Aquastat relay chattering and not working properly!

Reply

  #1  
Old 12-08-10, 07:23 AM
Member
Thread Starter
Join Date: Dec 2010
Location: United States
Posts: 66
Received 0 Votes on 0 Posts
Aquastat relay chattering and not working properly!

Hello, new to the forums here but have done a bit of browsing and seems to be a good knowledgeable bunch of members.

My problem.

I have a Weil Mclain boiler that is fairly new. I think within the last 8 years or so. it is using a Honeywell Aquastat i dont have the model number now but i believe it is very similar if not identical to the L8124A. I also have a thankless coil (I believe) for domestic hot water. The boiler maintains temperature for hot water and cycles properly for hot water calls.

When my thermostat calls for heat the relay in the aquastat chatters here and there but for the most part worked for a couple of days. Now its to the point where the relay wont click over to fire the burner and start the circulator. I noticed when i tap the aquastat i can get the relay to chatter flicking the burner on and off and sometimes it will chatter and then stay on. Sometimes for a couple of min other times it will hold until the thermostat isnt calling for heat anymore.

Is there anyway to solve this issue without replacing the Aquastat? Im confident i can handle replacing the aquastat but id rather not drop the 150 on a new unit right now. Especially when the only problem seems to be a faulty relay?

Any suggestions?

I will report back this evening with the exact model of the aqustat i have.

Thanks for your help!

Ethan
 
Sponsored Links
  #2  
Old 12-08-10, 11:32 AM
Member
Thread Starter
Join Date: Dec 2010
Location: United States
Posts: 66
Received 0 Votes on 0 Posts
I just noticed that there is another section for gas and oil fired furnaces. I figured this would be best fit under boilers and hot water systems. Maybe I was mistaken?

I dont want to create another thread to avoid cluttering the forums. If this is in the wrong section can a MOD move to the appropriate section please?

Thanks,

Ethan
 
  #3  
Old 12-08-10, 12:34 PM
Member
Join Date: Jan 2008
Location: Southeastern Pennsylvania
Posts: 2,947
Received 0 Votes on 0 Posts
hi ethan –

I’m not one of the experts here on the forum. But I had the identical problem that you have with the 8124A. The relay would sometimes make and sometimes it would not. Finally found that if I tapped the box it would chatter and stay closed – sometimes.

First noticed that sometimes there was a real long inexplicable delay between when the t-stat would call for heat and when the burner and circulator would come on. Then I discovered that the 8124 would usually eventually close the relay on its own – but who knows when. I guess a little vibration in the house or something would cause it to finally close? Drove me nuts till I figured out what was going on.
I got the following good advice here for a good old fashioned try – but unfortunately I still had the problem.

Originally Posted by plumbingods View Post
Before replacing the $200.00+ control, here is an old trick that sometimes helps out. Take a piece of light grit sandpaper, or the scratch part of a book of matches, with the power OFF, clean the contacts of any carbon from the relay in the control. Sometimes a carbon build-up is the cause of a poor connection.
But maybe you could give that a try also.

I then got real good advice here on the replacement for the 8124A – the Honeywell L7224U. The L7224U was pretty easy to install and it has a display and push buttons to set values inside the box. You can easy read/set things like upper limit, differential, current boiler temperature, etc. You can read out when the burner and/or circulator are turned on, etc. Much better than the 8124A. Didn’t need to change any wiring at all.

Maybe the experts might have something to say.

Good luck!

 
  #4  
Old 12-08-10, 12:44 PM
Member
Thread Starter
Join Date: Dec 2010
Location: United States
Posts: 66
Received 0 Votes on 0 Posts
zoesdad,

Thanks for responding.

So the install was pretty easy for the L7224u? I see it uses the thermistor instead of that imersion bulb. Did you have to drain the boiler first? Or the well that it sits in inst actually open to the water its just inserted in the tank?

Thanks,

Ethan
 
  #5  
Old 12-08-10, 04:17 PM
Member
Thread Starter
Join Date: Dec 2010
Location: United States
Posts: 66
Received 0 Votes on 0 Posts
Ok so i got home and was able to see the model number on the Aquastat

The cover says its a Honeywell L8124A, C
L8151A

Why are there two model numbers on this? Is the L7224U still ok to use?

They do seem to be the same but i wouldnt want to purchase the L7224U for $150 and not be able to use it

Thanks,

Ethan
 
  #6  
Old 12-08-10, 07:48 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
Hi Ethan, please tell us the make/model of your boiler and the type of fuel (oil or gas or?).

The L7224U is designed for oil fired systems.

I am not sure I understand why Honeywell says this is for OIL only... aside from the fact that there is no output for LOW VOLTAGE gas valves, it seems as though it would work for older gas systems that have 120V gas valves.

The 7224 is listed as a replacement for the 8124A and C models.

The 8124 A and C models are functionally equivalent to the 8151.

What you describe sounds to me as though there is a cracked solder connection on the circuit board. Do you own a soldering iron and know how to use it? or perhaps you know someone who does?

I would never use sandpaper on relay contacts... there is a plating material (tungsten) on them that will be damaged by doing so... I know, I know, people do it all the time, but it's wrong. The most abrasive thing you should use is a 'burnishing tool', and the cheapest burnishing tool you can find is a piece of shirt cardboard, or a matchbook cover. Soak the cardboard with DEOXIT GOLD, press the contacts together and slide the cardboard between...

No, you don't have to drain the boiler... the 'well' is a dry well into the boiler.

Cheaper here:

L7224U1002 - Honeywell L7224U1002 - 120 Vac Oil Electronic Aquastat
 
  #7  
Old 12-08-10, 08:31 PM
Member
Thread Starter
Join Date: Dec 2010
Location: United States
Posts: 66
Received 0 Votes on 0 Posts
Hello NJ Trooper.

The model of the boil is a Weil Mclain P-WTGO-4 this is an oil fired burner with a tankless coil for domestic hot water.

I though it might have been a bad solder connection as well. Well the thought crossed my mind anyway mostly because the jarring of the unit seemed to change its state intermittently. I dont know why i dismissed the idea though...

I do have a soldering iron and am quite good with one actually. Can the L8124A be taken apart easily to access the bottom of the board?

I didnt end up using the sand paper as i dont see this to be the problem anyway. The relay isnt energizing at all when its not operating. Its not like its changing states but not making connection on the contacts.

Thanks for the link to pex supply. That is a few bones cheaper then other places i found.

Thanks,

Ethan
 
  #8  
Old 12-08-10, 08:57 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
Yes, you can disassemble the aquastat, obviously very carefully. Main thing is to NOT KINK that capillary tube.

Tag and remove the wires. Take some digital pics if you think they will help you get it all back together.

There is a screw clamp that holds the aquastat body onto the lip of the immersion well. Loosen that.

Slide the aquastat and bulb straight away from the boiler.

You should see several metal tabs around the perimeter of the circuit board. Carefully bend those away to release the board from the chassis.

Cracked solder joints may not be immediately visible to the untrained eye, but it sounds as if you have some experience... check all the solder connections on the board. Reflow any that appear questionable... do NOT use ACID CORE solder. Use ONLY ROSIN CORE solder made for electronic work.

I have found that it is usually best to actually remove the old solder and start fresh, so if you have some 'solder wick', or a 'solder sucker', then use that. If not, just reheat the joint and add a minimal amount of new solder... you of course don't want big blobs of solder on everything.
 
  #9  
Old 12-08-10, 09:23 PM
Member
Thread Starter
Join Date: Dec 2010
Location: United States
Posts: 66
Received 0 Votes on 0 Posts
YAHTZEEE!


I took a quick look at it after you had mentioned some bad solder joints and saw that it came apart pretty easy. As you said it was just the four tabs holding the board to the enclosure. Since it was such a simple procedure to remove it i couldn't help but take a look at the back of the board...and WOW they have a horrible QA department. There was such a small amount of solder on the transformer that controls the relay and the relay itself. Almost no solder was visible on the pad side. Its almost like they did this intentionally so the unit would fail after a short period of time. (5-10 years is my guess) which is pretty short for such a simple control.

Anyway I reflowed and added a tad of solder to the joints that looked questionable to me put it back together and PRESTO! HEAT WE HAVE! The whole thing took about 10 min for me and saved me at least the $119 I would have spent on the new aquastat. Although the digital version would be nice...

Thanks again for your comments and guidance Trooper. Im ashamed that I even dismissed the thought of bad solder joints.

Thanks again!

Ethan
 
  #10  
Old 12-08-10, 10:05 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
I love it when a plan comes together!

Stay warm!
 
  #11  
Old 12-09-10, 07:00 PM
Member
Join Date: Jan 2008
Location: Southeastern Pennsylvania
Posts: 2,947
Received 0 Votes on 0 Posts
Glad to hear about the success ethan! And Trooper has another notch in his belt (and I learned some new stuff again).

I kept my old 8124A around as a spare ( I don’t throw anything out). And I took it apart as you guys discussed and looked at the back of the board just for the heck of it. I think mine is also skimpy on solder as you indicated yours was. But I’m not sure. I never soldered (except some plumbing parts. But that’s not the same I guess, ha-ha). Sounds like your skill and knowledge came in really handy. (My boss could spot soldering problems too – and he was always talking about things like “cold solder joints”).

Originally Posted by ethan169 View Post
… The cover says it’s a Honeywell L8124A, C
L8151A…
Ethan
That’s the same exact information I have on mine on a paper label inside the box cover and I was confused. Guess Trooper clarified that. I just discovered L8124A1114 stamped on the bottom of the box. The 7224 worked fine as the replacement. Hope you never need it! (Damn cold already for second week of December.)
 
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: