Plumbing, heating & bathroom guides

Both 6mm and 8mm shower glass are toughened safety glass, so both are safe. 8mm is a third heavier and stiffer, so doors feel more solid, flex less and can stand taller — ICON's 8mm doors are 1950mm high against 1850mm for 6mm. 6mm is lighter to carry and fit and costs less. Choose 8mm for wetroom screens, wide doors and a heavier feel; 6mm for bath screens, smaller enclosures and tighter budgets.

Start with the space and the tray. In a recess with walls on three sides you only need a door: hinged and pivot doors swing out, bifolds fold in, and sliding doors suit long trays. In a corner, add a matching side panel to a door, or choose a quadrant, offset quadrant or corner entry enclosure. For a walk-in shower fit a wetroom screen, and over a bath a bath screen. The shower tray is always sold separately.

Measure the shower tray first: the door or enclosure is sized to the tray, not the room. Then measure wall to wall at the top, middle and bottom of the opening and use the smallest figure. It must fall inside the door's adjustment range — most ICON doors adjust 40mm, so a 900mm door fits openings of 850–890mm. In a corner, measure both sides of the tray; for a quadrant, check the corner is square.

Standard UK shower trays are square from 700 x 700mm to 1000 x 1000mm, quadrant from 800mm to 1000mm, and rectangular from 900 x 700mm up to 1800 x 900mm, in widths of 700, 760, 800 and 900mm. Lengths go up in 100mm steps. For a small en-suite, 800 x 800mm or 900 x 900mm are the usual choices; for a main bathroom, 1200 x 800mm or 1200 x 900mm.

Stone resin trays are heavier and stiffer, feel solid underfoot and can be made slim, at 30mm to 50mm high. Acrylic-capped trays are lighter and usually cheaper, but rely on reinforcement underneath and can flex or creak if they aren't fully supported. Hybrids such as Nuie's Pearlstone pair an acrylic surface with a strong, light resin core. Whatever the material, most cracked trays come down to poor bedding: a tray must be fully supported on a level base.

A wetroom has no tray: the whole floor is waterproofed (tanked) and laid to fall to a drain. A walk-in shower gets the same open look from a low-profile tray and a fixed glass screen. Either way you'll usually want a screen, because without one the spray soaks the rest of the room. ICON wetroom screens are 8mm glass, 2000mm high and up to 1400mm wide, with a support bar included and a 300mm hinged return panel available.

PVC shower wall panels are large waterproof sheets — ours are 1000 x 2400mm and 10mm thick — that lock together with a tongue-and-groove joint and glue straight onto the wall, often over old tiles. Compared with tiles they're quicker to fit, usually cheaper once you count the labour, and have no grout lines to go mouldy. Tiles still win on hardness, scratch resistance and choice of finish. For a fast, low-maintenance shower or bath surround, panels are hard to beat.

Yes — rigid SPC click vinyl is a good bathroom floor because its stone-plastic core is waterproof and won't swell like laminate. The joints and edges aren't watertight, though, so fit it on a flat, dry subfloor, leave the expansion gap and seal it with flexible silicone, and floor around a bath, shower tray or WC pan rather than under them. Our SCN boards are 6.5mm thick with underlay built in, and a pack covers 1.79 m².

Choose an LED bathroom mirror about the width of your basin or vanity unit — 500 x 700mm suits a cloakroom or small basin, 600 x 800mm a standard 600mm vanity. A heated demister pad keeps it clear after a shower, and a built-in shaver socket charges a shaver or toothbrush. Check its IP rating suits the zone it's going in (IP44 is the usual minimum in zone 2, beside a bath or shower), and have a qualified electrician wire it.

Measure the space first: 400–500mm vanity units suit cloakrooms and small en-suites, and 600mm is the usual main-bathroom size. Wall-hung units keep the floor clear and make a small room look bigger but need a solid wall or proper support; floor-standing units hold more and are easier to fit. In a busy or steamy bathroom, a waterproof PVC carcass such as SCN Aqua won't swell or rot the way MDF can. Then match the basin's tap holes, waste and trap.

First find out what you have. In a gravity-fed system, water comes from a tank in the loft, and pressure depends on height: about 0.1 bar for every metre between the tank and the outlet, so a shower just below the loft may get only 0.1–0.2 bar. Combi boilers and unvented cylinders run at mains pressure. Then choose taps and showers whose minimum working pressure is below what you have, or add a shower pump (gravity systems only) or an electric shower.

Work out the heat the room needs, then choose radiators whose rated output adds up to it. As a quick guide, multiply the room's volume in cubic metres by about 30 W if it's well insulated, 45 W if average or 60 W for solid walls and single glazing, then adjust for room temperature, outside walls and big windows. A 4 × 3.5m living room with a 2.4m ceiling needs about 1,500 W, or 5,200 BTU.

The numbers count the panels and the sets of convector fins. A Type 11 has one panel and one set of fins, a Type 21 two panels with one set of fins between them, and a Type 22 two panels with two sets of fins. More panels and fins give more heat from the same height and length, but make the radiator deeper. As a rough guide, a 600 × 1000mm Type 22 gives nearly twice the heat of a Type 11.

Size a towel rail like a radiator: a typical bathroom needs roughly 500–850 W (1,700–2,900 BTU), more if it's large or poorly insulated. Check the Delta T the output is quoted at — our SCN chrome rails are rated at ΔT60, about 27% higher than the ΔT50 most radiators use. Chrome gives out noticeably less heat than the same rail painted, and a rail covered in towels less again.

A combi heats water on demand straight from the mains, with no cylinder or tanks — ideal for flats and homes with one bathroom. A system boiler heats a stored hot water cylinder, usually unvented at mains pressure, so two bathrooms can run at once. A regular (heat-only) boiler also uses a cylinder, plus cold water and expansion tanks in the loft, and suits older homes with gravity systems or low mains pressure.

Size a combi for hot water, not heating: its kW sets how many litres a minute it can heat. At a typical 35°C rise, 24kW gives about 10 litres a minute, 30kW about 12 and 35kW about 14. As a rough guide, 24–28kW suits a flat or small house with one bathroom, and 30–35kW a three- or four-bedroom home with a bathroom and en-suite used one at a time. For two showers at once, look at a system boiler.

Central heating water slowly corrodes steel radiators into black magnetite sludge, which blocks radiators, pumps and boiler heat exchangers. BS 7593 sets out the fix: clean and flush the system, add inhibitor to slow the corrosion, and fit a magnetic filter on the return to the boiler to catch what's left. Check the inhibitor level every year at the service, top it up after any drain-down, and clean the filter at every service.

To bleed a radiator, turn the heating off and let it cool, open the bleed valve at the top a quarter turn with a radiator key until water comes out, then close it and top the boiler pressure back up to its cold setting — usually about 1–1.5 bar. To balance, open every valve, then turn the lockshields down on the radiators nearest the boiler so the furthest ones heat up as quickly.

Compression fittings seal with a brass nut and olive, need only two spanners and can be undone — ideal for visible joints and connecting to taps and valves. Push-fit joints push together by hand on copper or plastic pipe, quick and flame-free. Soldered fittings (end feed or solder ring) are the neatest and cheapest per joint but need a blowtorch. Press-fit is fast and flame-free but needs a press tool. Most plumbers use a mix.

Use 15mm pipe for single outlets — basin and kitchen taps, toilets, radiator tails and most showers on a combi. Use 22mm for main runs feeding several outlets, bath taps, gravity-fed and pumped showers, and the heating flow and return near the boiler. Bigger pipe carries more water with less pressure lost, which matters most on low-pressure systems. 28mm is for larger homes and commercial systems.

Table X is the standard half-hard copper tube for hot, cold and heating pipework above ground in UK homes, and it can be bent with a pipe bender. Table Y has thicker walls and comes soft in coils for underground and buried supplies. Table Z is thin-walled hard copper that shouldn't be bent. All are made to EN 1057 in metric outside diameters — 15mm and 22mm in most homes.

BSP (British Standard Pipe) sizes are named after the bore of old iron pipe, not the thread you measure, so a 1/2" BSP thread is about 21mm across the outside and a 3/4" about 26.4mm. Measure the outside of a male thread and match it to the chart. Parallel threads (BSPP) seal with a washer or O-ring; tapered threads (BSPT) seal on the thread with PTFE tape or jointing compound.

In UK homes, basins and bidets use 32mm (1¼") waste pipe; baths, showers, kitchen sinks, washing machines and dishwashers use 40mm (1½"); 50mm is for long runs and commercial kitchens; and WCs use 110mm soil pipe. Each appliance needs a trap — 75mm deep for basins, sinks and machines, 50mm for baths and showers — and the pipe needs a steady fall to the drain.

Lift the cistern lid and look at the water level. If it's up at the top of the overflow tube or running out of the overflow pipe, the fill valve isn't shutting off: lower the float, or replace the valve or its washer. If the level is below the overflow but water still trickles into the pan, the flush valve's seal is leaking: replace the seal or the flush valve. Turn the water off at the isolating valve first.

Lag every pipe in the loft, garage, under floors and on outside walls with foam insulation that fits the pipe, isolate and drain outside taps, and keep the heating on low or on frost setting in a freeze. If a pipe does freeze, turn the water off at the stop tap and thaw it gently from the tap end with a hairdryer or warm cloths — never a flame. If it bursts, turn off the stop tap and drain the system straight away.

Allow about 100 W of cooling per square metre for a typical UK room with a 2.4m ceiling, and 125–150 W if it's sunny, on the top floor or full of people and computers. A 20 m² bedroom needs about 2–2.5 kW (7,000–8,500 BTU); a 30 m² living room about 3–3.75 kW, which is a 12,000 BTU unit. Multiply kW by 3,412 to get BTU per hour, then pick the next size up.

For a room you want properly cool and quiet, a wall-mounted inverter split is the best choice: the noisy compressor sits outside, it heats as well as cools, and it uses less electricity for the same cooling than a portable. Portables need no installer but vent hot air through a window hose and are loud. Floor-standing cabinets suit big open spaces like shops and gyms, and multi-splits run up to three rooms off one outdoor unit.

A plumbers' merchant is a trade counter stocking the parts plumbers and heating engineers fit every day — fittings, valves, boiler spares, radiators, pipe and bathroom ware — in trade sizes and brands. Over a DIY shed you get a deeper range, staff who know the parts, matching from your old one, and trade accounts. London Plumbing Supplies is an independent plumbers' merchant at 186-192 Chingford Mount Road, Chingford, London E4 9BS, open 7 days.

Bring the old part if you can — matching it on the counter is the surest way to get the right replacement. If it's still fitted, bring clear photos of it and any labels, the make and model, and the key measurements: pipe size, thread size and, for tap cartridges, the spline count and length. For boiler spares, the boiler's seven-digit GC number identifies the exact model.