MasterTemp Trips Breaker / Service light is on

[dw886]

Hi-

I've got a 250K MasterTemp heater that has been tripping the breaker this pool season. The "Service Heater" light is on, but none of the diagnostic LEDs on the back of the panel light up, and to be honest, who knows if the the two issues are even related. I read through the MasterTemp Further Reading located here: Pentair MasterTemp Heaters - Further Reading, but without an error code, I'm not really sure where to start.

Any thoughts on whether or not the breaker / service heater are related, or how I can go about narrowing this down without any lit diagnostic LEDs?

Thanks!

 

[ajw22]

How far into the startup sequence does the breaker trip?

The only thing in the heater that takes much electricity is the air blower.

Show us pics of the insides of the heater.

I am going to guess that rodents got into the heater and maybe the air blower and built nests and chewed wires. They can destroy a heater.

 

[dw886]

I probably should have described it a little more elaborately. From what I can tell, there's two different scenarios that happen:
1.) The heater calls for heat, doesn't hit whatever issue that is causing the service heater light to come on (or the breaker to trip), and the heater would run indefinitely until it hit the setpoint. When this happens you can hear the blower start up, the heater ignite, and the exhaust start - the blower blows continuously and the ignition cycles as required. Say the water is 78, and I turn on the heater and set it to 88. The heater if it doesn't fail in the first 5 minutes, it'll run for 10 hours continuously and raise the temp by 10 degrees.
2.) Something happens during the first 3 - 5 minutes, the service light turns on, and / or the breaker trips. When this happened this morning, I turned the heater off, waited 10 seconds, and then scenario #1 took over - it's been running fine since...

The problem really comes in when it's set to say 88 degrees, and the water temp drops to 87. Then it'll start cycling on / off over the course of an hour depending on the water temp rather than continuously running. I'll go outside a few hours (or days) later, and find that the heater has tripped the breaker during one of the startup sequences, or the heater just isn't running with the "Service Heater" light on.

I've attached a photo of the inside. Not much for critters in my area outside of a few bunnies, some geese, and a few partridge. We don't see much in terms of rodents, but if there's something I should take apart further to investigate let me know.

Thanks!

 

[ajw22]

Is the heater on a dedicated breaker or are other devices on it?

Is the breaker GFCI?

What amp is the breaker?

Heater set for 120V or 240V?

 

[dw886]

IntelliChem, SWG transformer, and the heater are all on a 15A double throw GFCI breaker @ 240V. The breaker will not trip for weeks if the heater isn't running. If the heater is running then it'll trip every so often.

 

[ajw22]

We don’t know if it is an overamp breaker trip or a GFCI trip.

What is your breaker setup? Do you have a non GFCI breaker you can move the heater to as a test? Or as a test replace the breaker with a non-GFCI breaker.

 

[ferretbone]

No ants? Bugs? This sounds like one of those problems I chase around and around for weeks only to find something dumb like ants eat on the copper of the wires in the timer box where the heater get its power, or where the power enters the heater.

 

[dw886]

I can swap the breaker for the heater. The only problem that I have is that the tripping is sporadic so it'll be tough to understand if the issue actually happened - who knows, it could even be a weak breaker.

One other observation that may trigger some thoughts:

So yesterday when I started this thread, the water temp was 77, and the breaker had tripped sometime in the last 4 days (don't know when - I wasn't around).
1.) I reset the breaker, turned the heat on the intellicenter to 88, and the heater fired up.
2.) After a few minutes, the "Service Heater" light was on, so I turned the heater back off manually.
3.) I waited a few minutes, and turned it back on. It's now been running continuously since yesterday at about this time (at least 24 hours of cycling) trying to heat the pool (without the "Service Heater" light turning on or the breaker tripping).

The odd thing that's happening now is that it won't take the pool over 84 - this has never been an issue in the past - I can heat the pool to 88 when it's 45 outside in the early spring if I so desired.

The temp on the Mastertemp panel is set to 104 - so it's not that the heater is limiting what the Intellicenter can call for - Intellicenter is hooked to the heater via the Fireman's switch.

 

[ajw22]

The odd thing that's happening now is that it won't take the pool over 84 - this has never been an issue in the past - I can heat the pool to 88 when it's 45 outside in the early spring if I so desired.

This is a separate problem from your CB tripping. I figured we would look at your CB trip first.

You are probably getting a HLS problem. The heater is over heating and trippong the High Limit Switch. You only see the Service Heater light since the HLS resets when the heater stops and cools down, and then it cycles again.

The HLS is often caused by lack of sufficient water flow through the heat exchanger. This can be due to several things:

• Thermal regulator not opening.
• External bypass open.
• Internal bypass broken.
• Pump too small or on too low rpm.
• Clogged filter.
• Scale in heat exchanger.

Start by checking the thermal regulator.

You need to stand by the heater and observe it while it short cycles. See what the water temperture display does. Do you hear the heater knocking or boiling water? Have the top cover open and the board flipped over to observe the diagnostic LEDs to see which one lights as the heater shuts down before it resets.

 

[dw886]

Thanks Allen - fine with separating the two. I'll replace the breaker and see what happens.

As for the heating issue, the "Service Heater" light has not been on since yesterday morning just after I reset the tripped breaker. Right now it's cycling where the burner fires for 30 seconds (and the "Heating" LED goes on solid amber), and then the burner shuts down for about 30 seconds (and the "Heating" LED blinks amber), repeats. Heater display only shows 89 or 90 and never seems to change, no diagnostic LEDs are lit. Flowvis shows 35 GPM on the output side of the heater. VS pump is running at 2,000 RPM. Salt cell also shows good flow. The only thing that I can hear the is the blower and when the burner fires - not sure how loud the boiling would be - I can hear a little bit of water turbulence but I'm not sure if it's from the heater or the pump that's right next to it.

 

[ajw22]

Increase your flow rate with the VS pump at 2400 RPM.

 

[dw886]

Took the VS to 2800, which is about 63 GPM according to the FloVis - the burner is still cycling every 30 seconds. When I initially start the heater, it runs longer (like maybe 90 seconds - 2 minutes), and then all subsequent cycles are 30 seconds on, 30 seconds off.

 

[ajw22]

Time to replace the thermal regulator.

Bypass valve next if the thermal regulator doesn’t fix it.

When you replace the bypass you will get a look if the heat exchanger is scaled.

 

[dw886]

Thanks! Thermal regulator on it's way - I'll report back.

 

[dw886]

So the Thermal Regulator is on it's way - should be here tomorrow. In the mean time, I did have a chance to witness it trip the breaker this afternoon. Here's what happened:
1.) I turned up the heat on the IntelliCenter while standing by the heater - the heater had been off since Wednesday. This caused the fireman's switch on the heater to tell the heater to turn on, which it attempted to do.
2.) The blower kicked in, and ran for a number of seconds. I could then hear the burner light, and it only stayed lit for a few seconds.
3.) After 20 or 30 seconds, the burner tried to light again, as as soon as you heard the click of ignition, the breaker tripped.

I then reset the breaker, and watched the same sequence of events. It tripped the 3rd time the burner tried to ignite.

I reset the breaker a third time, and tried to capture this on video, and low and behold now it didn't trip, and it's been running for the last 30 minutes (although it's now cycling every 30 seconds like I was describing in my previous posts) - I'm hoping the thermal regulator fixes this part...

 

[ajw22]

The burners lighting for a few seconds then going out and retrying three times is symptomatic of a flame sensing problem. The problem and solutions are described in Heater Flame Sensing - Further Reading

Now why the CB trips after the third retry is strange. IT should throe the Service Heater Light and have the Fenwal LED flashing after the third retry.

As I said in post #6 we don’t know if it is an overamp breaker trip or a GFCI trip. The heater only draws a few amps and nothing in the heater should draw enough to trip a 15A CB.

Does the CB trips tend to happen early int he morning or times when it is damp out? Because the flame sense errors can be caused by ground problems that are worse when it is damp out. And dampness can cause GFCI trips.

Open up the box that has the pages hanging on it and you will find the Fenwal box. See if everything is clean and tidy in there.

@swamprat69 @JamesW thoughts?

 

[dw886]

So the thermal regulator seems to have helped with the cycling. What's odd is that the old thermal regulator that I pulled seemed to function as well when running it under hot tap water. There was a small foreign piece of plastic on the end of the thermal regulator (round, white, about the diameter of a dime but thinner, with a hole in the center - not sure where this came from), and I'm wondering if that was stopping movement of the thermal regulator and preventing it from opening within the heater.

I think the breaker tripping after the third try is a red herring. From more observation, it's just that it doesn't trip every time, it only trips sometimes. Once the heater fires up, it seems far less likely to trip. If it makes it through the first 5 minutes without tripping the breaker, it would cycle for days if the call for heat never was met. I observed it a few more times yesterday - heater was cold, and I turned the heat up because the kids were going to swim after football games. Seems like it always trips either right before the ignitor fires, or just after. Yesterday I saw it trip 3 times where it wouldn't light at all (happening on the first ignition attempt) - I'd hear the blower start and run for a few seconds, and then when it tries to ignite the first time, the breaker will trip.

I took a look into the Fenwal box, and the ground inside of there "looks" good. Everything looks fairly clean inside of there. I suppose the first step is to swap out the breaker?

 

[ajw22]

My guess is you have some corrosion on an electrical connection causing a GFCI leakage trip. The corrosion conductivity is increased with some dampness when cold. Once the heater gets hot the moisture burns off all is good until another cold moist startup.

Your challenge is to find and clean all the electrical connections.

 

[dw886]

So I swapped out the GFCI breaker for a non-GFCI. I think that there's a flame sensing issue, because the blower starts up, the heater lights, and then after about 1-2 seconds, ignition goes out, but the blower continues to run. This process of lighting / going out happens 3x, and then the heater goes into "Service Heater" with no diagnostic LEDs lit on the rear of the control board. I think that the flame sensing issue is causing the GFCI to trip, so I'm going to try to fix the flame sensing problem, and then leave the GFCI issue for last.

 

[ajw22]

The Fenwal box has an LED thst should flash if you have a flame sending error.

Heater Flame Sensing - Further Reading

www.troublefreepool.com