the dripping.
 

Last edited by kgalligano; 03-30-15 at 06:08 PM.
  #32  
Old 03-31-15, 02:03 PM
Member
Thread Starter
Join Date: Jul 2012
Posts: 32
Received 0 Votes on 0 Posts
I tested the water pressure into the house today. No issues. Water pressure is at 50 PSI with no water used, 40 PSI when the washer is on, which is well above the needed pressure to seal a clean BFP. Given I have gone though 3 BFP, I am thinking "the problem isn't the backflow preventer, but rather the piping between the backflow preventer and wherever the transient is being induced" as gilmorrie suggested.

At this point, since the drip is minimal, I think I am going to let it drip and take care of it during my annual tune up.

The one interesting thing is that the BFP only leaks when the boiler is near the high limit and the domestic water is on and not when the boiler is cold (112 F) and the domestic water is on. Maybe the slight change in PSI of the boiler, from 12 to 21 PSI (from cold to hot) is just enough to cause the leak to occur. Just guessing...
 
  #33  
Old 03-31-15, 04:16 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 1 Vote on 1 Post
Maybe the slight change in PSI of the boiler, from 12 to 21 PSI (from cold to hot) is just enough to cause the leak to occur.
For this to be true, referring to the diagram, check valve B would also have to be leaking.



For water to come from the vent, it has to be leaking past diaphragm C, which seals to chamber D.

If you have 40-50 PSI of city water pressure on diaphragm C, then the ONLY way for that to leak is if there is either 'crud' under it's seat, OR for B to be leaking and the pressure at the boiler end to be HIGHER than the inlet pressure.

I'm still thinking 'crud'... A tiny piece of something under seat C will cause leakage.

How long is the pipe from the main water supply (the one that flows water whenever a tap is used in the home) to the BFP? There could be significant amount of crud in that line.

The next time it's out, rig up a garden hose to that line and run it full blast... turn it on and off to bust that crud loose. Then reinstall. You can also rig stuff to flush the valve itself.

For example, if you fed water INTO the vent E with no connections to the inlet or the outlet, the water would flow past C, and out the outlet (and maybe the inlet too).

If you feed water into the inlet, with the outlet open, you can flush out A and B.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: