Say, I have an oil fired furnace with a honeywell aquastat L8124-A 1007 controller and a tako circulating pump. This is a 2 zone home. With both zones calling for heat (tako circulating valves opened and green led light on valves lit), and furnace firing, the circulating pump does not run.

Should I be going after the tako circulating pump cartidge, or a new L8124A?
Thanks,
navy-heater

 

First you need to troubleshoot is a systematic manner with a voltmeter and find out if you are getting 120V to the pump, and if not, where the voltage is being lost. Don't just start replacing parts.

 

Tell us what the settings are on the dials in your aquastat.

 

I have 120v between the L1 and L2 terminals. With the transformer contact energized, and a call for heat recognized by the Taco zone valves, and the furnace firing just fine, I have 0 volts between the C1 and C2 terminals which are supposed to provide voltage to the circulator pump. So, I think my problem is in the honeywell L8124-A 1007---not the circulator pump or motor.

 

So, I can go over to home depot and get a new honeywell L8124-a controller, but I got to tell you it looks like it will be more than just wires connections to make up. Is it possible to replace the L8124 withut going into the temperature sensor that goes in the heat exchanger? Is replacing a L8124 something a regular guy can do or am I asking to get a butt kicking?

 

It may be the aquastat, but first tell us:

WHAT ARE THE SETTINGS ON THE THREE DIALS IN THE AQUASTAT?

 

Hi 210
Low 170

Diff 15

 

OK, before you do anything else, turn the LOW down to 150, the HIGH down to 180, and the DIFF is OK where it is. Then try again, if the circ still doesn't run, we'll talk about how easy it is to change the aquastat, or at least do a bit more troubleshooting. Why spend $150 if you don't have to, right?

Do you know why the settings are as high as they are? Is this an 'inherited' setting from a previous owner?

 

Thanks, I will change to the suggested settings right now. The L8124 was replaced by a certified HVAC tech from a reputable local company in SE CT last year. I should have been worried when the first L8124 he installed smoked itself within 30 minutes (wired it wrong with respect to the transformer). But the guy came back the next day with a replacemnet (2nd replacement actually) and he set the 170, 210, 15 dials to where they are. If it matters, this same aquastat manages the furnace as well as the hot water for showers and so on.

 

So i changed the hi to 180, lo to 150 and lef tthe diff at 15...after that, with the thermostat calling for heat, the C1 C2 terminal differential voltage was still 0 volts. So teh circulator is still not running. Time to swap the L8124a?

My local home depot has no L8124a, but the fellow there is proposing a L8148 1017...is that going to be ok?

 

Yeah, it sounds like an aquastat problem. I don't understand why it only lasted a year though... I believe that there is or should be a warranty, you might want to check that out. Another poster here recently had a replacement unit under warranty for no charge.

No, the 8148 is not the same thing, it won't manage your hot water coil, you need the 'triple' aquastat (8124) with the LOW limit control to do that. Also, and more importantly, I believe that the model number you gave is 8148A1017 and that model is for LINE VOLTAGE burner or gas valve. You have a 24VAC gas valve! You hook that unit up, and as soon as you fire the burner your gas valve will be destroyed almost instantly.

If you order from these guys you will probably have the part within a day or two of ordering.

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I looked at the two different models that they have, and honestly, I don't know what the difference is between the two. Even the Honeywell catalog is unclear... either one will work.

After you tag all the wires and remove them, there is a single screw that holds the aquastat onto the 'well'. Loosen that screw and slide the unit straight off, the sensing bulb will slide out of the well.

When reinstalling, do not kink the capillary tube! Make sure that the bulb is fully inserted into the well. Tighten the mounting clamp and re-wire...

Stick with the setting I gave previously. There should be no reason you need 210° water to heat your home, waste of fuel... and the LOW setting at 150° should be adequate. This LOW setting controls only the domestic hot water coil, and you may notice that you don't have as much hot water with the lower setting. If so, you can turn it up of course, but always keep the LOW at LEAST 20° BELOW THE HIGH. Keep in mind that the higher you run those dials, the more fuel you will burn... so go for the lowest LOW setting that is consistent with adequate hot water to the home.