Line Voltage Conversion to 24v

[Tazzman]

Hi,

I’m interested in converting my Line Voltage Thermostat to24v. Then with the intensions of havingan Internet assessable Stat. I know Ineed a step down transformer, or as well I’ve been told I should use a DefinitePurpose Contactor. Providing this willmake my conversion in current if I’m not mistaken the Stat requires 3 legs;Hot, Neutral & Ground. Clearly Iwill have 2 of the 3. Can I run a 3^rdwire & pick up this ground with the ufer of my home? Can this Project Conversion be done?
Thanx, Tazzman

[HayZee518]

low voltage

sure its possible. what you'll be purchasing as an extra is a control relay with a 24 volt ac coil and a 120 volt rated open contact[or] also a 120 volt to 24 volt ac control transformer. get back to me and I'll draw you a diagram.

[Tazzman]

Thank you for your help. I diagram would be great. That 3rd leg is it important? Thanks again....

[HayZee518]

switching relay

I found this item on amazon dot com. its a honeywell relay with an internal 24 volt transformer. there are two 24 volt thermostat connections and a straight forward wiring diagram.
Honeywell R845A1030 Circulator Relay, 120 Volt DPST - Amazon.com

[Tazzman]

Thanks. Maybe I should have made mention that it is 220 & that I have 3 separate Line Voltage Stats that I wish to combine into 1 Internet access Stat...

[HayZee518]

thermostats

as long as we are failing to mention things - I'll ask a few myself.
first: where are you located?
if your line voltage is 220, that should show you in europe or england.
if your existing thermostats are line voltage, you must have electrical baseboard heat. or at least a heat pump.
judging from your name, you must be in new zealand or australlia.
is your power 60 or 50 hertz?

[Tazzman]

as long as we are failing to mention things - I'll ask a few myself.
first: where are you located?
if your line voltage is 220, that should show you in europe or england.
if your existing thermostats are line voltage, you must have electrical baseboard heat. or at least a heat pump.
judging from your name, you must be in new zealand or australlia.
is your power 60 or 50 hertz?

That's Funny. I live in North East Iowa. So yes I'm at 60Hz & do have Base Board heaters at 220. Each room in my Home has its own stat. Of the 6 stats I only really ever heat 3 of the rooms & that keeps me fine in the winter. In any event I would like at some point to have these on one Stat......

[HayZee518]

stat & heat

ok, I'm trying to visualize the most practical way of connecting up your loads.
each heater comes off its own breaker at the panel. am I correct?
you can use a 120 volt to 24 volt transformer as your control circuit.
each heater I'm guessing draws at least 20 amp.
therefore for each heater you wish to control you'll need a two pole single throw relay or definite purpose contactor.
the Allis Chalmers brand used in HVAC should suffice. this type uses 24 volts as the control voltage.
I'll look into it and see if I can come up with a stock number, then submit to you a diagram of how to hitch it up.
for starters, the line runs to the existing thermostat location, then goes to your load.
at each location [stats] you'll need to remove the stat and splice the lines to the loads [wires] so that they're on all the time.
you'll be breaking the chain at the panelbox.
you'll be taking a two wire from each breaker of each heater - go to the relay, then connecting the load[s] to the relay terminals.
confusing? yes but the diagram will show what I got in mind.
the common digital stat will operate all three contactor's control coils.

[HayZee518]

ditto: subject

I found the following at a hvac parts supply house: site is: HVACPARTSOUTLET dot COM

Carrier Bryant 2-Pole 24-Volt 30Amps Contactor HN52KC025
Your Price: $36.86
Carrier Bryant 2-Pole 24-Volt 30Amps Contactor HN52KC025
Carrier Bryant 2-Pole 24-Volt 30Amps Contactor HN52KC025
This should start you off.
Get one for each heater you wish to control.

[HayZee518]

Heaters

I've attached a diagram of how to hitch up a circuit for your heaters
The diagram shows 3 active contactors and 3 spares.
If you wish to connect up additional heaters to their own contactor
operating off the common digital "stat" just duplicate the wiring.
You'll need to find a metal enclosure for all the parts.
The control transformer is a 120 volt primary with a 24 volt secondary
Size should be around a 50VA size.
Get two terminal strips of three or two screws each for inter connections
Suitable hardware for fastening the parts inside the enclosure.
A lug for the grounds

[Tazzman]

Yes that is correct. Each BB Heater has it's own Breaker. How you explained/spelled this new install out is how I visualized as well. As you pointed out it's the Homework on the Hardware of devices that I will need. As well finding a new Stat that will use only 2 wires with an Internet access feature. Most likely that 3rd ground is not important for it's operation although, I will run it anyhow and maybe just pick up a Ground of the Ufer of my Home. You have been very helpful & I sincerely appreciate youhelp. May I ask which state you live in? Tazzman

[HayZee518]

heaters

I'm in NY and I hold a master electrician's license from Massachusetts,
what is this"Ufer" you refer to?

[Tazzman]

This is the technical definition. Concrete-Encased Electrode.

An electrode encased by at least 50 mm (2 in.) of concrete, located within and near the bottom of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (½ in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4 AWG. Reinforcing bars shall be permitted to be bonded together by the usual steel tie wires or other effective means.

[HayZee518]

grounding electrode

your point???

At a power company I worked for in Massachusetts, there is a 345KV three phase switchyard.
It measured roughly 300 ft X 600 feet in a rectangle. Beneath the gravel roadbed about two feet down is a copper grid of copper coated rebar forming 1 foot squares.
It is exo thermally welded together at each junction point and at each cable running to above ground structures. the minimum wire size is 350mcm.

[HayZee518]

grounding electrodes

I think you opened up a can of worms about a grounded electrode encased in concrete.
This brings about a question about the concrete. Has it enhanced qualities with regards to composition.
Does the mix have more or less limestone in it? Does it have more or less sodium chloride in it?
What is the ratio of gravel to sand to portland cement in it?
Is the concrete [cured] or is it still wet?
What encases the concrete, dry sand or wet sand or is the ground wet? What is the ground resistance
where the electrode is located?
What earth bound chemicals [naturally occurring] are in the soil?
Insofar as what is stated regarding rebar splices, I beg to differ that the splicing wires afford a suitable bond
between each rebar at a junction. The tie wires are iron wire. If the ground rods are copper clad, there might be
electrolytic activity between the copper and iron wires.
They state that the rods cannot be smaller than 1/2 inch. Most commercially available ground rods are either
galvanized steel or copper clad steel no less than 5/8 inch diameter, 8 foot long.
Connections to the ground rod is either through a bolted "burndy" ground lug or exothermally welded connection.
The grounding electrode conductor is always stranded cable as opposed to a solid ground and is always bare.