Work through bleeding, repressurising, balancing and fine-tuning every radiator over a weekend or two, so the whole system runs quietly and efficiently.
BT-01Plan the work and get readyRead right through this guide before you start, and set aside a free weekend plus a couple of evenings. The whole job usually takes 2 to 3 sessions spread over 1 to 2 weeks, since the system needs time to settle between stages. Check your boiler's manual for its normal pressure range, turn the heating off so radiators are cold, and buy a radiator bleed key, a digital thermometer and spare washers before you begin. Tell everyone in the house that the heating will be going on and off during this period.
1 each · Radiator bleed key 1 each · Digital thermometer 1 each · Adjustable spanner 2 each · Old towels or dust sheets BT-02Bleed every radiator firstFollow the HomeGraft guide "Bleed a radiator" on each radiator in the house, working from the one nearest the boiler to the one furthest away. This clears trapped air so the later steps show you the system's real behaviour, not air locks. Expect this to take half a day for an average house, and keep old towels handy to catch drips.
1 each · Small catch bowl BT-03Top up the system pressureBleeding often drops boiler pressure, so follow the HomeGraft guide "Repressurise a combi boiler" straight afterwards to bring it back to the level shown in its manual. Check the pressure again after an hour, since it can settle lower once the air has fully cleared. If pressure keeps dropping over a day or two, you likely have a leak somewhere — that's a job for a Gas Safe registered engineer or plumber, not something to keep topping up yourself.
RULES1 each · Filling loop (if not fitted) KNOW THE RULES
Work on the boiler itself beyond topping up pressure must be done by a Gas Safe registered engineer. This is a legal requirement for gas appliances, not just good practice.
BT-04Balance the whole system room by roomWith pressure correct, follow the HomeGraft guide "Balance your radiators" across every radiator in the house in one sitting, starting with the one nearest the boiler. Work through them in sequence, since adjusting one radiator changes the flow through the others. If any radiator stays cold at the bottom while you do this, leave it unbalanced for now and move straight to the next phase before finishing the round.
1 each · Flat-blade screwdriver (for lockshield valves) BT-05Fix radiators that stay cold at the bottomFor any radiator that wouldn't balance properly, follow the HomeGraft guide "Fix a radiator that's cold at the bottom" to deal with the sludge build-up causing it. Once it's sorted, go back and finish balancing that radiator before moving on to the next phase. If several radiators across the house are badly sludged, get a quote for a professional power flush from a heating engineer, since a full flush needs pumping equipment you won't have at home.
1 bottle · Chemical radiator flush 1 each · Flushing hose adapter BT-06Fit new thermostatic radiator valve headsFollow the HomeGraft guide "Replace a thermostatic radiator valve head" on any radiator with a worn, stuck or inaccurate TRV head, doing one radiator at a time so you don't lose track of which valves are open. This is a sensible point to upgrade to smart TRV heads if you want remote control, since a head swap doesn't need the system draining. Re-bleed any radiator you disturb before moving on to the next phase.
3 each · Thermostatic radiator valve head BT-07Quieten noisy radiators and pipesFollow the HomeGraft guide "Fix noisy radiators and pipes" to deal with any banging, gurgling or ticking noticed since starting the work. Noise often only shows up once flow rates have changed, so this phase makes more sense after balancing. Before drilling or fixing any new pipe clips or brackets into a wall, use a cable and pipe detector, and still expect to find something unexpected even on a wall you think is clear.
RULES1 pack · Rawlplugs and screws 2 metre · Pipe insulation lagging KNOW THE RULES
Always check for hidden cables and pipes with a detector before drilling or fixing into a wall, even if you believe you know what's behind it.
BT-08Fit radiator reflector foil for efficiencyFollow the HomeGraft guide "Fit radiator reflector foil" behind radiators on external walls, once the system is balanced and quiet. Doing this last avoids fitting foil behind a radiator you then have to pull out again for valve work. It's optional, but worth doing on any radiator against an outside wall, since it stops heat being wasted into the brickwork.
4 each · Radiator reflector foil roll BT-09Final check and re-balanceOnce every phase is done, bleed and balance the whole system one more time, since fitting new TRV heads and foil can slightly shift the flow. Check the boiler pressure again and write it down, so you have a baseline to compare against if problems appear later. The whole project typically takes a long weekend plus a couple of follow-up evenings over the next week or two, and total materials usually run from about £60 up to £250 depending on how many TRV heads and how much foil you fit, more again if a power flush or leak repair turns out to be needed.
1 bottle · System inhibitor top-up 1 each · Notebook for pressure log Travis Perkins and Tooled Up links are affiliate links: if you buy after clicking, we may earn a small commission at no extra cost to you. B&Q and Amazon links are plain searches and earn us nothing.
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