Honeywell L8148 E 1273 Coil Resistance

Reply

  #1  
Old 03-19-14, 06:25 PM
Member
Thread Starter
Join Date: Mar 2014
Location: USA
Posts: 10
Received 0 Votes on 0 Posts
Honeywell L8148 E 1273 Coil Resistance

SlantFin Victory V-120 EP

Light off became intermittent. I found I could start it by manually closing the contacts of the relay in the aquastat.

I am showing 30 Ohms across the relay coil. I couldn't find a spec sheet for the relay.

The diagram on page 17 of the installation manual shows "1K" between terminals "W" and "T" (the coil). Am I interpreting that correctly to mean a coil resistance of 1000 Ohms?

If so, I assume it's a bad relay coil and time for a new aquastat.

Thanks in advance if anyone can confirm this.

Rich
 
Sponsored Links
  #2  
Old 03-19-14, 06:41 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 Rich, welcome.

Am I interpreting that correctly to mean a coil resistance of 1000 Ohms?
No, the 1K is only the reference designator for the relay. 1K is the coil, 1K1 is one set of contacts, 1K2 is the other set of contacts.

I believe that 30 ohms is about right.

Is the transformer in the aquastat producing the correct 24 VAC (nominal) voltage on the secondary? You can measure this between the "TV" and the "W" or "Z" terminal (the latter are jumpered together)

What happens when you jumper the T and TV terminals together to simulate a thermostat call?
 
  #3  
Old 03-19-14, 06:50 PM
Member
Thread Starter
Join Date: Mar 2014
Location: USA
Posts: 10
Received 0 Votes on 0 Posts
That answers my question!

I have the transformer out and will check the secondary voltage.

Thanks,

Rich
 
  #4  
Old 03-19-14, 07:29 PM
Member
Thread Starter
Join Date: Mar 2014
Location: USA
Posts: 10
Received 0 Votes on 0 Posts
The transformer is putting out a steady 30.7 VAC.

I had the circuit board out looking for a bad solder joint but so far it looks OK.

I'll have to put it back together or set up something safe to check the "TV"-"W". (I sometimes get ahead of myself taking things apart. :NO NO NO: )

The mechanical operation of the relay seems OK but I guess I should have checked that first.

I'll report back when I get a test on the relay. Thank you for your help.

Practice image post:
Name:  Circuit Board 1.jpg
Views: 1004
Size:  26.4 KB
 
  #5  
Old 03-19-14, 07:57 PM
Member
Thread Starter
Join Date: Mar 2014
Location: USA
Posts: 10
Received 0 Votes on 0 Posts
Jumping "T" and "TV" gives a good activation of the relay - no chatter or drop off.

Thanks,

Rich
 
  #6  
Old 03-19-14, 09:01 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,482
Received 25 Votes on 19 Posts
Those particular Honeywell relays are notorious for mechanical failure. Intermittent operation is the clue.
 
  #7  
Old 03-20-14, 06:22 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Those particular Honeywell relays are notorious for mechanical failure. Intermittent operation is the clue
More notorious is the solder connecting them to the PC board.

Rich, I don't believe that you've mentioned what is connected to the T and TV terminals.

Do you have a system that is ZONED with electric zone valves? Or just one thermostat connected there at T and TV?
 
  #8  
Old 03-20-14, 08:55 AM
Member
Join Date: Nov 2009
Location: Lake Champlain Islands, Northern Vermont
Posts: 40
Received 0 Votes on 0 Posts
Yup...I have the same Aquastat on a SlantFin boiler, and the solder joints failed on it twice.

First time, it burned a trace on the back of the board, behind the relay. I added a jumper wire over the burned trace, and resoldered both ends, and then it worked normally again.

The second was much more subtle. It was an OK looking solder joint, but under a magnifying glass (or we used a little USB microscope), you could see a subtle ring in the solder around the pin, and this is where it was an open solder joint. I just resoldered it, and again back to normal operation.

I'm currently looking at options to replace it the Aquastat...and some folks here have suggested a Hydrolevel or Beckett smart boiler control as a replacement.

If anyone has opinions on the Hydrolevel vs. Beckett, please post your thoughts in my thread...
http://www.doityourself.com/forum/bo...nt-l8148a.html
 
  #9  
Old 03-20-14, 12:06 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,482
Received 25 Votes on 19 Posts
My suggestion is to build your own. Cannibalize the thermally-operated switch(s) and use them with high quality discrete components to make a robust and infinitely more adjustable unit. I can give some details later if you are interested.
 
  #10  
Old 03-20-14, 01:45 PM
Member
Thread Starter
Join Date: Mar 2014
Location: USA
Posts: 10
Received 0 Votes on 0 Posts
Trooper,

When I purchased the house 3 years ago the 10+ y.o. system had two Taco circulator pumps and 4 zones (in parallel), three for heat and one for hot water. Three of the four zone valves were stuck so I replaced them with identical Honeywell valves. (There is evidence that one or both of the Taco pumps were replacements.)

The very hard well water had seeped around fittings and the site-made manifolds so I replaced the check valve, boiler feed valve and pressure relief valve. I also replaced all calcified fittings and made new manifolds. Remarkably the inside of all the 1-1/4" copper tubing, the stuck zone valves, and fittings were without any buildup. (Pictures available.)

The wiring was a rat's nest only a plumber could love ( no offense ) so I neatened it up and soldered or made good mechanical connections. I saw the max current limit in the manual and recall the total was within the limit. I'll do that again.

The system ran fine in this configuration for two years.

The fact that the relay worked well with the jumper makes me wonder if there is a problem with the thermostat wiring. I had disconnected all zones except the hot water for troubleshooting. I'll check the thermostat wiring for continuity.

I just installed a small electric water heater and have a wood stove so there is no time factor. (Yes, there is no Mrs. Maddog )

Thanks for the help and insight you have already provided.

Rich
 
  #11  
Old 03-24-14, 05:26 PM
Member
Thread Starter
Join Date: Mar 2014
Location: USA
Posts: 10
Received 0 Votes on 0 Posts
Aquastat Operation

Furd - Thanks for the suggestion. I'm not yet sure that the thermal switch isn't my problem. I need a thermometer to give it a good test.

I would appreciate if anyone would confirm or correct my understanding of how the aquastat operates. (Please excuse the amateurish schematic.)

Name:  Aquastat Operation.jpg
Views: 2121
Size:  37.5 KB

Thanks for any input.
 
  #12  
Old 08-14-14, 01:06 PM
Member
Thread Starter
Join Date: Mar 2014
Location: USA
Posts: 10
Received 0 Votes on 0 Posts
Results

After a summer of procrastination I finally started to think about heat today.

After determining that the low voltage side of the start relay for the vent blower wasn't getting voltage I traced the voltage loss to somewhere between T1 and the blue wire terminal going to the thermal switch. If I put a test lead between T1 and the yellow wire on the start relay, bypassing the aquastat relay, the blower starts. If I have terminals TV and T connected (call for heat) the burner lights.

While it could be the contacts on the relay, a bad solder joint or crack is likely since the other half of the relay powers the circulator pump reliably.

While I will try to find a bad joint just to see if I can repair it, I'm shopping for a new aquastat.
 
  #13  
Old 08-14-14, 05:54 PM
Member
Thread Starter
Join Date: Mar 2014
Location: USA
Posts: 10
Received 0 Votes on 0 Posts
Follow Up

Bit the bullet and took it apart again. I had looked for bad joints before but this time went over it with a magnifier.

Found one that looked a little sketchy and I did have a few open readings with an Ohm meter. Wasn't sure so I also did a few other joints related to the T1 to relay output. The joint shown is the relay leg and a bad joint here would stop power to the blower relay.

Have had 6 good light-offs with no shutdowns. Success? Too early to tell. I'll give it a thorough test over the next few days.

Since I'm not that good at soldering PCBs I think I'll still replace the aquastat and keep this one as a spare.
 
Attached Images   
  #14  
Old 08-14-14, 06:03 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 52,668
Received 340 Votes on 318 Posts
Those are horrible soldering jobs. No wonder those controls go intermittent so often.
The orange joint looks pretty weak. Wouldn't hurt to hit them all. You need to heat the connection hot enough to get the solder to flow evenly.

Name:  Solder Joint.jpg
Views: 1202
Size:  24.5 KB
 
  #15  
Old 08-14-14, 06:30 PM
Member
Thread Starter
Join Date: Mar 2014
Location: USA
Posts: 10
Received 0 Votes on 0 Posts
Thanks, I got that one and several others. At least now I know where the problem is and the worst case is a new aquastat.

It also explains why that for a while I was able to start it by gently pressing on the relay. It was enough to make contact but eventually worked the joint enough where it no longer made contact and stopped working.

Unfortunately most of my soldering experience was before PCBs were in common use. I think you're right about heating it thoroughly. I should get a decent iron, an old board and practice.

Thanks again,

Rich
 
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: