Raypak 266A Cupro heater

mazik

New member
May 25, 2025
4
Michigan
Hi All!

In need of some help please and thanks in advance. I have a 2 year old 266A cupro heater!!!! Opening this season was fine and pool was running fine. However within the last week or so the heater keeps reading a HL2 code and is turning off. There is also a banging noise from time to time and periodically my salt cell red light is on for "flow" and the supplies in the pool seem weak when I stick my arm in. Today we took out the heat exchanger and cleaned it out and reinstalled and is still reading HL2. Any insight would be great.
 
Welcome to TFP.

When did you last clean your filter?

What type of filter do you have?

What is your filter PSI?

All your symptoms point to low water flow. The banging is due to water boiling in the heater. Then the boiling water overheats the heater causing the HL2 shutdown.

Algae can clog a filter

Can your pool pass a Overnight Chlorine Loss Test? If not, you need to follow the SLAM Process to get your pool algae free.


 
Welcome to TFP!!

Allen has you on the right track.

I'd also have you post several picture of your equipment pad, so we can see all the equipment, piping and valves. If it takes several pictures, use several pictures.
 
You can have algae in crystal clear water.

Algae cannot be seen until you get a large algae bloom.
 
Sand filters can capture the algae, but are slower than other filters when doing so. Some will escape and get put back into the pool. If not already killed by having enough CL, it grows to be even more of an issue for the filter to get in a timely manner.

Backwashing will clean out a good amount of dirt (including captured algae), but it is not capable of complete flushing of all of the sand. Under normal circumstances, it is good enough.
But, either due to extra heavy loads, or over a long time, the sand can get sticky and start to clump together. Water will find a way, typically by creating channels in the sand that then doesn't get filtered well (or at all). Symptoms include higher pressure than when it was all shiny new and clean, needing to backwash more often, dirt blowing back into the pool, etc.
Many jump at changing the sand - but that is almost never needed. Do a deep clean: Deep Cleaning a Sand Filter

When I had mine, I made it a once a year thing. It is amazing the amount that comes out of even very well backwashed sand.
The counterintuitive thing is that a slightly dirty sand filter filters better, until it gets way too dirty. So after cleaning, some will add DE powder to help. That easily gets flushed out in a backwash, But usually the minimum quantities you can buy mean you will have several lifetimes supply. If the pool is otherwise looking great, no need to go that extra mile.
 
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