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Ultra Outdoor Sensors

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in THE MAIN WALL
Hey all,

I have two local clients with Weil-Mclain Ultras both installed by the same contractor. Both are Ultra 80s running on Propane. Both are having similar yet strangely different issues...

The first is a series 1, and its outdoor sensor was indicating that it was 220 something degrees outside. As you might expect, it was not responding to calls for heat because of this.

The second is a series 2 ultra, and its outdoor sensor is ALSO indicating that it is 220 something degrees outside. However.. quite strangely.. the unit is operating flawlessly, it's targeting an appropriate water temperature and responding to calls for heat. Now, it was warm out so the "appropriate water temp" may well be the minimum temp, I didn't think to check. But the point is, it is responding to calls for heat for sure.. which it shouldn't do if it really thinks it's 220 something degrees outside!

Anyone run into these things? Has there been a rash of bad sensors, or could a simple wiring error result in this kind of issue? and how could the series 2 boiler be operating at all???

Any thoughts would be greatly appreciated. We have a call into the rep but it never hurts to doublecheck...

Comments

  • jp_2
    jp_2 Member Posts: 1,935
    2nd one

    i would say the second one is correctly set up and the first one, not.

    it shhould be smart enough to realize the 220F is in error, and operate using a different parameter. thermocouples run high when 'open', so will a resistive device.
  • Steverino
    Steverino Member Posts: 140
    Bad Sensors?

    Yes, there have been some bad sensors. This seems to occur within the 1st year after installation. I remember a post here a month or so ago concerning the use of a different sensor...I plead ignorance...a sensor that has a different resistance?
  • Josh_10
    Josh_10 Member Posts: 786


    I have seen this a few times with any brand that uses that sensor. I have remedied the issue by sealing up the sensors with silicone.
  • Steverino
    Steverino Member Posts: 140
    Sensor

    Josh, help me out here..."seal up the sensor with silicone". How do you mean? Thanks!
  • Josh_10
    Josh_10 Member Posts: 786


    Around the edges and where the wire penetrates the unit. Just a real light bead with your fingers.

    And by all means this is my own experience as an installer. I have noticed that these units are easily penetrated by water and spiders. In the wet climate I live in there are an abundance of both.

    Just a mere suggestion.
  • Unknown
    Unknown


    Interesting, and this has cut down on or eliminated issues with the sensors for you?
  • Josh_10
    Josh_10 Member Posts: 786


    All I can say is every time I have done this I have never had a problem. What-so-ever.
  • Unknown
    Unknown


    Well thank you very, very much for that Josh. I'll let the installer know and when he switches out the sensor we can try it out.
  • Guy_6
    Guy_6 Member Posts: 450
    10K or 12K

    Find out whether it is a 10 or 12K sensor, and try swapping it for a different brand/type. As a matter of fact, even if you put the wrong sensor on, it will be off by a matter of less than 20 degrees, and should not get near 200 (unless you live near Sea World the hottest place that I have ever been). That test will at least point you in the correct direction.

    Guy
  • hr
    hr Member Posts: 6,106
    spider logic

    I've been told that spiders can get inside some of the various outsoor sensors and mess them up. I guess they get a leg, possibly a wet leg(s) :) across the two wire terminals and create false readings. Or building a nest across the terminals.

    Sounds off the wall, but somewhat possible also. I have a dealer that swears it happens with the small HTP outdoor sensors. He suggest you silicone them shut after connecting the wires.

    hot rod

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  • Steverino
    Steverino Member Posts: 140
    sensors

    Josh, thanks much for the info. It does make sense.
  • Constantin
    Constantin Member Posts: 3,796
    Seems plausible...

    ... IIRC, all of these sensors are thermistors, i.e. they vary their resistance based on the temperature. If a spider's body were to rest on the thermistor disc or to accumulate enough wet silk across it, then you'd end up with a lower resistance...

    A quick squirt of conformal coating might make the thermistor immune to electrical shenanigans, though the easier approach is to seal the box. I have two boxes out there and a total of 6 different sensors in them. It's enough to make you wonder when mfgrs will wake up and start using networkable sensors like the 1-Wire system.

    4 of the sensors out there are thermistors, of which 3 are for equipment from various manufacturers (Lennox, Viessmann, Tekmar). The remaining 3 sensors are for my 1-wire system. If mfgrs were to use something like 1-wire then I'd only need one box out there...
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