Taco SR501-4 Switching Relay, 1 Zone

We needed this to go between a new Lathem time clock and an existing bell system. We couldn’t understand how to install it so we had to call the electrician who sorted it out.Once installed it’s worked perfectly.

I already had a 6 zone Taco relay that was being fully utilized so I purchased this unit to add an additional heating zone. The item is simple to wire and is working well. My only complaint is that it makes a slight humming sound which is audible in the room above my boiler.

Needed this to convert an old line voltage thermostat to a new low voltage smart thermostat and it worked great. Easy to install ad great value.

Only 4 stars because the picture is not accurate, received a plastic case.Nonetheless, worked like a charm for my tankless + google nest hookup

Thought it was the one with metal housing as the photos indicated at my time of purchase. Sadly it is the new plastic one and won't mach my existing system; if I had the time I would return it. This kind of thing really pisses me off here: though I am sure it will work fine these are rock solid.

Works well.

I ordered a open box item that was supposed to be new condition. Opened the box, it looked good. Opened the cover to look at how to install it, not so good. Taco failed to even attempt to solder on the thermostat wire terminals. Not sure how it got it's quality sticker that was clearly on the board. Kind of a show stopper. For some reason Amazon treats Amazon warehouse as a third party vendor. Options were then limited. But luckily the rep I talked to on Christmas eve at 2230 made it right. Hoping to get it resolved with taco. Any type of qa check would have caught this mistake.

This product is exactly what i needed to make ny radiant heating boiler system function correctly and not kill my zone pump.

the ZC terminal stays hot and the ZR gets live when the thermostat comes on so I use it to power a fan