A high head or low suction pressure can cause a higher discharge line temp. Think of it this way: if the compressor is working against a higher pressure in the discharge line, it will need to do more work (higher compression ratio) to get it to that pressure.
What is the difference between head pressure and pressure at discharge?
The pressure at the discharge of the pump, however, will be higher for the heavier solution. That’s why we would not be able to do simply looking at a pressure gauge and figure out what is pump’s discharge head ability is. Hopefully this post reveal some light on the difference between head and pressure.
What causes discharge line temp to be high?
A high head or low suction pressure can cause a higher discharge line temp. Think of it this way: if the compressor is working against a higher pressure in the discharge line, it will need to do more work (higher compression ratio) to get it to that pressure.
What is head pressure and how does it affect HVAC?
HVAC systems work by compressing vapor to cool things. Sometimes, this vapor can build up near the top, creating very high pressure. Higher head pressure causes more energy as it takes more energy to maintain that pressure.
What causes high discharge temperature on a compressor?
In short, high discharge temp can commonly be caused by: Low charge (high suction superheat, low suction pressure, low subcool) Keep in mind that keeping the discharge line and compressor temperatures in check will greatly increase compressor longevity with refrigerant-cooled compressors.
What causes high discharge line temperature?
What causes high discharge temperature? High discharge temperature is the result of temperatures in the compressor head and cylinders becoming so hot that the oil loses its ability to lubricate properly. This causes rings, pistons and cylinders to wear resulting in blow by, leaking valves, and metal debris in the oil.
What causes low discharge line temperature?
There is also low Discharge Superheat to consider. The most common cause of low Discharge Superheat is flooding to the compressor. That condition will more than likely be associated with an Electronic Expansion Valve over feeding the evaporator. It could also point to an Accurator or check valve issue.
What is discharge line temperature?
It is desirable to limit discharge temperatures to below 250°F to 275°F (121°C to 135°C) to assure adequate packing life and to avoid lube oil degradation. At temperatures above 300°F (149°C), eventual lube oil degradation is likely, and if oxygen is present, ignition is possible.
What would cause high discharge pressure?
One common cause of high discharge pressure is the cooling medium (air or water) flowing across the condenser: either there is not enough or the temperature of the cooling medium is too high. This is normally easy to identify with a simple visual inspection of the condenser.
What would happen to the discharge line temperature with a decrease in suction line temperature?
What would happen to the discharge line temperature with a decrease in suction line temperature? It's possible to cause less of a discharge temp increase if the superheat is low, but if it's low due to low charge, restriction or underfeeding it can cause more of a discharge temp increase.
What is the purpose of the discharge line thermostat?
The discharge thermostat is a safety device that turns off power when the compressor discharge temperature reaches a certain level. The clip-on type has a manual reset. The discharge thermostat can be reset by depressing the red button if power is turned off.
Is the discharge line high or low pressure?
The high side, or discharge line, will be the line connected to the compressor from the bottom or lower position. It will not be wrapped in insulation and will be warm to the touch.
What does high head pressure mean?
Head pressure is the pressure generated by the gas compressor of your air conditioning system. This is something that we measure when we think that you might have a refrigerant problem. Head pressure that's within a reasonable range isn't a problem. It's high head pressure that's the issue.
What causes high head pressure on a heat pump?
Restricted airflow/a dirty coil will cause high head pressure, the same way that a dirty outdoor coil will cause high head pressure in cooling mode. Be sure to also check filters and make sure that register grilles have not been closed off in certain rooms. Take pressure readings at all three ports on the outdoor unit.
What causes high head pressure and high suction pressure?
Overcharging of refrigerant, liquid slugging of the compressor, oil contamination and other sources can damage compressor valves. Refrigerant overcharging will show up as high head pressure, normal suction line pressure, normal superheat, high sub-cooling.
What causes a higher discharge line temp?
A high head or low suction pressure can cause a higher discharge line temp. Think of it this way: if the compressor is working against a higher pressure in the discharge line, it will need to do more work (higher compression ratio) to get it to that pressure. This increases the electrical consumption of the motor in the compressor, ...
Why is my condenser discharge line temperature high?
You can also see an increased discharge line temp if you have a high suction superheat at the condenser due to an uninsulated or improperly insulated suction line . On the condenser side, anything that causes a high head will also cause a high discharge line temperature: overcharge, low condenser airflow due to improper motor or blade, ...
Why is suction pressure low?
If your suction pressure is low, but the superheat is low (low evaporator airflow or heat load), it can cause LESS of a discharge temp increase than if the suction is low due to low charge, restriction, or evaporator underfeeding. That is simply because the suction temperature is lower, but a low suction temperature is still less important ...
Why is my heat pump running in heat mode?
In the case of heat pump units running in heat mode, the most common causes are dirty air filters or other indoor airflow restrictions (because the condenser is now inside during heat mode). In short, high discharge temp can commonly be caused by: Low charge (high suction superheat, low suction pressure, low subcool) Severe overcharge.
What temperature should a compressor be?
First off, if your discharge temperature (as measured with a thermometer at the compressor) is over 225°, you have an issue. At that temperature on the discharge line, you will have an internal compressor temperature of over 300°, and the oil will begin breaking down, so even if you check for no other reason, check to make sure you are under 225°.
Why is a pump head important?
Head is useful because it evaluates a pump’s capacity to do a job. If you have to pump a liquid up to 10m and your pump doesn’t have at least 10m of head, then there is no chance it will work. Your pump will need at least 10m plus the friction loss to get the required flow at the discharge point.
What is the most important factor when inspecting a pump?
One of the most important factor when inspect a pump is to find out the real Static Head or How much height that the pump can lift the fluid .
Is the pressure at the discharge of a pump higher for heavier solution?
The pressure at the discharge of the pump, however, will be higher for the heavier solution. That’s why we would not be able to do simply looking at a pressure gauge and figure out what is pump’s discharge head ability is. Hopefully this post reveal some light on the difference between head and pressure.
Why is head pressure important in HVAC?
However, when head pressure gets too high, the electric motors have to work harder to maintain that pressure. The result is that a higher head pressure in the compressor pulls more electricity.
What is the head pressure of a pump?
Head pressure, also called discharge pressure, is a type of pressure in pump systems determined by the height difference between a discharge point and some fluid. HVAC systems work by compressing vapor to cool things. Sometimes, this vapor can build up near the top, creating very high pressure. Higher head pressure causes more energy as it takes ...
What is undercharge refrigerant?
Refrigerant under-charge. A system is a refrigerant undercharge when the amount of refrigerant in the system is lower than the factory-set level. Under-charge refrigerants will not build up enough condenser pressure to condense and so will not regulate temperatures as effectively. Conversely, a system with too much liquid refrigerant can have high ...
What causes high suction pressure?
Common Causes of High Head/Low Suction Pressure (+ What to Do) 1 Faulty condenser fan motor.#N#A bad fan motor can also manifest as a rattling sound coming from the condenser. Sometimes the fan might just be loose, and other times it may need to be replaced if the frame or blades are cracked or broken. 2 Dirty condenser coils.#N#Dirty condenser coils reduce their efficiency and prevent pressurized vapor from condensing. You can clean dirty condenser coils with a foaming condenser cleaner, but you should not clean them with just water and a cloth. 3 Blocked refrigeration device.#N#A blocked refrigeration device can increase pressure by bottling up coolant liquid. Refrigeration devices like tubes can become blocked by solid materials or bent to restrict liquid flow. 4 Overcharged refrigerant.#N#Overcharged refrigerants can be pushed into the suction line and get over the crankcase. This can cause compressor damage and compressor failure. This can be fixed by draining the system of refrigerant liquid. 5 Non-condensing gases in the system.#N#Non-condensing gases can contribute to pressure as they do not phase change to a liquid. You can remove these gases by draining the coolant line. 6 Extreme operation over-designed specification.#N#If your HVAC system is operating in extreme conditions, then it can create high head pressure. In these cases, you need to recalibrate your system so it is not taxed as highly.
What does high suction pressure mean?
High suction pressure is most likely a sign of a bad compressor valve. This can also result in lower head pressure than normal and sub-optimal cooling. Turn off the condenser fan unit and see if the pressure does not fall. If it does not, then the problem is likely condenser valves, and they need to be replaced.
How does a blocked refrigerator affect the compressor?
A blocked refrigeration device can increase pressure by bottling up coolant liquid. Refrigeration devices like tubes can become blocked by solid materials or bent to restrict liquid flow. Overcharged refrigerant. Overcharged refrigerants can be pushed into the suction line and get over the crankcase. This can cause compressor damage and compressor ...
What is the normal head pressure for a refrigerant system?
Normal head pressure for an air refrigerant HVAC system is approximately 58-80 psi, depending on the exact ambient indoor temperature.
