Pump Sizing for Circulation

1.Use the chart below or one appropriate for your conditions to determine the heat loss in the length of the hot water supply and return piping. For example, 100 ft of 1-1/2 in bare copper tubing results in a heat loss of 5300 Btu/h.

Approximate Heat Loss from Piping at 140 ºF Inlet, 70 ºF Ambient *

Nominal Size, in.	Bare Copper Tubing,	1/2 in. Glass Fiber Insulated
	Btu/h-ft	Copper Tubing, Btu/h-ft
3/4	30	17.7

1	38	20.3

1-1/4	45	23.4

1-1/2	53	25.4

2	66	29.6

2-1/2	80	33.8

3	94	39.5

4	120	48.4

*Source: 2003 ASHRAE Handbook HVAC Applications

2.Determine the acceptable temperature drop at the last fixture in the loop. For example, if the supply temperature from the water heater is 120 ºF (49 ºC) and an acceptable temperature at the last fixture is 100 ºF (38 ºC) then the acceptable temperature drop is 20 ºF (7 ºC).

3.Calculate the required pump flow rate using the following formula:

FLOW RATE (gpm) =	HEAT LOSS (BTU / h)
	500 X ACCEPTABLE TEMPERATURE DROP (ºF )

4. Based on the above calculations select a pump for the type of circulation system you will be utilizing:

A). Preferred Method (reference drawing WH-1-RGE) - Reference pump manufacturers flow vs. pressure specifications to select a pump that can provide the flow rate calculated above while overcoming the pressure loss through:

•Tank water heater (reference manufacturer’s information)

•All building supply and return plumbing in the circulation loop (reference local plumbling codes, standards, or practices)

B). Optional Method (WH-1-R) - Reference pump manufacturers flow vs. pressure specifications to select a pump that can provide 3 gpm of flow or the flow rate calculated above, whichever is greater, while overcoming the pressure loss through:

•Tankless water heater (reference flow vs. pressure curve of the model being used)

•Optional storage tank (reference manufacturer’s information)

•All building supply and return plumbing in the circulation loop (reference local plumbling codes, standards, or practices)

NOTE: Only use pumps of brass or stainless steel construction. Do not use pumps of iron construction as they will oxidize and clog the inlet filter on the appliance.

ATO-705A-P, GT-305-NI, GT-705-NI, ATI-505-N, ATI-705A-N specifications

American Water Heater has long been regarded as a trusted name in the water heating industry, and among its impressive lineup is the ATI-705A-P, GTS-705-PEA, GT-705-PE, GT-305-NE, and GTS-705-NEA models. Each of these units incorporates cutting-edge technologies and design features, ensuring high-performance and energy-efficient water heating solutions for modern households.

Starting with the ATI-705A-P model, it stands out for its high-efficiency water heating capabilities. This unit is equipped with a powerful gas burner that ensures rapid heating. It features an intuitive digital thermostat, which allows users to easily set their desired water temperature, ultimately improving user satisfaction and comfort. The ATI-705A-P also incorporates a durable tank lining that prevents corrosion, extending the lifespan of the product.

Moving on to the GTS-705-PEA and GT-705-PE models, these units are known for their eco-friendly design and energy efficiency. They use advanced insulation technology to minimize heat loss, ensuring that energy is conserved while still delivering hot water on demand. Both models are equipped with high-performance heating elements that provide a quick recovery rate, making them ideal for households with higher hot water needs.

The GT-305-NE model is particularly noteworthy, equipped with a powerful burner that provides consistent hot water supply, making it an excellent choice for larger homes. Its compact design allows for versatile installation options, while still maintaining a large capacity. This model also includes a high-efficiency rating, ensuring energy savings and environmental benefits.

Finally, the GTS-705-NEA offers an innovative approach with its user-friendly features and smart technology integration. It provides Wi-Fi connectivity, allowing users to monitor and control their water heater remotely. This added functionality ensures convenience and efficiency, keeping hot water readily available at all times.

In summary, the American Water Heater ATI-705A-P, GTS-705-PEA, GT-705-PE, GT-305-NE, and GTS-705-NEA models present a range of impressive features and characteristics that cater to diverse household needs. With a strong focus on energy efficiency and advanced technology, these models not only deliver reliable hot water but also contribute positively to the environment, making them wise investments for any home.