I'm using a Universal Module, UM506, to control a recirculating hot water pump. I have the module set to "momentary" so I get about a 1-2 sec. on pulse every time I hit the button on the controller. 99% of the time the module works perfectly.

Sometimes the module hangs up and does not return to the off state. This causes the pump to run constantly, until I disconnect the module or unplug the pump. I have tried three new modules and they all do the same. I find it hard to believe that I have run into three intermittent modules in a row.

When the module is stuck in the on state, I found that I can hit the off button on the controller and the relay will click off.

What do I need to do the make sure this module will always operate in the "momentary" mode?

Thanks.