# Cleaning flat plate heat exchanger



## headrc (Dec 26, 2011)

We have been having a problem this year with our radiant heat system.  It is a system using an outside wood boiler on an open loop which transfers heat to the closed loop system for heat by a  flat plate heat exchanger.  It has worked great for the last three years ...but this year it is not keeping up with our heat needs.  I have come to the conclusion that the heat exchanger must need to be cleaned.  We are getting a hug drop in temp in the heat exchange over to the closed loop.  If anyone has any input on cleaning a flat plate heat exchanger I would appreciate it.  After reviewing manuals etc it is suggested to use a phosphoric acid solution of 5% and preferably backflush it for an in place cleaning.  However, I have Wye strainers ahead of the pump and just reversing flow goes against their flow.  I really don't want to have to try and turn them around etc. ...and right now pulling the heat exchanger in the middle of winter will be a major undertaking due to the lack of foresight to allow for this.  So unless back flushing against the strainers is not a big deal ...I guess I am forced to go with regular flow with the phosphoric acid solution etc.  Then ...I find today that finding the phosphoric acid locally is a little bit of a problem.  Has anyone ever used CLR to do this process?  That I know I can get locally.  If I have to get the phosphoric acid it looks like I may have to have it shipped in.  I know that CLR  is not the same thing ...but will it work?  Again ..any suggestions are much appreciated.  Thx RH


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## dogwood (Dec 26, 2011)

RH, You might find some useful information on this thread: https://www.hearth.com/econtent/index.php/forums/viewthread/42386/P0/


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## headrc (Dec 27, 2011)

TY ..checking it out now !


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## benjamin (Dec 28, 2011)

Farm stores usually sell phosporic acid as milkstone remover. Typically it's a pink liquid under $10 for a gallon jug.  

I assume you mean that the heat exchanger is plugged up, that's what the high temp drop means to me.  If it was moving enough water and the surfaces were fouled then the temp drop would be very low, right?

What about backflushing the heat exchanger using plain water and/or compressed air and the strainer as an access point?  just a thought.


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## headrc (Dec 28, 2011)

Hi ...I did try backflushing with plain water.  The result was a minor improvement.  I received input today that white vinegar might do the trick.  Also another source said the product CLR might work.  So I will try white vinegar first then the CLR probably.  I have a 40 degree temp drop over the heat exchanger.  I am certain that is not right.  And of course what prompted this is that the radiant heating system is not keeping up with the weather like it has for the last couple of years.  Thx,  RH


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## DaveBP (Dec 28, 2011)

Vinegar works faster when heated rather than room temperature.


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