Laars boiler shutting itself off

Reply

  #1  
Old 04-04-12, 03:04 AM
Member
Thread Starter
Join Date: Apr 2012
Posts: 5
Received 0 Votes on 0 Posts
Laars boiler shutting itself off

This one is make both me and the installer crazy:

I have a hot water Laars Endurance gas boiler that has recently been shutting itself down spontaneously. The system was installed in 2007 by a factory-trained servicer, and has worked since then with some minor repairs along the way (faulty DMW priority switch and power valve; plus a new igniter and circuit board 2 months ago). The overall system is a 4-zone HW heat + DHW going to a mix of flat panel radiation and cast iron baseboard (newly installed in 2007).

Symptoms are as follows:
Upon arrival (the house is only used on weekends), the boiler is cold and its LED panel reads ‘OFF’ (~60°, 12 psi). Boiler can be restarted manually, and all controls appear to work properly. T-stats are already calling for heat, zone valves open, boiler comes up to temp and circulator pump turns on. Normal boiler operation is 170-207°, 18-20 psi.


What is abnormal is the following:
The house comes up to temp; T-stats are satisfied; house cools off; T-stats call for heat a second time, and the boiler goes dead for a minute and then the power comes back on. However, the boiler is not supposed to go dead and does not turn itself back ‘ON’. The observed sequence is: LED panel is ‘ON’, then goes black, then the LED reads ‘OFF’ (which means it is getting electricity, but is not functioning. The proper sequence is the LED panel should remain lit all the time). Readings of the water pressure over the past few cycles fluctuate from 12-24 psi.

I’ve checked the following:
System for leaks--I’ve isolated the only zone that may possibly be a problem (zones all have separate shut-off valves), no observed leaks anywhere;
Zone valve wiring--I’ve traced and checked (R=24V pos, W=zone valve motor, end switches to 24V neg + boiler control);
Zone valve + T-stat operation--switches on and off as called for, zone valve motors work, valves open and close as called for, boiler responds to call for heat (when ‘ON’);
Circ pump--turns on when zone valves are opened;
Expansion tank--some minor moisture out of air valve, and I replaced the tank with a new one.

These are the likely culprits:
Low water cut-off (add-on, required by local code);
Boiler circuit panel or some other internal boiler circuit.

I am inclined to blame the low-water cut-off, though why would it start acting up now after 4 years?
The pressure fluctuations also worry me; it is usually right around 18 psi whenever I’ve looked at it in the past.
Anyone have any thoughts? My installer will deal with any boiler internal issues, but doesn’t want to make the service call for any of the externals. Thanks in advance.

Equipment list:
Laars Endurance EBP 110 (sealed combustion, w/ DHW);
4 Honeywell V8043e zone valves;
1 Taco circ pump;
Honeywell Pressuretrol PA404a low water cut-off
Extrol 30# expansion tank (replaced with Flexcon HTX30);
4 Honeywell T87 thermostats;
Spirovent air eliminator;
Watts fill valve (set at 10-12 psi);
Watts PRV (30 psi)
24V transformer (unknown make)
 
Sponsored Links
  #2  
Old 04-04-12, 03:15 PM
Member
Join Date: Jul 2009
Location: Toronto
Posts: 1,174
Received 0 Votes on 0 Posts
My guess would be the low water cutoff.
Hard to tell, need to be there and see it in action
 
  #3  
Old 04-04-12, 03:17 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Your low water cut off isn't truly a low water cut off... it's a low PRESSURE switch. There's subtle differences in the way it will protect the system (or not).

Has the system displayed any 'fault codes' ?

In case you don't have the manual:

http://www.laars.com/LinkClick.aspx?...edownload=true
 
  #4  
Old 04-04-12, 05:17 PM
Member
Thread Starter
Join Date: Apr 2012
Posts: 5
Received 0 Votes on 0 Posts
My guess is that it's the low water/pressure switch as well, though why it should suddenly begin acting up after 4 years seems strange. The pressure does fluctuate quite a bit (± 5 lbs), which might be normal but I've never noticed it to that degree. Could the control board have any effect on the pressure fluctuations?

My installer wants me to bypass the T-stats--he thinks the newer T87s are crappy, but honestly I can't see how they would affect the boiler operation. They seem to be calling for heat properly and I like their simplicity.

I have the manual. The system has not displayed any fault codes; it goes directly to black (no power), then displays 'OFF'. I may call Laars tomorrow to see if they can provide any insight. If it is the circuit board, it's still under warranty.
 
  #5  
Old 04-09-12, 02:04 PM
Member
Join Date: Mar 2012
Posts: 1
Received 0 Votes on 0 Posts
I would have to guess the low water cutoff...but with gas boilers you can never really tell without checking them out in person. best of luck!
 

Last edited by NJT; 04-09-12 at 03:20 PM.
  #6  
Old 01-24-13, 12:24 PM
Member
Join Date: Jan 2013
Location: USA
Posts: 1
Received 0 Votes on 0 Posts
I have the same problem - exact to the dot on the symptoms. Would love to hear if you solved the problem.
 
  #7  
Old 01-24-13, 07:12 PM
Member
Thread Starter
Join Date: Apr 2012
Posts: 5
Received 0 Votes on 0 Posts
The short answer is no, although the system is now working, I don't believe the problem is solved. What transpired is as follows:

After I trouble-shooted (is this a word?) virtually everything on the system, the servicer (one of the two factory-authorized in the state), came out and replaced an internal pump and something else internal, neither of which worked until he replaced the circuit board. No one ever figured out why two circuit boards went bad within two months of each other.

There is more to this story. After 5 months of light summer use, the circuit board goes out again--this time completely. No re-start, no low-pressure cut-out problem, just dead, black panel. The servicer tells me to bypass the low-pressure switch and pull the panel off to see if the C.B. is 'burnt'. I do this without success. Servicer comes out the next day.

He replaces the C.B. once again (this is 3 new circuit boards within 10 months) and proclaims all is well. He then sends me a bill ($500 for the C.B. + $450 time and labor) saying that it was not covered by warranty because I 'tampered' with the boiler. It's still working so far, but I don't think it's a permanent fix. I am waiting for it to die again any week now.

I believe that there is an internal problem with the boiler that came up as a result of routine service done on the boiler one year ago. Since then, the C.B. has failed after a short working time (Nov 2011---Feb 2012---May 2012---Oct 2012). I have petitioned my servicer to have someone from Laars troubleshoot the machine, and he told me that would never happen. When I asked why not, he said A) since he did not buy the boiler--although he did all of the installation work--it was not under warranty, B) that the boiler was 6 years old, C) that I am somehow responsible for it breaking, D) that circuit boards go bad all the time.

As a result of this last discussion, I will replace this boiler with a Buderus as soon as I am able. If a company (or in this case, its authorized repair person) cannot support a boiler for more than a few months at a time (and at a $1000 a shot), the boiler is no good to me. Which is too bad; one of my two other #EDP 110s has been flawless for 8 years (even though morons installed it); I wanted to see an American company succeed in designing and building a world-class product. Silly me...
 
  #8  
Old 01-25-13, 04:07 AM
poorplmbr's Avatar
Member
Join Date: Feb 2003
Location: long island ,new york
Posts: 298
Received 0 Votes on 0 Posts
That "low water cut off" is a pressure switch for a steam boiler, not meant for a hot water system...
 
  #9  
Old 01-25-13, 07:42 AM
Member
Thread Starter
Join Date: Apr 2012
Posts: 5
Received 0 Votes on 0 Posts
If a low-pressure switch is meant for a steam system, not a hot water one--and I'm not doubting you--I have a few questions about that:

1) How would a low-pressure switch cause these type of problems? My understanding is that it works sort of like a kill switch; that if the pressure drops below a certain rate (or too quickly) it merely shuts the power off. The symptoms of the boiler were much more complicated than that.

2) Why would this type of switch suddenly become a problem after 4 years of otherwise reliable service? If this didn't 'belong' in the initial installation, wouldn't it have caused a problem much earlier on?

3) Do you have any recommendations for a make and model of low-water switch that would be appropriate (for this 4-zone, single-family house)?

Thanks,
Edward
 
  #10  
Old 01-25-13, 08:49 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
I don't think that Poor was suggesting it was causing the problem, just noting that type of switch is NEVER seen on a hot water system. It's absolute intent is to control a STEAM system.

I too had mentioned the pressure switch early on...

It is, after all, just a pressure switch and could be used in various other applications if it were appropriate.

Here is a link to the Honeywell info sheet for that switch FYI.

http://customer.honeywell.com/techli...it/60-2341.pdf

What is most odd about this being used on your system is the fact that the switch BREAKS connection when the pressure goes above the setpoint. In a steam system this is exactly what one would want... turn off the burner when the steam pressure is at/above setpoint.

You said that you have a 404A and the above describes the action of the A model.

The B model has the reverse action and perhaps this is what you actually have on your system?

This would be a much more appropriate choice for use on a hot water system, (actually not only more appropriate, but the only model of this switch that would even work).

For example, lets say that you want to 'cut off' the boiler system if the pressure drops below 9 PSI... and would re-enable at 10 PSI. With this switch on the system you could set the operating range to 9 (it's max setting) with a 1 PSI differential.

The use of pressure switches on a hot water system is not often done. It is possible to have low water and still have pressure (for example, if system is low on water and aquastat malfunctions in a 'runaway' condition, 9-10 PSI of steam could EASILY be produced), so it's not a 'definite' indicator of a problem. Still, if you DO have low pressure, you MIGHT want to cut the boiler off...

Much better for LOW WATER conditions are controls such as "Guard Dog RB series", "HydroLevel", I believe Taco has them, and a few others I'm not recalling at the moment. Hit up Google to find different LWCO controls.
 
  #11  
Old 01-25-13, 09:33 AM
Member
Thread Starter
Join Date: Apr 2012
Posts: 5
Received 0 Votes on 0 Posts
I get all of that in theory and agree with it. It should be a low-water switch and not a low-pressure switch (actually neither is needed for this boiler; the internal circuitry will shut it down if it senses anything wrong like that--it's only to satisfy local code which has not kept up with hi-efficiency boiler operation).

What I don't get is why this may create a problem after being in service for four years. And as I noted in my earlier post, I don't even believe this was the problem at all--only a symptom. At this point however, it is somewhat of a moot point. I will replace this boiler with another make as soon as I get the thousands of dollars it will cost me. Anyone have any recommendations for reliable, high-efficiency direct-vent manufacturers? I'm thinking Buderus is the best option.

Thanks,
Edward
 
  #12  
Old 01-25-13, 09:59 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
What I don't get is why this may create a problem after being in service for four years
I don't think anyone ever implied that it was the problem.

When it was believed that you had an actual LWCO, then yes... those probes need periodic cleaning and will false trip if they aren't maintained.

Again, after it was realized that you had a PRESSURE switch, it wasn't suspect.
We were just informing that is what you had... FYI...
 
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: