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Hi all,

I'm trying to set up autosized primary-secondary heating and chilled water loops, with variable speed primary and secondary flow pumps.

I am modelling as recommended elsewhere in this forum (see here). Only difference is:

• I am using headered pumps because it lets me set a minimum pump flow rate as a fraction of maximum (useful when autosizing)

• I have bypass on all supply / demand components (if I get it working I will remove the ones that wouldn't normally be in the system)

• I have multiple coils on the loop

I need minimum flow rates on both primary and secondary otherwise the energy estimation will be unrealistically low (in the order of 60% on primary and 5%-25% on secondary). I have tried setting a minimum flow on the pumps (fraction) and on the loop object (flow rate), neither works. I suspect the control hierarchy does not allow these limits to be implemented - but given I've only built a couple of models in energy plus I could be way off.

Has anyone found a way to model this? Preferably in a way that I can include in a measure.

I've tried and abandoned the 'common loop' function - doesn't model variable flow on primary.

Sorry can't upload because I'm new.

Thanks

Bob

Hi all,

I'm trying to set up autosized primary-secondary heating and chilled water loops, with variable speed primary and secondary flow pumps.

I am modelling as recommended elsewhere in this forum (see here). Only difference is:

• I am using headered pumps because it lets me set a minimum pump flow rate as a fraction of maximum (useful when autosizing)

• I have bypass on all supply / demand components (if I get it working I will remove the ones that wouldn't normally be in the system)

• I have multiple coils on the loop

I need minimum flow rates on both primary and secondary otherwise the energy estimation will be unrealistically low (in the order of 60% on primary and 5%-25% on secondary). I have tried setting a minimum flow on the pumps (fraction) and on the loop object (flow rate), neither works. I suspect the control hierarchy does not allow these limits to be implemented - but given I've only built a couple of models in energy plus I could be way off.

Has anyone found a way to model this? Preferably in a way that I can include in a measure.

I've tried and abandoned the 'common loop' function - doesn't model variable flow on primary.

Sorry can't upload because I'm new.

Thanks

Bobnew.

I'm trying to set up autosized primary-secondary heating and chilled water loops, with variable speed primary and secondary flow pumps.

I am modelling as recommended elsewhere in this forum (see here). Only difference is:

• I am using headered pumps because it lets me set a minimum pump flow rate as a fraction of maximum (useful when autosizing)

• I have bypass on all supply / demand components (if I get it working I will remove the ones that wouldn't normally be in the system)

• I have multiple coils on the loop

I need minimum flow rates on both primary and secondary otherwise the energy estimation will be unrealistically low (in the order of 60% flow on primary and 5%-25% flow on secondary). I have tried setting a minimum flow on the pumps (fraction) and on the loop object (flow rate), neither works. I suspect the control hierarchy does not allow these limits to be implemented - but given I've only built a couple of models in energy plus I could be way off.

Has anyone found a way to model this? Preferably in a way that I can include in a measure.

I've tried and abandoned the 'common loop' function - doesn't model variable flow on primary.

Sorry can't upload because I'm new.