25 May 2005
Figure 5-1. Hot Water Boiler
Description of Hot Water Systems. A typical hot water (hydronic)
Figure 5-2, except that a fired or non-fired heat exchanger is used rather than a chiller.
Hot water boilers (fired and unfired) differ from steam boilers described in Chapter 3
Provide heated water but do not generate steam.
Do not have deaerating heaters. (These are not required because there is
essentially no makeup water requirement and thus very little air enters the
Require recirculating pumps to distribute the heated water to the
Require expansion tanks that contain a cushion of steam or nitrogen.
Do not contain a condensate return because there is no steam generated,
but there is a return system.
Do not require blowdown.
Are fabricated with mild steel components, but also may contain copper
heat exchanger tubes, particularly in unfired systems.