Help needed with chattering relay

n1st

I have a Honeywell L8124A1015 with a chattering relay and the furnace will even shut off for a second or two at times. This only happens with 1 of the 2 zones. There is a single Taco circulator and 2 Honeywell V8043F1036 zone valves. The wiring is a bit confusing for my inexperienced eyes, but it looks like the thermostat is connect to the zone valve, then the zone valve switches the aquasttat. Does this make sense? What is the most likely cause of my problems? Zone valve? Thermostat? Thanks in advance.

HomerJSmith

n1st, that's exactly how it works. The fact that one zone works without chattering and the other doesn't indicates to me that the aquastat is ok. This can be verified by jumping the TT connection on the aquastat. If everything is fine, look to the offending zone valve. Jump the end switch connection screws on the offending zone valve. If everything is ok, then replace the power head as the micro switch in the zone valve may not be making good contact. It is possible that a wiring connection may be loose or the motor may be loose in the zone valve. Or there may be an intermittent in the thermostat, if the zone valve and wiring checks out ok.

Jamie Hall

Check the wiring and connections all the way through from the zone valve to the aquastat. It's more likely that something is slightly loose. If that doesn't check out, then yes, the power head in the zone valve will bear a closer look.

SteveSan

Attach is the wiring guide to wire in your Honeywell V8043 zone valve. If the relay is chattering you might need to wire in the 1000ohm 1/2watt resistor that comes with the Taco ZVC. Any questions please call into Taco Tech Support 401-942-8000. We are here until 5pm EST.

MikeL_2

N1st,
Before you replace the power head, make sure you can easily rotate the ball & shaft assembly with your thumb and forefinger. Sticky or frozen shaft assembly's can put stress on the motor and strip the gears; stripped gears can disrupt the valves end switch......

HVACNUT

Chattering from the aquastat is not related to the zone valves. TT on the aquastat does not cross voltage from the zone valves. It's simply the load side of a switch.
The L8124 has the the older style clapper relay. The contacts are probably worn and pitted. Not making good contact. You can pull the cover off, and while a zone is running, push the clapper in a few times and you'll hear the change in pitch.
It might be time to upgrade. Look at the Hydrostat 3250 Plus. A much better control. And probably cheaper.

n1st

Both valves open and close at the same speed and have the same range. I have the problem even if I jump the lines going to the thermostat, so its not the problem. I guess the micro switch is the culprit. I watched YT and it looks like an easy job to swap out the head, so that's my plan. Thank you all for the suggestions and thoughts.

mattmia2

what you would need to jumper is the end switch on the zone valve that causes the problem, not the t-stat. since those don't switch much current, it seems more likely that a wire is loose in the low energy wiring than the end switch contacts themselves are bad (or some mechanical problem is preventing them from making fully)

HomerJSmith

If you think the points in the aquastat relay are pitted or burnt, use a point file to dress them or 100 grit wet & dry sandpaper to dress them.

https://www.oreillyauto.com/detail/b/gearwrench-4041/paint---body-repair-16614/body-repair-16510/body---trim-tools-25197/files-17947/726f2b869d12/gearwrench-ignition-file/2153d/4398667?q=files&pos=19

n1st

I've jumpered the wires to aquastat TT at the valve's switch screw terminals many times yet I could not make the relay stutter. So, I think the wiring between valve and aquastat is good. Yet when I push the micro switch in with my finger or cause the motor to push the micro switch, it does stutter - on the one valve. It doesn't stutter nearly as often if I give it a firm brisk push. But the valve presses the switch head very slowly. The switch will also stutter if I press the micro switch in with more pressure than necessary with my finger - pushing it past make. Which seems odd. It seems like the switch internally isn't making a clean make/brake.

HomerJSmith

So, replace the powerhead.