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Transformer/ pump relay combo

CBRob
CBRob Member Posts: 273
Tekmar snowmelt control calls for this 40VA transformer and this multi function relay.

I see there are other "all in one" pump relay controllers out there.
Would it be a cleaner looking direct replacement to put a pump relay in place?

Comments

  • hot_rod
    hot_rod Member Posts: 21,860
    A plug in transformer is another option, if you just need 24V?
    The transformer you show would need to mount to a box to enclose the 120V wiring.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    CBRob
  • CBRob
    CBRob Member Posts: 273

    This is 40VA and is a pump relay, would it be a good substitute?
    GGross
  • CBRob
    CBRob Member Posts: 273
    The tekmar relay is pretty big and harder to fit in a box. 
    For the transformer they spec 40 VA, are there any other specs that a transformer of 24 volt might require?
  • CBRob
    CBRob Member Posts: 273
    @Mike_Breault

    Have you seen any transformer/ relay substitute for the snowmelt control work?
  • hot_rod
    hot_rod Member Posts: 21,860
    That relay box only has a 15 or 20 Va transformer at the most. If the control needs a 40 Va, better just get the correct transformer. Here is a wall plug in transformer we used with the Caleffi snowmelt control. It was very sensitive to voltage so we had these built to a tighter tolerance.
    Tekmar should be able to steer you to the correct transformer. Does it need 40 Va?w
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    CBRob
  • CBRob
    CBRob Member Posts: 273
    The one that tekmar specs is 40 VA

    Probably should go with what they spec, but seemed like there should be an easier, all in one way.
  • hot_rod
    hot_rod Member Posts: 21,860
    Does the snowmelt control also need 24V? the 40Va transformer is way over kill just to power that ice cube relay. Which model control are you looking at?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 21,860
    I'm not so up to speed on the latest tekmar product. The spec sheet shows a wide range of power draw! maybe it depends on which sensor you use. A tekmar rep could answer the question best.

    That cube relay would need a deep box to accomodate it. the transformer could mount to the bottom on a knockouts
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • GGross
    GGross Member Posts: 951
    Tekmar 301P or a Caleffi ZSR101will do the trick if you want it all in one in a nice box.
  • hot_rod
    hot_rod Member Posts: 21,860
    GGross said:

    Tekmar 301P or a Caleffi ZSR101will do the trick if you want it all in one in a nice box.

    I don't think the 20Va transformers in the relay boxes will power the control and sensors?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • GGross
    GGross Member Posts: 951
    edited October 2023
    Huh, I have done this before with no trouble, single 654 snow/ice sensor, OD sensor? All of Tekmars application guides show 2 complete sets attached to a single 40VA transformer so I never really thought twice about a 20VA transformer. Wouldn't be the first time I was wrong and probably won't be the last!

    EDIT: @hot_rod Yeah I was mistaken I just got off the phone with the Tekmar rep and he said they have had trouble with the 654 on smaller transformers. I must have been using a different relay with a larger transformer in the past
  • hot_rod
    hot_rod Member Posts: 21,860
    GGross said:

    Huh, I have done this before with no trouble, single 654 snow/ice sensor, OD sensor? All of Tekmars application guides show 2 complete sets attached to a single 40VA transformer so I never really thought twice about a 20VA transformer. Wouldn't be the first time I was wrong and probably won't be the last!

    EDIT: @hot_rod Yeah I was mistaken I just got off the phone with the Tekmar rep and he said they have had trouble with the 654 on smaller transformers. I must have been using a different relay with a larger transformer in the past

    This number on the 654 sheet had me wondering?

    The 3, 4 and 6 Caleffi ZSR relay boxes have a removable/ replaceable/ reset able fuse protected 40 Va now.

    There are probably earlier versions on the shelves with 12 or 20 Va, however.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • CBRob
    CBRob Member Posts: 273
    40 VA transformer is pretty straightforward, but the tekmar 003 relay is big and bulky.
    The times I've used it I've had to source a control box to enclose it in rather than your typical electrical box when they knock out.
    It's only being used to take a 24 volt signal and relay a circulation pump.
    Any potential problems substituting an enclosed relay that fits in a box knockout?
    It's powering a 26-99 1/6 hp pump.

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,567

    This control is less expensive and does everything that the separate Transformer and relay you origionally poster and everything that the UPZCP-1 control does.
    https://www.supplyhouse.com/DiversiTech-D-90113-Fan-Center-DPDT-Relay-120V
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    CBRobMikeAmann
  • CBRob
    CBRob Member Posts: 273
    Is there a duty rating for transformers?
    I understand hertz and kinda understand the VA, but it is only apparent power in AC current.
    The 654 snowmelt must pull a decent load for it's assorted temp sensors and computer.

    Not every transformer that says 40VA seems to be able to delivery the watts continuessly.
  • CBRob
    CBRob Member Posts: 273
    Do folks just stack boxes to make a space for this tall relay? 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,567
    The relay I indicated above is rated 40VA. however I always add a Smoke Keeper
    Here is the relay comparison from the Grundfos to the Fan Center. If you can read wiring diagrams you will see that they are identical as to function.


    https://www.supplyhouse.com/DiversiTech-D-90113-Fan-Center-DPDT-Relay-120V
    Just mount the relay on a square box.

    This is the Smoke Keeper I referred to above. It keeps the factory installed smoke inside the transformer.



    You keep referring to putting components into a box of some type. I wonder if you can take a picture of the box you have that you want to put this stuff into?

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    MikeAmannLarry WeingartenCBRob
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,567
    edited October 2023
    As far as transformer ratings go. VA stands for volts x amps. So, if you have a 24 volt transformer rated at 40 VA, that transformer will produce a maximum current of 1.666 AMPs at 24 volts. When connected to more loads so the draw is greater than 1.667, the windings will heat up enough to open the windows that keep the factory installed smoke inside.

    It just so happens that watts is also volts x amps

    Transformers are rated in VA because they will product that much power
    Loads are rated in Watts because they will consume that much power.

    This is done for a very scientific reason... To confuse the masses.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    CBRob
  • CBRob
    CBRob Member Posts: 273
    Grundfoes let me down 👎

    Bought this transformer relay combo believing it was 40 VA

    It would shut down intermittently from over heating I guess 

    Turns out it is not 40VA but just 6VA.