LAARS HEATING SYSTEMS
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Air Vent
Another device used to purge air from the Circuit.
Should be located at the highest point in the Circuit.
Branch
The section(s) of supply and return piping, including
the heat distribution units (see below), connected
directly to the trunk. Also referred to as a "zone."
By-pass
A section of pipe (including an adjustable valve) that
diverts part of the water flow from undersized piping
to the boiler. Adjusted to maintain minimum flow
requirement (GPM) through the boiler.
Circuit
Entire water circulation piping, beginning and ending
at the boiler (Series Loop System).
Expansion Tank (Compression Tank)
Installed in the circuit to accommodate excess water
produced by heat expansion.
Heat Distribution Units
Transfers heat from the water supplied by the boiler to
the area to be heated through the use of baseboard,
convector, radiator, finned tube. Also known as
"radiation."
Isolation Valve
Used to isolate the boiler from the circuit. It minimizes
the amount of water drained from the system.
Primary-Secondary Piping
Two or more interconnecting circulating loops, each
with its own pump. Primary=System Circuit;
Secondary=Boiler Circuit.
Reverse-return Piping
Balanced, equal flow (first in, last out) piping. Utilized
with multiple boilers and/or radiation. Applied with
single system pumps, or primary-secondary pumps.
Side Wall Power Venter
This Laars accessory allows the boiler exhaust to be
routed horizontally through an adjoining outside wall,
rather than gravity venting with a chimney or stack
when local codes allow.
System Purge Valve
A device used to purge air from the circuit. Should be
located as close as possible to the cold water feed,
but not immediately after the cold water feed.
Trunk
The section of piping which connects the boiler return
and supply with the branch(es). Also known as a
"main" or "header." Should be same size as boiler
inlet/outlet connections.
Vent Damper (optional in Canada)
Standard on JV boilers. This energy-saving device
prevents heated air from exiting the open vent when
the boiler is not operating.
Zone Pump
Circulators installed in branch piping that divert hot
water coming from the boiler into various areas
(zones) of a building.
Zone Valve
Diverts hot water from the boiler into various areas
(zones) of a building.
Glossary of Terms
