Install Instructions
4 Water connections
32
Low temperature return water systems
Any non-condensing boiler and venting system will develop
operational problems when exposed to inlet water temperatures
below 140°F. Lochinvar offers a low temperature protection
valve (LTV) that is factory preset to maintain 140°F inlet water
to the boiler regardless of the system return water temperature.
See Table 4A for available valve kits.
TABLE 4A
LTV VALVE KITS
MODEL LTV VALVE KIT
497 - 747 100172001
987 - 2067 100172000
Be sure to install the LTV valve per the piping diagrams
included with the kits. Alternatively, a bypass as shown in FIG.
4-6 may be piped into the system. This piping is like a primary/
secondary boiler installation with a bypass in the secondary
boiler piping. Inlet water temperatures below 140°F (60°C)
can excessively cool the products of combustion resulting in
condensation on the heat exchanger and in the flue.
Condensation can cause operational problems, bad combustion,
sooting, flue gas spillage and reduced service life of the vent
system and related components. The bypass allows part of the
boiler discharge water to be mixed with the cooler boiler return
water to increase the boiler inlet temperature above 140°F
(60°C). This should prevent the products of combustion from
condensing in most installations. The bypass should be fully sized
with a balancing valve to allow for proper adjustment. A valve
must also be provided on the boiler discharge, after the bypass.
Closing this discharge valve forces water through the bypass.
Start boiler adjustment with the bypass valve in the full open
position and the boiler discharge valve half open. A small
amount of the higher temperature boiler discharge water is
mixed with the system water to maintain the desired lower
system temperature. A remote low temperature range operator
is recommended to control the boiler operation based on the
lower system temperature. (See Terminal Strip Connection
Options starting on page 40).
Radiant floor and snow melt heating
systems
This type of heating boiler application operates in a low
temperature range which requires a boiler bypass as described
under the Low Temperature Bypass Requirements section. A
non-metallic rubber or plastic tubing installed in a radiant (in
floor) system must have an oxygen barrier to prevent oxygen
from entering the system through the walls of the installed
tubing. Excessive oxygen absorption into the system will result
in an accelerated rate of corrosion causing a sludge buildup.
This excessive corrosion will also damage the boiler and system
components. Sludge formed as the result of excessive oxygen
in the system can restrict water flow resulting in a premature
boiler failure. Any boiler damage due to excessive oxygenation
is non-warrantable.
TABLE 4B
SYSTEM TEMPERATURE RISE CHART
Temperature Rise Based on Boiler Input in Btu/hr
Btu/hr 10°F T 20°F T 30°F T 40°F T 50°F T 60°F T
Input Output GPM Ft/hd GPM Ft/hd GPM Ft/hd GPM Ft/hd GPM Ft/hd GPM Ft/hd
495,000 401,000 80+ * 40 4.0 27 1.6 20 0.6 16 0.6 13 0.6
645,000 522,000 129+ * 52 5.1 35 3.0 26 1.2 21 0.8 17 0.6
745,000 603,000 149+ * 60 * 40 4.0 30 1.6 24 1.2 20 0.7
985,000 798,000 197+ * 80 5.2 53 2.4 40 1.4 32 1.0 27 0.8
1,255,000 1,017,000 251+ * 102+ * 68 4.3 51 2.3 41 1.6 34 1.1
1,435,000 1,162,000 288+ * 116+ * 78 6.0 58 3.7 47 2.2 39 1.7
1,795,000 1,454,000 360+ * 146+ * 97+ * 73 6.2 58 4.2 49 2.4
2,065,000 1,673,000 414+ * 168+ * 112+ * 84 8.7 67 6.0 56 4.5
+ These flow rates exceed recommended flow rates of boiler. If these system temperature rises are used, an external piping bypass must be
installed.
*These foot head calculations exceed the maximum allowable flow rate of the boiler. Requires Cupro-Nickel heat exchanger.
Installation & Service Manual