# Plastic to Metal Connections



## OldSchool (Jan 30, 2010)

We were called in to replace a heat exchanger on a pool at a large hotel. The stainless steel heat exchanger had female connection and we installed it with the same type of plastic male adaptors. Called back in because it was dripping at the connection several days later. Cut it out and retighten. Again several days later it started dripping again. Finally figured out that the stainless steel was expanding faster than the plastic when the system was beening heated. Replaced with Brass nipple into heat exchanger and plastic female adaptors.... this way the brass when expanding would seal tighter into female and no leak would occur. Been over 6 months and no problem.


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## GREENPLUM (Jul 27, 2008)

PVC for hot water?


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## ILPlumber (Jun 17, 2008)

Victaulic works wonderfully in this instance.


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## TheMaster (Jun 12, 2009)

OldSchool said:


> We were called in to replace a heat exchanger on a pool at a large hotel. The stainless steel heat exchanger had female connection and we installed it with the same type of plastic male adaptors. Called back in because it was dripping at the connection several days later. Cut it out and retighten. Again several days later it started dripping again. Finally figured out that the stainless steel was expanding faster than the plastic when the system was beening heated. Replaced with Brass nipple into heat exchanger and plastic female adaptors.... this way the brass when expanding would seal tighter into female and no leak would occur. Been over 6 months and no problem.


 Until the plastic loses its elasticity then it cracks,but hey that might be a few years from now....dont worry about it:laughing:


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## OldSchool (Jan 30, 2010)

GREENPLUM said:


> PVC for hot water?


It was a new hotel about three years old. The original installer used PVC Schedule 40 pipe and fittings from pool pump to heat exchanger from boiler. Original heat exchanger rotted from switching system from chorine to salt system. Replace with better grade stainless heat exchanger for salt system.


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## longplumb (Nov 15, 2009)

Have seen this same problem in our area in several new motels. They had used pvc sch. 40 directly into boiler/heat exchanger . Did away with that and used brass to get away from boiler and then went to pvc sch. 80. Have not had any problems since.:thumbup1:


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## Protech (Sep 22, 2008)

Why not switch to cpvc in the hot areas?


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## OldSchool (Jan 30, 2010)

The problem was not the pipe or the fittings. What I am trying to get across is that metal expands faster than plastic. If you have metal female and plastic male it is possible that the metal female expands faster causing a leak. To rectify this use metal male and plastic female connection.... this way the metal expands into the plastic making the connection tighter.


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## GREENPLUM (Jul 27, 2008)

OldSchool said:


> The problem was not the pipe or the fittings. What I am trying to get across is that metal expands faster than plastic. If you have metal female and plastic male it is possible that the metal female expands faster causing a leak. To rectify this use metal male and plastic female connection.... this way the metal expands into the plastic making the connection tighter.


Ima not gonna buy what youre sellin.:thumbsup:


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## OldSchool (Jan 30, 2010)

GREENPLUM said:


> Ima not gonna buy what youre sellin.:thumbsup:


 
I dont know if any of you guys ever did a pool heater. This is the pipe configuration as follows.... Remeber this is a large hotel and not residential. 
1. Piping from boiler to exchanger was metal (steel) 
2. Piping from pool pumps to heat exchanger was PVC
3. Heat exchanger was stainless steel 

Heated water from boiler flows to heat exchanger - from heat exchanger to pool.

Connections at heat exchanger was stainless female. Original Plastic male connection on female stainless. Heat exchanger was rotting from new salt system. Lots of corrosion when we got there. Repiped the same way. Leaks keep occuring at conncetions of stainless and plastic. Retighten several times. Finnally decided to change connections to threaded brass nipple and plastic females. Completely solved the problem.


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## tooslow (Jul 17, 2009)

*pvc to steel*

Flanged connection is the safest.


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