Pentair MasterTemp 400 Pool Heater Issue

[frank1823]

I have never owned a pool with a heater so I dont know what is normal or not but I have two possible issues. One is the sound of my Mastertemp when it fires up. It literally sounds like a jet engine spooling up. It is a very deep low frequency sound that I find rather satisfying, but my wife feels very strongly against. It only does it when the burner lights, then quickly fades. I would like to know if anyone else who has this MasterTemp system can confirm this is normal and nothing you can do about it or there is a way to at least partially mitigate the sound. The other thing is the heater turns off continuously when the temperature gets above around 87. Say I set it for 90 degrees. It will eventually get there but after reaching 87 it will run for a couple minutes, turn off for a couple, then back on. Continues this on and off cycling until getting to the desired temp instead of running continuously until reaching the desired temp. The last few degrees will take an hour or two to get to because of this continuous cycling on and off. This would not be as big an issue if it wasn't for the whole 747 engine firing up sound, lol. Any insight would be very helpful.

 

[mknauss]

The sound is familiar. The cycling when you get to setpoint may be exacerbated by a low flow. Increase your pump rate a few hundred rpm when running the heater and see if that solves it.

 

[JamesW]

Possibly low flow and maybe a bad thermal regulator.

Minimum flow is 40 gpm, so make sure that the flow is good.

What is the pump RPM?

Pull the thermal regulator to see if it looks ok.

Try running the heater with the thermal regulator out to see if the problem goes away.

Below is a fully open thermal regulator.

If the regulator only opens a little bit, then the gap acts like a whistle as water goes through the gap.

 

[Poolbreh]

When you say the temp is 87f where are you getting that reading? On the heater? The reason I ask is, your bio says you have an easytouch, which I assume you are using to heat the pool, and it has its own temp sensor probe. I just wanted to clarify that you aren’t just seeing the temp difference between the two.

 

[jaggedvisions66]

Have the gas pressure checked. Or the air/fuel mix might be off

 

[frank1823]

The sound is familiar. The cycling when you get to setpoint may be exacerbated by a low flow. Increase your pump rate a few hundred rpm when running the heater and see if that solves it.

I can understand cycling after it has reached the setpoint but it starts cycling 4 to 5 degrees before. I typically run the pump at a minimum of 2800 rpm, but usually ramp it up to the maximum 3450 to combat the low flow when the heat is on. Increasing the rpm does seem to help but only a little.

 

[mknauss]

No reason to run a VS pump above 3000 rpm. There is virtually no additional flow for a large amount of electricity expended.

Not sure. Mine works just great right up to the set point. Same system.

 

[ajw22]

I can understand cycling after it has reached the setpoint but it starts cycling 4 to 5 degrees before.

It is called short cycling.

One of the safeties is overheating which shuts the heater down. It is likely the HLS indicating the internal water temperature is getting too high. When the heater shuts down the HLS cools down and closes and the heater restarts. And around and around it goes.

Like was said above it is an internal water flow problem in the heater, Either the thermal regulator or the bypass valve or both.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[1poolman1]

An often overlooked problem is the heater not being set to 104 (maximum) and allowing the automation to take over. that is the proper way to set them up. They measure temperature at different places in the water stream. Pentair and StaRite heaters have a loud "whoosh" noise on ignition that fades to a low rumble, normal operation. Not knowing how old the heater is, I have seen 86 or 87 degrees on heaters with failing thermistors too many times to count.

 

[frank1823]

An often overlooked problem is the heater not being set to 104 (maximum) and allowing the automation to take over. that is the proper way to set them up. They measure temperature at different places in the water stream. Pentair and StaRite heaters have a loud "whoosh" noise on ignition that fades to a low rumble, normal operation. Not knowing how old the heater is, I have seen 86 or 87 degrees on heaters with failing thermistors too many times to count.

I do believe the unit itself is set to maximum but I'll double check it today. The heater as all the equipment is almost new. It was installed last year. It has always behaved in this manner so I didn't know what was normal. But it does seem off.

 

[ajw22]

You should not have these problems in a year old heater.

What is the size of your gas meter?

Post pics of the data plate on your gas meter, pic of the gas meter pipes feeding the heater, and the heater on the equipment pad.

 

[frank1823]

You should not have these problems in a year old heater.

What is the size of your gas meter?

Post pics of the data plate on your gas meter, pic os the gas meter pipes feeding the heater, and the heater on the equipment pad.

I will get that information when I get home later today and some pics. It seems it should not have issues being relatively new. Thanks for the feedback.

 

[JamesW]

Try running the heater with the thermal regulator out to see if the problem goes away.

 

[frank1823]

You should not have these problems in a year old heater.

What is the size of your gas meter?

Post pics of the data plate on your gas meter, pic of the gas meter pipes feeding the heater, and the heater on the equipment pad.

When I got home I did check to make sure the temperature was set to the maximum on the actual unit. It was actually at 99 so I was hopeful that was my whole problem. I changed it to the max of 104 and the problem persisted. I tried to post the pictures you requested but it says the uploaded photos are too large for the server.

 

[ajw22]

I tried to post the pictures you requested but it says the uploaded photos are too large for the server.

Turn off HDR on the camera app on your phone or use a photo resizer to get the pics below I think 4MB.

IPhone hack for resizing pics

Hey all !!! I broke the dreaded iPhone pic upload problem a while ago and have tried several times to upload this all from my phone but lost track of the several steps while writing it down. Or the pics came out of sequence. But today. TODAY Is the DAY !!!! IOS has a built in resizer...

www.troublefreepool.com

 

[frank1823]

I did end up replacing the thermal regulator valve (thing that looks like a car thermostat with spring attached). When I removed it to inspect it it had some rust or some other kind of buildup on it that looked like it was restricting the opening and closing of it. Put in a new Pentair kit with spring and valve. No difference whatsoever. I guess I will try running it without the valve completely to see what happens. As I said this is relatively new equipment. Was put in about a year ago. The underside of the control panel diagnostic LEDs have the one for HLS lit up which is the high limit switch circuit. Which I believe often points to the valve that I just replaced. I guess I can replace the HLS itself as well although it looks brand new and shiny since it pretty much is new.

 

[ajw22]

2nd request...

What is the size of your gas meter?


Post pics of the data plate on your gas meter, pic of the gas meter pipes feeding the heater, and the heater on the equipment pad.

 

[JamesW]

Do you have a picture of the system?

It's under warranty, so you can just file a warranty claim.

 

[frank1823]

2nd request...

What is the size of your gas meter?


Post pics of the data plate on your gas meter, pic of the gas meter pipes feeding the heater, and the heater on the equipment pad.

Here is the gas meter and lines going to the heater.

 

[frank1823]

Do you have a picture of the system?

It's under warranty, so you can just file a warranty claim.

I presume it should be under warranty however the waters are a little muddied so to speak. We had a falling out with our pool contractor. We had to get a lawyer involved over some construction issues they came up short on so we have no relationship with the company and do not want them on my property again. So I feel like we are in limbo with warranty issues unless Pentair sends out their own techs to work on these things but I suspect warranty will be administered through the installing company.