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Thread ID: 140649 2015-11-18 20:43:00 Question for the electrical gurus Tony (4941) PC World Chat
Post ID Timestamp Content User
1411621 2015-11-20 04:54:00 i'm not a fan of the low voltage electrics in the same outlet as mains electrics.

do you have to have the temp gauge there?
fit a decent one and re run the sensor wire.The display is certainly in a very convenient place. I don't think I can install another wired version without having visible wires all over the place, which is why I was floating the idea of a wireless solution if one was available.
Tony (4941)
1411622 2015-11-20 07:06:00 I use to do water and humidity measurements tests from cylinders and cabinets. Two companies we dealt with were Honeywell UK and Contherm logics controllers. Both their products worked well together. I think today Honeywell UK has wireless thermostats. Visit Google Image (goo.gl) search results. kahawai chaser (3545)
1411623 2015-11-20 07:17:00 Before discarding the present system, I'd suggest improving the thermal contact between sensor and pipe.

One simple way would be to remove the clip and bind the sensor to the pipe with copper braid, then lag it well.
Terry Porritt (14)
1411624 2015-11-20 07:25:00 Tony...You say that the reader part is battery powered, that will be for the digital readout. The thermocouple is not power supplied at all.

A thermocouple is two dissimilar wires welded into each other at the ends, only one end of course. The ones I used to make were Chromel & Alumel, 8 gauge. I would put the ends in a vice & twist about 5mm together. Then using the carbon core out of a "D Cell" battery in an electric welder I would touch the carbon on onto the wires. It would give a blob of fused metals. This blob is the part that makes the power required to go to the reading instrument. The output from this 'couple is only milliamps/millivolts. Yes the length of the wire is critical but you are nowhere near that. The lead from the couple has to be the right "compensating Cable. When the couple output gets to the reading instrument it is amplified to work the readout. But I doubt that in your case.

The equipment I worked on was always mains powered & the Zero point could be adjusted. The other thing I could do was disconnect the Couple & measure the output. From a book I could see what that reading should show as temperature.

So how does this help you? Probably none. So what I would do is disconnect the couple & see what the readout is. I assume you cannot calibrate the reader. Next I would move the sensor to the top of the pipe. There is a compound like window putty, but for hi-temp. Put some of this on the pipe & bury the sensor in it, then wrap in up in any temp insulating tape etc. you have to hand. The temp change will be slow to record. It is also possible that the Couple output is too small to work the new instrument. Without an instruction book it is hard to tell. I hope this diatribe is of some help!!!! PJ
Poppa John (284)
1411625 2015-11-20 21:55:00 Thanks everyone for all your suggestions.

I think for the moment I'm going to stick with what I've got as it works OK apart from being 15° low. Even at my advanced age I can add 15 to the indicated temperature in my head. I will keep looking out for other solutions though and if I can find something that works, I'll post back here.
Tony (4941)
1411626 2015-11-21 21:47:00 There are various types of thermocouple made from different metals. It's possible the new display expects a different type to what you actually have. Agent_24 (57)
1411627 2015-11-21 22:41:00 There are various types of thermocouple made from different metals. It's possible the new display expects a different type to what you actually have.I don't think that's the case. It was supposed to be a one for one replacement. Tony (4941)
1411628 2015-11-22 03:16:00 *supposed* to be. If I had a dollar...

Probably worth checking that.
Agent_24 (57)
1411629 2015-11-22 03:24:00 *supposed* to be. If I had a dollar...

Probably worth checking that.Checking is difficult as the replacement happened about 13 years ago. (It takes me a while to get round to fixing these things...) As far as I can remember the two units certainly looked the same from the outside and AFAIK the replacement came from the supplier of the original unit..
Tony (4941)
1411630 2015-11-23 03:11:00 Won't it be easier to aim one of them cheap and simple infra-red temp guns for a quick reading? I think though a fiddle factor may be required, perhaps a emissivity or thermal heat capacity factor for a copper/water interface. kahawai chaser (3545)
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