Need help with Hayward H400 Pool heater

[steelman93]

Hello everyone. I am getting an LO error on my Hayward H400 heater and need some help troubleshooting. Here is the history on it:

Installed less than a year ago and has worked flawlessly in that time. 3 weeks ago a critter climbed into the heater and my dog went berzerk trying to get to whatever the critter was. She destroyed the power cord to the SWG and the flow switch that goes to the Aqualink. In addition, there were two wires that came off of a brass plug on the outlet of the Hayward heat exchanger that she destroyed, but I do not see where these go, and my Hayward owner's manual is not clear. It shows one side going back into the side of the heat exchanger and the other side not connected to anything.

I replaced the flow switch and power cord for the SWG, but can't get the heater to come on. When I turn it on, the blower comes on and then 2 minutes later shuts off and I get a "LO" error.

My gut feeling is that the problem is the brass plug is some kind of a flow switch but in the owners manual I don't see it referred to at all. In addition, I am using an Aqualink panel to control the heater so I assumed that the Jandy flow switch was controlling that but am not sure. Can anyone help me on this? If in fact this brass plug with wires is necessary, where do the two leads that come off it go? I do not see a place for it in the front of the heater. Will I need to take the top of the unit off? (Which I believe requires the removal of the sides? Any help is appreciated.

TIA

 

[ajw22]

Yes, you need the brass plug and wires connected. It is part of the heater safety systems.

The heater knows nothing about it is connected to a Jandy Aqualink and other flow switches are meaningless to the heaters.

Post pics of your heater and the things that were broken and repaired.

@ps0303 @1poolman1

 

[1poolman1]

The "brass plug" is actually one of the limit switches. If there is enough wire, try splicing them back together. If not, you will need to get a new one. The heater is sensing an "open" condition on the limit switch and won't allow the ignition process to go any further than "fan on."
This site has some suggestions as well:

Hayward Pool Heater LO Code [Reasons + Solutions] - FireplaceHubs

Faulty water temperature switch, malfunctioning vent pressure switch, and defective temperature limit switch are accountable for displaying the Hayward pool heater LO code. Also, the damaged flow switch diaphragm and clogged filter are responsible for showing this code on your pool heater...

fireplacehubs.com

 

[steelman93]

Yes, you need the brass plug and wires connected. It is part of the heater safety systems.

The heater knows nothing about it is connected to a Jandy Aqualink and other flow switches are meaningless to the heaters.

Post pics of your heater and the things that were broken and repaired.

@ps0303 @1poolman1

thanks for the reply. I don't really have a picture...it is just the plug. The other two cables were self explanatory...just a power cord to the SWG and the flow switch from the SWG. I will order a new flow switch for the Hayward

 

[steelman93]

The "brass plug" is actually one of the limit switches. If there is enough wire, try splicing them back together. If not, you will need to get a new one. The heater is sensing an "open" condition on the limit switch and won't allow the ignition process to go any further than "fan on."
This site has some suggestions as well:

Hayward Pool Heater LO Code [Reasons + Solutions] - FireplaceHubs

Faulty water temperature switch, malfunctioning vent pressure switch, and defective temperature limit switch are accountable for displaying the Hayward pool heater LO code. Also, the damaged flow switch diaphragm and clogged filter are responsible for showing this code on your pool heater...

fireplacehubs.com

thanks for the reply. I will contact Hayward to make sure I get the right part number based on my serial number.