Could use some advice on how to fix or find the problem I'm having with my hot water heater system. I'll give a little background and i'll try not to go on too long. For the last couple year I have had water discharging from the pressure relief valve in the system. I used to just let it fill in a bucket and dump it every couple days. Last summer I decided to try to empty the expansion tank. Turns out the valve to isolate it would not close completely. I had a plumber come in close that tank off and attach a bladder expansion tank. Thought that would solve the problem but still have water discharging. I have a contract with a company to service anything with the boiler. They came by last night and I showed them how the bucket was filling up under the pressure relief valve. They disconnected the new expansion tank and tested the psi. It was 12 so that is working fine. They said it may be the pressure reducing valve letting water in slowly. So he shut off the main water supply and told me to call back if water was coming out. When he left the PSI were at 24 since the boiler was fired up. When I checked it this morning it was at 8 PSI. I turned on the main supply got it up to 12 PSI. Bled the radiators upstairs got all the air out and had to put more water in to get it up to 12psi. Now with the main water supply off at 10am it was at 12psi and when I got back at 12pm it was at 10psi. Do I have a leak? I don't see water anywhere. I've attached some pics below of the system. What would cause it to discharge water if I'm losing pressure with the main water supply off

Thanks Jay

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