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IMPORTANT
• Some indirect water heaters may not be suitable for use with a steam boiler. Consult the water heater
manufacturer’s guidelines before installing it in this type of system.
• Boiler water temperatures and flow rates in this type of system may be considerably lower than those upon which the
water heater manufacturer’s ratings are based. This may result in substantially longer water heater recovery times.
2) Flow Restrictor (Recommended) - If water is drawn from the tankless coil at a rate in excess of the rating in Table 1b, the
temperature of the hot water may be too low to be of use. The use of a flow restrictor will prevent this problem by limiting
the rate at which water can pass through the tankless heater. If a restrictor is used, select one having a rating in GPM
approximately equal to the rating shown in Table 1b. If possible, locate this restrictor at least 3 feet from the tankless heater
inlet so that it is not subjected to excessive temperatures when no water is flowing through the coil.
3) Pressure Relief Valve (Required) - Limits the pressure in the tankless heater and piping. Use an ASME constructed valve
designed for domestic water service, such as the Watts #3L. Note that this is a pressure relief valve, not a T&P valve.
Select a valve with a pressure setting less than or equal to the working pressure marked on the tankless coil. Pipe the
discharge to a safe location using piping the same size as the discharge connection on the valve.
4) Hose Bib Valves (Recommended) - These valves permit the coil to be periodically “backflushed” to remove sediment.
WARNING
A mixing valve does not eliminate the risk of scalding.
• Set the mixing valve and boiler low limit adjustments as low as possible.
• Feel water before showering or bathing.
• If anti-scald or anti-chill protection is required, use devices specifically designed for such service. Install and
maintain these devices in accordance with the manufacturer’s instructions. Do not use the mixing valve as a
substitute for pressure balancing valves or other devices required by plumbing codes to protect against
scalding.
TANKLESS HEATER PIPING
KSZ Series boilers equipped with tankless heaters are supplied with a Honeywell L4006A limit control and a 3/4 NPT well.
For shipping purposes, these components are shipped unmounted. This control is mounted in the 3/4 tapping in the center
of the tankless coil.
Make the piping connections to the coil before installing the L4006A. When making the “OUT” connection, make sure
that the piping is routed so that it will not interfere with the L4006A.
Pipe the heater as shown in Figure 12b. The components in this system and their functions are as follows:
1) Mixing Valve (Required) - During the heating season, the water exiting the tankless heater may be 180 degrees or more.
The mixing valve blends hot water leaving the tankless heater with cold water so as to maintain the hot water supplied to
the fixtures at a fixed temperature. This saves energy, increases the amount of usable hot water available to the
homeowner, and reduces the risk of scalding.
Install a mixing valve with a setting range of approximately 110 to 130F. Follow the manufacturer’s instructions for
installing this valve. Usually a “heat trap” will be required between the coil and the “hot” connection on the mixing valve.
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