Flakes/Scale Buildup in Heat Exchanger

Geckoeyes

Member
Jun 8, 2017
16
Lake Orion MI
Hello,

I continue to struggle with flakes/scale buildup in my heat exchanger (I posted in 2018 on this). Last spring I had to ream scale out of my heat exchanger in order to restore flow. I also set up controls so the heater starts a half hour after the pump is running and shuts off a half hour before the pump shuts down. Pool chemicals have been well balanced all season (PH 7.5, TA 100, CH 225, CYA 30, CSI -0.09) . I use 8oz metal magic a month for stain control.

Just before closing last year I noticed some flakes were coming out of the returns again. I pulled the manifold off and the heat exchanger needed to be reamed again already after just one season (see picture). I tested the unitherm governor and it is functioning. Can I run without this governor? I am concerned it may not open soon enough as it is the only flow restrictor I can think of in the system? Flakes turn yellow and slowly dissolve in muriatic acid test. Do I need to get a phosphate test? What else can I try? Besides this scale issue and light staining I have no other issues with the pool.

Thanks in advance.

1621441744163.png
 

Geckoeyes

Member
Jun 8, 2017
16
Lake Orion MI
Yes. All last year I had a control system that turns off the heater a half hour before the pump shuts off for the night. It also doesn't turn the heater on unless the pump has been running for a half hour. Here is a picture of my equipment if that may be helpful. Thanks for your help.

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JamesW

TFP Expert
Mar 2, 2011
28,256
Calcium carbonate would dissolve completely and create lots of bubbles.

If the chips don’t dissolve completely in acid, then I would suspect calcium phosphate or maybe a different calcium compound.

It does not appear that the scale is adhering to the copper walls very much.

It seems odd that most of the scale is flakes that are loose in the tubes.

Calcium scale can be calcium silicate, calcium carbonate, calcium phosphate or calcium sulfate.

https://www.poolspanews.com/facilities/maintenance/analyzing-three-types-of-scale_o

https://www.poolspanews.com/facilities/maintenance/calcium-phosphate-scale_o

https://aquamagazine.com/service/the-case-of-the-mysterious-pool-deposits.html

https://aquamagazine.com/service/the-mystery-of-the-pointed-crystals.html

Test for phosphate and sulfate.
 

JamesW

TFP Expert
Mar 2, 2011
28,256
1621441744163-png.334771


This shows that only the 4 right tubes have scale. Is this correct?

What are the make and model of the heater?

Are the In and Out of the heater plumbed correctly?
 

Geckoeyes

Member
Jun 8, 2017
16
Lake Orion MI
This photo is from the side where the water flows in and out. When I ream it I do it from the other side (return header) and there is actually build up in every tube to some extent (solid on the tube walls, not all chips). The 4 right tubes you mention always have the most blockage but all of them do have some. This is the side with the unitherm governor FYI. I did confirm the in and out are plumbed properly. The model is Raypak P-R206A-EN-C. I have called them about it and they weren't much help. Here is a diagram of my flow situation. You can see why I was curious about running without the unitherm governor. I confirmed the bypass components are all in good shape as well. Thanks so much for your time!!! I am hunting for a somewhere to get your suggested tests performed. I would purchase a test kit if affordable as well.


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