Domakihub Balance Radiators for Even Heat and a More Efficient Boiler
Adjust your lockshield valves correctly and every room in your Greek property will reach the same temperature without wasting fuel.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
Uneven heating — one room scorching while another stays cold — is one of the most common complaints from homeowners, holiday rental operators, and hotel managers in Greece. The fix is almost always balancing: a methodical adjustment of each radiator's lockshield valve so hot water is distributed fairly across the whole system. The video above from PlumberParts walks through the process visually; this guide gives you the step-by-step instructions and the context to do it safely in your own property.
Why Radiators Go Out of Balance
Central heating works by pumping hot water from a boiler through a loop of pipework to every radiator in the building. The radiators nearest the boiler sit on the path of least resistance, so they fill with heat first and often run far hotter than rooms at the far end of the circuit. In Greek properties — particularly older stone houses, apartment buildings, and holiday villas where the heating layout may never have been commissioned properly — this imbalance can mean bedrooms are barely warm while the living room is unbearable.
Over time the problem compounds: residents crank the thermostatic valves on hot radiators fully shut, which pushes even more pressure onto the overheating units and does nothing to help the cold ones. Balancing restores order by deliberately throttling the easy-flow radiators and giving the distant ones their fair share of the pump's output.
What You Need Before You Start
The job requires a thermometer — a cheap digital infrared thermometer is ideal, though clip-on pipe thermometers work equally well — plus a lockshield valve key or a set of adjustable spanners, a radiator bleed key, and a notepad. Allow a full working morning; the process involves heating the system to operating temperature, taking measurements, and then returning to fine-tune, so patience matters more than mechanical skill.
Before you begin, bleed every radiator to remove any trapped air. Air pockets create cold spots that will skew your temperature readings and make the balancing exercise pointless. Once all radiators feel warm to the touch with no cold patches at the top, you are ready to start.
How to Balance Your Radiators: 5 Steps
- 1
Close every lockshield valve in the system
The lockshield valve is the capped valve at the opposite end of the radiator from the thermostatic (TRV) or manual control valve. Remove the plastic cap and use a spanner or valve key to close it fully by turning clockwise. Do this on every radiator in the property before you switch the boiler on. This resets the system to a known baseline so you can open each valve from scratch in a controlled sequence.
- 2
Turn the boiler and pump on and wait for the system to reach full temperature
Switch your boiler to its normal heating mode and leave it running for 20 to 30 minutes until every radiator is hot and the system has stabilised. Do not adjust anything during this warm-up period. Your goal is a stable, representative picture of how water flows through the circuit at operating temperature — typically around 70-80 °C flow on most Greek gas or oil-fired systems.
- 3
Identify the radiator closest to the boiler and open it first
Starting from the radiator physically nearest the boiler (or the first one on the main flow circuit), open its lockshield valve one full turn. Use your thermometer to measure the temperature of the pipe feeding into the radiator (flow pipe) and the pipe leaving it (return pipe). The target difference between these two readings is 12 °C — this is known as the Delta T and it tells you the radiator is giving up the right amount of heat to the room. If the gap is smaller, close the lockshield slightly; if larger, open it a little more. Record the final valve position.
- 4
Work outward through the system, radiator by radiator
Move to the next radiator in the circuit and repeat the process: open the lockshield, measure the flow and return pipe temperatures, and adjust until you hit a 12 °C Delta T. Progress methodically to the furthest radiators, which will need their lockshields opened more than the closer ones. Do not skip any radiator or return to adjust a previous one until you have completed the full circuit at least once, as each adjustment affects the pressure available to subsequent radiators.
- 5
Run a final check and record your settings
Once every radiator has been balanced, walk through the property and check that all rooms are reaching a similar temperature and that the thermometers confirm a consistent Delta T across all units. Make a written record — or photograph each lockshield position — so that if a valve is accidentally knocked or a plumber works on the system in future, you can restore the balance quickly. Revisit the settings each autumn when the heating season begins in Greece, particularly in holiday rental properties where the system may have sat idle for months.
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FAQ
- How long does balancing a central heating system take?
- For a typical Greek villa or apartment with 6 to 10 radiators, allow 2 to 4 hours including warm-up time. Larger properties such as hotels or multi-floor buildings can take a full day, especially if you need to return to fine-tune valves after the first pass.
- Will balancing radiators reduce my heating bill?
- Yes, noticeably. When radiators closest to the boiler absorb all the heat, the system has to run longer to warm distant rooms, burning more fuel. Balancing distributes heat evenly so the boiler reaches its target temperature faster and the pump cycles less frequently — both of which lower fuel consumption and reduce wear on the equipment.
- Do I need to rebalance after a plumber works on the system?
- Almost certainly. Any time a radiator is removed, a new one is added, or the pump or boiler is replaced, the flow characteristics of the circuit change. Treat a full rebalance as routine maintenance after any significant work on the central heating, and budget an annual check at the start of each heating season.