Split system or is it?

[Kirky]

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.

[jonjon]

I'd be telling the client to pay up as you did everything practicable to make sure you was working on the correct system

[frank]

How can your new system hold it's pressure and the one below spit out refrigerant and oil?

[monkey spanners]

Sounds like they have crossed one of the pipes, maybe outside? Think i'd disconnect them at the outdoor on the previously good system and blow through the suction and see where it comes out. If it is the difference between getting paid or not, a bit of piping outside to correct the crossing over plus you already have 7.1kg of refrigerant to play with....

[MikeHolm]

Or the customer was giving a load of BS. It's happened before. "honest good sir, it always worked fine up till now" (pretty customer bats big long blond eyelashes)

[Kirky]

Exactly Frank how can it? The pipes are definitely not crossed at the outdoor we have removed them and can see the run until 4m or so from the indoor when we lose it in the wall lining. So if it is crossed it's got to be close to the indoor. These units have been in operation since 2007. They must have worked to some extent. The suction pipework seems dead but the liquid is spitting out one end and pulling a vacuum at the other so they must of crossed the liquid line but if that's the case the systems wouldn't have ever worked? So maybe they have teed together the liquid line but why ?

[Kirky]

We could just braze up the open ends of the remaining pipework. We didn't remove it all because it's embedded in the wall lining so we just crimped up each end as we thought it was dead. In order to get to the old indoor open ends we need to remove our new indoor. The funny thing is I've spoken with the initial install company and they swear blind all systems are stand alone splits and were working well when they left. Somebody is telling porky pies

[Neddy]

Pipework is crossed. 7.5 Kgs of Refrigerant recovered on a 7.1Kw split on a 15 meter run? If that was the case the system would have been tripping on HP all the time prior to the compressor failing. Blow each pipe out with OFN.

[mikeref]

How can your new system hold it's pressure and the one below spit out refrigerant and oil?
Somehow the unit below is connected to the old pipework. Maybe a misprint by OP as to "The other end of liquid line..."
Suction line sucked and liquid line painted the room with oil when the lower kit was switched on.
Pulling 7.5 KG instead of 7.1 could be a clue.

[Kirky]

Yes the two systems were definitely connected and when we have recovered the charge from the system we were replacing we have recovered the charge from the system below hence the 7.5kg. If say the liquid lines were crossed how would each individual system have ever worked. They are in srperate rooms on different floors must of been ran independently at some point over the last 7 years.

[monkey spanners]

I've seen it done on refrigeration systems, and they ran for years without anyone noticing.

If it is pulling a vacuum on one end of the 'liquid line' and blowing out of the other, it can't just be a simple Tee in the pipework, it must be sucking through the small line, then the evap, then to the outdoor unit and back to the crimped pipe.

If you can prove it is a problem dating from the original install the customer will have no grounds for not paying you for the replacement system and should in fact be paying for the alterations needed to get the system working again.

[Kirky]

I just can't get my head round this one. Ok I can understand that sometimes pipework gets crossed accidentally. But if they had crossed the pipes then can't see how the systems would work. Ok so let's assume you turn on system 1 and system 2 is off system 1 is put in full cooling the compressor starts pumping down the liquid line to the wrong indoor which is off why doesn't the evaporator freeze? Then how does the refrigerant get back to the outdoor if the suction pipe is connected to another outdoor ? What happens if one unit is in heating and one in cooling can't see how that would work. Anyway maybe I'm just over thinking this. Anyway I have a meeting with the customer on Friday so will see how things go.

[mikeref]

Reminds me of a mix up in condensate lines within plaster-board walls. Every room was supposed to have a one on one wall mounted split, and a dedicated condensate line attached to their hand wash basin.

Eventually one condensate line blocked and created a small water feature. My attempt to use air pressure on the evap outlet failed so i prepared the evaporator outlet for a blast from the basin side. Little did i know. That procedure pushed slime into the next door office before their drain line disconnected.

The wall had to be torn out.
Original installers connected 2 rooms to one drain and didn't use PVC glue on several joins.:off topic:

[Kirky]

They had crossed the liquid lines.