Replacement for 8124 a 1007

Vonroman · October 24

My oil burner I recently disconnected the hot water coil . I have a hot water heater now . I want to replace the triple aquastat with a more efficient model. But not digital. Is the 8148 adequate. But what is the full name and number for 8148. To replace 8124 a 1007

Big Ed_4 · October 24

Just lower the low limit to 120* , enough to keep the system swelled to prevent leakage and rusting….

EdTheHeaterMan · October 27

There is a little wiring trick that you can use:

I remember reading an article in Fuel Oil News a few decades back that gave specific instructions on how to make a L8124A control on an oil burner with a tankless coil, into a cold start control at low cost to you. That should be done when the plumber disconnects the tankless coil and installs a stand alone electric or gas water heater. Here is the way to do it.

Remove the Blue wire from the B terminal on the LO limit of the control and you will make that L8124A into a cold start boiler control. The required high Limit is still in control of the burner circuit. Back then the control had a stab terminal, so the article mentioned that you need to put a wire nut on the blue wire that you removed. Today's control has an insulated spade connector, so all you need to do is remove it and you are done.

The circulator is still connected thru that LO limit control so you will want to set that LO setting as low as you can get it.

If you want to go a step further, you can just remove the R and the W wires from the LO limit stab terminals and wire nut them together. Then you can leave the blue wire connected. That red and white wire will connect the relay contacts 1K2 directly to the C1 terminal so the LO limit reverse contacts will not keep the circulator from operating. Leaving the blue wire connected to B is just a safe place to keep it since there will be power on it whenever the burner circuit is powered.

Vonroman · October 31

This not not the same

Vonroman · October 31

EdTheHeaterMan · October 31

Older version of the same part. Here is the way to make this a cold Start control

Screenshot 2024-10-30 at 11.05.51 PM.png

Just be careful where you put that wire nut. If it gets stuffed between the ivory block and the black relay, it may make the relay stick and that will over heat your home. (ask me how I know this).

Sootmaster · October 31

It looks like ZR and ZC are being used. I would pull the blue and cap it to keep ZR/ZC functioning.

EdTheHeaterMan · October 31

https://forum.heatinghelp.com/discussion/comment/1817267#Comment_1817267

Actually ZC will get power all the time when R and W are wire nutted together. When a zone relay sends power to ZR, that will power the burner thru the Limit as it should. ZC and ZR will operate as needed with the R and the W connected. Just pulling the blue wire will only stop the burner from operating to maintain a minimum temperature. The low limit will still prevent the circulators from operating below the set point of the low limit. That is not a feature of a cold start boiler. The circulator and the burner should start at the same time.

Don't you agree?

Vonroman · November 1

Vonroman · November 1

Agreed. I will disco the blue wire and cap only ..than I can control high limit and low limit to prevent burner, from coming on to heat removed boiler...

Also this aquastat is a two zone. For 1 and 2 floor. And cellar second zone...what do you recommend for an upgrade aquastat.

Thanks for your valued knowledge

SuperTech · November 1

Honeywell/Resideo L7224U or Hydrolevel 3250 are the best choices for an upgrade. You can make it cold or hot start and keep the circulator off until the boiler heats up to prevent condensing. And they both have a thermal purge feature to help with energy savings. I don't ever install any old mechanical aquastats anymore. The new digital aquastats have much better features and I don't have as many problems with them.

EdTheHeaterMan · November 1

If you have money to burn, and are going to get a new control anyway You can purchase the L8148 A control. That control does not have the ZC or ZR terminals so you will need to completely rewire your additional zone in order to bring on the burner without bringing on the zone pump that is connected to the L8148 A that you purchase.

The Electronic controls are less expensive and I really liked the L7224U. it will do what you need and does have the ZR terminal you need to operate the burner from the additional zone control.

But look closely at the internal wiring diagram of the L8148 and the L8124 and see what happens when tou just connect the red and the white wire as illustrated.

Diagram to follow:

EdTheHeaterMan · November 1

The Cold Start Control is on the left. Your control is on the right. (with the additional zone)

I have places the wire nut on the Red and White wire in the diagram on the right.

You can see that the Cold start control does not have a "Low Limit" with R, W, & B
You can see that your control has the low limit disconnected and faded out.
You can also see that the Red wire will be powered so the 2K1 contact will closed by the zone 1 thermostat AND the ZC is powered to operate your additional zone relay (not highlighted)
The L8148 cold start has a High Limit (Red Box) between the 1K1 contacts and the B1 to the burner (Green Highlight)
Your control has the same wire. It also has the ZR for the other zone control

The thermostat for zone one is connected to T T in the L8148 cold start to operate K1 (Green Highlight)
The thermostat for zone one is connected to T Tv on your control to operate the K1 relay (Green Highlight)
Finally to connect the additional zone relay to operate the burner on the Cold Start L8148 you would need to place the wire that is currently on ZR in your control to the B terminal on the L8148. That screw needs a torx screwdriver to be able to do that.

So what ever new control you purchase, you will need it to have the ZR and/or you will need to do some major rewiring. It is easier to keep the control you have because it has everything you need.

I hope this helps.

Mr. Ed

Vonroman · November 7

I decided to go with the digital.

Replace the now L8124L 1007. Withe the newer digital. L7224 U. Question: is the sensing tube the same length...

Hard to find this information. Thanks

Vonroman · November 7

Correction::: L8124 A 1007.

EdTheHeaterMan · November 7

the electronic double and triple aqua stats are less money than the old mechanical ones. You can mount the L7224U the same way as the L 8124. That way the temperature probe will be long enough.

You may find that the additional zone wiring to ZC and ZR may operate a little differently.I have found that getting a call for heat from The switching relay at the same time as the L7224 may cause the burner to drop out for a second or two then immediately come back on.

Don’t throw your old L 8124 away. Just in case you get that problem. That way you can reinstall it and connect the white and red wire as l previously recommended.

Replacement for 8124 a 1007

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