Noise from SPDT relay

I wasn't sure if this was a good question for an HVAC or electrician sub.

I have a heated floor setup for my garage. The thermostat for the garage runs into a White-Rodgers 90-113 SPDT relay that is then connected to my recirculating pump. With cold temps here and the system starting to run, I am hearing a bang noise and then a hum from the system. At first I thought it was the Grundfos recirculating pump, but that is silent and running fine. The bang and hum appears to be coming from this relay. I read that the humming noise can be caused be a bad relay, wiring issue, or improper voltage to the relay.

I already have an electrician coming out to add an additional outlet to the circuit that runs where the relay is. Would you suggest getting that electrician to test that circuit to ensure it really is an isolated issue with the relay or just go ahead and call in an HVAC technician? I have no idea if the electrician would be able to replace the relay even if they decided it was the culprit. Would an electrician be able to handle this?