diff --git a/scripts/add_existing_baseyear.py b/scripts/add_existing_baseyear.py
index 84d20b72..7eff0e2e 100644
--- a/scripts/add_existing_baseyear.py
+++ b/scripts/add_existing_baseyear.py
@@ -597,7 +597,7 @@ def add_heating_capacities_installed_before_baseyear(
             n.madd(
                 "Link",
                 nodes,
-                suffix=f"{heat_system} gas boiler-{grouping_year}",
+                suffix=f" {heat_system} gas boiler-{grouping_year}",
                 bus0="EU gas" if "EU gas" in spatial.gas.nodes else nodes + " gas",
                 bus1=nodes + " " + heat_system.value + " heat",
                 bus2="co2 atmosphere",
@@ -666,6 +666,22 @@ def add_heating_capacities_installed_before_baseyear(
             )
 
 
+def set_defaults(n):
+    """
+    Set default values for missing values in the network.
+
+    Parameters:
+        n (pypsa.Network): The network object.
+    Returns:
+        None
+    """
+    if "Link" in n.components:
+        if "reversed" in n.links.columns:
+            # Replace NA values with default value False
+            n.links.loc[n.links.reversed.isna(), "reversed"] = False
+            n.links.reversed = n.links.reversed.astype(bool)
+
+
 # %%
 if __name__ == "__main__":
     if "snakemake" not in globals():
@@ -734,6 +750,9 @@ if __name__ == "__main__":
             ),
         )
 
+    # Set defaults for missing missing values
+    set_defaults(n)
+
     if options.get("cluster_heat_buses", False):
         cluster_heat_buses(n)