Radiant heating applications | Weil-McLain 310, 80, 230, 105, 155

3 GAS-FIRED WATER BOILER — Boiler Manual

Install water piping (continued)

Radiant heating applications	Figure 9

1.The Ultra boiler is ideal for use in radiant heating. The Ultra boiler’s unique heat exchanger design allows it to work well even in condensing mode. So there is no need to regulate boiler return water temperature in radiant heating applications.

2.Connect boiler to system as shown in Figure 9 for typical radiant heating applications. The primary/secondary piping shown ensures the boiler loop will have sufficient flow. Size the system piping and circulator to provide the flow and pressure drop needed for the radiant system.

3.Add the high limit control (Figure 9, item 22) to ensure supply water temperature will not exceed the maximum allowable for the radiant system. Wire this limit control between low voltage terminal strip terminals 6 and 7.

4.When using a closed-type expansion tank, connect the expansion tank and make-up water piping as shown in Figure 4, page 13.

5.Connect DHW (domestic hot water) piping to indirect storage water heater as shown.

The PhDControl Module turns off space heating during DHW heating. The boiler circulator will turn off, preventing hot water from circulating to the system. The flow/check valve shown on the boiler outlet piping prevents gravity circulation in the boiler loop during DHW heating.

6.Controlling the system circulator

a.To cycle the system circulator from the Ultra PhD control module, add a circulator relay wired to the boiler circulator terminals as shown in the Ultra Control Supplement

7.Setting boiler outlet water target temperature.

a.Follow procedure in Ultra Control Supplement to set space heating target temperature to the desired supply temperature for the system. For outdoor reset operation, install and connect the outdoor temperature sensor supplied with the boiler.

NOTE 1: To ensure adequate flow rate through the boiler, use the following pipe size on all boiler loop piping (connecting boiler to and from the primary/secondary connection, item 21):

Ultra-80 or Ultra-105 – 1" or larger. Ultra-155 or -230 – 1¼" or larger. Ultra-310 – 1½" or larger.

Typical radiant heating system piping plus optional DHW

Use at least the minimum piping size at left and pipe the boiler using only primary/ secondary piping as shown. Failure to follow these guidelines could result in system problems.

Legend

Figure 9

1Ultra boiler

2Indirect water heater (DHW), if used

3Boiler relief valve (see page 12 for piping details)

4Relief valve discharge piping (see page 12 for details)

5DHW circulator (see page 14 for suggested sizing)

6Isolation valves

7System circulator

8Diaphragm (or bladder) type expansion tank (see page 12 for piping of closed- type expansion tank, if used)

9Air separator [with automatic air vent only on systems using diaphragm (or bladder) type expansion tank]

10Flow/check valves (with weighted seats to prevent gravity circulation)

11Purge/drain valves

12Boiler circulator

13Zone valves, when used (zoning may also be done using manifold-mounted valve actuators)

20Make-up water supply

21Primary/secondary connection

22High limit temperature control, set to protect radiant tubing

Part number 550-101-233/0903