Raypak whistling help

[PoolStored]

@ajw22 @JamesW or anyone else.

New Raypak 336 digital heater last June (P-336A-EN-X)...you have seen all my other threads to maximize longevity of this heater (chemicals, flow etc.). Harwil flow switch in parallel with pressure switch. Bypass is 100% to heater.

2200 RPM gives me 39 GPM, 14.3 temp rise, 2400 RPM gives me 45 GPM, 12.5 temp rise.

Started heater yesterday at 2200 RPM, same as last year. No whistling, water temp 64 F. After 24 hours heating, I went back out and the heater is whistling, water temp 84 F. Raised RPM to 2400 and whistling decreased by 80%.

Filter is clean, I can't believe there is any sediment in the heat exchanger. Burner orifices look like new. Pipe is 1.3" OD from meter, and 1" OD from behind the heater to heater. Total length is maybe 10' from meter to heater. There is no regulator on the line...straight from meter to heater.

What is the next step?

Something up with the unitherm? Why would it go bad in a year? Replace? Output water does not exceed 97 degrees, so unitherm never kick in, unless it is bad and allowing bypass.

Should I check gas pressure? How do I do that on the heater gas valve? Heater gas valve PN is 003900F

Thanks

 

[ajw22]

Start with the easy stuff first.

If the whistling changes with flow, then focus on the water, not the gas.

Unitherm governor is easy to check and could get some corrosion.

You may have picked up some debris in a pipe. Open up the unions, drain the water from the heater, check for any debris and blockages, reassemble, and see if it still whistles.

Sometimes just shaking it up clears things.

 

[Newdude]

heater is whistling,

Maybe teach it the words ?

 

[JamesW]

 

[JamesW]

https://s3.amazonaws.com/AWSProd/sites/raypakcom/documents/6500.00.pdf

 

[JamesW]

Pull the Unitherm Governor and test it in water as per instructions.

Try the heater with the UG out and see if the noise stops.

The UNITHERM GOVERNOR helps prevent condensation and scale.

It is a thermostatic mixing valve used to control and regulate the water temperature in the heat exchanger.

The patented Unitherm Governor is a thermostatic mixing valve specifically designed to maintain constant heater internal temperature between105°F (41°C) and 115°F (46°C) despite continually changing flow rates from the filter and changing pool temperatures.

This narrow range is needed to prevent damaging condensation on the burners which will occur if the heater runs for any length of time below100°F (38°C).

It is also needed to inhibit scale formation in the tubes by maintaining temperatures well below accelerated scaling temperatures.

 

[PoolStored]

Inlet outlet clear. No corrosion. Seal was oddly twisted (third pic), but when assembled correctly, the indent in the seal indicates to me it was installed properly and was sealed.

Popped it in some 120 degree water and no movement...ordered a replacement.

.

 

[JamesW]

Output water does not exceed 97 degrees, so unitherm never kick in, unless it is bad and allowing bypass.

The UG opens when the heater is firing.

The heater output temp is not the same as the output of the heat exchanger because the output of the heater has mixed bypass and heat exchanger water.

 

[JamesW]

Popped it in some 120 degree water and no movement...replace?

Yes.

 

[JamesW]

https://s3.amazonaws.com/AWSProd/sites/raypakcom/documents/241236.pdf

 

[JamesW]

Harwil flow switch in parallel with pressure switch.

It should be in series.

 

[PoolStored]

It should be in series.

Ha ha, it is I misspoke

 

[JamesW]

Try the heater with the UG out and see if the noise stops.

 

[PoolStored]

Try the heater with the UG out and see if the noise stops.

Quiet as a mouse. Should I not run it until I get new UG? Run it without the UG?

 

[JamesW]

The UG mostly prevents condensation.

If the water is cold and creating condensation, then you do not want water going through the heat exchanger.

The Unitherm Governor is a thermostatic mixing valve specifically designed to maintain constant heater internal temperature between105°F and 115°F.

 

[PoolStored]

So water temp is 84 degrees. So, don't run it until I get the new UG? Has this potentially damaged the heater?

 

[ajw22]

So water temp is 84 degrees. So, don't run it until I get the new UG?

You can run the heater at 84F.

What temperature do you heat it to?

You do not want to run the heater with water in the 60's or below wiothout the UG.

Has this potentially damaged the heater?

No.

With the UG not opening the full flow was not going through the heat exchanger.

 

[PoolStored]

84 Degrees. Started the heating with 64 degree water, so I should be good. I need to go to the raypak tech docs and read up on how this works.

 

[PoolStored]

With the UG not opening the full flow was not going through the heat exchanger.

Couldn't that be too hot and cause damage?

 

[ajw22]

84 Degrees. Started the heating with 64 degree water, so I should be good. I need to go to the raypak tech docs and read up on how this works.

If the UG had failed open then some corrosive condensation could have been created in the heater.

It works like a car radiator thermostat.

When the water is cold it bypasses some of the water from the heat exchanger so that the water in the heater can warm up faster. As the incoming pool water warms it meters more water into the heat exchanger. This minimizes the Heater Condensation - Further Reading caused by cold water.