National Oilheat Research Alliance 29
To determine total head loss, the head loss
for the zone valve must be added to the head
loss of the associated piping.
Add 2.31 foot of head for the zone valve to
the 6 foot of head for the piping and the total
head loss with the zone valves included is
8.31.
The proper circulator for this application
will have to provide 6gpm (flo rate is cumulative)
and overcome 8.31 foot of head.
The proper circulator for this application is
Circulator #5 or the medium setting on a
3 speed circulator.
Expansion Tanks
Sizing expansion tanks is easy—use the
tank manufacturer’s guidelines if they are
available.
For example, some manufacturers’ recommendations
can be found at this link:
http://www.elmcoduddy.com/htx-sxht_sizing.
pdf
If manufacturers’ guidelines are not available,
there are rules of thumb for sizing tanks:
Diaphragm tanks—1 gallon for each 7,000
Btuh of heat load. For example, if the heat
load is 100,000 Btuh, the tank should be a
minimum of 15 gallons (100,000/7.000 =
14.3).
Steel compression (air cushion) tanks—1
gallon for each 5,000 Btuh of heat load. For
example, if the heat load is 100,000 Btuh,
the tank should be a minimum of 20 gallons
(1,000/5 = 20)
For detailed information on properly sizing
expansion tanks see page 3-28 in IBR
Manual.