Pentair MasterTemp 400 cycles on and off in Spa mode

[drogers]

Hey all,
I have a Pentair MasterTemp 400, which is about 2 years old. Recently it started cycling off and on while attempting to heat my spa. It cycles every 2-3 minutes and runs for a minute or two at a time. I did run it for about 10 minutes while circulating my pool as well, and didn't detect it cycling at all, which makes me think it may be pressure related, but I'm not sure that to look at next.

Cleaned my filter cartridge today, which helped flow, however it didn't fix the problem.

Any suggestions???

thanks!

 

[drogers]

Found the manual for the heater, and tried adjusting the water pressure switch - no joy. Seems like the water pressure switch might need replacing. Next dry day I'll pull things further apart and jump across the WPS to see if it'll run for more than a few minutes. Anyone know if replacing that doohickey is expensive or a possible DIY item for a competent DIYer?

thx

 

[spishex]

Does your service light come on? If so, you'll need to take a look at the backside of your control and see which LED is lit. That will give us more of an idea.

 

[drogers]

Ah-HAH! Took a look at the backside of the board, and the HLS light comes on. Also found out this doesn't start until the inlet temp gets up to ~69-70*, which explains why it didn't happen when I was running it on the whole pool (pool is about 54* right now).

So, is replacing the HLS something I can do? Or can it be adjusted at all? Can I bypass it for a few minutes to test that it is truly the problem?

 

[drogers]

Ok, did a little more reading and poking. Found the HLS and shorted it - heater stays on. Just to be safe, I drew some water off the heater drain which is right below the outlet and HLS - it temp'd at 104*, so the HLS is at least 30* off. Then I pulled the HLS to look for visible corrosion/damage/buildup of some sort -nada.

Anyone think it's a bad idea for an ign'ant sap like me to order a new one from poolcenter or somewhere and just swap it out? $30 for a new switch is a lot cheaper than the $65 warranty service call.

 

[budster]

Understanding that the HLS is one feature in the "safety circuit" for a heater, IF you can replace it properly, I see no reason why not. It's pretty easy to do.

 

[spishex]

Your heater has a two year warranty, and they've only been making the mastertemp for a couple of years now. Any chance you're still covered?

 

[MikeyLV]

I have the same issue, but not sure which switch is which. On the attached diagram, from what I've read, the HLS is either 5, 6, or 7. Was it easy to replace?

 

[TRW]

Hello all,
I have a pentair master temp 400 heater that is acting the same as in this thread. I checked behind the panel and the light that was on was; LED5, U11. Does anyone know what that indicator would mean. Thanks

 

[jpcdmd]

Check the thermostat, its very easy to replace. Its located near the inlet/outlet ports. Take a screwdriver and use the shaft to unscrew the retaining cap and it pops out. I was getting similar issues with it shutting off and found out my thermostat was corroded. It started with the HLS error and then switched to another error code (can't remember which one). Ordered new one on Amazon Prime and was good to go in 48hrs.

 

[Pool Clown]

jpcdmd is correct. If the heater heats to about 70-80 degrees then starts to cycle, the problem is most likely the thermostatic by-pass. When it does not operate correctly, it causes higher than normal temps in the header and the HLS will open.

 

[AugerN]

Is this the temperature sensor that is wired directly back to the IntelliTouch?

Also, While removing this sensor, a portion of the plastic (about 1inch of the outer plastic) broke off and fell back into the PVC pipe. This is in the inlet pipe to the heater. I don't see that there is any filter/screen within the heater to catch this - what would happen if I still run the system with the new sensor? Otherwise I may have to replumb that section to try to find it (if I can). Because once the sensor was removed, the open system then refluxed the water so that piece may have moved retrograde and I'm not sure where it would have truly ended up. Thanks in advance for the help!

jpcdmd is correct. If the heater heats to about 70-80 degrees then starts to cycle, the problem is most likely the thermostatic by-pass. When it does not operate correctly, it causes higher than normal temps in the header and the HLS will open.

 

[Pool Clown]

No. What broke for you was the water temp sensor. You should probably fish that out. It may pass, it may not. BTW, you may want to consider relocating that temp sensor. It should go between the filter pump and the filter.

 

[AugerN]

Thank you Pool Clown! Then what part number is the thermostatic bypass that I need to replace (sorry to be such a novice) as mine seems to be doing the exact same cycling as mentioned above. Thank you for the help!

 

[Pool Clown]

You can get #16 by itself, or you can get the kit #15.

Click on the exploded view for a larger view.
They call it a regulator, so you wont confuse it, when ordering, with the by-pass #8

Sta rite Max E Therm SR Heater Parts (Water System)

 

[AugerN]

Ordered! Thank you for the help! Now to try to find that stupid little broken plastic piece... Ugh.

 

[AugerN]

Just to clarify, I can pull this out and replace #16 without having to take off the manifold, correct?

 

[Pool Clown]

Yes.

 

[AugerN]

You rock! Thanks for your help Pool Clown!