View Full Version : High failure rate of reheat valve actuators
Has anybody been experiencing a higher than normal failure rate on the HW M6410A 1029 floating actuator used on reheats with XL10 or microcel controllers? The actuator internal gear slips and cannot drive the reheat valve closed. Sometimes they have been in service for only two or three years. I've been changing out about three or four every month for the last few years. Thanks for any replies.
02-06-2009, 01:18 PM
These actuators don't automatically "declutch". In other words, they keep driving the motor as long as you power them to open or close, even if the valve stops dead. What happens is the actuator drives to the end of the valve stroke, then the gears start to slip. Over time, this causes the teeth at the end of the stroke to wear down, and the valves won't close all the way. Take one of the failed actuators apart, and you might see what I am talking about.
Make sure you do not have the actuator drive times set too high. The default for most Excel 10 controllers is 150 seconds, while the drivetime on the M6410A is 125 Seconds. That's 25 extra seconds of drivetime on every stroke - control overshoot AND wear and tear on the actuator. Just a thought, but we have seen this happen before.
We have switched to Spartan valves. They are a lot cheaper, and the actuators come with a "time-out" feature that automatically cuts off power to the motor when the valve reaches either end of stroke. The actuators also come with a clear cover, which sounds hokie, but it makes visual inspection a lot simpler. Good luck!
02-06-2009, 05:16 PM
Very interesting. I just replaced one M6410a last week. Found one of our techs wired the new one incorrectly so yesterday I re-wired it. But it wouldn't close. It ran all the time - Could feel it spinning in my hand. First thought was not enough torque to close. But wouldn't close with actuator in my hand. Money down the drain.
Question - this valve was wired to a W7763 controller. That will make it run al the time?
Correct? That is how the Honeywell partner had it set up.
02-07-2009, 12:51 PM
The W7763 has actuator drivetime as one of it's configuration variables, and the default is 150 seconds. If it was wired incorrectly, however, you might have had 24VAC on the open or closed terminals continuously, which would have caused the motor to never quit. In theory, they are supposed to shut off the motor if they overdraw on amps, but that takes a long time to happen when the actuator reaches the end of the stroke, and if the gears are worn and the actuator cannot reach the end of it's stroke, then it will never happen.
Our assessment of the M6410A is that it's not a bad actuator, but it's neither a great one. They are kind of like lightbulbs - some last 6 months and some last 10 years, but none will last forever. Our jury is still out on the Spartan units as we just started using them last January. So far, so good.
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