Heater whining

[doncaruana]

My mastertemp 250 learned a new trick this year!

When it's running, as in I think this is the point where the fan is on, but the heat isn't quite engaged yet, I hear a pretty loud sound from it. And when the heat is on, it's actually worse and more of a squealing.

From reading around, it sounds like this may be either one or both of the thermal regulator or the blower fan. It does seem to be heating ok (hard to tell this early in the year, just opened less than 48 hours ago). I can post a video of both modes if that would help diagnose.

Are either of these user serviceable or, as I enter my 12th summer with this unit (I've replaced some parts over the years), should I seriously consider replacing the entire unit? Quick search says thermal regulator can be had for around $80 but a blower motor for almost $700 and the whole unit for $3000. I've replaced the thermistor and the control board in the past, so I am willing and able to roll my sleeves up...

 

[ajw22]

You can remove the thermal regulator and run the heater for a quick test to see if the noise disappears.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

The thermal regulator is behind a screw off cap between the in/out pipes in the heaters header. With the pump off, unscrew the cap and pull the regulator out. Note, if the regulator does not come out easily and feels like it hung up on something, then the bypass is broken and hanging in the way. If it comes out with no issues I'm sure you find it's all gunked up. Then use you fingers and stick them in the opening and feel up around towards the top middle and you should feel a round button like item, that's the bypass. If you feel it and it seems to be solid, then you are good with that.

To test the thermal regulator Put it in hot water (130 to 140 F) to see if it opens.

The thermal regulator is sensitive to water chemistry and can get erosion.

 

[doncaruana]

You can remove the thermal regulator and run the heater for a quick test to see if the noise disappears.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

The thermal regulator is behind a screw off cap between the in/out pipes in the heaters header. With the pump off, unscrew the cap and pull the regulator out. Note, if the regulator does not come out easily and feels like it hung up on something, then the bypass is broken and hanging in the way. If it comes out with no issues I'm sure you find it's all gunked up. Then use you fingers and stick them in the opening and feel up around towards the top middle and you should feel a round button like item, that's the bypass. If you feel it and it seems to be solid, then you are good with that.

To test the thermal regulator Put it in hot water (130 to 140 F) to see if it opens.

The thermal regulator is sensitive to water chemistry and can get erosion

Whining goes away when I crank up the speed of the pump to high speed. Sitting in front of the heater now, about to mess with regulator. Not sure how I get some water to the right temp though.

 

[ajw22]

Whining goes away when I crank up the speed of the pump to high speed.

That says it is unlikely to be the blower motor.

Sitting in front of the heater now, about to mess with regulator. Not sure how I get some water to the right temp though.

What does getting the water to a temp have to do with it?

Check the thermal regulator and the bypass valve. You could have something broken off acting as a reed and vibrating in the water header.

 

[doncaruana]

Here's what it looks like. Didn't seem to open very well. Haven't run it without the regulator at all yet.

That says it is unlikely to be the blower motor.



What does getting the water to a temp have to do with it?

Check the thermal regulator and the bypass valve. You could have something broken off acting as a reed and vibrating in the water header.

Getting to temp = testing it by putting it in hot water to see if it opens. Still messing with that but only got it to open slightly. I felt around inside and everything seemed solid. Haven't tried running it with regulator out yet.

Here's what it looks like.

 

[ajw22]

You have a food thermometer?

Put the thermal regulator in a pot of water on the stove with the food thermometer measuring the water temperature and turn on the heat and watch if or when it opens.

 

[doncaruana]

Ran it without regulator, no whine.

Had to call my wife to find out where the food thermometer was.

Boiled some water for good measure anyway, this is as far as this thing opened up. I can get the regulator right now from a brick & mortar. Off I go...

 

[doncaruana]

Got a new regulator, tested it the same way, world of difference. Opened up wide! So the old one was definitely bad. Put it in the heater, fired it up... No change, same sound.. The sound seems like it's coming from that manifold vs the blower. Bypass valve??

 

[ajw22]

Yup, you have to unbolt the manifold and inspect things. Disconnect the water lines, disconnect the sensors, and 6 bolts remove the manifold.

You might as well have a replacement bypass valve on hand to install.

Get the O ring kit and replace the O rings when you have it open.

 

[doncaruana]

Yup, you have to unbolt the manifold and inspect things. Disconnect the water lines, disconnect the sensors, and 6 bolts remove the manifold.

You might as well have a replacement bypass valve on hand to install.

Get the O ring kit and replace the O rings when you have it open.

These parts?
Bypass Valve Kit
O-Ring Kit

I'm not understanding though why the whining went away when I pulled the regulator out...

 

[ajw22]

These parts?
Bypass Valve Kit
O-Ring Kit

I'm not understanding though why the whining went away when I pulled the regulator out...

Yup

 

[doncaruana]

Yup

Help with my continuing education please. Why did the whining stop when I removed the regulator if that wasn't the problem?

 

[ajw22]

You said...

Whining goes away when I crank up the speed of the pump to high speed.

Running it without the thermal regulator greatly increases the water flow through the heater...

I'm not understanding though why the whining went away when I pulled the regulator out...

 

[doncaruana]

Thanks!

I'm also getting a lot of air in the return jets at normal speed but I don't think in the basket (need to double check that still). Could they be related?

 

[ajw22]

I'm also getting a lot of air in the return jets at normal speed but I don't think in the basket (need to double check that still). Could they be related?

I doubt it.

Something is vibrating in the water path of the heater.

 

[JamesW]

Can you show looking into the inlet and the regulator?

Do you see the disc at the top?

 

[doncaruana]

Can you show looking into the inlet and the regulator?

Do you see the disc at the top?

I took this when I had the regulator out. I reached in and felt up with my finger and it was solid. Not sure where the inlet pipe view you showed would be.

 

[JamesW]

At the top.

Heater inlet.

 

[doncaruana]

At the top.


Heater inlet.

Ah. I have not gone to that level of disassembly yet.

 

[JamesW]

You have unions, so it is easy.