diff --git a/backend/epc_api/json_samples/real_life_examples/RdSAP-Schema-21.0.1/uprn_100061275133/elmhurst_summary.pdf b/backend/epc_api/json_samples/real_life_examples/RdSAP-Schema-21.0.1/uprn_100061275133/elmhurst_summary.pdf
index 2d86d5cee..4a604044a 100644
Binary files a/backend/epc_api/json_samples/real_life_examples/RdSAP-Schema-21.0.1/uprn_100061275133/elmhurst_summary.pdf and b/backend/epc_api/json_samples/real_life_examples/RdSAP-Schema-21.0.1/uprn_100061275133/elmhurst_summary.pdf differ
diff --git a/backend/epc_api/json_samples/real_life_examples/RdSAP-Schema-21.0.1/uprn_100061275133/elmhurst_worksheet.pdf b/backend/epc_api/json_samples/real_life_examples/RdSAP-Schema-21.0.1/uprn_100061275133/elmhurst_worksheet.pdf
index 01308a944..9bb10c008 100644
Binary files a/backend/epc_api/json_samples/real_life_examples/RdSAP-Schema-21.0.1/uprn_100061275133/elmhurst_worksheet.pdf and b/backend/epc_api/json_samples/real_life_examples/RdSAP-Schema-21.0.1/uprn_100061275133/elmhurst_worksheet.pdf differ
diff --git a/scripts/hyde/build_100061275133.py b/scripts/hyde/build_100061275133.py
index 93ddab7b7..106488c79 100644
--- a/scripts/hyde/build_100061275133.py
+++ b/scripts/hyde/build_100061275133.py
@@ -1,7 +1,9 @@
-"""Elmhurst build for UPRN 100061275133 (RdSAP-21.0.1, MID-TERRACE HOUSE, band B,
-SOLID BRICK 250 mm uninsulated, pitched insulated (assumed) loft, floor to
-UNHEATED space, mains-gas COMBI (PCDB 19008) + gas room-heater SECONDARY, DUAL
-meter, 11 DG windows ~18.32 m², TFA 116. Lodged SAP 63; engine 65.0 (Δ +2.0).
+"""Elmhurst build for UPRN 100061275133 (RdSAP-21.0.1, SEMI-DETACHED HOUSE, band B,
+SOLID BRICK 400 mm with EXTERNAL insulation, pitched 300 mm loft, ground floor
+SUSPENDED, no insulation (assumed) — no per-bp floor_construction_type lodged,
+mains-gas COMBI (PCDB 18908, Worcester Greenstar 4000 88.70%), no secondary
+heating, single meter, 12 DG windows ~15.32 m², TFA 78. Lodged SAP 76; engine
+76 (76.33, exact match after the §5 (12) floor-infiltration fix).
 
 Per-cert Elmhurst validation. Uses set_single_window (deletes the shared
 assessment's carried-over window rows) + reset_transient_state at the end so the
@@ -124,7 +126,10 @@ def _glazing(page):
 def ventilation(page):
     E.goto(page, "VentilationAndCooling", "WebFormVentilationAndCooling.aspx")
     E.click_tab(page, "TabContainer_TabPanelVentilationPanel")
-    E.set_text(page, f"{VP}TextBoxIntermittentFans", "1")
+    # Cert lodges no extract-fan count; RdSAP 10 Table 5 age-band default for
+    # band B (A-E) is 0, and our engine's ventilation_from_cert computes 0 —
+    # was wrongly entered as 1 here, inflating Elmhurst's (8)/(21) ACH vs ours.
+    E.set_text(page, f"{VP}TextBoxIntermittentFans", "0")
     cool = page.locator(f"#{E.FP}{VP}CheckBoxFixedSpaceCooling")
     if cool.count() and cool.is_checked():
         E.commit(page, cool.uncheck)
@@ -142,21 +147,16 @@ def ventilation(page):
 
 
 def space_heating(page):
+    # PCDB exact-boiler entry (elmhurst_lib.set_pcdb_boiler): the cert's
+    # main_heating_index_number 18908 resolves to Worcester Greenstar 4000
+    # GR4700iW 25 C NG, 88.70% winter efficiency — matching the SAP engine's
+    # PCDB lookup exactly, vs the generic "Combi condens" SAP-Table code
+    # (84%) the old dialog-driven entry carried a keep-hot artifact from.
     E.goto(page, "SpaceHeating", "WebFormSpaceHeating.aspx")
     page.wait_for_timeout(1000)
-    mhc = page.locator(f"#{E.MH1}TextBoxMainHeatingCode")
-    code = mhc.input_value() if mhc.count() else ""
-    if code and code not in ("0",):
-        print(f"clearing leftover MainHeatingCode {code}")
-        page.evaluate("""(id)=>{const e=document.getElementById(id);if(e){e.value='';
-            e.dispatchEvent(new Event('change',{bubbles:true}));}}""", f"{E.MH1}TextBoxMainHeatingCode")
-        page.wait_for_timeout(400)
-        E.save_close(page)
-        return
-    E.set_heating_dialog(page, f"{MH1B}ButtonMainHeatingCode",
-                         "^Gas", "Mains gas", "Boilers", "Post 1998", "Condensing",
-                         "Combi condens")
-    print("code:", page.locator(f"#{E.MH1}TextBoxMainHeatingCode").input_value())
+    E.clear_main_heating_code(page)
+    desc = E.set_pcdb_boiler(page, 18908)
+    print("PCDB boiler ->", desc)
     E.set_heating_dialog(page, f"{MH1B}ButtonMainHeatingControls",
                          "^Boilers", "^Standard", "CBE Programmer, room thermostat and TRVs")
     print("control:", page.locator(f"#{E.MH1}TextBoxMainHeatingControls").input_value())