Ray pak heater - 400k btu - "sensor failure"

Pauls234

LifeTime Supporter
Jul 4, 2012
443
Chicago, IL
Hi all,

(Edited - initially I wrote system failure, it actually said "sensor failure" now corrected)

Opening the pool and went to fire up the heater for the first time since October.
It started heating for maybe 15 seconds and then just stopped with an error code of "sensor failure". There was some steam (or maybe smoke) coming out of the top for a bit, but I assume that's just a result of a short burst of heat that just went through the system.

In case it is relevant, I have in the past gotten a hi limit 2 fault, though we determined (based on discussions here) that it was likely a sensor issue rather than an actual overheat.

I doubt I'll be able to get a pro here today or tomorrow (if I can even find one at all) so any thoughts on troubleshooting I can do would be appreciated.

Thx
Paul
 
Last edited:

ps0303

TFP Expert
In The Industry
Jul 6, 2011
4,049
FL
On the Raypak units, a Hi-Limit 2 error could also be an indication of a bad Unitherm Governor or a bypass problem. Check the Unitherm Gov. first though as it's easier to get to.
 

Pauls234

LifeTime Supporter
Jul 4, 2012
443
Chicago, IL
Thanks Paul. Will check into that. I've also corrected the error message.... what happens is, it starts heating then very quickly shuts itself off with the error code "sensor failure" though I doubt it changes your advice.
 

Pauls234

LifeTime Supporter
Jul 4, 2012
443
Chicago, IL
Well, I removed the unitherm governor, tested it by putting it in hot sink water and it functioned properly. I also removed some panels and hit the insides with a shop vac everywhere I could reach. Fired it up, but got the same result - began heating as normal for a short time (less than a minute?) and then just turned itself off with that same "sensor failure" message.

Anything else simple I can try or very modular parts I can replace on my own before I call in a pro?