Heater issue?

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Sendit6

Sendit6

Well-known member
Aug 16, 2023
80
Pittsburgh
Pool Size
30000
Surface
Vinyl
Chlorine
Salt Water Generator
Hi All - I haven’t updated my signature with pool size, equipment, and all other necessary things but I will eventually.

Anyhow, we’re having an issue with our heater, it’s a new Raypak Avia 404, that shuts off after roughly 10 min. The digital screen says two things:
Flue Extremely Low
and
High Flow Fault

I called Raypak yesterday and the tech that I spoke with said that those are indicators that the water flow through the heater is too high/fast for it to heat it properly.
He asked what pump size we have, told him it’s a 1.5 HP for an 18x36 pool.

He said to:
1. Install an external bypass with a ball valve to slow down the flow.
Or
2. Switch to a variable speed pump to slow down the flow.

I haven’t done either yet, but in the back of my mind I keep thinking that this is a large heater, why couldn’t it handle the flow from a 1.5 hp pump or even a larger pump.
 
Sendit6 said:
Hi All - I haven’t updated my signature with pool size, equipment, and all other necessary things but I will eventually.

Anyhow, we’re having an issue with our heater, it’s a new Raypak Avia 404, that shuts off after roughly 10 min. The digital screen says two things:
Flue Extremely Low
and
High Flow Fault

I called Raypak yesterday and the tech that I spoke with said that those are indicators that the water flow through the heater is too high/fast for it to heat it properly.
He asked what pump size we have, told him it’s a 1.5 HP for an 18x36 pool.

He said to:
1. Install an external bypass with a ball valve to slow down the flow.
Or
2. Switch to a variable speed pump to slow down the flow.

I haven’t done either yet, but in the back of my mind I keep thinking that this is a large heater, why couldn’t it handle the flow from a 1.5 hp pump or even a larger pump.
Click to expand...
Which 1.5hp pump do you have? Depending on that and the rest of the system, a high-performance 1.5hp single-speed pump can easily exceed the 100GPM maximum flow rate of that heater. Its always best to listen to the recommendation of the manufacturer. Go VSP and you'll never regret it.
 
From the manual:

External Auxiliary Bypass Valve Where Required - An auxiliary bypass valve should be used when flow rates exceed 100 GPM (379 lpm). Usually a high-performance pump size larger than two horsepower will exceed this flow rate. This valve is required to complement the function of the automatic bypass valve, particularly when starting the heater in winter or early spring when the spa or pool temperature is below 50°F (10°C). It also serves to eliminate needless pressure drop through the heater and accompanying reduction in the flow rate to the spa jets. FROM HEATER TO HEATER TO POOL/SPA FROM POOL/SPA FULL PORT BALL VALVE OR GLOBE VALVE* BYPASS VALVE *NOTE: Do not use a gate valve. Figure 21. Auxiliary Bypass Valve
Click to expand...
 
I seriously doubt that the pump is exceeding 100 GPM.

What is the filter pressure?

Check the inlet and outlet temperature and this should help estimate the flow.

Check the stack flue temperature.

Check the heat exchanger (HX) flow estimate.

Get the optional flow sensor to see what that says.

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Flue Extreme Low

Flue temperature is below 140°F (60 °C). Service required.

Press MODE to remove lockout.

There is no way that the flue will be below 140 degrees due to high water flow.

You have a different issue.

Maybe a bad temperature sensor.

Maybe some sort of installation error.

What does Raypak say?

What does the installer say?

All new heaters need to be "Commissioned", which means that the installer goes through a checklist and measures all critical metrics to verify proper operation.

Raypak – AVIA troubleshooting

Raypak Pool & Spa, Residential and Commercial Hydronic Products -
www.raypak.com www.raypak.com

 
What is the Flame Strength?

Maybe you have a weak flame due to low gas pressure?

Did the installer verify the Static and Dynamic gas pressure?

Did the installer get the voltage input correct?

If the input voltage is incorrect, the heater can be damaged or malfunction.


1697322484937.png
 

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For a 1.5 HP WhisperFlo on a typical system curve, the flow will be about 78 GPM.

Even if you go to a 2.5 HP WhisperFlo, the flow is only about 87 GPM.

The excessive flow answer seems very unlikely to me.

The heater by itself adds about H = 0.004F^2 to the system curve.

1697323144319.png

1697323231466.png

1697323724890.png
 
The flow through the heat exchanger is listed as 10 to 19 ideal.

The formula for temp rise to flow is Temp rise = 670/GPM.

GPM = 670/Temp rise.

At 10 gpm, the temp rise should be 67 degrees.

At 19 gpm, the temp rise should be 35 degrees.

Note: The outlet temp high limit is 180 degrees F.

Note that this is before the water is mixed with the water that goes through the internal bypass.

About 19% to 25% of the water goes through the heat exchanger and about 75% to 81% goes through the internal bypass.

1697332845785.png
1697321112118-png.535672


1697332004687.png

AVIA HD with NiTek – Raypak

Raypak Pool & Spa, Residential and Commercial Hydronic Products -
www.raypak.com www.raypak.com




399,000 btu/hr at 84% efficiency 335,160 btu/hr transferred to the water.

335,160/(GPM X 60 x 8.34)

Y = 670/X

Y = 670/X, y from 30 to 90 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.
www.wolframalpha.com www.wolframalpha.com

180°F

 
Last edited:
1poolman1 said:
Which 1.5hp pump do you have? Depending on that and the rest of the system, a high-performance 1.5hp single-speed pump can easily exceed the 100GPM maximum flow rate of that heater. Its always best to listen to the recommendation of the manufacturer. Go VSP and you'll never regret it.
Click to expand...
Olympic.
 
1poolman1 said:
Which 1.5hp pump do you have? Depending on that and the rest of the system, a high-performance 1.5hp single-speed pump can easily exceed the 100GPM maximum flow rate of that heater. It’s always best to listen to the recommendation of the manufacturer. Go VSP and you'll never regret it.
Click to expand...
Olympic.
JamesW said:
I thought you decided on a heat pump?

What pump do you have?
Click to expand...
Olympic 1.5 hp pump.

I decided against a heat pump because I didn’t want to wait for the heat-up times required when the temps don’t get high enough in the spring and dip in the fall. I essentially wanted on-demand heat at the fullest potential it could be.

I am aware that they both do basically the same function of set the desired temp and they will kick on to maintain. But the gas will obviously cost more to achieve that.
 
JamesW said:
Did the installer get the plumbing right?

Sometimes the installer gets the plumbing backwards and the In and Out are reversed.
Click to expand...

My head is spinning reading all of these helpful replies. I think what I need to do is check the obvious things that I can on my own but then call someone who can troubleshoot this thing, meaning a pro. But that’s the thing, if my pool guy can’t get it right, and the hvac co. who installed it can’t either, who do so call?

I now wish I would have just went with a heat pump.
 
Sendit6 said:
Olympic 1.5 hp pump.
Click to expand...
What model number?

What is the filter pressure?
Sendit6 said:
But that’s the thing, if my pool guy can’t get it right, and the hvac co. who installed it can’t either, who do so call?
Click to expand...
Did you call them to come back and get it fixed?
Sendit6 said:
I now wish I would have just went with a heat pump.
Click to expand...
You could have just as many problems with a heat pump.

In my opinion, the flow is probably not over 100 gpm.

You can get a lot of data from the unit and that data would be helpful to diagnose the problem.

Raypak has a dealer locator that you can use to find a service provider.

However, you need to start with the installer.

Contact the company and ask for their best person.

Contact Raypak and ask them to help you.

Where to Buy – Raypak

Raypak Pool & Spa, Residential and Commercial Hydronic Products -
www.raypak.com www.raypak.com
 
Even if we used the 2 HP model Performance Curve, the system would need to be H= 0.005F^2 to hit 110 GPM.

To exceed 100 GPM, the system would need to be better than about H = 0.00625F^2.

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Last edited:

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