Revision history [back]

I got stuck over the weird behavior of my model. My model is a small office building with the following chilled water loop and condenser water loops.

I bullet-point the situation.

• The problem is that cooling towers and condenser pumps are off even when there is a cooling demand on the chilled water loop and the chiller is operating. The annual end use of Pumps and Heat Rejection is extremely small.
• The problem occurred after I changed Pump Control Type from Continuous to Intermittent.
• When there is a cooling demand on the chilled water loop, a cooling demand on the condenser water loop is 0.
• There is a lot of Chiller Condenser Heat Transfer even though the condenser pumps and cooling towers are off, which makes no sense.
• Chillers cool the chilled water even though the condenser loop is off.
• Chiller Condenser Inlet Temperature is constant throughout the year (25.74°C for Chiller1 and 25.84°C for Chiller2), which is the weirdest thing in my model. Chillers cool chilled water without running cooling towers probably due to this constant condenser inlet temperature, but I don't know why the temperature at this node is constant.
• Unmet hours are not detected even though the condenser loop is off.
• Free convection in CoolingTower:TwoSpeed is not modelld.
• Plant Loop Volume is autosized. I hardsized it to 0m3 as a trial, but the problem was not solved.

The charts below are one-week extracts of the simulation results in summer.

Cooling towers and condenser pumps are off.

Chiller Condenser Inlet Temperature and Cooling Tower Outlet Temperature do not match at all.

I have put the idf files here. Their version is V9-6-0. The model with continuous pumps is just for comparision.

I have modelled similar systems several times before, but this is the first time I have this problem. Any suggestion for solving this problem would be appreciated.

I got stuck over the weird behavior of my model. My model is a small office building with the following chilled water loop and condenser water loops.

I bullet-point the situation.

• The problem is that cooling towers and condenser pumps are off even when there is a cooling demand on the chilled water loop and the chiller is operating. The annual end use of Pumps and Heat Rejection is extremely small.
• The problem occurred after I changed Pump Control Type from Continuous to Intermittent.
• When there is a cooling demand on the chilled water loop, a cooling demand on the condenser water loop is 0.
• There is a lot of Chiller Condenser Heat Transfer even though the condenser pumps and cooling towers are off, which makes no sense.
• Chillers cool the chilled water even though the condenser loop is off.
• Chiller Condenser Inlet Temperature is constant throughout the year (25.74°C for Chiller1 and 25.84°C for Chiller2), which is the weirdest thing in my model. Chillers cool chilled water without running cooling towers probably due to this constant condenser inlet temperature, but I don't know why the temperature at this node is constant.
• Unmet hours are not detected even though the condenser loop is off.
• Free convection in CoolingTower:TwoSpeed is not modelld.
• Plant Loop Volume is autosized. I hardsized it to 0m3 as a trial, but the problem was not solved.

The charts below are one-week extracts of the simulation results in summer.

Cooling towers and condenser pumps are off.

Chiller Condenser Inlet Temperature and Cooling Tower Outlet Temperature do not match at all.

I have put the idf files here. Their version is V9-6-0. The model with continuous pumps is just for comparision.

I have modelled similar systems several times before, but this is the first time I have this problem. Any suggestion for solving this problem would be appreciated.

I got stuck over the weird behavior of my model. My model is a small office building with the following chilled water loop and condenser water loops.

I bullet-point the situation.

• The problem is that cooling towers and condenser pumps are off even when there is a cooling demand on the chilled water loop and the chiller is operating. The annual end use of Pumps and Heat Rejection is extremely small.
• The problem occurred after I changed Pump Control Type from Continuous to Intermittent.
• When there is a cooling demand on the chilled water loop, a cooling demand on the condenser water loop is 0.
• There is a lot of Chiller Condenser Heat Transfer even though the condenser pumps and cooling towers are off, which makes no sense.
• Chillers cool the chilled water even though the condenser loop is off.
• Chiller Condenser Inlet Temperature is constant throughout the year (25.74°C for Chiller1 and 25.84°C for Chiller2), which is the weirdest thing in my model. Chillers cool chilled water without running cooling towers probably due to this constant condenser inlet temperature, but I don't know why the temperature at this node is constant.
• Unmet hours are not detected even though the condenser loop is off.
• Free convection in CoolingTower:TwoSpeed is not modelld.
• Plant Loop Volume is autosized. I hardsized it to 0m3 as a trial, but the problem was not solved.

The charts below are one-week extracts of the simulation results in summer.

Cooling towers and condenser pumps are off.

Chiller Condenser Inlet Temperature and Cooling Tower Outlet Temperature do not match at all.

I have put the idf files here. Their version is V9-6-0. The model with continuous pumps is just for comparision.

I have modelled similar systems several times before, but this is the first time I have this problem. Any suggestion for solving this problem would be appreciated.

I got stuck over the weird behavior of my model. My model is a small office building with the following chilled water loop and condenser water loops.

I bullet-point the situation.

• The problem is that cooling towers and condenser pumps are off even when there is a cooling demand on the chilled water loop and the chiller is operating. The annual end use of Pumps and Heat Rejection is extremely small.
• The problem occurred after I changed Pump Control Type from Continuous to Intermittent.
• When there is a cooling demand on the chilled water loop, a cooling demand on the condenser water loop is 0.
• There is a lot of Chiller Condenser Heat Transfer even though the condenser pumps and cooling towers are off, which makes no sense.
• Chillers cool the chilled water even though the condenser loop is off.
• Chiller Condenser Inlet Temperature is constant throughout the year (25.74°C for Chiller1 and 25.84°C for Chiller2), which is the weirdest thing in my model. Chillers cool chilled water without running cooling towers probably due to this constant condenser inlet temperature, but I don't know why the temperature at this node is constant.
• Unmet hours are not detected even though the condenser loop is off.
• Free convection in CoolingTower:TwoSpeed is not modelld.
• Plant Loop Volume is autosized. I hardsized it to 0m3 as a trial, but the problem was not solved.

The charts below are one-week extracts of the simulation results in summer.

Cooling towers and condenser pumps are off.

Chiller Condenser Inlet Temperature and Cooling Tower Outlet Temperature do not match at all.

I have put the idf files here. Their version is V9-6-0. The model with continuous pumps is just for comparision. I closed the link.

I have modelled similar systems several times before, but this is the first time I have this problem. Any suggestion for solving this problem would be appreciated.