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Transformer Voltage Compatible

sdguy

Unregistered

1

Sunday, March 10th 2013, 3:15pm

Transformer Voltage Compatible

Hi,

I recently purchased a Irritrol RainDial 1200R External controller. After I received it, I changed my mind on the location of the controller and now would prefer to just use a plug in transformer. I have an old RainBird model controller that has a transformer rated at 26.8vac/1a. How sensitive is the new RainDial controller to different voltage coming? Can I reuse my old transformer or do I need a transformer that is truly 24vac? If so, are generic (RadioShack) versions good enough or do I need to find an Irritrol version somewhere?

Thanks,

Darryl

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

2

Sunday, March 10th 2013, 5:24pm

You'll be fine with the existing plug-in transformer.

treetopvt

Starting Member

Posts: 1

3

Tuesday, July 30th 2013, 1:14pm

Replacing blown transformer

I have a non-functioning 26.5V @ 50VA transformer. What is the important number to match? Voltage, VA, or calculate the mA? I am having trouble finding a like spec'd transformer.

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

4

Wednesday, July 31st 2013, 10:41am

RE: Replacing blown transformer

Quoted from "treetopvt"

I have a non-functioning 26.5V @ 50VA transformer. What is the important number to match? Voltage, VA, or calculate the mA? I am having trouble finding a like spec'd transformer.
Sight unseen, the 50 VA is the key number, and not the 26.5 V - modern solid-state controllers subtract a small amount of voltage through the circuitry, unlike the purely mechanical controllers of the past, so the higher voltage number has become customary. Since modern valve solenoids will operate with as little as 18 volts, the difference between a supply transformer rating of 26.5 VAC or 24 VAC is not important.

On the off chance you were going to be powering obsolete Rainbird Thermal Hydraulic valves, you might have to go bigger than 50 VA, depending on the system's wiring.

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