Burnham 40A - Manual (Page 6)

6
Select a circulator which will provide at least the
minimum flow rate at combined pressure drop.
B. System Zone Control The Alliance TM water
heater must be installed as a zone separate from the
space heating system. The domestic hot water zone's
piping and circulator must be sized for a minimum
flow rate with all zones in use and a maximum flow
rate with only the water heater in use. For this reason,
the preferred method of zone control is with
circulators.
1. Circulators - With space heating zones using
circulators, the Alliance™ should be added as an
additional zone with a circulator.
2. Zone Valves - Select a valve with low pressure
drop to assure adequate flow through the water
heater.
3. Hybrid - The space heating zone can be zoned
using zone valves and Alliance™ zoned with a
circulator. Refer to Figures 3 and 5.
C. Domestic Hot Water Priority Two options are
available, Priority and Non-Priority.
1. Priority Demand for space heating is interrupted
or postponed until the domestic hot water demand
is satisfied. This option provides maximum delivery
of domestic hot water. Priority is recommended
when:
a. Boiler net output is 100,000 Btu per hour or
less, or
b. When boiler output required to satisfy domestic
hot water demand is at least 50% of the boiler
output required to satisfy space heating demand,
or
c. When an interruption in space heating can be
tolerated during a long domestic hot water draw.
The delay in space heating may not be noticed due
to the fast recovery time of the Alliance
TM water
heater. Certain water heater system malfunctions
(such as domestic hot water zone circulator failure)
could delay space heating indefinitely.
When zoning with zone valves, priority can be
provided with a three-way valve. Carefully size the
valve for proper flow to all zones.
2. Non-Priority Boiler output is divided between
space heating and domestic hot water heating.
Delivery of domestic hot water can be reduced
during simultaneous space and domestic hot water
heating operations, depending on such factors as
boiler output, boiler over sizing, number of space
heating zones calling for heat and ratio of domestic
hot water load to space heating load.
D. Component Location
1. Alliance™ Location
When such a location cannot be avoided, a suitable
drain pan must be installed under the water heater.
The drain pan must be connected to a drain.
Adequate clearance from combustible materials and
for service must be provided.
The Alliance TM is design certified for installation on
combustible flooring.
The Alliance™ may be installed in a closet or
alcove.
2. Boiler Location - Locate the boiler as close to the
Alliance™ as practical.
3. Fixture Locations - For fastest delivery of hot
water, place Alliance
TM close to points of use.
E. Additional Recommended Components
1. Shut-off Valves - Allows isolation of water heater
from domestic water system and/or boiler system
during service.
2. Unions - Allows water heater movement during
service if adequate clearance cannot be provided.
3. Vacuum Breaker - Protects water heater's tank
from possible collapse if a hot tank is allowed to