Honeywell L8151A Triple Aquastat

Reply

  #1  
Old 07-28-13, 05:05 AM
Member
Thread Starter
Join Date: May 2013
Location: USA
Posts: 153
Received 0 Votes on 0 Posts
Honeywell L8151A Triple Aquastat

Hi all, With assistance from this forum (thanks to NJ Trooper) I've had success with previous jobs I've performed on my oil furnace so I'm hopeful someone will be able to offer me assistance with the next one.

I have an oil furnace (Dunkirk) with a Becket burner. It won't come on (Looking on the bright side I'm not using any oil The down side is the water is darned cold in the morning ). I get power to the zone controller with zone priority (for indirect HW - the domestic hot water coil has been disabled). Priority zone LED lights up when it asks the oil furnace to heat the water but the furnace does not run. It only runs if I put pressure on the contactor and hold it down. Once the pressure is released the oil furnace stops running. I've used my multimeter and the aquastat is getting power to the PC board but from there I do not know where else to test. My guess is I'll have to swap out this aquastat for a new one. (I've had power fluctuations in my house which I believe fried it and I pray/believe/hope they have been resolved). Other than the electrical connections in the aquastat, is it much of a chore to swap out the old stat for a new one? What might be some of the surprises that I may encounter? I believe the aquastat has a remote bulb. Will I have to remove that too or will that de-couple from the aquastat? Will I have to drain the oil furnace to change out the aquastat?

Thanks in advance for taking the time to read my story and offer any assistance. Roger
 
Sponsored Links
  #2  
Old 07-28-13, 12:35 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Hi Roger,

Don't be so quick to condemn the aquastat. Let's do due diligence and test a couple things first.

You said:

Priority zone LED lights up...
On what piece of equipment does this LED light? In other words, what make/model zone controller? If it's a TACO model, aren't there actually TWO LEDs for each zone? A yellow and a red?
 
  #3  
Old 07-29-13, 04:23 AM
Member
Thread Starter
Join Date: May 2013
Location: USA
Posts: 153
Received 0 Votes on 0 Posts
NJ Trooper - Sorry I didn't get back to your questions yesterday. I went to church first thing yesterday morning and then treated my oldest brother to breakfast. Shortly after getting home, I had all kinds of visitors throughout the day with the last one not leaving until late in the evening. By that point I was shot and went to bed.

To answer your questions -

1) The zone controller is a AZ - 6CP made by Argo. The old controller was made by Argo too but it didn't have a priority zone. Of the 6 zones, only 4 are wired to it. One for the indirect (priority zone) tank and the other 3 are for zones that are to heat emitters in the house.

2) You are correct, the zone controller has more than one LED. The first LED is from the LED array - it flashes during normal operation (Yup, it's flashing). The 2nd LED is green indicating when the zone is calling for heat (In this case when the aquastat on the indirect calls for heat. Yes, it lights up) The 3rd LED is red indicating that the zone valve is fully open (Yes, it lights up). At this point the oil furnace should turn on to heat the water and circulate it to heat the water in the indirect. However, it will only turn on if I put pressure on the contactor. Once pressure is released the oil furnace turns off, the contactor will not stay closed.

Everything worked fine for about a month or more until I began having electrical surges about a month and half ago and then it stopped working. Roger
 
  #4  
Old 07-29-13, 03:56 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Hi Roger, you don't have to apologize! We've all got our regular lives to attend to...

On the Argo panel, the X X terminals are wired to the T T terminals in the 8151 ?

What happens if you carefully short the X X terminals on the Argo together to simulate a call?

Just to rule out the wiring between them, what happens if you carefully short the T T terminals in the 8151 ?

Have you tried forcing one of the heating zones to call for heat ? Same result ?

If you have a multimeter, set it to read AC VOLTS and measure across the T T in the 8151 when there is NO call from the Argo. What voltage do you read?
 
  #5  
Old 07-29-13, 05:13 PM
Member
Thread Starter
Join Date: May 2013
Location: USA
Posts: 153
Received 0 Votes on 0 Posts
NJ Trooper, When I short the X X terminals on the argo, the furnace will run as long as I don't break the short. As soon as I break the short it stops.

The voltage I read at X X was 28.5 volts.

The results are the same when turning up the thermostat on one of the heat zones.
Roger
 
  #6  
Old 07-29-13, 05:19 PM
Member
Thread Starter
Join Date: May 2013
Location: USA
Posts: 153
Received 0 Votes on 0 Posts
Missed answering one of your questions - the wire from the X X terminals on t argo are connected to the T T terminals on the 8151.

Roger
 
  #7  
Old 07-29-13, 05:44 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
When I short the X X terminals on the argo, the furnace will run as long as I don't break the short. As soon as I break the short it stops.

The voltage I read at X X was 28.5 volts.
That is telling us that the 8151 is NOT the problem.

When a zone or the indirect call for heat, the Argo panel is supposed to close the X X contacts, exactly what you did with the short across them. In other words, by shorting them, you are simulating what the Argo would normally (SHOULD normally) do in order to call the boiler to fire.

Right now it's looking like the Argo is at fault, not the aquastat!

Give me a few minutes to look at the Argo manual again... standby.

Inside the Argo is a row of 6 LEDs. The second from the bottom is labeled " X X CONTACT "

What does that LED do when there is a call for heat or indirect?
 
  #8  
Old 07-29-13, 06:04 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Do you also have the "DPM-2" Outdoor reset module installed?

Is your boiler pump wired to the Argo panel? or directly to the 8151?
 
  #9  
Old 07-30-13, 05:29 AM
Member
Thread Starter
Join Date: May 2013
Location: USA
Posts: 153
Received 0 Votes on 0 Posts
The LED second from the bottom labeled "X X contact" lights up when it calls for heat or the indirect.
 
  #10  
Old 07-30-13, 05:33 AM
Member
Thread Starter
Join Date: May 2013
Location: USA
Posts: 153
Received 0 Votes on 0 Posts
I do not have the "DPM-02" Outdoor reset module installed.

If you mean the circulator pump it is connected to the 8151.
 
  #11  
Old 07-30-13, 05:27 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Roger, I can't absolutely conclude without being there, but from what you've told me so far, I am nearly certain that the problem is with the Argo panel, specifically the 'endswitch relay' which operates the X X panel output.

If you know any electronic technicians, they MAY be able to find a replacement relay and repair your panel... but short of that, it would seem you need to replace it.
 
  #12  
Old 07-30-13, 05:40 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Roger, I have a temporary 'work around' for you.

Since the circulator pump is being controlled by the 8151 and the only thing that the Argo panel is doing is operating the zone valves, you can do some minor re-wiring in order to get the boiler working for hot water only while you are sourcing a replacement panel.

LABEL ALL WIRES BEFORE REMOVING!

CUT POWER TO THE SYSTEM BEFORE STARTING! 120VAC INSIDE! YOU CAN BE KILLED!

Remove the two wires from the X X terminals in the Argo panel. These two wires go to the T T terminals in the 8151.

Remove the two wires in terminals 3 & 4 in the Argo panel that are on the channel for the indirect water heater zone valve. (this should be "channel 1".)

Connect these two sets of wires together. Polarity is not important. BE CERTAIN THAT THEY DO NOT TOUCH ANYTHING ELSE! Hopefully you will have enough wire length to do so without having to 'extend' them with pieces of wire. You should probably use small wire nuts to connect them together...

This will allow the indirect water heater zone valve to DIRECTLY call the boiler for hot water by 'bypassing' the defective control panel.

When you get the replacement panel, just re-wire back the way it was.
 
  #13  
Old 07-31-13, 03:37 AM
Member
Thread Starter
Join Date: May 2013
Location: USA
Posts: 153
Received 0 Votes on 0 Posts
NJ Trooper - I was talking to one of my younger brothers about this yesterday (he's an electronics technician) and said exactly the samething you said, the relay may be dirty or bad. When I get home from work this evening I'm going to remove the entire panel and see if he'll have a look. He also mentioned something of a "cold solder joint". I'll report back when we have resolved this issue.

Thanks for helping me through this. I appreciate it very much.

Roger
 
  #14  
Old 07-31-13, 03:25 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Yep, yer bro is on the money. Could easily be cold (or cracked) solder connection.

Please do let us know!
 
  #15  
Old 07-31-13, 05:22 PM
Member
Thread Starter
Join Date: May 2013
Location: USA
Posts: 153
Received 0 Votes on 0 Posts
NJ Trooper - Sometimes a short term fix is sitting under ones nose and it's so obvious that I simply overlooked it. I had completely forgotten that I still had the old Argo zone controller safely stored away. The old one did not have the priority zone capability but in this case, who cares!? I'm using just one of the zones to give me hotwater until the other board is repaired or replaced (It's a cobjob install but it'll get me by). So, my oil furnace is now making hotwater as I type. I can't wait to take a hot shower in the morning. One doesn't realize how much it is missed until it is not there.

As soon as my brother finds the problem with the troublesome board, I'll let you know.

Thanks again for your help with this problem.

Roger
 
  #16  
Old 08-06-13, 05:20 AM
Member
Thread Starter
Join Date: May 2013
Location: USA
Posts: 153
Received 0 Votes on 0 Posts
Update

Hi, Well, unfortunately, my younger brother was unable to find the problem with the board. I had the day off from work yesterday so I re-installed it, connected all of the wires and lo and behold the darn thing works as it should now. For how long? Who knows! But it'll buy me some time to save my pennies and purchase another board in the event this one craps out again. Or, at the very least purchase a couple of solid state relays to have on hand.

At the moment my best guess is during the original install, one of the connections wasn't good causing it not to work properly. It'll be interesting to see how long this thing runs.

Roger
 
  #17  
Old 08-06-13, 03:51 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Bummer...

But, maybe he did 'fix' it... did he happen to touch up any solder connections? It don't take much of a crack in solder to cause intermittent operation.

Worst case until you can get another one, if it craps out again go back to post #12 and do the 'work-around'. At least you will have hot water!
 
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: