Honeywell Aquastat

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  #1  
Old 01-06-19, 05:33 PM
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Lightbulb Honeywell Aquastat

I have a Utica Fuel Oil furnace that uses a Honeywell Aquastat that appears to no longer work when there is a call for heat. I can manually move the relay in the Aquastat enclosure and the circ pump and boiler start up.

I let go of the relay and the system shuts down.

My issue is trying to determine which Aquastat is the correct replacement. The inside cover of the Aquastat says the Honeywell relay is the L8418A type with the following specs:

120V, Full Load = 7.4 amps, and Locked Rotor = 44.4 amps

Unfortunately, there are different L8418A types out there. There is another number on the label, 134083 Rev. E which may be helpful.

It is of the horizontal layout (longer horizontal, then height). Unfortunately, there are several L8418A xxxx types out there, I just don't know which one to purchase. Any guidance you can provide would be deeply appreciated.

R,

Flash

right now I am bypassing the safety by keeping the relay manually on.
 
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Old 01-06-19, 06:27 PM
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First is to verify that it is an L8418A and not an L8148A
 
  #3  
Old 01-07-19, 04:04 AM
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Yes, you are correct, L8148A. I guess it would be easier if I typed it correctly. Thank you!

Flash
 
  #4  
Old 01-07-19, 06:41 AM
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flash-

A similar question has come up before on the forum. I asked the same thing about those numbers long ago (canít find the thread right now, it was for a different Aquastat, the 8124A).

As far as I remember no one really knows what those other Honeywell numbers are following the L8124A or the L8148A and it seems that they can be ignored e.g. : L8148A1017, L8148A1124, L8124A-1007.

Maybe the numbers are some kind of coding for the rev#, date, etc.

Those Aquastats can be horizontally or vertically mounted, that is, there are no vertical or horizontal models.

You donít have to stick with the old Aquastat. You can switch to an electronic Aquastat like the L7224U. Those are cheaper and have more capabilities.
 
  #5  
Old 01-07-19, 08:35 AM
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Honeywell's documentation cross references the L8148A1017 to L8148A1124 and others - see https://media.statesupply.com/filema...-guide2014.pdf so 1017 is the current version.
The Aquastat can be mounted horizontally or vertically - different number is mainly for the label on the cover
 
  #6  
Old 01-07-19, 11:32 AM
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f,
That is a Horizontal mount aquastat. The difference in aquastat model numbers is what they offer and how they are mounted. Although they all serve pretty much the same function except if you have a cold start (high limit) or a triple action (warm start), used when a tankless coil is installed.

It all depends on the room you have on your boiler how the manufacturer specified your model. That being said you are not locked into that configuration if you want to change it but beware the wire terminal placements may be different and may not reach so you may have to rewire if you go from horizontal to vertical but they will function the same plus the differential settings may be different if that's important to you.

All that being considered zoesdad I believe has the right idea. The replacement he recommends has all the functions of yours and more. It's a much better updated control and can be mounted either way, although you still may have to do a little rewiring but in my opinion would be well worth it.

The sight below will show you your options and the replacement control recommended.

https://www.supplyhouse.com/sh/contr...well+aquastats

https://www.supplyhouse.com/Honeywel...ronic-Aquastat

Just my opinion, hope this helps a little.
 
  #7  
Old 01-08-19, 06:33 AM
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spott Ė

The reason I said the L8148A can be mounted either horizontally or vertically is because I have a manual that says this (along with a figure that shows the bracket in 2 different positions, vertical and horizontal):

Mounting
The L8148A,J has a case that can be converted to either horizontal or vertical mounting (Fig. 1).
- but I see supply.com shows it as a horizontal mount. Little confusing.
 
  #8  
Old 01-08-19, 09:08 AM
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Z,
You are right, there is nothing preventing you from mounting it either way. The control is made to go in all different boilers and some have space restrictions if you have a tankless coil with different H & C openings and the wiring. Aside from that they do the same thing.
 
  #9  
Old 01-09-19, 12:28 AM
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L7224u

Thank you for all of the responses. Just a couple of follow-on questions.

1. I am not looking to make any changes to any control function, just want to replace the controller. I presume that the transfer of connections is relatively easy from the L8148A to the L7224U. Meaning, that is is easy to locate the connections on the L7224U for the power, circ water and other inputs. As I shared, I am not looking for any new features/functions, just want to replace so I donít have to bypass safety.

2. Looking at the directions, it is not clear to me if the L7224U comes with the bulb that is inserted into the well. If not, I assume it is fairly simple to transfer/use the existing bulb. If not, is there a part number I should use and is it necessary to use any fill component (for conduction through the well to the bulb)?

Thank you again for all your assistance/responses.

Flash



 
  #10  
Old 01-09-19, 06:25 AM
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The L7724U does come with its own bulb and a little tube of thermal paste to put in the well to enhance the heat transfer to the bulb. But some of the experts on this forum have said in the past that they donít use the paste because ,I think they said, it can harden and cause more problems than itís worth. I donít remember exactly however, what they thought the problem was.

I didnít use the thermal paste and have not had a problem. The electrical connections on the L7724U are straight forward and map to the L8148A.

Scroll down on this link to

Reply: use of a thermal conducting grease with aquastat sensors
there is a good discussion about the paste,

https://inspectapedia.com/heat/Aquas...sis_Repair.php
 

Last edited by zoesdad; 01-09-19 at 07:04 AM. Reason: added "Scroll...
  #11  
Old 01-09-19, 05:35 PM
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...they don’t use the paste because, I think they said, it can harden and cause more problems than it’s worth...
I had a situation once whereby I tried to remove a sensor bulb from a well on an old oil boiler that had been replaced, and the paste was as hard as concrete. The boiler had been drained and off-line for some time. I could not get the bulb out of the well.
 
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