Considering Adding a Pressure Pump (Hidroneumatico) to Your Gravity Feed System?

About every 6 months, someone new pops onto Mexican expat construction and home repair forums and asks about the in’s-and-out’s of improving their household water pressure by adding a hidropneumatico (pressure-pump) that includes a bladder & tank system.

There are a number of issues and alternate problems that need to be considered first before choosing to install a pressure pump system on an existing gravity feed water system. If you rule out other likely problems, and still need/want even higher pressure, then there are also issues to consider about what type of system to buy, how to protect it from the weather and sun, and who to hire to install it.

Common misconceptions and frequent advice that is off the mark
Some expats advise that the person should get a bigger tinaco:
~ Getting a larger tinaco usually does little to affect pressure, unless your tinco re-fills only slowly. Bigger tinacos fill much more slowly, actually giving noticeably lower pressure in gravity feed systems.
~ Raising the height of the tinaco does increase pressure in a gravity-fed system, so raising your tinaco even 4-5 feet may make all the difference.

Some expats advise installing large pipes (1½ inch-3 inch) in the plumbing between the tinaco and house.
~ If your tinaco is only 5 to 9 feet higher than your faucet or shower head, increasing the size of the “down-pipe” will not increase pressure noticably (unless you have really small ID plumbing.) 3/4 inch ID plumbing is usually sufficient in most instances.

Is the “Pressure Problem” really due to low pressure, or might there be other issues?
~ Are you sure that the problem is the pressure? e.g. Some types of shower heads work much better than others in gravity feed systems. As seen in the next 4 points, reduced flow can be the actual cause of seeming pressure problems. e.g. Do you have low flow and low pressure at all points in the system, or in just selected areas? If you answered that the pressure is too low at ALL points in the system, then you really might need to raise the tinaco or buy a hidropneumatico.

~ Does your “new” system have vent pipes on every high point in the system’s sections? If you don’t have vent pipes at strategic points, the systems often get small/partial cavitations at high points – where a little trapped air greatly reduces flow. There are some good tricks for removing these cavitations/air-bubbles if you want to send me a PM.

~ Have you definitively ruled-out physical blockages? I have seen 5 different “new” systems where the workers got small rocks, sand, bits of concrete, and other dreck in the new plumbing – partially blocking the little valves beneath sinks & toilers, or blocking the flexible connectors, etc etc etc and lowering flow and pressure.

~ If there were ever runs of white PVC pipe running in sun-exposed areas, the pipes are almost guaranteed to grow algae inside, and then bits of algae break loose and partially plug narrow spots in the plumbing. This algae lasts for years.

~ Physical blockages must be physically removed by either opening up key joints & connections & fixtures, or blast the gunk out with a high pressure flow of water, or suck out the gunk with strong vacuums – like from creative use of a rigid-walled garden hose.

After Resolving all other likely problems/issues: What equipment should you consider:
~ Pressure pump systems that cost less than about $2,500 – $2,700 pesos generally use lower quality components and tend to fail within 1 – 3 years.
~ Even if you buy a better quality hidroneumatico system (spending more than $3,000 pesos on the pump and bladder system), like an Evans brand system, many of these models must be protected from the sun and weather, because their plastic parts break down in our tropical sun.

Potential Issues Unique to Retrofitting a Gravity-Fed Water System with a Pressure Pump:
~ Most Yucatecan plumbing jobs are done by workers who do not understand the materials or how to install them, or they take hidden short-cuts, which means that even Yuco-PVC systems with glued joints often do not tolerate pressures above 20 – 25 psi. I’ve had to repair 2 different systems where the workers made home-made unions by trying to glue a section of slightly larger pipe over the 2 neighboring pipes as a funky connector that leaks under the pressure of their new hidropneumatico. It’s really a challenge when the leak is hidden under a walkway or floor, and the water just flows down into the ground unseen.

How to Select a Plumber to Install the New Pressure Pump / Hidroneumatico System:
~ Hire only a well-qualified plumber who is well experienced and consistently successful with retro-fitting hidroneumaticos onto Yucatecan systems.
~ If your prospective “plumber” plans to install the new hidroneumatico without unions, find a new plumber.
~ If your prospective “plumber” plans to to use cheap parts – like a less expensive check valve – find a new plumber.
~ Ask your prospective “plumber” what range of working pressures he intends to use, and also ask how he plans to adjust the upper and lower pump pressure settings, and the bladder pressure, and what pressures he likes. If he looks at you blankly, or hesitates, or waffles or hand-waves about how that’s all preset at the factory, then consider finding a different plumber.
~ Figure out whether your prospective “plumber” has considered and ruled-out all the potential flow-issues described above. If he has not checked-out the 5 points I described above, it may be time to interview a different plumber.

Your final system settings should have a working range of about 5 psi, with the air bladder pressure set either at the low-pressure pump-start pressure or 3 psi below that value. Pressures set higher than 20 – 25 psi tends to cause problems with most Yucatecan plumbing systems. e.g. The D ring seals and coupling designs in flexible connections used here to couple faucets and toilets to the PVC pipes are just not designed to handle pressures higher than 20-25 psi, not to mention the potential for hidden leaks inside walls or under floors.

Hope you get all the pressure you want and enjoy years of strong showers and brisk flows.

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Feel free to copy while giving proper attribution: YucaLandia/Surviving Yucatan.
© Steven M. Fry

Read on, MacDuff.