Heater bypass valve

[rjb1211]

Pentair's website makes the following claim for their heaters:

Optional Smart Heater Bypass valve control diverts water flow when the heater isn’t needed to help save up to 35% in yearly operational costs.*

The footnote explains:

Savings amount based on lab testing conducted using MasterTemp 400® heater in conjunction with IntelliFlo® VSF Pump and Bypass Kit, which includes IntelliValve® controlled by heater. Test Conditions: Pump flow rate: 50gpm. Pump run time: 3000 hours/yr. Heater run time: 100 hours/yr. Electrical Cost: $0.21 per kWh. System TDH: Heater and Bypass Kit added to Standardized “Curve C” System Curve performance data as per California Energy Commission Title 20 Appliance Efficiency Regulations. Test conditions assume pump flow rate of 50gpm and Constant Flow operation utilizing a lower motor RPM when flow is bypassing the heater due to lower system TDH. Actual performance and any subsequent energy consumption/savings are dependent upon various characteristics of the plumbing system, including but not limited to, pipe size, pipe lengths, filter type, fittings, system design, equipment run time/settings and more.
If you have any automation (which is required to operate the valve anyway) how would bypassing the heater reduce energy consumption more than just having the pump run at a lower speed without the valve? Are they talking about the resistance of just going through the heater?

 

[flynwill]

Are they talking about the resistance of just going through the heater?

Yes that is exactly what they are talking about. The heater core is a significant restriction on the water flow, so more energy is needed to push a given amount of water through.

 

[JamesW]

If you have any automation (which is required to operate the valve anyway)

The valve is operated by the heater.

The arrow points to where the valve connects on the heater's control board.

how would bypassing the heater reduce energy consumption more than just having the pump run at a lower speed without the valve?

The test assumes that the flow will stay at 50 GPM with the heater on and with the heater off, but the flow can usually be reduced when the heater is off.

Are they talking about the resistance of just going through the heater?

Yes, most heaters are poorly designed from a hydraulic efficiency point of view and it is better to bypass the heater when the heater is not on.

They really need to redesign the heater for good hydraulic efficiency.

 

[ajw22]

If you have any automation (which is required to operate the valve anyway)

The bypass valve can be controlled directly by the heater board or by the IntelliCenter.

Are they talking about the resistance of just going through the heater?

With the heater bypassed you can run less RPMs and use less energy for whatever flow rate you desire.

 

[DrewLG]

With the heater bypassed you can run less RPMs and use less energy for whatever flow rate you desire.

...although note that the benefit of the heater bypass decreases dramatically if you have a variable-speed pump and are running it slowly. The more energy you're already saving by running at low speed, the less additional energy you'll save by also incorporating a heater bypass.

 

[Sendit6]

The valve is operated by the heater.

The arrow points to where the valve connects on the heater's control board.


View attachment 535414

View attachment 535415


The test assumes that the flow will stay at 50 GPM with the heater on and with the heater off, but the flow can usually be reduced when the heater is off.

Yes, most heaters are poorly designed from a hydraulic efficiency point of view and it is better to bypass the heater when the heater is not on.

They really need to redesign the heater for good hydraulic efficiency.

Should water be running through the heater when it isn’t on?

 

[ajw22]

Should water be running through the heater when it isn’t on?

Yes.

See the recommended valve settings in...

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/parts-sheets/heaters/pentair_heater_auto_bypass_valve_replacement%20_kit.pdf

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com