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HHW pump running even when boiler is off

I am running into an issue, in OpenStudio, where the constant speed pump (intermittent control) in my HHW plant runs even when the boiler is not firing. As a result, the pump runs (cycling somewhat unpredictably) throughout the summer months, causing the HHW loop to continuously heat up - I assume due to waste heat from the pump.

I don't fully understand how the controls work by default, but I would assume that if there is a demand for heating at a coil, the pump runs, and then the boiler fires to maintain loop temperature (?). This would mean that something is telling the pump that there is a demand for heating; however, after assessing zone temperature, I can't see why that would be. Is there any basic troubleshooting around this issue (e.g. don't set the controls to intermittent)? Or, as a worst case scenario, is there some way I can force the pump off during summer months using an availability manager?

Thanks!

image description

HHW pump running even when boiler is off

I am running into an issue, in OpenStudio, where the constant speed pump (intermittent control) in my HHW plant runs even when the boiler is not firing. As a result, the pump runs (cycling somewhat unpredictably) throughout the summer months, causing the HHW loop to continuously heat up - I assume due to waste heat from the pump.

I don't fully understand how the controls work by default, but I would assume that if there is a demand for heating at a coil, the pump runs, and then the boiler fires to maintain loop temperature (?). This would mean that something is telling the pump that there is a demand for heating; however, after assessing zone temperature, I can't see why that would be. Is there any basic troubleshooting around this issue (e.g. don't set the controls to intermittent)? Or, as a worst case scenario, is there some way I can force the pump off during summer months using an availability manager?

Thanks!

image descriptionHot Water Loop Plot

HHW pump running even when boiler is off

I am running into an issue, in OpenStudio, where the constant speed pump (intermittent control) in my HHW plant runs even when the boiler is not firing. As a result, the pump runs (cycling somewhat unpredictably) throughout the summer months, causing the HHW loop to continuously heat up - I assume due to waste heat from the pump.

I don't fully understand how the controls work by default, but I would assume that if there is a demand for heating at a coil, the pump runs, and then the boiler fires to maintain loop temperature (?). This would mean that something is telling the pump that there is a demand for heating; however, after assessing zone temperature, I can't see why that would be. Is there any basic troubleshooting around this issue (e.g. don't set the controls to intermittent)? Or, as a worst case scenario, is there some way I can force the pump off during summer months using an availability manager?

Thanks!

Hot Water Loop Plot