Product Handbook 2026 - Volume 1

Boiler house Level controls

2

Local regulations may restrict the use of this product to below the conditions quoted. In the interests of development and improvement of the product, we reserve the right to change the specification without notice. © Copyright 2015

TI-P402-68 AB Issue 3

APS1 Probe Simulator

Description The APS1 probe simulator is used in place of a level or conductivity probe to verify the correct operation of Spirax Sarco controllers. It can also be used to diagnose wiring/probe faults. It is connected to the level probe or conductivity probe wiring, avoiding the need to fire the boiler or alter water levels, and is quick and easy to use. The APS1 has switch settings covering all Spirax Sarco probe types and ranges. A potentiometer provides the variable input to a capacitance controller, and 4 mm test sockets are provided for connection of a multimeter, which is used to check the voltage when simulating capacitance probes. Switches simulate wet or dry (high or low resistance) conductivity level probe conditions, and resistors are built in to represent various conductivity probe ranges. The APS1 is powered by the controller under test, so needs no batteries or external power supply. The unit is fitted with two inputs, connected in parallel. One is for connection of a PT2 or PT3 plug tail, and the other is a DIN 43650 connector as used on conductivity and capacitance probes. Full operating instructions are supplied with each unit. Principal features: - A valuable diagnostic aid for Spirax Sarco boiler control installations. - Compatible with all TDS / level probes and controllers. - No need to fire boiler or alter water levels. - No battery or power supply needed. - Easy to operate.

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Test sockets

 





CP10 connector

Toggle switches











Potentiometer





DIN 43650 connector

 



Selector switch

 

 







Limiting conditions Maximum ambient temperature

Materials Case

55 °C

Die-cast aluminium

Protection rating

IP40

Coating

Nylon (grey)

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