Now twist on Raypak Hi Limit 2 error

[pgershon]

I have matching Raypak 406a heaters for my pool and spa, installed in 2011. Lat summer the spa heater would forever trip the Hi Limit 2 error, but generally when it reached 103 degrees or so. I replace 5th Unitherm Governor, the internal bypass and the hi limit switches, as well as insulating the switch area and decreased frequency of issues but did not make it go away. It is something I just live with.

This year, on starting up the pool heater, the water temp rose from 70 degree to 75, and then tripped the hi limit 2. I reset perhaps 15 times but could not keep the system running for more than 15 minutes. Finally I increased my variable speed pump to 3300 rpm (from 2800) and the RayPak seems to be staying on.

Any idea what could be causing flow issues? Usually I did not need to run pump this fast to heat pool. My pool was resurfaced this year but the pool heater was externally bypassed until the acid was gone and the dust stopped flowing. I will pop out the UG tomorrow and see what it looks like. I could also clean the internal bypass area if that might help. My pool flow (from eyeballing the jets) seems to be as strong as ever.

 

[ajw22]

Your heater NG or propane?

Look at what the color of the flame is? Is it blue with only yellow tips? Or all yellow ?

 

[pgershon]

Flame is quite blue. Compared pool and spa heaters and they are the same. Pool heater working now with pump @3300 rpm. Seems like a flow issue to me. Not sure how to diagnose for sure or correct.

Could I have dust causing some obstruction in DE filter that never clears with backwash? Alternatively, is there something that could be limiting flow in heater that o could correct?

 

[ajw22]

You may need to open up the DE filter and completely clean the grids.

DE Filter Use and Care - Further Reading

www.troublefreepool.com

 

[pgershon]

Opened up DE filter and removed the grids for much better cleaning. Did not disassemble as the junk (mostly plaster dust and aggregate from the resurfacing) came right off when hosed down well. Everything was clean and I put back, reloaded with DE, and I have heater going at 2800. Will bring down to 2500 where I usually have it for pool heat tomorrow - I want to finish getting my pool up to 83 degrees first. Thanks for the suggestion.

 

[pgershon]

One week later - pool heater still trips the high limit 2 each morning when variable speed pump runs at 2500. Once I bump up to 2800, there is no issue. Last year the heater worked fine at 2500 RPM from the pump. Does this sound like an issue with the heaters, or might my pump be slowing down? Pump was installed in 2012.

 

[ajw22]

Pool pumps don’t slow down.

The only thing that will affect the flow in the pump is the impeller.

 

[pgershon]

Pool pumps don’t slow down.

The only thing that will affect the flow in the pump is the impeller.

I am reactivating old thread as I seem to have similar issue this year as last. Ran pool heat for first time today. I got consistent HiRes2 shutoff at pool heater at 2500 rpm and 2800 rpm. It now seems to be running with VSP at 3300.

My question, why might pump require higher RPM each year to keep heater firing? If pump does not slow, should I open to check impeller? Of am I better off opening and examining the area where water heats in the heater (unitherm governor area)?

 

[ajw22]

Impeller can get seeds clogged in it.

Remove the UG and as a test see how heater runs without it.

 

[pgershon]

Actually I decided to remove the UG before I saw this. Ended up replacing it (good thing I had a spare from past bad experiences). Seal/gasket was completely warped and I doubt water tight. UG was also badly green. Hopefully it will work better now. I will report back. I did not check impeller - that seems more complicated.

 

[pgershon]

No more High Limit 2 errors since I changed UG. Heater brought temp from 75 to 82 successfully on large pool. Problem solved this time. Thanks for the help.