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Question:

Are there any disadvantages/advantages when connecting PVC to copper pipes that are used for hot water?

I know nothing about plumbing.originally my house has all copper pipes. Recently we had a leak coming from the hot water heater to the house. The plumbing company replaced the faulty pipes with PVC pipes. The plumber explained that they don‘t work with copper anymore and PVC is more reliable. My father told me he was lying because he just wanted to save labor, time, and money just to avoid working with copper.another thing my uncle told me was that the copper pipes expand when hot and pvc doesn‘t. So that might lead to leaks in the future.who is correct and who is wrong? and is there anything else that i might need to know about pvc to copper?

Answer:

Make sure that it is PVC before you make any assumptions. If it's an off-white color then it's probably CPVC. If it's PVC then you need to call the plumber back out quickly to replace it with either CPVC or copper. Of course you could wait and file a damage claim against the company when it blows.
PVC is not supposed to be used for any domestic hot water system where you have a water temperature of at least 120 degrees F and a pressure of at least 65 PSI. And actually the working pressure of the PVC pipe at say 140 F (for a commercial application) will go down dramatically to between 48 and 80 psi depending on what site you are looking at. But the bottom line is that it is not safe or practical to use in any domestic application where pressures can run between 45 and 95 psi. And I speak from experience. When I used a 2 Schedule 80 water pipe to repair a leak in a domestic hot water system in a commercial building a fitting came apart and leaked a lot of water until it was discovered. But this was the recommendation I was given by the plumbing supplier. He was wrong. CPVC pipe that does not expand or contract with the presence of hot water in the pipe is what you should use because the fitting and pipe connection is not stressed as a result. And so the pipe to fitting connection will be stable and will not distort or weaken or finally let go with the hot water. I know that a house domestic hot water system does not use any 2 pipe and perhaps that is why there doesn t seem to be a problem when using smaller diameter PVC pipe. But it is still not recommended. And even in the National Plumbing Code of Canada (which is a branch of CSA - Canadian Standards Association) states that all PVC pipe is not permitted for use in a hot water system. And so regardless of what you have been told if any PVC pipe that is being used in a hot water system does start to leak and cause damage - you will not be covered by the manufacturer, and possibly not even by insurance because it was the wrong pipe for the application to begin with.
hmm from the hot water heater to the house ? Where is your heater? A lot of plumbers are using a plastic pipe called IPEX among other names. (It is not PVC) Your father is right in that it saves time and labour FOR the plumber. If, in fact a leak came from a copper pipe it would have been cheaper to just repair the copper line (you didn't describe the problem in detail) Your uncle is right about expansion. As does your roof, but its so miniscule it is meaningless. If they persist, there are PEX to copper adapters but the PEX tool is expensive and if you aren't a contractor, not worth the purchase. Synpsis: Trust your dad

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