Tekmar 260/biasi Bolier

Old 06-09-07, 09:30 AM
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Question Tekmar 260/biasi Bolier

I am having some problems maintaining min temp with the Teckmar 260 controler and my new Biasi boiler.the manufacturer recommends a min temp of no less than 120. I have the control set at 135 and the digital readout on the controller at the low temp reads ~115. The gauge on the front of the boiler reads ~ 10-12 degrees hotter which would be ok. Is this an issue with the aquastat that the teckmar is connected to? the aquastat supplied with the Biasi is a high limit only, is this the proper setup for the unit?.My installer seems to be lost in when it comes to the control. They even contacted teckmar about it with no solution.Or should I just go with the Biasi mounted gauge and stop fussing about!
Old 06-09-07, 06:11 PM
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If I'm reading this right, it sounds like your tekmar sensor is probably reading low. Check the manual for the ohms->temp calibration procedure.
Old 06-09-07, 07:22 PM
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How is it piped and configured? Where is the sensor?
Old 07-03-07, 04:53 PM
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I assume you have the 260 sensor on the supply side of the Biasi?

The manufacturer usually specifies a minimum RETURN temperature for the boiler, and Biasi assumes the boiler is being used in a low water mass hydronic system. Have you measured the return water temperatures to see how long it takes the return water to reach 140 degrees? If you're running an old converted gravity feed system, or have large castiron emitters you could have a problem.

My understanding is you want the Tekmar to maintain a minimum supply temperature of 150 degrees from the boiler (where the sensor is located), this ASSUMES the return temperature will be about 20 degrees lower and in the non-condensing range within several minutes of operation, and before boiler shutdown. My opinion, and i am a dumb homeowner, is that you want to raise that 135 degree setting to at least 150 degrees.

I'm also running a Biasi a with Tekmar 260. I'm adding a TV valve to keep the boiler returns above 140 degrees. The P/S piping will allow me to set the Tekmar for the lowest practical temperature range (the sensor is on the supply for the heating side of the P/S loop which has it's own circulator.) As does the TV port to the boiler return. Pete
Old 07-03-07, 05:10 PM
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To answer your other question: the Honeywell aquastat on the Biasi is a Safety High Limit that limits the maximum boiler temperature. The Tekmar can shut the boiler down earlier if it decides that the boiler temperature is adequate, but it is NOT a safety limit device!

Your installer should be the one who determines whether the boiler return is reaching a safe temperature range within the proper timeframe. Kinda sucks your stuck doing his homework.


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