Hi, just wanted to share this experience because it sounds like a lot of folks are having it.
TLDR: I took out the heat exchanger coils, cleaned and descaled them, ShopVac'ed the can out, and problem solved.
Unit is 5 years old. Was giving me issues last year. Water chemistry situation wasn't great. Started doing everything myself this season with help from this great website.
This season the issue was that it would turn on and blow for a couple minutes then stop with "Service Heater" light on. Exhaust temp was high (would get to the low 400's). No LED on the back of the board. Flow was sufficient. Put in new thermistor, thermal regulator, and stack flue sensor, still having the issue.
As a last ditch attempt to save it, I opened it up and took out the heat exchanger coils (there are videos how to do this online; definitely a lot of nuts/bolts to come off and required disconnecting gas line). Once I had the coils out I sprayed them on the outside w/ a garden hose. I then filled the coils w/ CLR lime remover I got at the hardware store. Let it sit a couple minutes, poured it out (carefully), repeated the process, then finally rinsed each coil for a couple minutes w water.
ShopVac'ed the debris in the can. Put it back together and now working.
I have zero engineering, pool work, construction or other relevant experience and I could do it with no special tools. Thought it would be good to share.
TLDR: I took out the heat exchanger coils, cleaned and descaled them, ShopVac'ed the can out, and problem solved.
Unit is 5 years old. Was giving me issues last year. Water chemistry situation wasn't great. Started doing everything myself this season with help from this great website.
This season the issue was that it would turn on and blow for a couple minutes then stop with "Service Heater" light on. Exhaust temp was high (would get to the low 400's). No LED on the back of the board. Flow was sufficient. Put in new thermistor, thermal regulator, and stack flue sensor, still having the issue.
As a last ditch attempt to save it, I opened it up and took out the heat exchanger coils (there are videos how to do this online; definitely a lot of nuts/bolts to come off and required disconnecting gas line). Once I had the coils out I sprayed them on the outside w/ a garden hose. I then filled the coils w/ CLR lime remover I got at the hardware store. Let it sit a couple minutes, poured it out (carefully), repeated the process, then finally rinsed each coil for a couple minutes w water.
ShopVac'ed the debris in the can. Put it back together and now working.
I have zero engineering, pool work, construction or other relevant experience and I could do it with no special tools. Thought it would be good to share.
