3 zone boiler, zone valves fed with aquastat transformer

tylerjgardner

Hey just wanted your opinion on this system. Im here for an intermittent issue. Im getting 22 volts at the spark box but unit isn't firing. I reset unit and its been working fine since. But it has 3 zone valves. No external transformer, they're all powered by the aquastat. Could this be whats causing intermittent issues? I feel like 22 volts is a little less than usual. (My kneeling pad is covering company sticker in case that causes issues).

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EdTheHeaterMan

Some Aquastats are designed for operating zone valves. What is the part number of the Aquastat including the last 4 numbers?

EdTheHeaterMan

If you happen to have the L8148 J 0000 which seems likely, there is a note in the instruction manual that states that you can connect 2 zone valves. Your system has three zone valves, therefore you may have a point with a low voltage problem.

But it appears that your system has operated before "as is" with 3 zone valves connected to the L8148J. So the question is "What has changed?"

You may have a defective ignition module (spark box). Try to operate the boiler with only one zone valve energized (the other two zones not calling for heat) and see if it works. The voltage to the spark box might increase to 24 or even 27 volts.

tylerjgardner

Thanks for the info. I dont know the model of the aquastat. I changed the ignition module last year. The boiler is from 1990 so he's going to replace it pretty soon. I wish I did what you suggested and had only one zone calling to check voltage again. Im already off site. Thanks again for the info!

4GenPlumber

22v should still fire that intermittent ignition module. One, or more of the end switches isnt making contact on those old Erie zone valves. When you go back, take a Pic of how its wired inside the L8148. It looks like there are 2 sets of wires between the zv and the relay? Does the circulator start and the burner circuit doesnt? Or both?

hot_rod

https://forum.heatinghelp.com/discussion/comment/1887823#Comment_1887823

it also notes 1 zone valve if ambient is 77f or higher, which is likely under the cover of that control on a hot boiler

Those Eries would be similar to the HW they mention, about 5W each

Could be the transformer is giving up if it has been overloaded for years.

Unloaded the 24v transformers can read as high as 27-28v

109A_5

Assuming the 120 VAC is good, if the 24 VAC is at 22 VAC at the transformer, Z to TV the Aquastat's transformer is probably mildly overloaded. Also the solder joints for the relay 1K where it is soldered to the circuit board go bad causing intermittent problems and eventual failure.

HVACNUT

That aquastat has a 40 va transformer in it, so it should be fine as far as setup. But 22 volts isn't fine. TV is 24 volts. W/Z is common. If you remove the wires and test the terminals, you should read 26-28 vac. If yes, the first thing I would do is remove the MV and MV/PV wires from the "spark box" and initiate a call for heat. Test the wires you removed for 24 volts. If yes, test the gas valve. If still 22 volts, work your way back.