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Assessing Heatmiser Neostat Accuracy: How and Why to Calibrate Them
Moving into our home brought the advantage of an already installed underfloor heating system, regulated by Heatmiser Neostats. These devices, promising precise control and energy efficiency, became a focal point of curiosity about their accuracy in temperature regulation after it was raised on a recent YouTube we posted. To assess this, I used a FLIR ONE thermal imaging camera to compare the thermostat readings against the actual environmental temperatures across different heating zones.
The process unveiled unexpected discrepancies between the Neostats' temperature readings and the thermal camera's more accurate measurements. Additionally, it highlighted hot spots within the thermostat units, potentially influencing the accuracy of the readings and, by extension, the effectiveness of our home's heating system.
Motivated by our findings, we recalibrated our Heatmiser Neostat thermostats.
How to Recalibrate Heatmiser Neostat Thermostats
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How do you know that the thermal camera or any other reference device is actually providing accurate readings?
What is the manufacturer's specified accuracy for the devices being compared?
@derek-m that thought crossed my mind while I was working on this, leading to a humorous vision where I found myself testing the device used for testing the thing that was testing the other thing. 🤣
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Posted by: @editor@derek-m that thought crossed my mind while I was working on this, leading to a humorous vision where I found myself testing the device used for testing the thing that was testing the other thing. 🤣
In the real World, the test equipment should be at least 3 times more accurate than the device being tested. So if the device being tested is specified as providing an accuracy of +/- 1C, then the test equipment should have an accuracy of +/- 0.33C or better.
This works all the way up the chain to National and International standards.
Obviously most people don't have access to intermediate standards let alone National or International ones, but there are still tests that can be performed at home.
Melting ice will be at 0C and boiling water will be at 100C, under standard atmospheric conditions of 1 atmosphere.
Heatmiser Neostats are also used by Grant. Theirs are Grant branded, but identical items. They have up to 3degC adjustable differential if I recall, so are well suited to renewable heating system control.
I had a Heatmiser Neostat installed with my Ecodan. I was told, I think, by Brendon that it was a simple on-off switch not suited to ASHP control. He advised stripping it out and installing Mitsubishi components. I did exactly that.
Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.
2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.
@morgan Likewise, I had a Neo Air Thermostat installed originally, at that time, my choice of a Homely smart controller was not yet available; as soon as the Homely kit was available for my Daikin, I had the system changed over. The Neo Air, is very crude - just on/off and not really very suitable for a heat pump system at all. Regards, Toodles.
Toodles, heats his home with cold draughts and cooks food with magnets.
@toodles I wish Homely was available for my Ecodan but apparently they have no intention of providing for it.
Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.
2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.
Posted by: @morganI had a Heatmiser Neostat installed with my Ecodan. I was told, I think, by Brendon that it was a simple on-off switch not suited to ASHP control. He advised stripping it out and installing Mitsubishi components. I did exactly that.
Ours will also probably go when we commence with the work of rectifying our installation. It’s going to be carnage. So much superfluous crap will be removed.
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📘 From Zero to Heat Pump Hero
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Posted by: @editorPosted by: @morganI had a Heatmiser Neostat installed with my Ecodan. I was told, I think, by Brendon that it was a simple on-off switch not suited to ASHP control. He advised stripping it out and installing Mitsubishi components. I did exactly that.
Ours will also probably go when we commence with the work of rectifying our installation. It’s going to be carnage. So much superfluous crap will be removed.
You must post a report/summary when it's done. I'm keen to know how it goes. Also still trying to get a Heat Geek to review my install.
Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.
2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.
@morgan we intend to document everything and show the difference. Where in the UK are you based?
New to heat pumps? Take the Heat Pump Fundamentals course and use INTRO50 at checkout for 50% off.
Rewritten and updated for 2027
📘 From Zero to Heat Pump Hero
🛠️ Bodge Buster
🎧 Prefer to listen? Heat Pumps Explained
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