Hayward heater wont start

[jtharp723]

I have a Hayward H series 400 k BTU heater, and yesterday it would hot fire up. The heater is about 15 years old and has never really given me any issues except i had the change the temp sensor once. I opened it up and did some brief diagnostics and I may have stumbled on something that may or may not be an issue. When you call for heat it does nothing, the blower makes no attempt to even start as it should before a problem would be coded. The thing i found is that the relay wiring from the Aqua Logic to the heater never shows power. I would assume that when i activate the heater there would be say 24 vac activated through that relay wiring to tell the heater to attempt startup. I am also checking for power at the actual wiring connections on the Aqua Logic board on the panel, so its not a broken wire to the heater. Is my assumption here correct, that there should be some low vac current in this line to start the heater. If so, i guess the million dollar question is what could be causing this issue.

Oh, and yes I have 240 v power at the heater control board ready for action.

I appreciate any help that can be offered.

I have uploaded a pic for clarity, i am checking for vac on both relay 1 and relay 2 with the heater activated.

 

[mas985]

Welcome to the forum!

I have a Hayward H series 400 k BTU heater, and yesterday it would hot fire up. The heater is about 15 years old and has never really given me any issues except i had the change the temp sensor once. I opened it up and did some brief diagnostics and I may have stumbled on something that may or may not be an issue. When you call for heat it does nothing, the blower makes no attempt to even start as it should before a problem would be coded. The thing i found is that the relay wiring from the Aqua Logic to the heater never shows power. I would assume that when i activate the heater there would be say 24 vac activated through that relay wiring to tell the heater to attempt startup.

That would be a wrong assumption. When there is a call for heat, the relay closes and the heater control detects that the relay has closed and starts the heater. You would not have any any voltage across those two pins when the relay is closed as it is a short circuit.

As to why the heater does not react at all, I suspect it has something to do with the heater control board.

What is the exact heater model that you have?

Is there anything on the display? It should display "Bo".

If the display is dark, check for power to the heater.

If the display, reads anything other than "Bo", report back what it is or look in the manual for error codes.

 

[jtharp723]

I thought i would post a followup as it may help someone else later. My front LED display has been shot for years, so i figured i would replace that first to hopefully help by displaying a trouble code. After installing the new LED display and button control it would not illuminate. This led to another diagnostic, and turns out the 3amp fuse on the main board was blown, replaced that fuse and the display worked. Turned on the pump, heater showed standby, so i turned it on and it worked fine. So at the end all of the heater operation hinged on a .25 cent fuse.