Update Rule11-16.md

docs/section11/Rule11-16.md

@@ -1,6 +1,6 @@
 # ServiceWaterHeating - Rule 11-16
 
-**Schema Version:** 0.0.36  
+**Schema Version:** 0.0.37  
 **Mandatory Rule:** True  
 **Rule ID:** 11-16  
 
@@ -17,15 +17,18 @@
 **Applicability Checks:**
 - look at each SHW Equipment: `for swh_eq in B_RMD.service_water_heating_equipment:`
   - if the fuel source is electricity, the rule is not applicable: `if shw_eq.heater_fuel_type == "ELECTRICITY": NOT_APPLICABLE`
-  - otherwise, continue to rule logic: `
-  - `CONTINUE TO RULE LOGIC`
+  - otherwise, continue to rule logic: `CONTINUE TO RULE LOGIC`
 
     ## Rule Logic:
     - create variable heater_fuel_type: `heater_fuel_type = swh_eq.heater_fuel_type`
+    - create a list that will be used to store the fuel types used in the proposed model swh equipment: `proposed_swh_eq_fuel_types = []`
+    - look at each swh equipment in the proposed model and collect a list of fuel types: `for swh_eq_p in P_RMD.service_water_heating_equipment: if !(swh_eq_p.fuel_type.in? proposed_swh_eq_fuel_types): proposed_swh_eq_fuel_types.append(swh_eq_p.fuel_type)`
 
     **Rule Assertion:**  
     - CASE 1: if the fuel source is NATURAL_GAS, then PASS: `if heater_fuel_type == "NATURAL_GAS": PASS`
-    - Case 2: Else if the fuel source is propane: `elif: heater_fuel_type == "PROPANE": UNDETERMINED and raise_message "BASELINE SERVICE WATER HEATING EQUIPMENT SOURCE IS MODELED AS PROPANE. VERIFY IF NATURAL GAS IS NOT AVAILABLE FOR THE PROPOSED BUILDING SITE AS DETERMINED BY THE RATING AUTHORITY."`
+    - Case 2: Else if the fuel source is propane and the proposed fuel source is propane: `elif: heater_fuel_type == "PROPANE" && len(proposed_swh_eq_fuel_types) == 1 && proposed_swh_eq_fuel_types[0] == "PROPANE": UNDETERMINED and raise_message "Both baseline and proposed service water heating equipment is modeled as propane.  Verify that natural gas is not available for the proposed building site as determined by the rating authority."`
+    - Case 3: Else if the fuel source is propane and any of the proposed fuel sources is NATURAL_GAS, then FAIL: `if fuel_source == "PROPANE" && "NATURAL_GAS".in? proposed_swh_eq_fuel_types: FAIL and raise_message "The fuel source for the baseline is propane, however the fuel source for the proposed is Natural Gas.  When natural gas is available on-site, natural gas is the required fuel source for the baseline model."'
+    - Case 4: Else if the fuel source is propane, then UNDETERMINED: `if heater_fuel_type == "PROPANE": UNDETERMINED`
     - Case 3: All others fail: `else: FAIL`