Thermo Products Models from 8 kW to 24 kW : 240 Volts ( single phase ) Flow-check valve

Install shutoff (ball) valves for servicing convenience. Install thermometers on the inlet and outlet lines.

Never plug the pressure relief valve to avoid creating a hazardous situation.

3.5.2 Flow-check valve

If the heating system uses a single circulator, a flow-check valve must be installed to minimize gravity flow and heat loss during non- draw periods.

3.5.3 Pressure relief valve

No boiler set-up is complete without a pressure relief valve. Its pressure rating must not exceed 30 psi (207 kPa). It must conform to the « ASME Boiler and Pressure Vessel Code» and limit the boiler operating pressure. It is a safety device, not a control device.

The BTU per hour rating of the relief valve must equal or exceed the BTU per hour input of the boiler(s) or heat source(s) as marked on the boiler(s) rating plate.

Connect the outlet of the relief valve to a suitable open drain, with the discharge at most 6” above the floor, far from any live electrical parts. The discharge line must pitch downward from the valve to allow complete draining and be no smaller than the outlet of the valve. The end of the discharge line should not be threaded or concealed and should be protected from freezing. No valve of any type, restriction or reducer coupling should be installed in the discharge line. Local codes shall govern the installation of relief valves.

3.5.4Operating pressure control : expansion tank

Operating pressure control components ensure minimum and maximum operating limits are observed within the design operating temperature range. These components allow bleeding air from the piping, prevent boiling and cavitation at the circulator inlet, while minimizing the amount of fresh water input. Please contact a qualified plumber or contractor for more information on this subject.

The expansion tank connection point must be carefully chosen to prevent a situation where closing a valve would isolate the tank from the

boiler or any part of the circuit. It is preferable to use a calibrated diaphragm expansion tank.

3.5.5 Makeup valve

Connecting a makeup valve must be done according to code. This valve must include a flow-check valve to maintain the minimum operating pressure by admitting fresh water from the cold water supply line in case a leak occurs.

3.5.6 Air bleeder

There should be as little oxygen as possible in the heating circuit to prevent corrosion. As foreseen in section 3.5.4, this excludes the use of air as a pressure regulator within the circuit.

Installing manual or automatic air bleeders prevents air accumulation within the system. The bleeders must be set at the highest points of the system to purge any air accumulated during system set-up and to check its air tightness. Bleed the air regularly from the piping, making sure the heating water causes no bodily harm or material damage.

3.5.7 Circulator zoning

A flow-check valve must be installed in each zone, preferably at the outlet of each circulator, to prevent water flowing to zones where no heat is currently required. (see figure 4).

3.5.8 Zone valve zoning

Zone valves with low pressure drop are recommended. (see figure 3)

3.5.9Circulator selection criteria

The COMBOMAXMC boiler includes a pre- mounted circulator. The information below will help you select additional units for multiple circulator set-ups.

3.5.9.1 Pump flow rate calculation

The boiler output rating must correspond to the calculated heating load. Use the equation below to calculate the pump flow rate:

COMBOMAXMC Electric boiler Set-up, use and care guide (revised January 2006), Page 6.