Hayward h400 heater error

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Omarf4

0
May 16, 2014
17
Dallas, Texas
Ok guys, second thread post here, so take it easy on me.

Tried to fire off my pool heater today but no luck. Hayward h400 with external automation control. Hit the heater button on panel but the display on actual heater has the following error codes:
- Bo , which is normal according to manual if externally controlled.
- SF - temperature sensor failure.
- HS - water temperature exceeds 105. Don't think so as pool temp is 74F.
- LO - water pressure switch, limit switch or vent pressure switch is open.

Where do I begin?

A few pieces of info:
- natural gas line open.
- automatic pilot switch system, so no manual lighting. Don't even here anything trying to come on at all or at least fire the burners.

Any help would be appreciated on where to start. My pool boy doesn't do heaters!!!
 
Do you have water flow to the heater? Check to make sure any bypass valves are positioned correctly. Once that is verified you may need to test each of the sensors that are causing the problem. Do you have and know how to use a volt/OHM meter?
 
Pump is on (variable speed - 2500 rpm) with water flow through heater. Minimum for this heater is 25 gpm so I assume pump is pushing enough flow. I even tried at max speed (3100 rpm) and still same result.

The heater is installed after the DE filter and right before the return line back to pool.

Very comfortable with voltmeter and have one handy. Will upload picture of the heater with cover off shortly.
 
Have you tried the obvious?

When I had error codes, I just killed the power to everything for ten minutes and it reset itself. It's fixed it twice over the last couple years.

The next thing to look for is spider webs or rodent damage. Mice really seem to like the teaste of vinyl wire insulation.

On my heater, first it checks for water flow, then it fires off the blower, and once it detects a draft, it opens the gas valve and starts trying to ignite. Spider webs in the air flow sensor will keep it from lighting.

Let us know what you find!
 
Omarf4 said:
Thanks Paul. Problem is I can't even find someone that wants to work it. Most just want to replace with a new unit. Any idea where to begin troubleshooting? Control board error code isn't being displayed but maybe it is the issue?
Click to expand...

Check all of your wiring and connectors. I then would take it out of bypass mode so you can operate it at the heater. Then I would start checking out each error code. SF error is your temp sensor. You could get a new one and without actually installing it you can unplug the old one and then just plug the new one on and see if the error goes away.

LO is possibly the pressure switch. First make sure you have good flow thru the heater and a clean filter. Then you could jump out the switch and if that error goes away, replace the switch.
 
Hey gang, quick update here.....spent the morning cleaning all the connections and doing circuit tests with a multimeter. All checked out clear. After the hard reset, all error codes are gone and the heater actually fires up!,,, blower kicks in but a second later, I get the SF and HS error codes.....so I am back at the thermostat issue.....where the heck is the thermostat on this thing? It's the h400 IDL model, not the IDL2 model....this unit still has the dip switches for bypass operation vs the idl2 which doesn't.
Help! Where is the thermostat?
Note: I have automation with external panel that has air temp sensor and water temp sensor. The temp sensor is in the picture above attached to the outflow from DE filter into the h400 heater.

Any help would be appreciated...I am very close to getting this thing working!
 

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Thanks again Paul. Appreciated all the help. I found the thermistor on the other side as you noted. Black/red/blue wires twisted together and run from the control board over to the thermistor. But, here is where it gets interesting.....
The way my h400 is wired, it's Setup for external thermostat connected to the terminal block to the right side of the transformer. So, I think we are now to either the remote thermostat isn't working or the thermistor needs replacement inside the h400 heater.
Remote thermostat is reporting both air and water temp, which seems to be working as its displayed on the aqualink rs4 panel correctly. So I assume it's the thermistor that's faulted here........will see about ordering the part and hope to god I am on the right path.......
If you have any other ideas to try, that would be appreciated.....thanks again!
 
YES it is!
Listen to this guy's luck....I walk into Leslie's pool supply asking for the thermistor...he didn't have in stock but the store 45 minutes away did....so I take a gamble and drive over, pickup the $112 thermistor...bring it back, plug it in the control board without actually installing it into the inflow header...and guess what, the heater fired right up and heating the pool as I type this!!!!!! This issue is now officially RESOLVED!
Will keep it hanging behind the control board for the day and then swapping it out at some point later...just don't want to deal with draining the heater for now....
Paul, you my friend, are a ROCKSTAR...thanks for the help...will be sitting in the pool this evening having a cold on for you!
 
You don't have to drain the heater to install. Just turn the pump off and then disconnect the thermistor from the board and unscrew from the header. Install new on and then turn pump on.

Glad I could help you resolve the issue. Hop you had a good holiday weekend.
 
For future reference, many times error codes and other issues can be resolved by simply pulling all the wires from the control board one plug at a time and re-seating them. This allows some of the oxidation to be rubbed off the control board pins. I've had luck with this many times over the years. Older units will have a higher instance of this problem for obvious reasons.
 
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