Upon arrival AC number 1 was locked out on 999 FP1 service codes pertaining to freezing conditions at the txv. During recent house renovations the discharge line water shut off valve at the flow center was inadvertently shut off stopping all water flow through the first floor 5 series water furnace geothermal. After re-establishing the water flow and testing the equipment the ground loops were found to be at 0 psi for the second time in 2 years. Positive confirmation of 55 PSI repressurization on April 16th 2024 is now at 0 psi again at today's visit. Multiple pressure tests at 55 PSI dropped to 40 PSI within 10 to 15 minutes each time during cooling operation of the equipment The low water pressure did not affect the second floor geothermal equipment operation and did not produce any service codes however this equipment is not designed to run at pressure lower than 15 psi and any actions or symptoms of low water pressure cannot be predicted ***The single geothermal ground loop