I have a customer that has called my company to try and explain why a hot water coil burst in cooling season(it burst at all the utubes on back side like it froze). The management company put new coil in and it burst in 2 days. This is a hot water coil that used a water heater to supply hot water. Of course they think by me installing it it will work. My concern is it will happen again. My thoughts are it is getting to much pressure and to hot. There is a pressure expainsion valve assembly that releives pressure on system on domestic side after tempering valve, but nothing on heating side(it is like this on all units). It is fed with cpvc 3/4". When i install the new coil i was going to replace relief valve on expansion valve assembly, put pressure gauage on pipe feeding the coil and monitor temp to see if water heater tstat is out of wack. He has had couple others burst as well. My orginal thought bad batch of coils. Any ideas?