raypak new gas pool heater issue hoping for some ideas


Mar 21, 2019
London Ontario
hi there,

we have someone coming out to take a look at a brand new heater Raypak 406a (running perfect for a couple months) a few symptoms looking to see if a tech on the forum has a suggestions as there are major delays to get someone out to look at it. if its a simple repair i have a gasfitter and a pool guy that can do basic stuff

>> just to add we had an issue with a cracked lateral on a sand filter so some sand would have got into the heater but that is fixed now
was wondering if 1 of the components could have been damaged (pressure switch / UC )
also thinking if something is preventing enough water from getting to the heater (pressure switch etc) then i read that the heat is disipated and can trigger the error and shut off below - or there is soot on the exhanger?

1) whistling noise when running right off the bat when it fires up
2) reduced heat coming out of jets
3) i think possibly reduced water flow coming out of jets - possibly restricted at heater
4) runs for 10-20 min approx then shuts off with High Limit 2 is Open error


In The Industry
Jul 31, 2021
San Diego
Make sure the filter pump is operating at 40gpm minimum. Pull the unitherm governor and inspect and test.CBF353BD-91DF-414B-B932-45DC211D096E.jpeg
Part 13HP
It would explain most of your symptoms.
Pay close attention to the video, the unitherm has to open completely.


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Do you have a RECIRCULATE position on your sand filter MPV?

If so set it to RECIRCULATE and see if your flow improves and your heater works .
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