www.fueloilnews.com | FUEL OIL NEWS | JANUARY 2017 45
may require a licensed electrician.
Let's look at an example of 24 Vac zoning. Again the low-voltage
transformer, Figure 4, acts as the primary power generator for zoning
with dampers and zone valves. It's true that the zoning panels used
today, Figure 5, are so much easier during the initial install and in my
opinion on that basis only are worth the additional costs. Servicing is
also simplified since each circuit can be readily checked at the board
for power in and power out. With today's boards you can also easily
mix line voltage with low voltage to accomplish amazing things like
Primary-Secondary pumping with an indirect and low voltage zone
valves and why I went with such a panel in my own home.
When wiring "old school" I've found that a simple little device
called a "barrier wiring strip" Figure 6. These can really simplify the
wiring and make it easy to troubleshoot too. In Figure 7 we show the
wiring for three wire zone valves, Figure 8, using the wiring strip and
in Figure 9 for four wire zone valves, Figure 10.
Finally, we should go over how to properly size a 24 Vac trans-
former. With the popularity of multi-zone systems and the use of
low-voltage zone valves come problems with knowledge of amperage,
or "those little amps have got ya again". So, the problem can be fixed
with just a little knowledge.
The problem? How do you size a transformer for a multi-zone
system using zone valves? There are three things you need to know
Figure 4
and the first two are pretty simple:
the primary voltage, normally 120 volts,
the secondary voltage, normally 24 volts, and
the volt-ampere output (VA).
So how do you find VA or Volt Amperes? There's only one
right way, by using this formula:
unknown VA = required VA x E
