Product Handbook 2026 - Volume 1

Boiler house Level controls

2

Safety information, installation and maintenance This document does not contain sufficient information to install the system safely. See the Installation and Maintenance Instructions supplied with the probe for full details. Installation note: Do not install the probe outdoors without additional weather protection. The probe is installed in a ½ " BSP female connection. If the probe is to be installed in a boiler shell or a turbulent tank, fit a protection tube. This should be as long as possible, and at least long enough to cope with expansion of the probe at higher operating temperatures. The Table below shows the maximum probe expansion possible 0 - 239 ° C.

Probe length in mm

Maximum expansion in mm (inc. 'dead' length)

470

13

550

15

600

16

650

17

2.3 23

750

20

800

21

900

23

950

25

1 050

27

1 200

30

1 350

34

1 500

38

Do not cover the vent and drain holes on the body.

Maintenance note: No special maintenance is required. Boiler water level controls and alarms do, however require periodic testing and inspection, which is described in separate literature. How to specify Capacitance level probes shall be Spirax Sarco type LP21 with stainless steel body, cover assembly and probe, and PTFE probe insulation. They shall be suitable for modulating and on/off level control and be fitted with a screwed connection for attaching a Spirax Sarco PA420 preamplifier. How to order Example: 1 off Spirax Sarco LP21 capacitance level probe with BSP connection. Probe length 470 mm.

TI-P693-15 EMM Issue 1

Page 3 of 3

LP21 Capacitance Level Probe

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