Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

24vac relay wiring

Options
I need to supply power to a 24v ac relay from the furnaces 24v system that powers the thermostat. My question is when my furnace calls for forced air to run I want to use that signal ( the common and Y1 wires) to power the relay to turn off my circulation pump. I not that familiar with  24v ac power so will that power draw the relay uses mess up the power to my thermostat, like blow a fuse or something?

Comments

  • Daveinscranton
    Daveinscranton Member Posts: 148
    Options
    Volts x amps = watts.  A common 24 volt transformer is 40 va.  40 volt amps.  40 watts.

    Depends on the size (rating) of the transformer as to how much you are using and what you have to spare.  You can measure the load with an ammeter in series with the load (24 volt side of the transformer).  Do not connect an ammeter across the poles of the transformer. Has to be in series.

    There is usually some head room on transformers.  A little uncommon to have something wired at the ragged edge of its rating, but anything is possible.

    Best wishes 
  • 4eeny_
    4eeny_ Member Posts: 8
    Options
    Ok thanks I will check that out
  • Daveinscranton
    Daveinscranton Member Posts: 148
    Options

    BTW. There is also a maximum current rating on the thermostat.  Cannot exceed that or your thermostat will not last.  

    Most 24 volt relays don’t draw a lot of current.  I have big relays.  They draw .3 amps.  
    4eeny_
  • pecmsg
    pecmsg Member Posts: 4,845
    Options
    4eeny_ said:

    I need to supply power to a 24v ac relay from the furnaces 24v system that powers the thermostat. My question is when my furnace calls for forced air to run I want to use that signal ( the common and Y1 wires) to power the relay to turn off my circulation pump. I not that familiar with  24v ac power so will that power draw the relay uses mess up the power to my thermostat, like blow a fuse or something?

    What circulator pump?

  • ratio
    ratio Member Posts: 3,625
    Options
    4eeny_ said:

    I need to supply power to a 24v ac relay from the furnaces 24v system that powers the thermostat. My question is when my furnace calls for forced air to run I want to use that signal ( the common and Y1 wires) to power the relay to turn off my circulation pump. I not that familiar with  24v ac power so will that power draw the relay uses mess up the power to my thermostat, like blow a fuse or something?

    Y1 is typically the first compressor stage, cooling for an AC unit or heating and cooling for a heat pump. W/W1 is the first stage of heat (non heat pump) or the first stage of aux/em heat (heat pump). G is the fan call, but it may not be asserted by the stat for furnace heat calls.
  • 4eeny_
    4eeny_ Member Posts: 8
    Options
    Sorry I may have my letters wrong, it’s the white wire that energizes when the forced air heat comes on, I didn’t explain well in my original post, the problem I have is my 3 circulating pumps (3 zones, basement, main floor and garage) run independently from my duel furnace (forced air/ fluid heater) so when my forced air is running my pumps continue to run cooling the fluid off. So what I need is when the forced air is running I want my circulating pumps to shut off( the pumps have their own relay controller with priority switch). I thought I could just wire a relay from my forced air signal to my pump controller
  • HVACNUT
    HVACNUT Member Posts: 5,833
    edited January 2022
    Options
    I guess its not a 2 stage thermostat?
    Are there 2 thermostats? One for the furnace and one for the circulator?


  • 4eeny_
    4eeny_ Member Posts: 8
    Options
    Yes, each pump runs off its own thermostat and I have an ecobee that runs the furnace
  • 4eeny_
    4eeny_ Member Posts: 8
    Options
    Also there is a aquastat that goes to the furnace from the fluid tank
  • pecmsg
    pecmsg Member Posts: 4,845
    Options
    Im still confused. Is this a furnace or a forced air unit with a hot water coil?
  • ratio
    ratio Member Posts: 3,625
    Options
    Sounds like two separate systems that need coordinated.

    Protip: Electricity don't know no color. What that mean is that the color of a wire is just a convenience to (sometimes) tell them apart. You gotta check what terminal it's attached to to know what it's supposed to be doing. & No guarantee that they're all wired the same.

    4eeny_
  • 4eeny_
    4eeny_ Member Posts: 8
    Options
    Yes, it’s a geothermal system , the furnace heats the fluid up for the floor pumps and then it also runs the forced air , it’s a Waterfurnace synergy3d, it’s just when the forced air is running it doesn’t heat the fluid so with all 3 floor pumps running it cools the whole holding tank off so much it takes forever to warm back up, so to run much more efficiently I want to stop the pumps when forced air is going
  • pecmsg
    pecmsg Member Posts: 4,845
    Options
    4eeny_ said:

    Yes, it’s a geothermal system , the furnace heats the fluid up for the floor pumps and then it also runs the forced air , it’s a Waterfurnace synergy3d, it’s just when the forced air is running it doesn’t heat the fluid so with all 3 floor pumps running it cools the whole holding tank off so much it takes forever to warm back up, so to run much more efficiently I want to stop the pumps when forced air is going



    You have in floor radiant heat with an air handler? No Furnace.
    If I'm reading this right when 2nd stage call's you're getting cold drafts?
  • ratio
    ratio Member Posts: 3,625
    Options
    Geo system with 3 radiant loops & one hydro air coil on a gas furnace? No air conditioning? I'm trying to get the complete picture.

    In any case, when the furnace/air handler runs, the radiant pumps are still operating & the geo system can't keep up so you want to lock out the radiant loops while the furnace/air handler is calling. I think we need a pic of the furnace.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,519
    Options
    @4eeny_

    You have to realize no one here that I know of has x ray vision. We cant see your equipment or have any idea what you have. You have to post some pictures or be able to describe your system so we can "see" what you have
    4eeny_
  • 4eeny_
    4eeny_ Member Posts: 8
    Options
    I’m can’t seem to get a photo on here, the Waterfurnace synergy3D dual capacity furnace is electric, no gas, it does forced air heating/cooling and also heats the fluid that the floor pumps circulate. The thermostat that controls the air temp on the main floor (ecobee) come from the furnace uses 24v ac, so when that thermostat calls for the forced air to run it sends a 24v signal to furnace to come on , I just want to use the power from that signal to run a 24v relay then I can get my  circulating pumps to shut off, I have things figured out on the pump end , I just want make sure running that relay from that signal wouldn’t  mess up power to thermostat or signal to furnace
  • pecmsg
    pecmsg Member Posts: 4,845
    Options
    Just put an Aqua stat on the fan. If the coil is cold, it won't come on!
  • 4eeny_
    4eeny_ Member Posts: 8
    Options
    Thanks for all your feed back guys, I think my concerns have all been addressed. I’ll get this hooked up now
    Cheers