I am doing electrical and maintenance for a building my church owns. I've done all different types of electrical engineering before, from wiring huge buildings to vintage tube amplifiers, but this has been my first experience with HVAC. I've learned a lot, I feel fairly comfortable with the electrical side. I have a licensed HVAC tech that I call for all things freon-related, and so far we havent needed any gas repairs.
3 of our units are original to the building, and we dont have the money to replace them. They run, but I am going to have to do a lot of maintenance.
The paperwork that I have lists these units as TRANE SFCB 5 TON, the schematic is form 4-7422 A.
One unit, when fan is set to AUTO, and the thermostat is calling for heat, the fan will not engage. If you set the fan to ON, the fan will engage and heat is produced. If you have it set to AUTO and the thermostat is calling for cooling, you get fan.
My reading of the schematic says the Fan Time Delay Relay is the culprit and needs to replace.
1. Do the experts concur?
2. Where can I buy such a relay, as inexpensively as possible? The goal is to spend as little on these units as possible, get through another two seasons, and hopefully replace them in a couple years.
3. In the event that I cant locate a replacement FTDR, I am going to get a generic 24vAC time delay relay and wire the coil between W and common, and the contacts between R and G. That's basically what the stock FTDR does, except the stock relay disconnects G from the fan contactor when the fan is engaged through the heat relay. Why is this? I dont see a potential for backfeed, maybe I'm missing it?
There is another identical unit that works perfectly, however when the thermostat is calling for heat, there is a very loud buzzing from inside the unit that resonates through the ducts. I am assuming one of the relays (possibly the same one) is going bad, but it has been too cold for me to crack the unit and confirm. A friend suggested it could also be the inductor fan. Today was the first warm day and if this continues I will check it out Monday when I get back to the building. Is this a familiar problem to anyone?
3 of our units are original to the building, and we dont have the money to replace them. They run, but I am going to have to do a lot of maintenance.
The paperwork that I have lists these units as TRANE SFCB 5 TON, the schematic is form 4-7422 A.
One unit, when fan is set to AUTO, and the thermostat is calling for heat, the fan will not engage. If you set the fan to ON, the fan will engage and heat is produced. If you have it set to AUTO and the thermostat is calling for cooling, you get fan.
My reading of the schematic says the Fan Time Delay Relay is the culprit and needs to replace.
1. Do the experts concur?
2. Where can I buy such a relay, as inexpensively as possible? The goal is to spend as little on these units as possible, get through another two seasons, and hopefully replace them in a couple years.
3. In the event that I cant locate a replacement FTDR, I am going to get a generic 24vAC time delay relay and wire the coil between W and common, and the contacts between R and G. That's basically what the stock FTDR does, except the stock relay disconnects G from the fan contactor when the fan is engaged through the heat relay. Why is this? I dont see a potential for backfeed, maybe I'm missing it?
There is another identical unit that works perfectly, however when the thermostat is calling for heat, there is a very loud buzzing from inside the unit that resonates through the ducts. I am assuming one of the relays (possibly the same one) is going bad, but it has been too cold for me to crack the unit and confirm. A friend suggested it could also be the inductor fan. Today was the first warm day and if this continues I will check it out Monday when I get back to the building. Is this a familiar problem to anyone?