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Q. Should I use 100ohm or 1000ohm RTD’s?<\/strong><\/p>\n A. In many HVAC applications, the RTD is some distance from the controller or transmitter. This is where the 1000 ohm RTD has a big advantage. The sensitivity of the 100 ohm RTD is about 0.21 ohms per \u00b0F, while the sensitivity of the 1000 ohm RTD is about 2.1 ohms per \u00b0F. This means that the error in reading caused by the resistance of the wire will be much greater when using 100 ohm RTD’s. For example, if a 100 ohm and a 1000 ohm RTD are connected to a transmitter using 100 feet of 18 gauge wire, the error in reading caused by wire resistance is calculated as follows. 18 gauge wire resistance is 0.664 ohms\/100 ft.<\/p>\n Total resistance of wire = 1.328 ohms<\/p>\n For a 100 ohm RTD, error = 1.328\/0.21 = 6.3\u00b0F. This means that if your controller or transmitter is not located with the RTD, a 1000 ohm RTD should be used.<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]<\/p>\n","protected":false},"excerpt":{"rendered":" Q. Should I use 100ohm or 1000ohm RTD’s? A. In…<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"full-width.php","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"folder":[251],"class_list":["post-26977","page","type-page","status-publish","hentry"],"yoast_head":"\r\n
Complete loop for 2-wire RTD = 200 feet of wire<\/p>\n
For a 1000 ohm RTD, error = 1.328\/2.1 = 0.63\u00b0F.<\/p>\n