I have a gas boiler with the efficiency set to 100%, the efficiency curve set to 100% (flat curve), and two zones each with baseboard water heaters.
My problem is that the building is using 8690 kWh/year, yet the baseboard water heaters are only emitting 4785 kWh/year between them (an effective efficiency of 55%). What could be causing so much extra gas to be used? There's no storage tank and no DHW use.
Looking at some of the node temperatures it seems like my delta-T is very low. Could that lead to a near-doubling of annual fuel use? Where else should I look to diagnose the problem?
Boiler:HotWater,
PrimaryHeater, !- Name
NaturalGas, !- Fuel Type
4000, !- Nominal Capacity {W}
1.0, !- Nominal Thermal Efficiency
LeavingBoiler, !- Efficiency Curve Temperature Evaluation Variable
100% efficient, !- Normalized Boiler Efficiency Curve Name
75.00, !- Design Water Outlet Temperature {C}
autosize, !- Design Water Flow Rate {m3/s}
0.00, !- Minimum Part Load Ratio
1.00, !- Maximum Part Load Ratio
1.00, !- Optimum Part Load Ratio
Boiler Water Inlet Node, !- Boiler Water Inlet Node Name
Boiler Water Outlet Node,!- Boiler Water Outlet Node Name
100.0, !- Water Outlet Upper Temperature Limit {C}
NotModulated, !- Boiler Flow Mode
25.00, !- Parasitic Electric Load {W}
1.00; !- Sizing Factor
Curve:Linear,
100% efficient, !- name
1, !- Coefficient 1
0, !- Coefficient 2
0, !- Minimum X
1, !- Maximum X
, !- Minimum Curve Output
, !- Maximum Curve Output
, !- Input Units X
; !- Output Units
