DaveC Posted October 2, 2009 Report Share Posted October 2, 2009 I'm looking to buy a thermometer with a remote sensor and alarm so that I can monitor the temps in my greenhouse from the comfort of my living room and have the peace of mind that if the temp drops too low and I don't notice it I will be alerted. Can anyone give me any recommendations or tell me of ones to avoid please? Quote Link to comment Share on other sites More sharing options...
Peabody Posted October 2, 2009 Report Share Posted October 2, 2009 (edited) Maplin code L78AH might be suitable. It is a wireless thermometer costing less than £20. (transmitter in the greenhouse, receiver in the house). In the Questions for the product on the Maplins website someone asked if it alarms if the temperature drops below a set temperature and the answer was that it bleeps for 5 seconds every minute. Probably would take a lot of brain strain to figure out how to set the temperaturs alarm point. If I were you I would get a Greenhouse Sensation thermostat (about £40) It plugs into the mains and has a mains socket on a flying lead. The power is applied to the flying socket when the temperature goes below an easy to set temperature. Simply plug a small power supply (something like 6 to 12 volts - less than £10) into the socket and run a low voltage skinny cable back to the house - being thin it would go through the seal on a double glazed window. Then put a small piezo sounding device (less than £5 from Maplins) on the end of the wire. This should be a very reliable solution and be dead easy to set the low temperature at which the alarm goes off. Edited October 2, 2009 by Peabody Quote Link to comment Share on other sites More sharing options...
DaveC Posted October 2, 2009 Author Report Share Posted October 2, 2009 If I were you I would get a Greenhouse Sensation thermostat (about £40) It plugs into the mains and has a mains socket on a flying lead. The power is applied to the flying socket when the temperature goes below an easy to set temperature. Simply plug a small power supply (something like 6 to 12 volts - less than £10) into the socket and run a low voltage skinny cable back to the house - being thin it would go through the seal on a double glazed window. Then put a small piezo sounding device (less than £5 from Maplins) on the end of the wire. This should be a very reliable solution and be dead easy to set the low temperature at which the alarm goes off. Thanks mate but I need a battery operated system as the main reason that the temp. would drop below the required level would be a power cut to the greenhouse (about 90ft from my house) and therefore the system you suggested would fail as it would have to be connected to the same circuit. Thanks again for taking the time to make your suggestion though. Quote Link to comment Share on other sites More sharing options...
Peabody Posted October 2, 2009 Report Share Posted October 2, 2009 Dave, The Maplin wireless unit would be on it's wireless range limit so it would not be reliable. I have had a look on eBay and come up with "Room Thermostat HRT2" It is a Bimetallic strip thermostat that will incorporate a microswitch so that when the strip bends the microswitch will turn on. You would need to wire a PP3 battery in series with the thermostat and the piezo sounder. I wouild imagine it will have screw terminals on the rear. B&Q will have something very similar to the Ebay one. It is not a very HiTech solution but it should work pretty well. It would be able to cope with high humidities in your greenhouse OK. Quote Link to comment Share on other sites More sharing options...
jimfoxy Posted October 3, 2009 Report Share Posted October 3, 2009 (edited) Dave, I have an Oregon Scientific wireless unit but it is no longer sold: model EMR899 and remote sensor THC268 (the latter still are). It states that it can do 20-30m. In reality, on good batteries, it only just manages 15m through a single outside wall. Not sure if it has an alarm function but I think so (I don't use the feature - just the max, min memory functions, and the fact that I can have more than one sensor). In summary, I think the range values are given for open space so don't buy one where the distance you need is right on the edge of what they quote. Oregon Scientific have a range of other units - you might find something. Edited October 3, 2009 by jimfoxy Quote Link to comment Share on other sites More sharing options...
jesse Posted October 3, 2009 Report Share Posted October 3, 2009 (edited) I'm looking to buy a thermometer with a remote sensor and alarm so that I can monitor the temps in my greenhouse from the comfort of my living room and have the peace of mind that if the temp drops too low and I don't notice it I will be alerted.Can anyone give me any recommendations or tell me of ones to avoid please? A "digital thermometer with temperature alarm" has the main disadvantage, that you might miss the alarm. Typically it works like that: When the temperature for alerting is reached, the thermometer will do its alert-beep for two minutes at most (you can turn off the alarm by pressing a button). After that, a small blinking LCD segment will be all to show the pending alarm condition on the display. So what if you are not in the room during those two minutes while the alarm beeps? Would you like to have a close look at the display each time when you enter the room to find out whether an alarm is pending or not? Most likely, some kind of "wireless thermostat" is more what you are looking for. A wireless thermostat can switch not only a heating or cooling device (that's the typical intention), but you can use it also to switch an "alerting device", such as a flashy light to show some eye-catching alert. Edited October 3, 2009 by jesse Quote Link to comment Share on other sites More sharing options...
mobile Posted October 3, 2009 Report Share Posted October 3, 2009 Lidl often have wireless digital thermometers in store. I don't know if they have alarms but might be worth checking out if you have a local store. Quote Link to comment Share on other sites More sharing options...
flycatchers Posted October 3, 2009 Report Share Posted October 3, 2009 Hi Dave, I put a review on my web site on the one I use. That particular model seems to have been replaced by a more comprehensive model which covers humidity as well. The key snag is the actual range these wireless devices can handle. I am lucky my greenhouses are fairly close to my house and the weather station can pick up all 4 sensors I have set up. But I have had to locate the station in the kitchen as once moved to the study in the front of the house the station loses the signel. Also the alarm only runs for about 2 minutes (which I guess is the limitation of any battery operated devices). But even so I have been alerted on several occasions to problems in the greenhouse. And of course it is comforting to see what the temperature is in a particular house on a cold & frosty night! So far from perfect, but a useful addition! cheers bill Quote Link to comment Share on other sites More sharing options...
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