I'm getting ready to dig my 100' water line trench between my house and shop and am considering the different wiring that needs to be buried also. My HVAC man is telling me that he thinks that my long run of thermostat wires (approx. 130' total) will be too far to maintain voltage needed to throw my relays in the shop. I don't recall anyone here raising that as a concern. I could understand the problem if I was running 24DC, but I didn't think I'd have a problem with this being that the current is AC. Is this going to be a problem? My HVAC man is semi retired and probably won't be involved in my project, but I do respect his knowledge in this area.
Long run of 24VAC wires
- Thread starter Shelterman
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There are different gauges of t-stat wire. I always use 18 awg. It is worth the extra few bucks to use the heavier gauge. Unless you have some unusually large draw relays you should be fine at that distance.
Also put the wire in a pvc conduit should you ever need to replace or add conductors.
hr
Also put the wire in a pvc conduit should you ever need to replace or add conductors.
hr
Thanks for the fast reply. I really didn't think I'd have a problem but wanted to be sure. I'm planing on running two separate pvc runs, one for any AC lines and another for telephone, LAN, sensors, etc.
I see you are in my neck of the Ozarks. I'm in Houston...Texas County. Where in SW MO are you? You can pm me if you would prefer.
Thanks Again,
David
I see you are in my neck of the Ozarks. I'm in Houston...Texas County. Where in SW MO are you? You can pm me if you would prefer.
Thanks Again,
David
ewdudley
Minister of Fire
Shelterman said:
To be more sure, just go ahead and do the arithmetic for E = IR. Whatever you're driving is going to present a load of some specified number of amperes, and it should also specify a minimum operating voltage. Look up ohms per foot:
http://www.powerstream.com/Wire_Size.htm
And then calculate voltage drop for your candidate wire gauge.
E.g. 18 awg: 200 ft * 6.4 ohm / 1000 ft = 1.28 ohm. If load is 2.3 amperes, voltage drop would be 3 volts. If the device will work with 21 volts or so, you're all set, else need fatter wire.
[Just re-read the question, if all you're driving is relay coils then you're not talking a couple amperes, but merely a couple dozen milliamperes, so the voltage drop would be negligible. Stuff like zone valve motors might be another story.]
--ewd
woodsmaster
Minister of Fire
Don't know anything about it, but if you put the circulater in the shop wouldnt't that eliminate the need for wire?
I'm going to use Nofossil's "Simplest Pressurized Storage System" and thought I'd probably purchase something like this: http://www.pexsupply.com/Taco-ZVC406-3-6-Zone-Control-Module-with-Priority-3662000-p for my control module.
btuser
Minister of Fire
No. Just the opposite. Boiler, storage, pumps, zone valves, and controler will be in the shop. Wall thermostat will be in the house.
btuser
Minister of Fire
Well then you're all set. Depending on what thermostat you get you won't even need power, just a relay-like thermostat either a round or a battery powered thermostat that will close on demand and open on rise.
I have my 24 volt transformer in my Garn barn and have 400 ft of wire to the house that run thermostat's and relays and have no problems with voltage drops.
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