Pool and Spa heaters not working at start-up (Raypak 406A) - Now Hi Limit Error

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pgershon

Gold Supporter
Jul 15, 2012
634
East Hampton NY
Pool Size
30
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Pool has been running since first week of April with heaters bypassed. Opened the bypasses today and both heaters failed to work. Each heater is a 2011 Raypak 406A with 3-4 year old circuit boards (revision 1.08 and 1.07 digital). I will outline each separately as the problems are different, and I'd appreciate any suggestions on each problem for next steps. Last two year the heaters fired up like a charm.

Pool Heater:
Heater goes to spark when I turn on the heater at the Jandy control (it says firearm sw alert until it goes on, which is normal). But it never ignites. I hear it trying to start, but I do not see anything lighting inside when I remove cover of heater. Initially I had tried to start heater with the gas valve inside the heaters switched to off.But turning it on did not correct the problem. Seems to me it's either an igniter issue, or a gas issue. As I just switched the gas on this morning at the main valve, I will give this heater another try later in day. But what would be the next step in diagnosis?

Spa Heater:
Heater says open sw and not firearm alert when off or on. That suggests a water flow issue. But I hear water flowing through heater. And I do not see any water leaking out from it. Variable speed pump is on a pretty high speed although I could turn up. Any other suggested things to try?

Thanks in advance...
 
Quick updates:

Pool heater came on 20 minutes after start-up. I switched heater off and let it sit with gas on and water flowing. When I tried again, it lit up. Maybe there was an issue getting the propane gas to run fully through the system.

Spa heater open sw water went away when I turned up speed on spa pump. I am a bit concerned about the pump because last year and the year before, chlorinator required 1300 rpm and heater required 1800 rpm to work. This year chlorinator only works at 1800 and spa heaters needed 2250 rpm to run. I am not sure why the decreased efficiency? One thought is that I have not put the eyeballs on the returns yet. Could this affect pump efficiency? Maybe more water flowing so less pressure building in system?
 
pgershon said:
Quick updates:

Pool heater came on 20 minutes after start-up. I switched heater off and let it sit with gas on and water flowing. When I tried again, it lit up. Maybe there was an issue getting the propane gas to run fully through the system.

Spa heater open sw water went away when I turned up speed on spa pump. I am a bit concerned about the pump because last year and the year before, chlorinator required 1300 rpm and heater required 1800 rpm to work. This year chlorinator only works at 1800 and spa heaters needed 2250 rpm to run. I am not sure why the decreased efficiency? One thought is that I have not put the eyeballs on the returns yet. Could this affect pump efficiency? Maybe more water flowing so less pressure building in system?
Click to expand...
Sounds like you have a dirty filter. That is always the first place to look if there is any kind of waterflow alert on a heater or SWG (usually a pressure switch error code or message). Then look for a clogged pump or skimmer basket.
 
1poolman1 said:
Sounds like you have a dirty filter. That is always the first place to look if there is any kind of waterflow alert on a heater or SWG (usually a pressure switch error code or message). Then look for a clogged pump or skimmer basket.
Click to expand...
Thank you. Cartridge filter at the spa was indeed dirty. I cleaned it and now the heater looks normal at the pressure that ran it effectively last year.

One thing I do not understand however is that the pressure gauge at the spa filter did not change after I cleaned teh filter. It still reads about 5 psi when pump running. That would typically not make me think dirty filter. I wonder if the pressure gauge has gone bad after 3 years and giving me misleading readings.
 
One more update. Spa heater doing well - got to 104 degrees. Pool heater keeps tripping hi limit 2. This is an error I get frequently on the spa heater every year, especially as I try to heat water past 100 degrees. But the pool heater is tripping high limit at 75 or 76 degrees. I opened the unitherm governor compartment and inspected the governor. It did not look at all corroded (I believe I replaced it 2 or 3 years ago). There was some very fine gook in the area behind the unitherm governor so i rinsed the compartment with a garden hose and then reassembled. Problem has not gone away. Still trips at 75-76 degree water temperature. I also tried turning up pump speed but it had no effect or improvement.

I could change the internal bypass, but this feels like a different issue than what I experience with the spa heater given the heater trips consistently at lower temperature. One thought I had is that the flu/exhaust may be dirty. The heater sits under pine trees and collects a lot of needles etc. I do not believe I opened the top and cleaned it out in two years. Might this be my issue? Any other suggestions?
 
Things you can try for the High Limit error:
  • replace both high limit sensors and add thermal paste
  • replace unitherm governor
  • replace internal bypass
  • add a heat shield
Some folks have added a heat shield above the HLS sensors. This thread describes how the high limit fault was fixed by insulating the header around the sensors.

600px-Raypak_Heater_HLS_Heat_Shield.jpg
 
Thanks. I actually contributed to that thread you posted. Heat shield worked for a bit, then failed. But all of this was on my finicky spa heater trying to get to 104 degrees. The pool heater is tripping the high limit at 75 degrees, which makes me think the issue is less subtle than heat shield related. I ordered new hi limit sensors and a new unitherm governor as replacing certainly cannot hurt. I will see if cleaning the exhaust helps tomorrow as well. I will report back if and when I find a solution.
 
Another update. Still waiting for parts, but today the SW Open message was on pool heater. And, given the amount of pollen that has come down over the last few weeks, I replaced the DE media in the DE filter. Lo and behold, the SW Open message gone and no Hi Limnit error messages yet either. Not sure if it was pollen or an air bubble somewhere, but I have good flow and all is working. If the Hi Limit message comes back, I will have new hi limit sensors and a new unitherm governor waiting and ready/
 
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