Hi,
I have read many post from this and other forums to try to fix my heater. I have had it since 2016 and it has been troublefree until rodents found it earlier in the year. I've tried to test a lot of things but I have run out of things to do so I hope that the details below may help provide some clue as to what to do next. I am sorry if this is too long for a 1st post, but wanted to be as clear as possible and anticipate questions from similar questions on this site. Thanks in advance for any help you can provide.
-Bob
-------------------
Pentair Mastertemp 400, Natural Gas, made/installed in 2016. Replaced a previous Hayward unit that lasted >10 years. There were no changes in gas line when this was replace. Pool is ~30,000 gallons with built-in spa, chlorine.
Here is what is going on:
Start up:
1. Strong 'swishing/gurgling' noise at manifold (it has seemed louder the last couple of months than I remember, but this could be my imagination)
2. DE Filter pressure seems normal (~20psi)
3. Normal Heater startup:
a.128 is displayed initially, then
b. r13 (for board/sw version)
c. Manual water temp (up/down arrows) is set for 100
d. 'Svc Heater' red light for a second,
e. Blower starts
4. After about 30 seconds from power on:
a. Buzz (not a click) of gas valve and then heater operates ("whoosh")
b. Hot air coming from flue
c. Heater appears to operate normally for about 3-3.5 minutes
d. Water entering the hot tub through return jets is warmer than ambient water in the hot tub
e. Flue Exhaust temp (hold 'Spa On' for 5 sec) gets to ~300
f. Then shuts off, 'Heating' light changes from steady to flashing for about 30 sec, (red service heater light does not light)
g. The heater starts up again and runs for about 30 seconds (from buzz of gas valve to stopping of flame)
h. Repeats cycle over and over
Note: The time to shut off after the restart gets shorter as time goes on making me think it is something temp or temp sensor related. As such, the flue exhaust temp doesnt get much above 200 before it recycles.
Observations:
No Error codes on display, ever
No red Service Heater light at any time during recycle
No LEDs on Fenwal* (see below)
No LEDs lit under control board
But just in case, I shorted wire leads to PS, AFS, HLS and AGS and there was no change in behavior.
Removed lower bolt on water manifold, no water at all came out.
Removed ignitor, visual inspection looked good so put back in.
Replaced:
-Stack Flue Sensor (just because I had new one)
-Manifold bypass valve (old one looked fine; replaced because I had one). ports to heat exchanger are in very good shape, no signs of calcium/scale buildup.
-Removed thermal regulator (thermostat) from manifold and ran: without change in behavior
-Also tested regulator with hot water in kitchen sink and it opened
*This did start with a short cycle (start for a few seconds but then shut down after it tried to ignite) and Fenwal LED flashing 3 times. I read this was ignition lockout likely due to not detecting a flame so I did the commonly suggested fix to run a ground wire from the fenwal yellow wire chassis ground to 1 of the nuts holding the ignitor in. This solved the very short cycle problem which then led me to this longer cycle (works for the 1st 3 minutes, then cycles on/off at about 30 sec intervals for a while and eventually give up with red Service heater light)
The reason I had a spare Stack flue sensor is due to rodent damage earlier in the year. Got the E05 error code a while back, rodent chewed through stack flue sensor wires. Replaced it, worked fine, then rodent did it again a few weeks later.. So I ordered a couple sensors to be ready. There is a strong smell of rodent urine in the unit.
I checked every wire, tube etc for any signs of damage but nothing obvious EXCEPT that there is a hole in the top of the combustion chamber right next to the ignitor. It looks like it corroded through (maybe rat urine did it?) and at night I can see the glow of the ignitor if I take the top off of the unit.
I've run out of things to check.
Changing the control board seems like the next option, but that is $400-$500 so dont want to part swap without having good reason (or no alternative except to buy a new unit for $4000.
Again, sorry for a long post and thanks for any insight you can provide.
I have read many post from this and other forums to try to fix my heater. I have had it since 2016 and it has been troublefree until rodents found it earlier in the year. I've tried to test a lot of things but I have run out of things to do so I hope that the details below may help provide some clue as to what to do next. I am sorry if this is too long for a 1st post, but wanted to be as clear as possible and anticipate questions from similar questions on this site. Thanks in advance for any help you can provide.
-Bob
-------------------
Pentair Mastertemp 400, Natural Gas, made/installed in 2016. Replaced a previous Hayward unit that lasted >10 years. There were no changes in gas line when this was replace. Pool is ~30,000 gallons with built-in spa, chlorine.
Here is what is going on:
Start up:
1. Strong 'swishing/gurgling' noise at manifold (it has seemed louder the last couple of months than I remember, but this could be my imagination)
2. DE Filter pressure seems normal (~20psi)
3. Normal Heater startup:
a.128 is displayed initially, then
b. r13 (for board/sw version)
c. Manual water temp (up/down arrows) is set for 100
d. 'Svc Heater' red light for a second,
e. Blower starts
4. After about 30 seconds from power on:
a. Buzz (not a click) of gas valve and then heater operates ("whoosh")
b. Hot air coming from flue
c. Heater appears to operate normally for about 3-3.5 minutes
d. Water entering the hot tub through return jets is warmer than ambient water in the hot tub
e. Flue Exhaust temp (hold 'Spa On' for 5 sec) gets to ~300
f. Then shuts off, 'Heating' light changes from steady to flashing for about 30 sec, (red service heater light does not light)
g. The heater starts up again and runs for about 30 seconds (from buzz of gas valve to stopping of flame)
h. Repeats cycle over and over
Note: The time to shut off after the restart gets shorter as time goes on making me think it is something temp or temp sensor related. As such, the flue exhaust temp doesnt get much above 200 before it recycles.
Observations:
No Error codes on display, ever
No red Service Heater light at any time during recycle
No LEDs on Fenwal* (see below)
No LEDs lit under control board
But just in case, I shorted wire leads to PS, AFS, HLS and AGS and there was no change in behavior.
Removed lower bolt on water manifold, no water at all came out.
Removed ignitor, visual inspection looked good so put back in.
Replaced:
-Stack Flue Sensor (just because I had new one)
-Manifold bypass valve (old one looked fine; replaced because I had one). ports to heat exchanger are in very good shape, no signs of calcium/scale buildup.
-Removed thermal regulator (thermostat) from manifold and ran: without change in behavior
-Also tested regulator with hot water in kitchen sink and it opened
*This did start with a short cycle (start for a few seconds but then shut down after it tried to ignite) and Fenwal LED flashing 3 times. I read this was ignition lockout likely due to not detecting a flame so I did the commonly suggested fix to run a ground wire from the fenwal yellow wire chassis ground to 1 of the nuts holding the ignitor in. This solved the very short cycle problem which then led me to this longer cycle (works for the 1st 3 minutes, then cycles on/off at about 30 sec intervals for a while and eventually give up with red Service heater light)
The reason I had a spare Stack flue sensor is due to rodent damage earlier in the year. Got the E05 error code a while back, rodent chewed through stack flue sensor wires. Replaced it, worked fine, then rodent did it again a few weeks later.. So I ordered a couple sensors to be ready. There is a strong smell of rodent urine in the unit.
I checked every wire, tube etc for any signs of damage but nothing obvious EXCEPT that there is a hole in the top of the combustion chamber right next to the ignitor. It looks like it corroded through (maybe rat urine did it?) and at night I can see the glow of the ignitor if I take the top off of the unit.
I've run out of things to check.
Changing the control board seems like the next option, but that is $400-$500 so dont want to part swap without having good reason (or no alternative except to buy a new unit for $4000.
Again, sorry for a long post and thanks for any insight you can provide.
)
