Pentair Heater MasterTemp 250 whistle when gas starts flowing.

[JsVil]

My gas’s heater recently became a bit noisy. We tried to change the speed of pool pump Pool and no luck. For the spa which runs at 50gpm the noise disappears.

We feed 40gpm (flow meter) to the gas heater. The minimum flow for the gas heater to work is supposedly 25gpm. I am no sure if the flow meters are accurate.

The heater now seems to require higher flow. I used to feed 30gpm now it would make banging sounds and keep shutting off at that speed.

thanks everyone.

 

[ajw22]

How old is your MasterTemp heater?

We are seeing many corroded thermal regulators.

Remove the thermal regulator and see its condition and if it opens in a pot of hot water at 120F.

As a test try running the heater without the thermal regulator installed.

Check what your Stack Flue Temperature is.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

While running, press and hold the On button to display the exhaust temperature (Older Models).

The new models use the Menu to get the SFS.

Here is what the normal exhaust temperature should be:

• Below 250 degrees...very low
• 250 to 290 ..................low
• 290 to 350.................acceptable
• 350 to 480 ..................high
• Above 480...................error/shutdown.

Note: HD models can be up to 75 degrees higher. HD models use a cupro nickel exchanger and the efficiency is slightly lower resulting in less heat transfer and more waste heat.

If the exhaust gas temperature is higher then normal then water may be bypassing the heat exchanger through a broken bypass valve.

 

[JsVil]

My pool heater is less that 2 years old and my SFS is 341

 

[ajw22]

Check the thermal regulator.

 

[JamesW]

Is your plumbing bypass closed?

Remove the thermal regulator and run the heater and check the SFS with the thermal regulator removed.

 

[JamesW]

What's up with the exhaust extension?

It looks like water and debris can get into it?

 

[JsVil]

What's up with the exhaust extension?

It looks like water and debris can get into it?


View attachment 543510

Hi there, the exhaust extension. Is to prevent corrosive condensation on my pool equipment gate. We had issues in the past. The extension is not sealed at the bottom so if water gets in it will drip out before entering the heater.

 

[JamesW]

My pool heater is less that 2 years old and my SFS is 341

310 to 320 would be about right.

341 is borderline too high.

Check this periodically to notice any trends over time.

For example, if you install the heater and check the SFS on day 1 at 300 degrees and you check monthly and the temperature is increasing by a few degrees each month, this can indicate a slowly developing problem.

 

[JsVil]

Is your plumbing bypass closed?

Remove the thermal regulator and run the heater and check the SFS with the thermal regulator removed.

it is not closed just allows 40 gal to flow to heater during the day.

So the SFS has to be checked with the thermal regulator removed. I havent removed it yet. And what difference it will make on the temperature reading?

 

[JamesW]

it is not closed just allows 40 gal to flow to heater during the day.

Maybe you are not getting enough flow to the heater?

Why do you need more than 40 GPM total?

So the SFS has to be checked with the thermal regulator removed.

No, I just wat to see if there is any difference.

And what difference it will make on the temperature reading?

There should be no difference.

If there is, the thermal regulator is probably going bad.

 

[JsVil]

Maybe you are not getting enough flow to the heater?

Why do you need more than 40 GPM total?

No, I just wat to see if there is any difference.

There should be no difference.

If there is, the thermal regulator is probably going bad.

When we renovated our pool the pool company screwed up the design of our spillway (their mistake led to making it way larger that we had planned) so we need more flow in order for it not to break.

ALSO, the pool heater can handle a minimal flow of 25 gal according to the specifications, but my pool heater stars crackling if i lower the flow close to the minimum. So I don’t know if there is another issue.

 

[JsVil]

I haven’t had any luck with this. It must be very tight but I am afraid I could break it. First time trying on this heater.


Any suggestions?

 

[JamesW]

 

[JoyfulNoise]

Can you turn the cap at all?

If you’re having a hard time turning the cap, look into getting a bung nut or drain plug wrench. If you can find the right size drum nut wrench, those usually have long arms that can give you a lot of mechanical lever advantage.

 

[JsVil]

I watch that earlier. The issue is that the cap is stuck. How much force is too much? I am afraid to break something.

Thanks

 

[JamesW]

How much force is too much?

You will know when it breaks.

 

[JoyfulNoise]

See my post above.

You need a bung wrench or drum wrench. They will give you the leverage to undo the cap. The first time I did mine it was wicked tight … and I broke two long screwdrivers at the handle trying to get the cap off. That’s when I went to Ace and found the plug wrench. That and a cheater-bar helped. I thought o was going to shear the plastic off the manifold but it took a few good bangs of a 4 lb mallet on the cheater bar to break the threads free. I don’t what the heck Pentair did at the factory but that cap was torqued on there tighter than it needed to be.

 

[JsVil]

You will know when it breaks.

Haha I don’t want that

 

[1poolman1]

My gas’s heater recently became a bit noisy. We tried to change the speed of pool pump Pool and no luck. For the spa which runs at 50gpm the noise disappears.

We feed 40gpm (flow meter) to the gas heater. The minimum flow for the gas heater to work is supposedly 25gpm. I am no sure if the flow meters are accurate.

The heater now seems to require higher flow. I used to feed 30gpm now it would make banging sounds and keep shutting off at that speed.

thanks everyone.

A true whistle is usually from the gas line, especially on startup. It indicates that there is not enough gas getting to the heater, regardless of a manometer reading. What size pipe is running to the heater? Is it a flex supply? If so it needs to be replaced with 3/4" pipe. Not always easy, especially with that installation.
Is the meter at the house/property rated for enough gas to supply the heater? Most residential meters are rated for up to about 275 cfh (cubic feet per hour). Your heater wants 250 cfh. Turn on the heater with virtually anything else in the house that uses gas on at the same time (even a water heater which you don't ever really check) and the pool heater can whistle.