The heater fires, runs for about a minute and stops

[brucer]

I have a Sta-Rite SR400NA 400K btu unit and I'm having a problem. The heater fires, runs for about a minute and stops heating. it restarts about a minute later and continues this cycle. The HLS LED was lit so I replaced the High Limit Switch and it worked for a few days and now the problem has returned. Any suggestions are appreciated. I hate to buy a new control board unless I can be sure that's the problem.

[Edited to add model number]

 

[257WbyMag]

Welcome to TFP!

Heaters will do that if it senses that it isn't getting enough water flow. Have you checked into that?

 

[brucer]

Water flow appears to be normal. Valves fully open and pressure is normal.

 

[PoolGuyNJ]

Two things I can think of:
1) If you made plumbing changes, its possible you reconnected the in to the out. Heated water hits the high limit and trips, resets....

2) The internal bypass is stuck open.


Scott

 

[flintstone]

Be sure to check that you have the correct setting in your control panel. There are a number of heater items in a couple of the submenus that affect how your heater runs. The incorrect setting would allow your heater to start up, but shut off quickly thererafter. Well, mine did that until I found the correct setting.

 

[brucer]

No plumbing changes so I'll tear into it and check the internal bypass (when it stops raining!). Regarding the suggestion about the submenus, appreciate the suggestion but it wouldn't be applicable as I don't have a very sophisticated controller, just a dirt simple Intermatic remote control system.

 

[JamesW]

What are the make, model and age of the heater?

 

[brucer]

It's a Sta-Rite SR-400NA installed as part of new construction 3 1/2 years ago.

 

[JamesW]

This has a troubleshooting flow chart that might be helpful.

Note: Always be careful when working on heaters. They can be very dangerous. Don't do anything you don't feel comfortable doing.

 

[brucer]

Thank you, I do have that but just wanted to see if anybody had any other input before I start the major surgery on the thing.

 

[JamesW]

Are there any error codes, or does the heater just cycle on and off?

Note: The membrane pads on those heaters are not very reliable. They seem to go bad every few years. Sometimes the buttons don't work and sometimes they cause problems similar to what you're seeing.

 

[brucer]

No error codes - just the "Service Heater" light. The buttons appear to be OK as they are responsive.

 

[JamesW]

At this point, the best thing to do is follow the flow chart in the manual. If you have verified proper water flow to the heater, the Internal Bypass Valve and/or the Thermal Governor may be malfunctioning.

 

[brucer]

That's what I'll do. I'll report back tomorrow - if the rain stops.