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Pex Heat Transfer plates with copper tubing as a Solar water heater - Galvanic Corrosion?

Hi, 15 or so years ago I made a Copper tube Solar Hot Water heater for our future retirement home in southern Mexico where my wife is from, even though during those years we were located 56 degrees latitude north in Canada. I am debating upgrading its heating capabilities vs replacing. I noticed Pex heat transfer plates used in hot water floor heating systems seem inexpensive but aluminum. would they perhaps manage to attach to 3/4" copper tubing and if so would I experience galvanic corrosion due to the 2 dissimilar metals in contact with each other as one has happen when steel contacts copper over time?

For particulars of system read further.

As roof tower tank water storage is standard here in Tapachula Mexico, due to no Freezing I set the collector under the storage tank to act using gravity Thermal Cycling. Cold water drops to bottom, water in collector heats during day rises up midway into storage tank. At night coldest water stays trapped in collector, no cycling. Perfect.

The flaw(s)
Tank is exposed to sun so was getting natural heating as well. However during rains all the heat is lost in minutes and we get 100+ inches a year rain. Also overnight cooling of exposed tank makes for cool water in morning.

During a renovation we are adding a roof over the tanks (cold and hot) and walls to block UV, and will be adding a aluminum bubble wrap to hot tank as well. This means the collector will no longer create sufficient gain as we are loosing the gain from having a black tank on roof exposed to sun, thus the desire to add heat transfer plates or change the collector or add to the collector. On our 10 room beach hotel I used the same Thermo cycling system 11 years ago with the exception of using Pool type plastic hot water heaters. The plastic worked and were economical but they are deteriorating due to UV and due for replacement which I plan to do after determining how the house solar collector upgrade worked out. The hotel system benefitted from the roof covering tank system and tank insulation I had neglected to do on the older house system.


  • hot_rod
    hot_rod Member Posts: 16,278
    The aluminum and copper mix should be fine, AC condenser coils are often a copper tube with aluminum fins and they last many years outdoors
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • joseph annon
    joseph annon Member Posts: 49
    There was a company that made collectors out of aluminum plates with copper piping we removed them after more than ten years and saw no signs of corrosion on either the plate or the copper. However we get very little rain here a wet year is 16" of precipitation.