BZ15C thermohygrometer
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BZ15C thermohygrometer

Optimally illustrates the climate values in your classic car garage

Precise measurement data with high informative value

We recommend the thermohygrometer BZ15C for any vintage car owner that wants to protect his classic from the consequences of too humid or too dry air in the garage. If the humidity level is too high, the sheet steel of any vintage car will begin to corrode severely – if it is too low, leather and plastics become porous and brittle.

Owing to the special scale design with climate-related colour indication the mechanical hygrometer provides just the right guidance for humidity level and room temperature in the garage. You can tell from one look whether the humidity really is in the green range. With this instant, unambiguous readability you have already taken the most important precaution for your classic car to prevent a loss in value.

The measurement accuracy of the BZ15C is ± 3 % RH in the range from 20 to 100 % RH. The thermohygrometer is equipped with a high-quality mechanical measurement technology "made in Germany" that guarantees high measurement accuracy without the need for maintenance. This mechanism is employed to measure the change in length of a specially pre-treated synthetic fibre that expands in humid conditions and contracts when it is dry. The length variation is converted into a rotary motion using levers and axes and visualized by means of a needle. 

The device display can easily be calibrated and amended by way of a zero correction. Naturally, the BZ15C may also be mounted in your living area – it provides valuable assistance in monitoring the room climate for private collections of any kind. 

How to read the colour scale of the BZ15C

  • If the humidity level is 35 % RH or below, the garage air is usually too dry for leather and plastics. This can result in brittle leather, porous seals and cable breaks. Therefore, the pointer is located in the red range in this case. 
  • To prevent rust and corrosion from covertly beginning their destructive work and mould growth from going unnoticed behind the dashboard and inside the seats the humidity level should maximally range between 45 and 50 % RH – the green range. 
  • At a relative humidity of only about 55 % RH metal begins to corrode, and moisture accumulations can no longer dry out properly. At 70 % RH and above, mould finds an ideal breeding ground after only a few hours – this is why these precarious ranges are also highlighted in red on the colour scale of the BZ15C.

How to react when the needle points to red ...

... or keeps moving in the critical range. Then it is definitely time to take appropriate countermeasures such as increased heating and/or ventilation until the two pointers of the BZ15C have returned to "greener pastures". The optimum climate control for your classic car garage can be achieved by relying on professional dehumidifiers from Trotec such as the renowned devices of the DH-VPR+ series with intelligent ThinC! climate technology.

BZ15C – Special equipment features

BZ15C - Dimensions
The true size of the compact BZ15C becomes apparent through its advantageous dimensions. With a convenient diameter of 10.3 cm, the dial is easy to read even from a distance.
BZ15C - relative humidity display
At the top, the relative humidity is displayed in the measuring range from 0 to 100 %. Unwanted deviations from the desired target range become obvious at a glance.
BZ15C - Display temperature
Below this the room temperature is displayed. In the temperature measuring range, it records values between 0 and 40 °C with a temperature measuring accuracy of only ± 2 °C.
BZ15C - Side view
By no means aloof, the elegantly flat stainless steel housing of the BZ15C thermohygrometer presents itself with a shallow depth.

Application examples from practical experience:

BZ15C – vintage cars
The BZ15C thermohygrometer is recommended for every classic car owner who wants to protect his classic car from the consequences of air that is too humid or too dry, even in the garage. Because if the air humidity is too high, massive corrosion of the steel sheet of every classic car begins - if it is too low, leather and plastics become brittle and porous.
If the humidity is only up to 35% RH, the garage air is usually too dry for leather and plastics. Brittle leather, porous seals and broken cables can be the result - accordingly, the pointer moves in the red range in this case.
Already from approx. 55 % r.h. metal starts to corrode and moisture pockets do not dry up properly. From 70 % humidity, molds find ideal breeding ground after only a few hours - therefore, of course, these dangerous areas are also set off in red on the color scale of the BZ15C.
Technical data by comparison

All climate measuring devices in direct comparison:

To find the climate measuring device which exactly meets your requirements, please consult the concise overview of all climate measuring devices from Trotec, which we're providing to you here so that you can compare them directly to each other.

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Technical data by comparison

A few practical benefits:

  • High-quality mechanical measurement technology "made in Germany"
  • Special scale design with climate-related colour indication
  • Simple readability and interpretation
  • Incl. calibration option


BZ15C Thermohygrometer show in Trotec online shop

BZ15C Thermohygrometer

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59.95 £ 54.95 £ incl. VAT Show net price (VAT not included)


Technical data

Technical data
General information
  Article number 3.510.205.011
Air temperature [°C]
  Min. measuring range | Air temperature [°C] 0
  Max. measuring range | Air temperature [°C] 40
  Resolution [°C] 2
  Accuracy ± | Air temperature [°C] 2
  Accuracy [°C] 2
Relative humidity (%)
  Min. measuring range | Relative humidity [%] 0
  Max. measuring range | Relative humidity [%] 100
  Resolution | Relative humidity [%] 1
  Accuracy ± [% r.F.] 3
  Accuracy 20 % - 100 % [%] 3
Housing design
  Stainless steel
Ambient conditions
  Operation - min. temperature [°C] -10
  Operation - max. temperature [°C] 50
  Operation approx. - max. relative humidity (non-condensing) [%] 100
  Storage - min. temperature [°C] -10
  Storage - max. temperature [°C] 50
  Storage - max. relative humidity (non-condensing) [%] 100
Standard scope of delivery
Standard scope of delivery
  Operating manual
Ascertainable measured values and functions
Functions and features
  Measurement of air temperature and relative humidity

 standard equipment

 optionally available

 not available

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