I have a gas pool heater and it keeps on knocking. What can that be and how can I fix it? Any help is appreciated.
Gas heater knocking
- Thread starter Kefaru11
- Start date
- Jun 24, 2021
- 15,982
- Pool Size
- 29000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Welcome to TFP!!!
It is likely that your flow is too low. Turn up your pump speed and see if it goes away. Heaters have a minimum flow to keep them from overheating. Yours is likely overheating, causing the knocking.
Try turning pump up and report back.
It is likely that your flow is too low. Turn up your pump speed and see if it goes away. Heaters have a minimum flow to keep them from overheating. Yours is likely overheating, causing the knocking.
Try turning pump up and report back.
Bill1974
Well-known member
- Jun 18, 2014
- 661
- Pool Size
- 32000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
As PoolStored said, it's likely low flow. If increasing the flow does not resolve it, some of the heat exchanger could be clogged. Try back flushing the heater. Also check to see it's using the right amount of natural gas and not over fueling (not likely, but doesn't hurt to check), with NG you should be able to see how much gas is being used and equate that to the BTU output of your heater with an adjustment for efficiency (100 CF is about 104K btu). If your heater is 400K btu it should use about 1 cf in 15 minutes if it's running continuously. If there is scale build up impeding flow it might need a new heat exchanger or a cleaning with chemicals to dissolve the scale.
- Jul 21, 2013
- 65,181
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Welcome to TFP.
What model heater are we discussing?
What model pump and filter?
What is your filter PSI and when did you last clean your filter?
Can your pool pass a Overnight Chlorine Loss Test?
Knocking is usually caused by water boiling in the heater. Water in the heater should never get that hot.
Increasing water flow moves heat out of the heater faster and prevents boiling.
What model heater are we discussing?
What model pump and filter?
What is your filter PSI and when did you last clean your filter?
Can your pool pass a Overnight Chlorine Loss Test?
Knocking is usually caused by water boiling in the heater. Water in the heater should never get that hot.
Increasing water flow moves heat out of the heater faster and prevents boiling.
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