SR501

nick z.

Looked at a replacement boiler replacemnet job.There is 2 zones, and a P/S pump just for a loop of radiant.So there is a total of 3 pumps. Every pump has its own SR501 with all the controls wired into the boiler control to start the boiler on a call for heat.So in other words there are 3 t-stats wires all goig on the boiler control.Seems it wouldn't be good for the control to have all 3 zones sending voltage to it at once.Do I need to figure on a # zone control in my price? Thanks Nick

Steve_2

SR501

The SR501's are not sending any voltage to the boiler. Each 501 has a dry contact that closes when the t-stat calls for heat. These would then be wired to the T-T terminals on the boiler.

If you had used a zone controller, the zone controller would have a common dry contact essentially doing the same thing.

nick z.

Thanks ,I always assumed that it sent 24 volts to the T.T.Thanks for the response.