Wika Model A52

The Wika A52 is a bimetallic dial thermometer built to EN 13190 — the cost-effective standard for temperature indication in HVAC systems, machine building, equipment manufacturing, and building services. Despite its entry-level positioning, it carries a robust stainless steel case and accuracy class 1 for nominal sizes from 60 mm — genuine German-engineered measurement at a working-plant price.

The A52 is the axial (back mount) version; its sibling R52 provides radial (lower mount) connection for panel and pipe orientations where the stem must enter from below. The maintenance-free bimetal measuring system needs no power, no capillary, and no calibration routine in normal duty — the wide selection of stem lengths and nominal sizes adapts it to ventilation ducts, hydraulic power packs, chilled and hot water lines, and test benches alike.

A52 or R52 — this is the mistake that costs a re-order. The two are the same thermometer; only the connection differs. A52 = axial, the stem leaves the back of the case, for reading face-on to a duct or vessel wall. R52 = radial, the stem leaves the bottom, for reading a pipe from the side. Decide which way the dial has to face before you order.

Nominal sizes: the family spans NS 25, 33, 40, 50, 63, 80, 100 and 160 mm. In HVAC and building-services work 63, 80 and 100 mm are the sizes normally specified — and class 1 accuracy applies from NS 63 upward, so if the reading matters, do not go below 63.

Scale ranges run from −30…+70 °C at the low end through the common HVAC selections (0…+60, 0…+120, 0…+160 °C) up to 0…+500 °C. Pick a range where your normal working temperature sits in the middle third of the dial — a gauge reading at the very bottom of its scale is a gauge you cannot trust.

Three things to send with an enquiry: the nominal size, the scale range, and the stem length (plus whether you need a thermowell). A thermometer ordered without a stem length cannot be quoted, and a stem too short for the pocket will read the pipe wall rather than the fluid.

Specify an A52 when a plant needs a permanent local temperature reading with no wiring — AHU coils and duct runs, chilled and condenser water headers, hydraulic and lube-oil tanks, compressor discharge lines, and test rigs — or when an old mercury or gas-filled dial thermometer needs replacing with a maintenance-free bimetal equivalent.