Cold spots, one room that never warms up, a valve that quietly drips — small heating faults that cost comfort and money every day they're ignored. We work out what your radiators are telling you, then put it right.
Diagnosis
Where a radiator is cold matters more than the fact it's cold. Cold at the top with a warm bottom means trapped air — air rises, collects at the top of the radiator and stops hot water reaching it. That's a bleed and, if it keeps recurring, a hunt for where air is getting into the system in the first place.
Cold at the bottom or across the middle with a hot top is the opposite problem: sludge. Magnetite — black corrosion debris — is heavier than water, settles in the base of radiators and blocks circulation. Bleeding does nothing for this; the fix is a power flush, then a magnetic filter and fresh inhibitor so it doesn't come back.
And a single radiator that never warms while the rest run hot usually isn't broken at all. Either the system is out of balance and that radiator is last in the queue for hot water, or a thermostatic valve pin has stuck shut over the summer.
Symptom to solution
| Symptom | Likely cause | The usual fix |
|---|---|---|
| Cold at the top | Trapped air | Bleed the radiator; trace recurring air ingress |
| Cold at the bottom or middle | Sludge build-up | Power flush, then a magnetic filter and inhibitor |
| One radiator always cold | Poor balancing or a stuck TRV pin | Rebalance the system; free or replace the valve |
| Rooms heat unevenly after a new boiler | System never rebalanced | Full balance across every radiator |
| Drip or damp patch at a valve | Worn gland or failed olive | Repack or replace the valve |
A power flush is the deepest of these remedies: a machine circulates cleaning agent through the whole system, dislodging and capturing the sludge that gravity and time have packed into radiators and pipework. It restores circulation, quietens a kettling boiler and protects the heat exchanger — which is why installers expect a clean system before fitting a new boiler, and why manufacturers write water quality into their warranty terms.
Beyond repairs
TRVs let each room ask for the temperature it actually needs, instead of every radiator running flat out whenever the boiler fires. Bedrooms and spare rooms stop being heated to living-room temperatures, which shows up on the gas bill — and heating controls earn points on a domestic EPC, a cheap win for landlords near a band boundary.
Balancing shares the flow of hot water fairly between radiators by adjusting each lockshield valve in turn. It's the finishing step most heating systems never get — and the reason "the back bedroom is always freezing" so often has nothing to do with the radiator in it.
Corroded radiators that weep at the seams, undersized panels that never quite heat the room, or a radiator in the wrong place for your new layout — we replace like-for-like, upgrade to higher-output panels, or move radiators during renovation work.
After any flush or repair we re-dose the system with inhibitor and, where there isn't one, recommend a magnetic filter — the pairing that keeps sludge from re-forming. An annual boiler service then keeps an eye on the whole system, year on year.
Whether it's one dripping valve or a whole-house flush, tell us the symptoms and the radiator count via the quote form and we'll price it properly — or see everything else under boiler services.
Common questions
It depends on the job — bleeding and balancing is far quicker than a power flush, and the number of radiators matters for both. Tell us the symptoms and how many radiators the property has via WhatsApp or the quote form and we'll reply with a fixed quote, usually the same working day.
Almost always sludge — corrosion debris that settles in the base of the radiator and blocks circulation. Bleeding won't help, because the problem isn't air. The fix is a power flush to clear the system, then a magnetic filter and inhibitor to stop the sludge returning.
Not always, and we won't sell you one you don't need. Cold-bottomed radiators, black water when bleeding and a kettling boiler point that way; a single stubborn radiator often just needs balancing or a freed valve. We diagnose first and quote the remedy that fits.
Balancing adjusts the lockshield valve on each radiator so the flow of hot water is shared fairly around the circuit. Without it, radiators nearest the boiler take more than their share and the furthest rooms stay cool. It's particularly worth doing after a new boiler or new radiators are fitted.
Usually, yes. TRVs give you room-by-room control so you stop heating empty rooms, which shows up on the gas bill — and heating controls including TRVs also earn points on a domestic EPC, a cheap win for landlords near a band boundary. Send the radiator count for a fixed quote.
Tell us the property type and postcode — we'll come back with a fixed quote and the earliest available date.