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Hello,does anyone know what the standing and circulating PSI should be for PP12N boiler? Thanks for any assistance.Arthur
Paloma Pak needs
11 feet of head to raise the manifold seat leaving 7 feet of head to circulate the water.If the diaphragm is not lifted by the water pressure, there can be no flow of gas to the burners.
Water Diaphragm Safety Valve
This valve is an integral part of the boiler's safety section to prevent "dry firing." The water diaphragm valve body casting consists of two sections, one upper and one lower which is separated by a reinforced neoprene diaphragm. The valve as a whole is held together by five phillips head screws.
The upper section of the valve holds the "0" ring, and S.S. lift pin (spindle) which rests on the diaphragm plate. The "0" ring allows the pin to travel smoothly up and down and also acts as a water seal.
The lower section of the valve has two threaded connections, one male and one female. The male thread is connected to the boilers heat exchanger. The female thread is connected to the %" "return" (right side) piping.
A venturi is located internally on the right side of the water diaphragm valve where the heat exchanger tube is connected to the valve. (To locate and remove the venturi, close isolation valves and drain boiler. Remove the "right side" tube connections and the venturi will be inside the threaded portion of the water diaphragm valve). By using a pair of pliers, gently remove the venturi. Once removed, notice two "0" rings and two orifice holes. Inspect this venturi for any restrictions such as excess solder, sludge, or other foreign material. Any excess restriction at this point is very critical and might cause the gas control to remain closed. The purpose of the side venturi holes between the "0" rings are to draw water off the top of the diaphragm as the venturi creates a suction effect as a result of water flow. The venturi is designed to fit only the proper way, so reassembly is simple.
The complete working process of the water diaphragm valve goes as follows: a thermostat call energizes the 24V relay which completes the 120V circuit to start the high head pump. The high head pump creates 18 feet of head. As the water is circulated by the pump, it enters the inlet side of the water valve (at right back) and forces the diaphragm up as the top cavity water is drawn off by the venturi. Above the diaphragm is the pin which is forced up by the upward motion of the diaphragm. As the pin moves up, it lifts the manifold seat open which allows the gas to flow to the main bumer(s). It is important to note that a force of 11 feet of head is required to raise the manifold seat leaving 7 feet of head to circulate the heated water. (If the diaphragm is not lifted by the water pressure, there can be no flow of gas to the bumers).
SERVICE NOTE: If the pilot is established, the pump is circulating, and all controls are functioning properly, but no main burner can be established, there is a slight chance that there could be foreign matter in the valve, or a rupture of the diaphragm.
The other reason the water diaphragm valve may not function is the pump may not be delivering sufficient flow to the heating system itself, or zone valves or piping may be restricting that flow.
In order to inspect the complete diaphragm valve, secure the heating system and drain the boiler by using the isolation ball valves supplied. At this time it will be necessary to disconnect the union connection to the supply side of the heat exchanger. Remove the operating control sensing bulb from the system return line and disconnect the return side union, loosen the two phillips head retaining screws at the gas manifold and drop the entire assembly out of the unit. Remove the five phillips head screws from the water diaphragm valve top section, open and inspect the diaphragm, "0" rings, and venturi tube for damage or blockage. A repair kit is available, which includes a diaphragm "0" rings, and gaskets.
When installing the diaphragm, be certain that the large metal disc is on the top (facing up).
The spindle "0" ring is held in place by a staihless steel retaining clip. To remove the clip, there is a protruding tab that when grasped with a pair of pliers and pulled away from the casing, will snap out exposing the "0" ring for replacement. The "0" ring retainer re-installation is simply snap it back into the original position and bend the tab down to its original position.
Mike...thanks for your response. Would you or anyone else know what the PSI gauge should read? Arthurmerc0
Sorry about that....I meant Tim.0
For Paloma Pak it
should read at 18 LBS pressure. Make sure that someone didn't change the circulator. These systems require a high head pump typically a Grundfos 26-64 1/12 HP, 1.65 A water lubricated or its equivalent.
The longest single run of pipe is 200' system flow rate 4 GPM and it should be piped with Pri/Sec loop system.0
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