I just bought a house with a pool and spa, and the total size is 10,000 gallons. My Pentair LPG heater is oversized when I just heat the spa. It is rated at 400,000 BTU/hour and requires a very high flow to avoid tripping the low water flow switch. But the burner cycles on and off every few minutes due to high heat exchanger temperature. Is there a way to derate the burner?
Oversized pool heater
- Thread starter Ralph Rocket
- Start date
- Oct 25, 2015
- 5,158
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Rocket,
Welcome to TFP! You've come to the right place and already got a real expert helping. May I suggest your add your signature and the photo's requested? This will greatly reduce cycles between your question and your answer. It also helps us be more effective with our experts volunteer time. It's real simple to do, here's how. For what it's worth I don't think your problem is caused by min flow required by the heater. Most require 30 or 40 gpm only and your pump should easily provide that. I'm guessing that's why @JamesW needs some photos.
I hope this is helpful.
Chris
40 GPM should be plenty.
There is a different problem like maybe a bad internal bypass or a bad thermal regulator or maybe an external bypass.
This is usually a flow issue, so maybe a bad internal bypass or thermal regulator.
Pull the thermal regulator and look for the internal bypass disc at the top of the regulator pipe hole where the thermal regulator goes.
Look into the inlet to see if the internal bypass looks ok.
Can you show the entire system?
Internal bypass.
You can see the spring part if you look into the inlet.
You can see the disc part if you look into the thermal regulator hole.
Pull the thermal regulator and look for the internal bypass disc at the top of the regulator pipe hole where the thermal regulator goes.
Look into the inlet to see if the internal bypass looks ok.
Can you show the entire system?
Internal bypass.
You can see the spring part if you look into the inlet.
You can see the disc part if you look into the thermal regulator hole.
- Oct 25, 2015
- 5,158
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
And I might add some other flow restriction where there's a manual or automatic valve that's partially closed... with recent inspections it's likely valves were turned and not returned to their original position.
You may have a bypass valve in wrong spot or your filter may be too dirty. Also those mastertemps are absolutely horrific and the thermal regulator and bypass inside commonly go bad. When you say heating up and tripping. Are you referring to your stack flu sensor. If you look up under the control board inside the heater the back of the board will light up codes next to abbreviated letters (HPS, etc). Check and see if it's throwing a code light. Open the from panel of heater via 4 7-16 bolts and look up where the board is. Also make sure gas is on and not empty. Check for any rodent nests etc in there too. These heaters are an absolute nightmare unfortunately. One drop of water getting behind the keypad can short the boards and keypads out. Bad design.