Hayward H250 ED2C Service LO preventing heater from firing

[MarkHoop]

I am getting a LO alarm which I understand is related to flow and affects the PS. Here is what I know,
With flow through heater
1 - PS is open circuit when checking continuity on the PS connectors. Should this be closed with pump running?

I can verify flow as I have a check valve on the outlet of the heater and it is clear that there is flow.

No change of condition when the heater is bypassed (3 way valve on inlet).

Is there a way to jumper these to verify that my problem is the PS?

Anything I should try before moving on a new PS?

 

[ajw22]

The LO code can come from any of the 5 switches. I would not get myopic on the WPS.

You can jumper each of the switches as a test. Find each switch and the wires connected to it.

A Hayward LO code is a limit string open error that occurs when any of the safety circuits on your Hayward pool heater opens. This forces the heater to shut down to protect your heater from damage.

Usual reason for the LO code is lack of sufficient flow not closing the Water Pressure Switch. Low water pressure can be due to a filter that needs to be cleaned, low pump RPM if a VS pump, open heater bypass valve, low skimmer water level, or even a stuck weir door.

Also on the Limit String is the Temperature Limit Switch, Exhaust Gas Temperature Limit Switch, and Vent Pressure Switch.

 

[MarkHoop]

Would it make sense to consider that a Jandy check valve would cause a sufficient back pressure such that the flow would be reduced?

 

[ajw22]

Would it make sense to consider that a Jandy check valve would cause a sufficient back pressure such that the flow would be reduced?

No.

Your pump single speed?

 

[MarkHoop]

Yes, single speed Superpump. No flow issues last season. Skimmer is good and no stuck weir door. As I said I am getting an open circuit on the temp limit switches (2) and the pressure switch.

 

[ajw22]

As I said I am getting an open circuit on the temp limit switches (2) and the pressure switch.

If you are testing them properly it sounds like you have 3 bad sensors. It is strange for 3 to go bad at one time.

I assume you had your pump running and water circulating through the heater when you tested continuity on the WPS. And you disconnected the wires to the sensors before testing continuity?

 

[MarkHoop]

If you are testing them properly it sounds like you have 3 bad sensors. It is strange for 3 to go bad at one time.

I assume you had your pump running and water circulating through the heater when you tested continuity on the WPS. And you disconnected the wires to the sensors before testing continuity?

Disconnected the connectors at the temp sensors, disconnected the spade connectors at the PS. Tested all above with flow on and all were open circuit

 

[ajw22]

Disconnected the connectors at the temp sensors, disconnected the spade connectors at the PS. Tested all above with flow on and all were open circuit

Sounds like they need replacement.

Test the new sensors before installing.

 

[1poolman1]

Would it make sense to consider that a Jandy check valve would cause a sufficient back pressure such that the flow would be reduced?

Not unless it was stuck closed. Bad water flow is usually caused in front of the heater not afterward. The filter is the first suspect, then clogged basket(s), clogged impeller, stuck weir.

 

[MarkHoop]

Not unless it was stuck closed. Bad water flow is usually caused in front of the heater not afterward. The filter is the first suspect, then clogged basket(s), clogged impeller, stuck weir.

It is not stuck closed but rather open about 25-30% (best guess) but certainly not 100% (spring loaded). All other items have no issue as I have not seen an reduction in flow at my returns and the heater in-line.
Also, no significant increase in filter pressure although the sand would be somewhat of a buffer.

 

[MarkHoop]

Sounds like they need replacement.

Test the new sensors before installing.

How would you test the sensors?

 

[ajw22]

How would you test the sensors?

Same way you just checked continuity. The WPS you probably need to install to test with flow.

 

[MarkHoop]

Just thought I would close the loop. All 5 sensors and the PS all showed closed with the pump running however the wire coming off the terminal block had disconnected itself and therefore the test loop was open. Plugged the wire back onto the terminal block and all is good . Good thing I passed that electronics class!!!