Low Water Cutoff blocks water flow?

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Old 12-28-12, 03:03 PM
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Low Water Cutoff blocks water flow?

Hello:

My Safgard model 170, LWCO is installed between the boiler (above the boiler) and the non bladder expansion tank hanging from the basement ceiling. What from the LWCO would block water flow to the expansion tank? Could this LWCO be reset without replaced?


Situation summary:

Recently, the boiler pressure relief valve overflowed with over 30 psi. To rectify, I drained the expansion tank. Overflow situation was not corrected. I checked the tank (second draing), but with the second draining, no water came out from the tank. I measure the temperature with a multi meter on the piping before and after the LWCO. There was a 6 degree Celsius difference. I also grasped the piping, did not feel any sensation of water flow.

It seems the LWCO is somehow causing a blockage, thereby creating the relief valve to overflow. Any suggestion is appreciated. Thanks.

Happy New Year to all.
 
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Old 12-28-12, 03:26 PM
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Are you positive that you completely drained the tank and that a complete charge of air was sucked in? Did you valve out the line between the tank and the boiler? If there is no such valve, you'd need to depressurize the system.

Does your tank have a red Airtrol tank fitting? Please post photos of your setup.

I'm surprised that the LWCO is in the line between the boiler and the tank. Maybe your photos will resolve my thinking.

I have no experience with the safgard model, but I notice it takes a special tee: http://www.hydrolevel.com/pages/pdf_...del170_opt.pdf Is yours installed in accordance manufacturer's instructions, including minimum pipe size? It need so be in a large line that has continuous flow when the pump is running, so that the line will drain back into the boiler if the boiler's level goes down, not in a deadleg.

I've had good results with my Guardog LWCO.
 
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Old 12-28-12, 04:27 PM
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It seems the LWCO is somehow causing a blockage
I wouldn't be so quick to jump to that conclusion.

Besides a water-logged compression tank (which you may not have completely drained, more about that below), there are other reasons for over pressure.

1. Your pressure reducing valve (aka 'fill valve') may be leaking through.

2. If you have a 'tankless hot water coil' in your boiler to provide domestic hot water it may have developed an internal leak.

Gilmorrie asked about HOW you drained the tank... I'm going to expand on that a bit.

Usually there is a valve in the line from the boiler to the tank and that would need to be closed in order to drain.

Here's the thing though, I call it the 'drinking straw analogy':

Put a finger over a drinking straw and lift it out of the drink. The drink stays in the straw until you lift your finger.

The same thing happens when draining the tank. As the water leaves the tank a 'vacuum' is formed inside and the tank will not completely drain.

If you used a long smallish diameter garden hose coiled around the floor it almost surely did not drain completely.

If you have an old hose you can 'sacrifice', cut it just long enough to reach to a floor drain, laundry tub, bucket, whatever... so there are no loops in it and air can flow back up the hose and break the vacuum.

STILL this may not work... LOOSEN the hose fitting at the drain valve and allow it to suck air.

STILL may not work... try draining directly into a bucket with no hose attached.

STILL may not work... if you have a small air compressor try blowing some air back into the hose. (some of the oldtimers would get themselves a lungful and blow back into the hose... I for one don't advocate that practice, but if you ain't askeert of germs, go for it if you have the lungs for it)

Pics will be very helpful... there may be other solutions we'll see.
 
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Old 12-28-12, 08:05 PM
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Hello:

Attached please see diagram and photo. This bladderless tank has only one combination valve. It was drained without a garden hose and air was let in. In the first drain, about 3 gallons or more gurgled out. In the 2[SUP]nd[/SUP] drain, only about the size of a medium coffee gurgled out. Since it came out so slowly comparing to the first trial, I did not wait to the end. At hind sight, maybe I should. During draining, it was valve out from the overall system. After, all rads were bleed with boiler off.

The boiler (Olsen ODV-B) system including the LWCO was installed 5 years ago from passed September, by a licensed contractor. The LWCO was installed at the right angle elbow turn instead of in-straight-line as per manufacturers pdf (points B,C,D). I supposed they would use the proper tee.

As I took the photo, the system ran but with overflow, though I had the high limit set to 200 from the previous 220. This geared down obviously was insufficient. I may have to set the high limit to 180 C to minimise the overflow / control the psi until after the holidays. There was about a gallon of water from the overflow with a 2 storey house of about 1600 square feet in one operating cycle (on to off).

I also took the temperature at points before and after the LWCO. Again, they had a variance of about 6 degrees Celsius.

The hot water tank is separated from the boiler as a different entity.

There are no visible leaks in the system.

The fill valve is as new as the boiler, 5 years. I had it checked as well , per article suggestion, it seemed ok (pressure dropped)

Test #2, Water Feeder. Shut off valve to feeder. Drain enough water from the boiler to bring the pressure to 15 lbs. Wait and see if the pressure stays steady. If it does, replace the feeder. (watch if for about 15 minutes)

The original contractor is off on holidays till after the New Year. I am trying Not to open the system in this winter time for repair if I can find the reset for this Safgard LWCO. So far, I have been searching the web to no avail. I did switch off the power to the boiler system for 10 minutes before power on to re-test the system, did not solve the overflow problem.

I believe the LWCO should only kill the boiler when the water level is insufficient. I do not understand how would a LWCO sensor seemed to block the water flow (as evidenced by the temperature variance and feel test)? Or in my case, water cannot go around the elbow where the LWCO was installed. Something else blocked?

Kind regards. Thanks.
 

Last edited by NJT; 12-28-12 at 08:27 PM.
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Old 12-28-12, 08:30 PM
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James, I don't know how you tried to attach the pictures, but they did not come through. I suspect that you composed your reply in and off-line manner and copied and pasted... that won't work here.

Please try to upload your pictures again using the tools on the forum for doing so.

OR, set up a free account on Photo and image hosting, free photo galleries, photo editing | Photobucket and upload your pics to a PUBLIC album there. Come back here and place a link to your photo album or copy the " IMG CODE " and paste that into your message.
 
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Old 12-29-12, 08:32 AM
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Thank you.

Please see from photobucket 1) photo,

http://i1294.photobucket.com/albums/...pscc65d635.jpg

and 2) diagram.

http://i1294.photobucket.com/albums/...ps9cec787c.jpg
 
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Old 12-29-12, 09:04 AM
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Just I was afraid of: the LWCO does not look like it is installed per manufacturer's instructions. It should be on a minimum 1" pipe. It should be on a main supply or return to the boiler, not in the line to the exp tank, which is probably 3/4" and essentially dead-ended. It should be installed on a straight run of pipe, not on an elbow. The line from the boiler to the exp tank should be sloped upward throughout.

The minimum pipe size for the LWCO depends upon whether it is on a vertical or horizontal run of pipe.
 
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Old 12-29-12, 09:07 AM
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Can't tell much from the picture, please take a few more from different angles and a few further back. Remember that we need to 'be there' by means of pictures, one photo isn't enough.

The drawing does show that whoever installed that thing had no clue what he was doing. It's definitely NOT installed properly.

[mornin' Doug! ]
 
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Old 12-29-12, 09:14 AM
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Looking at it again, it seems likely that the line from the boiler to the tank could actually be plugged up with debris.

What happens if you hook up a hose to the drain and open it with the water feed to the boiler turned ON?

Maybe this will push the debris up into the tank and clear the line out?

If not, it would seem that you need to have some rework done on the piping... well, you do ANYWAY because that LWCO is installed wrong.

If that tank is all full of debris you might be looking at replacing that also.
 
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Old 12-29-12, 02:42 PM
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Thank you. Please see links for file “LWCO Piping.jpg” for a better angle.
http://i1294.photobucket.com/albums/...ps7c286549.jpg

Now that I spent sometime reviewing the overflow issue, I gained a bit more understanding on boilers.

Save to mention you guys have pointed out the wrongly installed LWCO etc, thanks again.

Benchmarking to [an article found on the internet] , on the pipings of Hot Water Supply Side: vs Hot Water Return Side:, my contractor, 5 years ago put the water feed valve / pressure reducing valve on the return side where as it should be on the supply side. He also missed the flow control valve.

I also checked today, his electrical connections of the LWCO, it was not connected as per LWCO manufacturer’s guidelines (terminals P1 & P2 hooked up in reverse).

Files named LWCO Boiler Connection linked for reference.
http://i1294.photobucket.com/albums/...ps654cf786.jpg
http://i1294.photobucket.com/albums/...ps08296717.jpg
http://i1294.photobucket.com/albums/...ps23043ed2.jpg
http://i1294.photobucket.com/albums/...ps24bbc73c.jpg

Man, the warranty had just expired in passed September. It seemed the whole setup was just geared to the warranty terms and then they started to break down %-(

I will get another contractor to take a look after the New Year to remedy the setup. Hmm, I wonder if I have a claim to this expense.

I wish all the best and good health to you and your family.

Thankfully, james
 
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Old 12-29-12, 03:46 PM
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my contractor, 5 years ago put the water feed valve / pressure reducing valve on the return side where as it should be on the supply side. He also missed the flow control valve.
In my opinion, the pressure reducing valve can be on the return side. That's where mine has been for decades, probably because of the constraints of my piping arrangement.

The piping between the boiler and exp tank needs to re-routed so the that LWCO is no longer in that stretch of pipe at all, and so the horizontal section slopes upward toward the tank (a pair of 120-deg els should take care of that).

While that work is going on, you can assess this blockage issue and the condition of the tank itself. But, as a temporary expedient, Trooper's idea of back-flushing into the the tank sounds good - might get you by until spring?
 
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Old 12-29-12, 05:55 PM
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I agree about the piping setup... it's not a 'show stopper'. There are 'old school' and 'new school' ideas and whoever installed your system probably installed it 'old school', the way he had done it successfully for years and years. OK, maybe modern thinking wasn't involved, but it worked, right? Don't sweat it.

Yes, the LWCO ultimately needs to be redone. I don't think that the P1 P2 reversal is a big deal if my thinking is correct that there is a relay inside the box between those two terminals. It may in fact NOT be wrong... it simply looks like the 'safeties' are on the other side... no big deal I don't think.

YES, please DO try backflushing the line into the tank! It's a simple thing to do...
 
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Old 12-30-12, 03:53 PM
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Short report. Situation resolved. Thank you Gilmorrie, Trooper.

Having clarified the supply/return piping and the LWCO electrical issues (there is an az2280 relay inside), I followed Trooper’s idea of back flush. Then, after boiler cooled, I ran water through it to assure a clear passage.

Put the system back in its operational state,
Started it up,
Ran the whole cycle,
Temperature went to 190 degree limit cut off,
PSI at about 17/18.

NO Overflow. Thank you %-)

Now, I can afford to wait till spring to correct the piping to the expansion tank and to relocate the LWCO to the riser or header, as well to put in a flow control valve. With this valve, I will be able to work around the boiler area without draining the whole house.

http://i1294.photobucket.com/albums/...ps739d4503.jpg

Kind regards.
 
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Old 12-30-12, 04:50 PM
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Next spring, when you tear into it, try to flush out the exp tank into a bucket, and see how much debris you get - and please report back here. Conventional steel expansion tanks last a very long time, even though they are cushioned with air, which might be expected to promote internal corrosion. Yet, I don't recall any reports here of such tanks springing a leak - and mine, going on 60 years old, is still fine and never loses its air charge. Possibly the oxygen in the air cushion gets depleted, over time, stopping further corrosion? Or maybe my B&G tank was coated internally?

Looking back on your saga, I believe the LWCO, improperly crammed into a 3/4" tee, was the source point of the clog.
 
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Old 12-30-12, 05:50 PM
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I believe the LWCO, improperly crammed into a 3/4" tee, was the source point of the clog.
I do too... and my advice is to keep an eye on the pressure over the winter to make sure it don't clog up again.

If it becomes a huge problem constantly clogging I might say to remove the LWCO for the winter and plug the tee. Connect the two wires on P1 and P2 with a wirenut... and watch that you don't lose water. LWCO is way over-rated anyway... still a safety device, yes, but MILLIONS of systems out there without one and no problems.

cushioned with air, which might be expected to promote internal corrosion.
The reason that commercial installations use nitrogen!

as well to put in a flow control valve. With this valve, I will be able to work around the boiler area without draining the whole house.
Flow control valve as in 'check valve'? Don't expect a check valve to make a positive shutoff. Some will, the the lifting disk type used in heating systems often do not. If it's isolation for service purposes you are after, install FULL PORT BALL VALVES.
 
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Old 01-04-13, 03:48 PM
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Yes, I am watching it since, the PSI is at about 12 when cold, no overflow when hot. I left the high limit at 200 instead of the contractor�s setting of 220 F.


Forgot to ask about the slope piping from the boiler rise to the expansion tank;


1) Is there a recommended angle (say 30 degrees, thinking of the 120 els) from the boiler rise?


2) Could I put a small horizontal length (if ok, max length?) first at the boiler rise, if due to existing exhaust fittings that I cannot put a �Y�, 120 els or other slopes right there?
Picture of venting exhaust link;
http://i1294.photobucket.com/albums/...ps739d4503.jpg


Thanks.
 
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Old 01-04-13, 04:00 PM
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You want to slope that line by about 1/2" (or more) per foot. Vertical sections are OK, no horizontal sections. The purpose is for air expelled from the system to rise into the tank. Without slope, the line can become air bound.
 
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Old 01-04-13, 04:49 PM
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left the high limit at 200
Drop that down to 180°. If you need more than 180 water to heat your home, something is wrong!

I really don't expect you need to worry about the slope of the piping too much in your install due to the fact that the way it is tapped into the supply riser it is VERY unlikely any air would ever get into that pipe anyway. Any air in the flow stream is going to cruise right past that tee fitting...

But technically, yes, slope up all the way to the tank with at LEAST 3/4" pipe.
 
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Old 01-04-13, 05:06 PM
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Any air in the flow stream is going to cruise right past that tee fitting...
True enough, in which case there needs to be an air scoop or some such diverter feeding air into the line to the tank. Bell & Gossett has sold their boiler airtrol fittings for decades to serve that purpose.

I forgot, yes, B&G specifies minimum 3/4" pipe.
 
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Old 01-04-13, 05:17 PM
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Bell & Gossett has sold their boiler airtrol fittings for decades to serve that purpose.
Yes, they still do sell the "ATF" fitting, but sadly it appears that the BOILER fitting, the "ABF" is now being made out of unobtainium which makes it invisible.

It was a great idea that ABF. Too bad nobody installs new compression tanks anymore!
 
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