Ruud HVAC Install Question: EXV Standalone Board
Hey folks,
TLDR: trying to figure out if this system should be using the standalone EXV controller or if the cables should be plugged directly into the furnace.
I just had a Ruud Communicating system installed. Inverter driven Heat Pump, Coils, and 2-stage high efficiency furnace:
- Heat Pump: UP19AY48AJVCA - Endeavor Ultra 4ton
- Furnace: R962V0855A21M4SCAP - Endeavor Classic Plus 96% 2-Stage
- Coil: RCFY4821SEAAMC - Endeavor Line
The install has been fairly rough so far. Thermostat threw an alarm about 30 minutes after tech left for the day. Next day was 12 hours of them re-wiring (one wire fault), troubleshooting, replacing refrigerant, EXV valve, etc. System was showing signs of restriction so the focus was on ensuring everything was flowing without obstruction and EXV was behaving correctly. At that point, system still wasn't working, but the wiring correction had moved it forward from alarming.
Next day they came out again, this time found another wiring fault where the EXV cable had become unplugged from the standalone EXV controller. That got the system running enough to not fail, but still sounds really rough in heat pump mode and the pressures are looking borderline for restriction. They suggested coming out on a warmer day (was ~65F) when there was heat load on the house in order to tune it, but indicated they believe the system is generally in good shape.
I'm still concerned. Decided to read through the manuals myself and validate everything I'm being told. The manual for the coil states the following after mentioning that the stand alone EXV controller is for non-communicating systems:
"When using an EXV coil with a communicating furnace other than modulating furnace plug the Vapor line Thermistor, EXV, and Pressure Transducer into the corresponding plug on the furnace control board."
Those are all plugged into standalone controller currently, which is then wired into the furnace.
I confirmed via diagram and visual that the furnace has ports for EXV and SUC open and available. There are two sensors on the coolant line into the coil, one wired to the furnace and one wired to the standalone EXV controller.
My suspicion is that the standalone unit isn't correct for this install. If that's the case, then we wouldn't need both those sensors either.
Hoping somebody can confirm or shed light? Thanks!!