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Dielectric unions
MikeL_2
Member Posts: 514
I spoke with rheem tech support today regarding a heat pump water heater install that we'll be doing this week. They do not require dielectric unions, but was wondering if there were any advantage using them?
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Nope, none whatsoever.MikeL_2 said:I spoke with rheem tech support today regarding a heat pump water heater install that we'll be doing this week. They do not require dielectric unions, but was wondering if there were any advantage using them?
Use a copper or stainless flex to furnish the required union connection. Or a rubber/polymer version to help eliminate vibration transfer.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
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When do you recommend using Dielectric unions ? I always thought they are used to protect the tank ?
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The dielectric unions are designed to stop the current flow that causes electrolysis. Two dis-similar metals in the presence of an electrolyte (water) can react and the less nobel metal will deteriorate.
Softened water has additional conductivity and more potential.Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
What about the connection between lets say a Bosch boiler and a iron manifold .. Where the connection out of the boiler is copper ?
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My experience is dielectrics on boilers cause more problems than they solve. Boilers are typically closed systems no constant source of electrolyte.
One reason why DI or filtered water is recommended for hydronic fills, if all or most of the ions are stripped out the potential for electrolysis is eliminated.
Here is some reading from Idronics 18
Water heater tanks get their protection from the anode rods.Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream3 -
Thank You for the time of explaining to me
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Decades ago I offered to fill hydronic systems with conditioned water. Most potential customers did not want to give up automatic water make up. Didn't even want to pay for side stream DI service. Years later when scale built up the problem became that cities object to flushing treated waterdown drains or on pavement.hot_rod said:My experience is dielectrics on boilers cause more problems than they solve. Boilers are typically closed systems no constant source of electrolyte.
One reason why DI or filtered water is recommended for hydronic fills, if all or most of the ions are stripped out the potential for electrolysis is eliminated.
Even when there is a water meter on make up nobody faithfully logged.
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Thank you, everyone for your contribution / information. As usual, the experiences and shared knowledge provide an opportunity for learning, and paths to pursue.0
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I didn't think about it as the anode protects the tank AND the connections, but it does.
You can fill the system with deionized water and hook it up to a prv to add the small amount of water the system would lose. It would still keep the water relatively demineralized.0 -
Dielectric unions will leak. The only question is when. Brass fitting or valve is the best dielectric to separate dissimilar materials. To protect hot water heaters you need to inspect and replace anodes as needed.Gennady Tsakh
Absolute Mechanical Co. Inc.0
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