WaterBoost ATX-300H 4.5 bar Horizontal Whole-House Mains Pressure Booster

The WaterBoost ATX-300H 4.5 is the largest high-pressure horizontal model in the ATX integrated accumulator booster range, built for lofts, eaves, under-bath voids and low cupboards. It connects directly to the incoming cold water mains, combining a 300-litre sealed horizontal accumulator vessel with the WB-Compact 4.5 variable speed pump mounted beside or in front of it — charging the vessel up to 4.5 bar and boosting both pressure and flow throughout the property the moment a tap or shower is opened. No break tank, no overflow arrangement, just two water connections required. The system delivers a peak burst flow of up to 80 l/min and up to 27 l/min at up to 4.5 bar for up to 11 minutes — before settling to a continuous boosted flow of 12 l/min at 3.0 bar until the vessel recharges. The 300-litre vessel provides 180 litres of useable working capacity. Variable speed inverter technology means the pump only generates the pressure your mains can’t already deliver, keeping running costs to a genuine minimum. Operation is measured at a quiet 40 dB(A), and the pump sits on a WaterBoost QuietPad anti-vibration base so nothing transmits through joists or floorboards. WiFi via the DAB H2D app enables remote monitoring and control, with a Power Shower mode for when you want everything the system has. A mains bypass fits in seconds using 2 clips if the unit ever requires attention. WRAS approved product — continuous flow stays within the water authority limit of 12 l/min. Fully sealed system — zero air contact with stored water, no hygiene management required. Completely maintenance free. Suited to 2-4 bed homes upwards with two or more showers running together, rain heads, body jets, top-floor bathrooms or an unvented cylinder that wants more than 3 bar can give. 5-year tank warranty, 3-year pump warranty. If 3.2 bar is enough, see the standard ATX-300H; step down to the ATX-250H 4.5 for two bathrooms. 4.5bar Max pressure 80l/min Peak flow 180L Useable capacity 5yr tank 3yr pump Warranty Horizontal · low profile Up to 4.5 bar WiFi · H2D app WRAS approved Zero maintenance Sealed — no air contact Variable speed 300L · 180L useable No overflow Dry run protection QuietPad fitted Bypass fits with 2 clips