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Lochinvar knight boiler system temp probe.

Gumby77
Gumby77 Member Posts: 22
I had a modcon boiler installed is summer and have a question about how the system temp probe is installed. I've dealt with similar things and this doesn't seem right. I can also confirm that it isn't working correctly by using my ir temp gun on the pump which says the water is 20F degrees warmer than it says on the display of the boiler. Can anyone confirm my suspicions please.

Thank you

Mike

Comments

  • JUGHNE
    JUGHNE Member Posts: 9,760
    Are you measuring the temp of the pump/motor or the pipe a few inches from it? Motor could show higher temp than water if water was relatively cool.
  • G Averill_2
    G Averill_2 Member Posts: 48
    The Lochinvar I & O manual is not very specific as to how this sensor is to be installed. Some of my contractors use a well in the piping, and insert the sensor there. Most will use zip ties to attach it directly to the piping, then cover it up completely with Armaflex style insulation,using zip ties again to keep the insulation in place.
    As JUGHNE is stating as well, the heat from your pump motor may be affecting your temperature reading.
  • Gumby77
    Gumby77 Member Posts: 22
    I'm getting the temp from the underside of the pump away from the motor. I can't get a temp from the copper pipe with the ir gun because of reflectivity, I assume. The temp probe is in an aluminum tube and not actually touching the copper pipe because of the valve and bracket are in between.
  • Gumby77
    Gumby77 Member Posts: 22
    Boiler is running 100% firing rate and on the boiler the temp said 104F and my reading was over 125F. It's fairly warm here right now (35F) and the boiler was trying to satisfy 108F system temp based on outdoor reset curve. The boiler never modulates for SH and satisfies the thermostat without ever hitting the called for system temp. According to the system temp probe.
  • Gumby77
    Gumby77 Member Posts: 22
    Do you all see any problem with pulling the probe out of the aluminum tube and zip tying the probe directly against the copper pipe and insulating as stated above?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,995
    It looks like you have an air space between the sensor and the pipe you are trying to sense. that's not good

    First measure the air temp in the basement. Remove the sensor from the pipe and see if you can read the air temp on the boiler display. That will show you if the sensor is ok.

    You could use a gear clamp (like a radiator hose clamp) to attach it to the pipe. Make sure it is making good contact and then insulate it. move it to a new spot if need be
  • Gumby77
    Gumby77 Member Posts: 22
    Yes, I pulled it out earlier and watched the two on the display go down quickly. I think I'll take your suggestion, which makes total sense. I have a call into the installer and they are telling me it's settings in the boiler that need to be changed and the way the probe is installed is OK except for the fact that electrical tape was used. Ugh.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,995
    Hard to tell from the picture but it looks like the sensor is clamped to the pipe hanger and to the valve and is not touching the pipe.
    It needs to be clamped to the pipe along it's entire length
    Gumby77
  • Gumby77
    Gumby77 Member Posts: 22
    It's not even clamped it's just taped on with electrical tape. I understand what you're saying and I'll do the modification. Thanks all.
  • NY_Rob
    NY_Rob Member Posts: 1,370
    edited October 2017
    The circulator in the loop with the probe is installed incorrectly too.
    It's shaft must run horizontal not vertical.


  • Leon82
    Leon82 Member Posts: 684
    Here is mine. It seems pretty close. It is installed I side the well it comes with
  • Gumby77
    Gumby77 Member Posts: 22
    I really wish they would have used a thermo well. With the not so good installation of the temp probe and now the pump being in the wrong orientation I'm getting a little upset. I'm going to have to really look over this install. I already had to do the programming of the outdoor reset curve because it was just left at factory defaults. I was told I needed to do nothing and the system would run at peak efficiency automatically.
  • Leon82
    Leon82 Member Posts: 684
    edited October 2017
    > @Gumby77 said:
    > I really wish they would have used a thermo well. With the not so good installation of the temp probe and now the pump being in the wrong orientation I'm getting a little upset. I'm going to have to really look over this install. I already had to do the programming of the outdoor reset curve because it was just left at factory defaults. I was told I needed to do nothing and the system would run at peak efficiency automatically.

    Look at the webstone flange. It looks like it will rotate. There is a ring which may be the Gap in the 2 pieces.

    That sensor is bigger than mine. Thy must have changed it since 2015.

    You should be able to rotate the pump and only loose the water in the housing by closing those valves
    Gumby77
  • Gumby77
    Gumby77 Member Posts: 22
    The sensor is inside of another aluminum tube, further decreasing it's thermal contact. The sensor itself is about half the size of the tube.
    Leon82
  • NY_Rob
    NY_Rob Member Posts: 1,370
    ^ Check the install manual for your boiler, there should be a chart with the resistance value for the system probe. If it's a standard 10K Ohm NTC Thermistor you can purchase a much smaller one from amazon or ebay which will make full contact with the copper pipe... as mentioned earlier.... insulate it too.
    Gumby77
  • hot_rod
    hot_rod Member Posts: 16,293
    The sensor would be better downstream of the circ it would see a better blended temperature.

    Wouldn't be too hard to build a well into that Webstone purge port, don't see that a purge valve is needed downstream of the pump?

    A hose clamp is a good way to get a sensor tight against the pipe.

    It's ideal to have the entire sensor in contact, but really the thermisistor is at the tip when you cut them open to see what is inside.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Gumby77
  • Gumby77
    Gumby77 Member Posts: 22
    That's a great idea hot rod. I'm sure there's a way to put a well in that purge valve. I have the contractor coming by to fix the probe and the pump, I'll see what they do. My guess is I'll have to do it over, haha.
  • Leon82
    Leon82 Member Posts: 684
    You can get a hose to pipe thread adapter then bush it down to the well thread. I think the wells are about 5 bucks.
    Gumby77
  • hot_rod
    hot_rod Member Posts: 16,293
    Simple off the shelf parts, probably even box store stuff :)
    FIP hose adapter- female hose swivel to 3/4 female NPT,
    1/2 fip would eliminate a bushing and get the well deeper into the tee.

    If the well is long you will need to open that purge port and do a flying connection. Remove the valve handle as it will pinch the well.

    Easy to build a custom well, measure the OD of the sensor and find a copper tube size that is close. This is an older style Lochinvar well, not sure what diameter sensor they use now?

    Some sensors are Euro size 6mm, about 1/4" OD, slips into 5/16 soft copper tube. Solder that onto an adapter and into the hose adapter.

    Measure the OD of your sensor and I can show you how to build a copper tube well.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream