Gas Heater vs SLAM

Diego168

Well-known member
Apr 9, 2019
46
Ct
Hello everyone.

I have a fiber glass pool that was installed early this year. They had installed a chlortab chlorinator which after reading this forum I switch to liquid chlorine for the remaining of the season. I have a Pentair master temp propane heater but there is no bypass valve. There had been times that I’ve had to SLAM but im wondering If im Hurting my heater everytime
I slam and if I should install a bypass valve.
Or for those of you that have a heater is there an internal bypass in the heater when the heater is off?

Thank you
 

Donldson

TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
3,941
NW Ohio
Heat exchangers are relatively unaffected by high chlorine, it is low pH that causes the most damage. On top of that the actual active chlorine level during SLAM is really quite low, it is less harsh than most public pools. So worry not, it's perfectly safe.
 
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sktn77a

Gold Supporter
May 16, 2010
1,416
Chapel Hill, NC
The problem with chlorine and heaters is when super, super, high concentrations of chlorine (100x SLAM or more) backflow from the chlorinator into the heat exchanger on a regular basis - eg every night when the pump switches off! That's why every manufacturer requires a check valve between the heater and the chlorinator. If it's copper, there will be problems. Stainless steel, maybe less so. Low pH is bad also and the two together.... Well, you get the picture.
 
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Diego168

Well-known member
Apr 9, 2019
46
Ct
Thank you both. Yes my pool builder install a chlortab chlorinator supper close to the heater and with no check valve. So I ended up not using the chlorinator switch to liquid for this season but will switch to salt for next season.
It was hard maintaining with liquid only as I don’t know my pool to well.
Last weekend I left and when I came back my pool was cloudy chlorine level was zero. Had to slam and is now ok.