Cleaning heat exchanger on Hayward 350

We recently were called to a customer’s site when the tenant tried to use the heater and it wouldn’t stay lit.  This was an older heater that had a bit of rust and soot build up in the heat exchanger.  We tested the pressure of the gas coming in to the heater and it was well below the required 4.0 WC” while the heater was fired so the first thing that we needed to do was have a plumber come correct the clogged up gas line.

Low gas pressure caused a very sooty flame.  You could barely see the flame through the heat exchanger and what you could see was a very unstable orange flame.  The flame was so unstable and air circulation so poor, that the flame would actually go out every few minutes.  This particular heater model (an older Hayward 350) is a continuous retry model so it would just relighting the flame, but it would take a very long time to heat the pool.

We had to take the top of the heater apart to remove the heat exchanger and clean it with a combination of compressed air and water.  I took a couple of pictures showing the before and after and the last picture shows the nice clean headers with a normal blue flame.

This cleaning process usually takes about 2 hours.  Some customers can get away with never performing this maintenance step, while others may need a more superficial cleaning once a season.  One side effect of letting a heat exchanger clog up like this is it can dramatically increase the temperatures inside the heater.  In the case of this heater, some of the wires in the safety circuit had insultation melted off  and had to be repaired. 

If you would like to schedule heater maintenance, contact us at 214-989-3888 or

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