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I suppose it could be a thermistor connected into a QAI but obviously the main problem is how to route the wiring. If very thin wire such as enamelled copper or very thin flat riboon are used then maybe these can go under the door seal without compromising this but probably won't look great from the outside depending how much of it you can see, otherwise you're looking for a natural aperture or perhaps where a tiny one can be safely drilled through the back and later sealed around the wire. Of course even if you get the sensor in you then have the question of where might be best to place it. Next to the existing thermostat sensor might I suppose be one place.
ie: temperature settings & variations can have a significant effect on food quality, in fridge & freezer - so it’s a more-than good idea to keep tabs on them, level & variation, and plotting data can help a lot, to see what’s happening, how well things are being maintained, and try to understand causes & modify behaviour (as in judging how much it’s wise to add to freezer load at once - SWMBO has a tendency to just pile it in, usually without having run it super-cold beforehand, but understands a graph when she sees one) ...
and Cortex being ace for tracking & plotting, of course, and raising alarms ...
‘am tempted to add a pulse power meter, too, to help with analysis - we’ve installed them on other things, but for fridge & freezer we’ve just a plug-in meter (that we move about, with the interest of the moment) ) that gives instantaneous & cumulative read-outs, but no tracking ...
BTW, wonder if the Idratek guys have thought of doing a remote-sensor version of their temperature sensing modules - with the sensor on a (say) 2m lead ... we've a number of QAIs with just one channel utilised, which seems a bit of a waste !
Last edited by chris_j_hunter; 14 February 2013, 03:19 PM.
Don't know if I've posted these before but just out of interest here is some data captured from a property some time ago when it was empty and doing some heating/cooling tests. Shown are temperature plots from sensor modules mounted on the ceiling and the wall of an open plan kitchen diner. Also the total house electricity meter plot for the same day. Have to admit when I first looked at the ceiling sensor plot I was a bit puzzled by the bumps on the cooling curve which were not present in the wall sensor data. Then it dawned on me that it must be heat from the fidge's heat exchanger rising up and flowing along the ceiling (sensor about 2m from fridge). Looking at the electricity metering data pretty much confirmed this (there is also another metering output just for the ring on which the fridge is connected but haven't got to hand).
Remote sensor version ... In fact the BRS module does have a breakout which could potentially get populated with a terminal block to allow an external sensor to be more easily connected rather than the onboard one, but to be honest the main obstacle is manufacturing the external sensors on a lead - I mean of the digital type that we use (not thermistors). It has actually been done by one or two people who wanted the high resolution/accuracy of these sensors but didn't want the module at the location, but strictly DIY with some guidance.
wondered if anyone is measuring fridge & freezer temperatures & feeding to Cortex ...
if so, then how ?
A few years ago, I put some 1-Wire DS18S20 into the fridge and freezer.
Why? Because I could.
I also put a CurrentCost IAM to capture the power usage.
I used very fine wire that went under the door magnets. It didn't seem to cause a problem.
I store and graph the temperatures and power usage.
It turned out very useful recently, when SWMBO left the freezer door open and some ice blocked the vents. It required a defrost to get it working properly.
The great thing, is that I could see immediately see what the temperatures were. The freezer was still cold but the fridge was getting warmer. I could fix it myself without having to get it repaired.
I think it is great. Very geeky, sure but it paid for itself.
Resurrecting a somewhat old thread ... Fast forward 9 years from my "Why do this?" question, I'm now definitely wanting to do this. In the last 4 years, I've now had 2 freezers stop working on me and lost the entire freezer contents because we'd not noticed until it was too late.
With this, I want to be able to monitor / track the internal freezer temp, so that I can trigger an alarm when it rises above a certain threshold.
I'm by no means and electronics sort of person - more of a software sort ... so was wondering if anyone had more of an "Idiots guide" to how best to achieve this? Is this still a QAI, some kind of thermistor on a lead, and some kind of resistor? (if so can anyone point me at the appropriate components please?)
Appreciate any help
Cheers
Cliff
Last edited by cliffwright; 16 August 2022, 07:57 PM.
Typically (and in the above case) these have a resistance of 10k at 25C (make sure you check before you purchase a particular brand). For a 10K probe, on the QAI you would use something like a 47K pull down resistor in order to try and make best use of the range over the low temperature areas.
Certainly know of at least one customer who is already doing such monitoring and generating alerts if things don't look right.
Also should mention that a dedicated thermistor input is now available on the new SRH and DRH modules and these also have an on board 10k/57k pullup (similar effect to QAI pulldown) option link so no external resistor required. Also the WiFi based SRM has a general analogue input (which would require the additional resistor like the QAI).
Typically (and in the above case) these have a resistance of 10k at 25C (make sure you check before you purchase a particular brand). For a 10K probe, on the QAI you would use something like a 47K pull down resistor in order to try and make best use of the range over the low temperature areas.
Certainly know of at least one customer who is already doing such monitoring and generating alerts if things don't look right.
Also should mention that a dedicated thermistor input is now available on the new SRH and DRH modules and these also have an on board 10k/57k pullup (similar effect to QAI pulldown) option link so no external resistor required. Also the WiFi based SRM has a general analogue input (which would require the additional resistor like the QAI).
Thanks Karam
So .. are you saying my simplest approach here is to buy a DRH-003 - and one of the above UFH probes, and this would pretty much give me a plug-n-play solution?
If a new module is required then it would be less costly to use a QAI-003 - unless you also have some reason to use relays or buttons that are provided by the DRH/SRH/SRM. As a valued customer I'm sure we'd be very happy to pre-fit the required resistor on a QAI module at this end so that you basically just have to screw in the two probe wires
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