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Boiler troubleshoot: no heat upstairs.
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Oftentimes when a boiler stops working, the higher levels of the structure stop heating. The lower level may have warm radiators but all the higher levels have cold radiators.
The above diagram is of an older system that has an expansion tank located above all radiation. These systems are no longer used but it is easy to use to explain how the water system can stop flowing when there is too little water in the system.
Lets suppose the domestic water stopped. Evaporation will lower the level in the tank until it reaches the level of the radiator. That will produce an air bubble in the piping. The bubble will stop the circulating pump from moving water throughout the system.
The higher levels will have the bubble before the lower levels.
The above diagram is of an older system that has an expansion tank located above all radiation. These systems are no longer used but it is easy to use to explain how the water system can stop flowing when there is too little water in the system.
Lets suppose the domestic water stopped. Evaporation will lower the level in the tank until it reaches the level of the radiator. That will produce an air bubble in the piping. The bubble will stop the circulating pump from moving water throughout the system.
The higher levels will have the bubble before the lower levels.
On the left is a boiler pressure-temp gauge. On the top is boiler pressure On the bottom is the temperature of the water in the boiler. If the pressure is well below 12# (18# for a 2 story building), and there is no heat in the uppermost floor, the pressure reducing valve is not feeding.
The video below covers troubleshoot of the valve. |
There is an adjustment on top of the valve used to change the pressure.
Generally, no adjustment is necessary because the valve was set properly when it was new. If it has been in use for over about 5 years and is not feeding, the screen on the inlet can be checked to see if it is plugged. If it is clear and water can be flushed through it and it still does not feed, you may try adjustment of the valve but it may not work. Also, if the valve begins to feed after adjustment, it may not stop feeding and will overpressure the boiler. When the pressure reaches over 25#, the relief valve will begin to leak.
Bottom line if, after 5 years, the valve stops feeding, it probably should be replaced.
Generally, no adjustment is necessary because the valve was set properly when it was new. If it has been in use for over about 5 years and is not feeding, the screen on the inlet can be checked to see if it is plugged. If it is clear and water can be flushed through it and it still does not feed, you may try adjustment of the valve but it may not work. Also, if the valve begins to feed after adjustment, it may not stop feeding and will overpressure the boiler. When the pressure reaches over 25#, the relief valve will begin to leak.
Bottom line if, after 5 years, the valve stops feeding, it probably should be replaced.