Hi all

recently was asked to replace what we thought was a stand alone split. Compressor was knackered so had to decant the refrigerant. The total charge recovered was 7.5Kg far to much for a 7.1Kw on 15m piperun. So rang the office just to double check. Customer confirms that it's a stand alone split. Checked out the outdoor 7.1 and indoor 7.1. Couldn't trace all the piperun the last 4m or so was within the walls must of been first fix when first installed. So customer confirms it's single split and from what we could see it was. So we split the flares at the indoor and removed it but because the pipes are embedded in the walls we just left the pipes in. All went well we installed the new system with a new piperun held its pressure so we left the system charged with refrigerant awaiting the power supply. 3 days later had a phone call from site reporting a refrigerant leak filling the room in which the new system was installed with gas and oil all over the wall. On closer inspection our new system was ok no leaks there. What we found after some investigation was that the old pipes left in for the previous system was spitting out refrigerant from the liquid line. At the other open end the liquid line was pulling a vacuum. Now this was happening when an indoor on the floor below was turned on. Having spoken with the company that did the initial install they have confirmed that all the systems fitted are stand alone splits. The customer has confirmed that previous to us reoving the knackered system this system on the floor below was working fine. My question is what the hell is going on. If they had crossed the pipes then how have the systems ever worked individually. What's clear is the two systems are connected via the pipe work somewhere why I do not know. Now the customer is refusing to pay because the system on the floor below was working until we removed the one above.