Expansion Tank for Water System: Manila Supplier for Commercial Buildings

Two different vessels get called an expansion tank in the Philippines, and specifying the wrong one costs you a return trip. The first is a true thermal expansion tank, a small sealed vessel with a rubber diaphragm that absorbs the extra volume water occupies when a closed hot water loop, a calorifier, or a boiler feed line heats up. Without it the pressure relief valve lifts every heating cycle and you lose water and treatment chemicals. The second is a diaphragm or bladder pressure tank, the larger vessel bolted next to a booster set, which stores a usable volume of water under air pressure so the pump does not start every time somebody opens a tap.

Building engineers, plumbers, and procurement staff across Metro Manila use expansion tank for both, often in the same email thread. When you send us an RFQ we confirm which one your system needs before we quote, because the sizing method, the working pressure, the temperature rating, and the price are all different. JOHOB Hardware Trading supplies both under our Pumping and Pressure Systems line, alongside the commercial booster pumps, transfer, and submersible pumps and the VFD control panels they connect to. If your drawing is a closed hot water riser, you need the first. If it is a domestic water booster fed from a cistern or a roof tank, you need the second, typically a hydropneumatic bladder pressure tank or a 200L diaphragm pressure tank for commercial booster systems. If it is a hot water booster, you often need one of each.

Thermal expansion sizing is arithmetic, not guesswork, and any supplier who quotes you a size without asking for numbers is guessing. You need four inputs: total system water volume including the calorifier and the pipework, the cold fill temperature, the maximum operating temperature, and the pressure relief valve setting. Water expands roughly 2 percent going from 25 C to 70 C, so a 2,000 litre closed loop generates about 40 litres of expansion volume. That expansion volume is not the tank size. The tank has to be larger because the air side is already precharged.

The working relationship is tank volume equals expansion volume divided by one minus the ratio of initial absolute pressure to final absolute pressure. With a 3.0 bar gauge precharge (4.0 bar absolute) and a 5.5 bar gauge maximum (6.5 bar absolute), that divisor is 0.385, so 40 litres of expansion needs about 104 litres of tank and you specify the next standard size up, 150 litres. Precharge is set to match static system pressure at the tank location, which on a high rise means the pressure at that floor, not at the pump room. Send us the riser diagram, the calorifier capacity, and the relief valve setting and we return the calculation with the quote so your consultant can check our work.

If your expansion tank is really the vessel on a booster set, the governing number is drawdown, meaning the litres you can actually draw before the pump restarts. Drawdown is a fraction of nominal tank volume, and that fraction is the acceptance factor: cut-out absolute pressure minus cut-in absolute pressure, divided by cut-out absolute pressure. A set cutting in at 3.0 bar gauge and out at 4.5 bar gauge gives 0.27, so a 300 litre tank delivers only about 82 litres of usable water. You then work backwards from motor starts. Most manufacturers cap starts per hour on larger motors, so if you want a three minute minimum run time at a 60 litre per minute average draw, you need 180 litres of drawdown, which means a tank of roughly 660 litres. That is why fixed speed booster sets in Manila condominiums end up with tank rooms full of vessels; sizing the pump itself follows our guide on how to size a booster pump for a commercial building.

A VFD duplex panel changes the calculation entirely: the drive holds setpoint pressure by modulating speed instead of cycling the motor, so the tank stops being a storage buffer and becomes a much smaller anti hunt and surge vessel. JOHOB supplies Chutian control panels built around Inovance drives for exactly this, quoted together with the pumps and the vessel as complete pump system packages so the three are matched rather than bought separately. The same logic drives a condominium booster pump replacement in Manila, where swapping to VFD control often shrinks the replacement tank scope.

An expansion tank quote is only as good as the data behind it, so these are the items our sales engineers confirm on every RFQ. Nominal volume in litres, and separately the drawdown or acceptance volume you actually need. Maximum allowable working pressure, which must exceed your relief valve setting with margin. Maximum operating temperature, since a standard butyl diaphragm rated for domestic cold water will not survive a 70 C hot water return. Diaphragm versus full bladder construction, because a replaceable bladder keeps the water off the steel shell and is the right call on potable duty and on any vessel you expect to service in place. Connection size and type, flanged or threaded, and the flange standard your contractor is working to. Shell material and internal coating, and whether the vessel sits vertical on legs or horizontal on a pump skid. Precharge pressure as delivered, which we set to your stated static pressure rather than leaving at factory default. Finally, the pump and control it will work with, since we would rather quote the vessel, the pump, and the panel as one matched package than have three suppliers each blame the other two on commissioning day. We respond to RFQs within 1 business day.

Equipment we supply carries manufacturer certification appropriate to its class. Pressure vessels are supplied to ASME where applicable, manufacturers hold ISO 9001 quality management system certification, electrical components including control panels carry CE marking, and TUV SUD testing is available on supplied equipment where the manufacturer holds it. We provide the documentation with delivery rather than promising it later, and we tell you in the quotation exactly which certificates apply to the items on that quotation. Standard lead times are 21 to 35 days ex stock and 45 to 90 days for made to order configurations, which covers non standard volumes, special pressure ratings, and matched pump and panel packages. Pricing is quote based and we do not publish prices, because vessel cost moves with volume, pressure rating, material, and the pump package it ships with. On tax, 12 percent VAT applies to VAT registered buyers in the ordinary case. PEZA and SBMA locators and registered exporters are quoted at zero VAT, and we handle the documentation for that treatment as part of the quotation rather than asking you to reconcile it afterwards. Ask for the certification pack up front if your consultant needs to review it before purchase order release.

JOHOB Hardware Trading delivers nationwide: NCR and the rest of Luzon, Visayas, Mindanao, and the PEZA, SBMA, and Clark economic zones. Metro Manila deliveries are the bulk of our expansion tank and pressure tank movement, covering condominium pump rooms, hotels, hospitals, commercial laundries, and food processing plants. We are a Philippines based industrial equipment supplier, not a drop shipper: we source from Philippine and Chinese factories, and every item ships with local warranty and after sales support so a diaphragm failure in year two is a phone call to a Philippine company rather than a warranty claim filed overseas. Because we also supply booster, transfer, and submersible pumps from Grundfos, DAB, Speroni, and CDL alongside VFD, star delta, soft starter, and MCC panels, we can quote the vessel as part of a complete matched system with the pipework, stainless steel flexible hoses, ball valves, and gate valves it needs. For projects that also require bulk storage, our sister brand TankSmith supplies modular water storage tanks in FRP, GRP, hot dip galvanised, and stainless as a turnkey install. Send drawings, an equipment schedule, or even a photo of the nameplate on the vessel you are replacing, and you get a response within 1 business day.

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