diff --git a/backend/Funding.py b/backend/Funding.py
index 71499b4d..ce712de4 100644
--- a/backend/Funding.py
+++ b/backend/Funding.py
@@ -341,20 +341,15 @@ class Funding:
             return 'Biomass Boiler'
         if mainheating["has_boiler"] and (main_fuel["fuel_type"] == "lpg"):
             return 'Bottled LPG Boiler'
-        if mainheating["has_boiler"] and (main_fuel["fuel_type"] == "mains gas") and (
-            mainheat_energy_eff in ["Good", "Very Good"]
+        if mainheating["has_boiler"] and (
+            (main_fuel["fuel_type"] == "mains gas") or (
+            (main_fuel["fuel_type"] == "unknown") and (mainheating["has_mains_gas"]))
         ):
-            # Assume higher efficiency condensing boiler
-            return 'Condensing Gas Boiler'
-
-        if mainheating["has_boiler"] and (main_fuel["fuel_type"] == "mains gas") and (
-            mainheat_energy_eff in ["Average", "Poor"]
-        ):
-            return 'Non Condensing Gas Boiler'
-
-        if mainheating["has_boiler"] and (main_fuel["fuel_type"] == "mains gas") and (
-            mainheat_energy_eff in ["Very Poor"]
-        ) and mainheating["has_radiators"]:
+            if mainheat_energy_eff in ["Good", "Very Good"]:
+                # Assume higher efficiency condensing boiler
+                return 'Condensing Gas Boiler'
+            if mainheat_energy_eff in ["Average", "Poor"]:
+                return 'Non Condensing Gas Boiler'
             return 'Gas Back Boiler to Radiators'
 
         if mainheating["has_boiler"] and (main_fuel["fuel_type"] == "mains gas") and (
diff --git a/backend/tests/test_funding.py b/backend/tests/test_funding.py
index 4cfe3b5e..6c237308 100644
--- a/backend/tests/test_funding.py
+++ b/backend/tests/test_funding.py
@@ -1076,7 +1076,7 @@ for _, x in tqdm(epc_df.iterrows(), total=len(epc_df)):
 
 errored_epcs = epc_df[epc_df["LMK_KEY"].isin(errors)]
 unique_combs = errored_epcs[["MAINHEAT_ENERGY_EFF", "MAINHEAT_DESCRIPTION", "MAIN_FUEL"]].drop_duplicates()
-i = 1
+i = 2
 x = errored_epcs[
     (errored_epcs["MAINHEAT_ENERGY_EFF"] == unique_combs["MAINHEAT_ENERGY_EFF"].values[i]) &
     (errored_epcs["MAINHEAT_DESCRIPTION"] == unique_combs["MAINHEAT_DESCRIPTION"].values[i]) &