Printed heat flux sensors · Manchester, UK
Peltyr's 0.4 mm printed sensors measure heat flow at a surface. Bare sensors are available from £99.99 ex VAT, with optional calibration. Connect to suitable measurement equipment for your test setup.
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Bare sensors are in stock in limited quantities. Pay by card at a secure Stripe checkout, or request an invoice or a quantity quote from the basket. Delivery is added at checkout: £4.99 in the UK, £14.99 to Europe and Canada.
One bare printed heat flux sensor board per unit with a short connection lead, supplied uncalibrated with the nominal sensitivity. Every board is checked before dispatch.
No wireless logger, no cloud dashboard, no automatic reports and no mounting hardware. You connect the sensor to your own logging equipment.
We measure the sensitivity of each sensor you order and report the value to you, so your readings are absolute rather than nominal. Tick the option on the product card or in the basket.
How it works
The sensor is a passive element. Heat flowing through it produces a small voltage, positive or negative with the direction of flow. Everything else is your measurement setup.
Fix the sensor flat against the surface under test, ideally a smooth, even surface or one coupled with a heat transfer pad. Record which face is against the surface, because that sets the sign of the signal.
Wire the two signal leads to a differential input on your logger or data acquisition unit. The full scale signal is under 1 mV, so you need a low noise input with microvolt resolution, or an amplifier in front of a coarser converter.
Log the voltage over the test and divide by the sensitivity to get heat flux in W/m². Use the nominal 4.7 µV per W/m² for comparative work, or the measured sensitivity from the optional calibration when you need absolute values.
Measuring a U value? Heat flux on its own is not a U value. You also need the temperatures on both sides of the building element, a measurement period long enough to average out the weather and heating cycles, and a recognised heat flow meter procedure to turn the two into a result.
What you need
Four things decide whether an experiment with a bare sensor works. We have not yet published a tested logger combination, so treat the guidance below as recommendations, not verified setups.
A logger or data acquisition unit with a differential analogue input and microvolt resolution. The nominal full scale signal is about 0.94 mV, so input noise, offset and drift decide what you can resolve. A 24 bit label on its own does not guarantee that. Tell us what you plan to use and we will say whether it is likely to work.
The sensor comes with a short connection lead: two heat flux leads to your logger's differential input, plus two thermistor leads on four wire versions. Extend with care, keep runs short and away from mains cabling. Lead colours and polarity are in the Q&A below.
Flat, in good thermal contact with the surface, with the face orientation recorded. Contact quality, draughts and direct sunlight all change what you measure. No mounting hardware is supplied; choose a method that suits your surface and test duration.
Sensors ship with the nominal sensitivity, which is fine for comparisons. For absolute heat flux values, order factory calibration at £60 per sensor, or calibrate against your own reference in your test rig.
Technical documentation. Ask for the current product facts, connection details and setup notes when you enquire and we will send what is available for the batch you order. A published datasheet and a documented measurement example are not yet available.
Applications
Heat flux tells you how much energy crosses a surface and in which direction, which temperature alone cannot. Three test questions it addresses.
How much heat passes through this wall, roof or floor, and what is its U value in situ?
Peltyr's sensors were functionally validated in whole house conditions at Energy House 2.0, University of Salford. A U value additionally needs temperature measurements and a suitable procedure.
See how heat moves through a wallWhich insulation, packaging or enclosure design loses heat fastest, and where?
Heat flux separates candidates quickly in a controlled comparison: flat packaging or insulation samples, or a heating and cooling experiment on a bench. We have not yet validated the sensor for these uses, so start with a small evaluation against your reference instrumentation.
Can a thin, low cost sensing element be built into your rig, product or logging system?
The sensor is a passive element with a two wire output, 0.4 mm thick, with quantity pricing from five units. Suitability depends on your signal chain and environment, so order two sensors to evaluate before committing to a volume order.
Temperature limits, durability and outdoor use are not yet characterised. Ask before using the sensor outside room conditions.
Building fabric
A surface temperature reading only tells you so much. A heat flux sensor tracks the heat that actually passes through the fabric. With the temperatures either side and a suitable procedure, that becomes a U value.
Technical specification
Nominal figures for the sensor you can buy today. Accuracy and operating limits are not published until we can show the evidence.
Prototype target specification. Not for sale, subject to change.
Q&A
Practical answers about our printed heat flux sensors, measurement equipment, calibration and applications. Planning a test? Contact jonas@peltyr.co.uk with your application, logger model, expected conditions and quantity.
Peltyr measures heat flux density: the heat passing through a surface per unit area, expressed in W/m². Its thermopile produces a small analogue voltage that corresponds to this heat flow. With suitable logging, calibration and temperature measurements, the signal can support thermal performance investigations and in situ U value measurements.
The current product is a bare printed heat flux sensing element supplied with a short connection lead. External data acquisition equipment, indoor and outdoor temperature loggers and automatic analysis software are separate. Calibration is an optional addition. Check the product listing for the configuration supplied with your order.
The bare sensor uses a wired analogue connection to external measurement equipment. Our packaged measurement kit and wireless logging system are in development. Register your interest for updates; confirmed availability and specifications will be announced when the kit is ready.
The sensor board has a nominal thickness of 0.4 mm. This low profile can help where space at the measurement surface is limited. Check the drawing for the supplied revision when designing a fixture: board dimensions, connectors, leads and mounting materials all contribute to the installed footprint.
The published heat flux range is ±200 W/m², with a nominal sensitivity of 4.7 µV per W/m². The sensitivity is in microvolts, not millivolts. At nominal sensitivity, 10 W/m² corresponds to approximately 47 µV, while ±200 W/m² corresponds to approximately ±940 µV. Use the individual calibration factor where available.
The thermopile generates its own voltage in response to heat flow and does not require an external excitation supply. Your logger or readout electronics still require power. The separate thermistor, where fitted, needs an appropriate resistance measurement circuit. Do not apply a supply voltage to the heat flux output leads.
Use q = (V − V₀) / S, where q is heat flux density in W/m², V is the measured voltage, V₀ is the applicable measurement offset and S is the sensor sensitivity.
Keep the units consistent: dividing a corrected reading of 47 µV by 4.7 µV per W/m² gives 10 W/m². For calibrated measurements, use the supplied calibration factor and instructions rather than the nominal value.
Look for differential DC voltage inputs with suitable resolution, low input noise, low offset and drift, and appropriate input impedance. The signals are small: at nominal sensitivity, a 1 µV error corresponds to about 0.21 W/m². ADC bit depth alone does not establish measurement capability; assess the complete signal chain at the sampling rate you intend to use.
Potentially. A suitable precision DAQ can record the analogue output for your own analysis. A microcontroller will generally need an external precision ADC and a carefully designed analogue front end. Send us your equipment model and required measurement performance before ordering so we can discuss the proposed setup. Compatibility should be verified for the specific configuration.
The documented four wire configuration provides separate connections for the heat flux thermopile and an onboard 10 kΩ NTC thermistor. The thermistor is a resistive temperature sensing component; it is not a thermocouple or an RTD. It does not replace the separate indoor and outdoor temperature measurements needed for a building U value test.
For sensors supplied with the documented brown, black, red and orange lead set, brown is the positive heat flux lead and black is the negative lead. Red and orange connect to the separate NTC thermistor circuit.
With the positive measurement input connected to brown, the documented blue to red heat flow direction produces a positive output. Always confirm the wiring and orientation against the instructions for your supplied revision.
Yes, but cable extensions and connections need care because the sensor produces microvolt level signals. Poor connections, electrical interference and temperature differences at junctions can affect the reading. Use suitable wiring and connections, provide strain relief, and check noise and offset after extending the lead. Contact us if your installation requires a particular cable length.
Good thermal contact with the measurement surface is essential. Choose mounting materials appropriate to the surface and experiment, minimise air gaps, and keep the setup consistent between tests.
The sensor and mounting layer can alter local heat transfer, so assess this effect where accuracy matters. Contact us about your surface and fixture before selecting an adhesive or thermal pad.
Calibration is recommended when you need quantitative heat flux results, comparisons against reference equipment or a documented measurement uncertainty. It establishes the sensitivity of an individual sensor under specified conditions. The nominal sensitivity is useful for initial evaluation, but should not be treated as an individual calibration result.
Calibration is available as a paid option. Please tell us your application and any requirements for calibration documentation, uncertainty or traceability. We can confirm the available service, price and lead time for your order.
A calibrated sensor is one part of the measurement system; the logger, installation and analysis also affect the result.
Accuracy depends on the sensor calibration, logger noise and drift, wiring, mounting, operating conditions and analysis method. U value measurements also depend on temperature sensor accuracy, sensor placement and the suitability of the measurement period. Discuss your required uncertainty with us so the evaluation can address the complete measurement setup.
Yes. The bare sensor provides an analogue voltage output, which your chosen logger records. File formats and export functions depend on that logger and its software.
You can analyse the recorded voltage using the relevant calibration factor and combine it with timestamp aligned temperature data. No Peltyr phone app is required to read the bare sensor.
You need a heat flux sensor with an appropriate calibration, suitable data acquisition equipment, indoor and outdoor temperature measurements, suitable mounting and wiring, and an appropriate analysis method.
All readings need a consistent time reference. A USB DAQ may require a computer to remain connected throughout the test; check how your chosen logger stores data.
For an appropriately configured test, the average method relates heat flux density to the temperature difference across the building element. With equally spaced, aligned readings, the calculation can be expressed as U = Σq / Σ(Tᵢ − Tₑ), giving W/(m²·K).
Validity depends on the measurement arrangement, test conditions and convergence criteria. ISO 9869-1 describes the heat flow meter method and its measurement and reporting requirements.
Allow several days. A 72 hour period is a common minimum starting point for suitable tests; elapsed time alone does not establish a valid result. Heavy construction, changing weather and heat storage can require longer measurement. A one to two week allowance may be useful for planning, with the actual duration determined by the applicable method and whether the results have converged.
A sustained temperature difference between inside and outside helps produce a measurable heat flow signal. Select a representative location, avoid direct solar exposure and local heat sources where required by the method, and account for thermal bridges and changing conditions.
A simple temperature difference threshold cannot guarantee a valid result; plan the setup and analysis together.
The two measurements complement each other. Thermography helps identify surface temperature patterns and possible thermal bridges. A heat flux sensor provides a local measurement of heat passing through its measurement location.
One sensor cannot map an entire wall or building; distinct constructions and non uniform areas may require multiple measurement points.
They can help reduce uncertainty in the fabric inputs used for heat loss calculations, particularly where the existing construction is unclear. Fabric heat loss is calculated from U value × area × design temperature difference.
The heating designer must also account for ventilation, infiltration and the other relevant elements on a room by room basis. A local sensor measurement does not itself determine the required heat pump size.
A heat flux test does not automatically change an EPC rating. EPCs use prescribed assessment methodologies and evidence requirements. Measured thermal performance can still inform retrofit planning, investigate assumptions and support design decisions.
If EPC treatment is important to your project, confirm the applicable rules with your accredited assessor before commissioning a test.
The analogue heat flux output can be evaluated for other thermal testing applications, including insulation assemblies, packaging development, heating and cooling products and measurement system integration.
Suitability depends on the heat flux level, temperatures, surface contact, environment and required uncertainty. Tell us about your experiment so we can discuss a suitable evaluation; application specific performance needs to be established by testing.
Use the specification for the supplied sensor revision and confirm suitability for your intended conditions. For elevated or very low temperatures, moisture, outdoor exposure, curved surfaces or embedded installations, contact us before ordering.
The sensor, connector, cable and mounting materials all need to be suitable for the complete installation.
Order through our website, or email jonas@peltyr.co.uk for an invoice, quantity quotation or application discussion.
For an evaluation, include your test objective, expected heat flux and temperature conditions, logger model, quantity and required delivery date. If your delivery country is unavailable at checkout, contact us to confirm shipping options and the total order cost.
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