Weil-McLain 550-141-850/0599 manual IIIg Water piping single-zone radiant or heat pump system

• Installation • Start-Up • Parts • Maintenance

IIIg Water piping — single-zone radiant or heat pump system

Single-zone radiant heating or heat pump

piping

Radiant heating systems and heat pump systems usually require system supply water temperatures below 130 °F. But the boiler outlet water temperature will be at least 150 °F during most operating conditions. So the piping must include a method of reducing the supply water temperature to the system.

Figure 13 uses two balancing valves to manually adjust the supply water temperature. Follow the instructions below to adjust these valves. Install the supply temperature limit control (item 14) as shown to protect the system from overtemperature conditions. Note also that this piping requires a separate system circulator, as shown, because of the higher flow rates of radiant and heat pump systems.

Manual adjustment of the supply temperature is limited to single-zone systems because multi-zone systems will cause varying loads, making it unlikely an acceptable valve setting could be found. See Figure 14a or 14b for multi- zone systems.

Figure 13 Single-zone radiant heating or heat pump system

Load

You may also apply the suggested piping of either Figure 14a or 14b if you want automatic supply temperature regulation or outdoor reset temperature control.

For additional information and alternatives in piping for radiant heating systems, refer to Weil-McLain

AlumiPex Controls • Pumps • Wiring Design Guide.

Adjust balancing valves

Use valves 15 and 16 to mix boiler supply water with system return water, reducing supply water temperature to the system.

1.Subtract the design system supply temperature from 150 °F. Call this number the temperature difference.

2.Open valve 16 and close valve 15.

3.Start the boiler and system.

4.Let the system warm up for about 15 minutes.

5.Note the temperature at gauge 9 (system supply) and gauge 8 (boiler supply).

6.Slowly close valve 16 while opening valve 15 until gauge 9 reads lower than gauge 8 by at least the temperature difference found in step 1.

7.Example: For a design supply temperature of 100 °F, the temperature difference would be 150 °F minus 100 °F, or 50 °F. Set the valves until gauge 9 reads at least 50 °F lower than gauge 8.

12"

max

Cold water

fill

GV Boiler

Legend

1 Boiler isolation valves

2Automatic air vent (with diaphragm-type

expansion tank), or connect to tank fitting (closed-type expansion tank).

3Diaphragm- or bladder-type expansion tank, if

used (For closed-type expansion tank, pipe from top of air separator to tank fitting as in Figure 10.)

	5	System circulator
	7	Hose bibb purge valve
	8	Boiler pressure/temperature gauge
	9	System supply temperature gauge
	10	Return temperature gauge
	14	Supply temperature limit control — Set at a
		temperature below the maximum allowed for
		the system or as directed by the system
		designer.
	15	Balancing valve
85015a	16	Balancing valve

Part number 550-141-850/0699 33