Using HW Copper for CW

[hagakure]

My sister's building (she lives with her fiance whos father owns the 6 family building) has been plumbed properly but the connection is wrong in the boiler room. I haven't been there to see but every apartment in her building is reverse hot water and cold water. The connections are 'right' at every fixture including the shower but hot comes when you turn the cold water handle and vice versa. If it was only the sinks I'd say just switch the speedy connections but it's also the showers and she wants it fixed.

My question is, if it is indeed only connected incorrectly in the boiler room and an easy fix, is it advisable to reconnect, putting cold water into the copper pipes that previously held hot water? if so, how long should I wait until running water through the line? I don't want to damage the pipes and leave them with an even bigger project. It's a fairly old building but it may have been replumbed somewhat recently

To answer any obvious questions, No I would not do anything without a permit and licensed plumber stamp, and I would never do anything unless I was 2000% sure I knew exactly what I was doing which is why I'm asking here.

Am I correct in assuming I would just have to wait the usual time you would after installing new copper?

I don't even use a wet rag when cleaning my joints because I'm paranoid about stressing the joints too soon and really you don't need a wet rag. A dry one works fine.

Thank you

[hj]

YOu can run cold water through the pipe as soon as the joints "cool". But, someone should check the entire system first to see the ACTUAL problem, because it would take a seriously screwed up "plumber" to do something like that.

[hagakure]

YOu can run cold water through the pipe as soon as the joints "cool". But, someone should check the entire system first to see the ACTUAL problem, because it would take a seriously screwed up "plumber" to do something like that.

Yes I'm only assuming that's the problem because the connections are all correct on the outside. right side for cold left side for hot. I've only been doing this 2 years and have very limited boiler room experience and no emergency experience so I wouldn't approach this lightly especially considering there are 5 other families in the building. New construction no problem. Renovation is exhausting just to think about.

[hj]

quote; Yes I'm only assuming that's the problem because the connections are all correct on the outside. right side for cold left side for hot.

That is a "symptom" but there are many places the problem could be caused. The entire system has to be "traced" to make sure WHERE it occurred and how to correct it.

[Winslow]

do the toilets have hot water coming into them also? Are the shower valves two handle or single handle?