Home › Heating › Heating Only Works Upstairs

PUMPS & MOTORISED VALVES

Heating Only Works Upstairs

If upstairs heats but downstairs stays cold, the system may have weak circulation, poor balancing, airlocks, closed valves or a downstairs zone-control fault.

↻
!

Isolate electrical power before opening pumps, actuators or wiring centres

Heating pumps and motorised valves may contain mains voltage and hot water. Stop if a pump is seized, very hot, leaking or if a valve actuator is buzzing continuously.

MOST LIKELY CAUSES

Start with these

Weak pump performance Flow may favour the easier upstairs route.
Poor balancing Upstairs radiators may take too much flow.
Downstairs zone valve fault The lower circuit may not open.
Airlock or restriction Pipework may be blocked or airbound.
◫ Symptom variations Match the exact circulation or zone pattern. ⌄
  • Upstairs radiators hot
  • Downstairs radiators cold
  • Heat improves when upstairs valves are closed
  • Downstairs pipework stays cold
  • One zone thermostat has no effect
✓ Quick checks Simple checks before removing covers. ⌄
  1. Confirm a heating demand exists.
  2. Check whether one zone or the whole system is affected.
  3. Listen for pump or actuator operation.
  4. Check system pressure and trapped air.
  5. Do not force seized valves or hot pumps.
1 Step 1 — Confirm the system is zoned Isolate power before removing covers or touching wiring. ⌄

Check whether upstairs and downstairs have separate thermostats or valves.

2 Step 2 — Check downstairs radiator valves Isolate power before removing covers or touching wiring. ⌄

Make sure TRVs and lockshields are not shut.

3 Step 3 — Reduce upstairs flow temporarily Isolate power before removing covers or touching wiring. ⌄

See whether downstairs begins to warm.

⌁ Common causes explained Why pumps and zone valves fail. ⌄

If upstairs heats but downstairs stays cold, the system may have weak circulation, poor balancing, airlocks, closed valves or a downstairs zone-control fault.

⌘ Advanced diagnostics Heating-engineer checks and repair work. ⌄
  • Check pump head and speed.
  • Inspect downstairs zone valve.
  • Balance the system.
  • Check for airlocks.
  • Assess sludge or pipe restrictions.
▣ Parts that may need replacing Common components linked to this fault. ⌄
  • Circulation pump
  • Zone valve
  • TRV
  • Lockshield valve
  • Automatic air vent
! When to call a heating engineer Conditions that should end basic troubleshooting. ⌄
  • The pump or actuator contains mains wiring.
  • The pump is seized, leaking or overheating.
  • A valve body is stuck.
  • One or more zones remain uncontrollable.
  • Internal testing is required.
? Frequently asked questions Common pump and valve questions. ⌄

Can I force a motorised valve open?

Use only the normal manual lever as described by the manufacturer. Do not force a seized valve body.

Why is a heating pump hot?

Some warmth is normal, but excessive heat with no circulation may indicate a seized rotor or failed motor.