Home Improvement → [Plumbing] Replace diaphragm tank with pressure pump

Our third diaphragm tank in 12 years is leaking. High ambient temperatures and lime deposits kill these tanks here in Mexico. Vendors do not sell replacement bladders. Our plumber, long-time and trusted, is suggesting a pressure pump, (see »goo.gl/MbRcdB ), a Pedrollo 35 1a, 1a. It's a new concept for me. Does anyone have any experience with these?

You don't say whether you have the tank to deal with thermal expansion in a closed system or as a buffer to prevent frequent start/stops of a well pump.

While I have no experience with the specific pump:

The pump you are linking to is designed to provide stable pressure by boosting the pressure when necessary. It certainly won't help to eliminate excess pressure from thermal expansion.

I don't think it can be used as a replacement for a well pump either since it doesn't have much lift power.

Simply using that pump as a replacement for the pressurized tank in a well pump is going to cause the frequent start/stops for the well pump that you are trying to avoid with the pressurized tank.

However it is certainly possible to use it in a system with a non-pressurized tank or cistern. The well pump will refill the tank when needed (make sure there is sufficient difference between the on and off setpoints for the float switch) and the pressure pump ensures constant pressure (regardless of the fill-level of the tank) within the plumbing of the home.

Thanks leibold. Perhaps I should have expanded on the 1980's construction techniques used here. My house is one of 18 houses in a gated community. City water is supplied to a below-ground cistern. Each house has a 2000 liter tank on the roof. A float switch lives in the tank. When activated a central pump in the cistern lifts (pushes) water to the roof-top tank. Water is gravity fed to the house below. Pressurization is an owner installed option.

Over the years as calcification has set in, the gravity feed becomes less tenable and choices are to re-pipe the house or give gravity a hand, hence the pump. All the houses are poured concrete. Great for withstanding hurricanes (I'm right on the beach), but lousy for getting into the walls and floors. Also, many of us have changed to on-demand hot water which requires a certain pressure threshold to activate.

After moving here there was a lot of learning (and teaching). When I said the word tierra (ground) to the electrician who was rewiring the house his initial answer was, "Que?" Fortunately the wiring was in conduit. Of course conduit down here means orange rubber hose. We dug down to the steel girder footing the kitchen corner and welded 0 gauge cable up to a central ground bar. Adventure in living continues.

It sounds like the pump your plumber recommends is perfect for your situation.
However if I were in your position I would also look into ways to reduce further calcification by installing a whole-house water softener (and maintain it properly!).
This will not only prevent the problem from getting worse, over time it should clear up some of the limescale in your plumbing (improving the flow rate).
Of course, with softened water your pressurized tank would last much longer too

Thank you for your informed opinion. Much appreciated. It goes in tomorrow. The problem with a softener (don't ask me how I know) is that it has to be installed outdoors, either next to the little cabin holding the pump, or on the roof near the tank. The sun reduces the plastic to junk in less than 2 years. Gauges fall apart, salt tank disintegrates, as does the tubing. Been there .

Can't you build a little housing around the softener to shade it?

you can buy a tank with a Teflon bladder, that should hold up..

You can. I can't. I just spent several minutes looking for one. I cannot find one within 100 miles of Cancun. Part of the price of living in Paradise is the acceptance that you're not in Kansas anymore.

Unfortunately, DataDoc, there are space constraints and practicalities to consider. The route to the roof is via two ladders attached to walls, The roof is about 60 feet up from ground level. Carrying 50 lbs. of salt up to the roof is no fun. It wasn't 10 years ago, and at my age it isn't now. The space available in my front garden is too small. There's a propane tank and the pumping station hidden by some hedge. No room for anything else. The pump sits in a concrete shelter the size of a dog house.

I figured the roof was out of the question, I thought maybe the ground had space available.

what about your side or rear yard?..

Thanks for your continued interest. However, if I had the room I would have used it. Rear yard is common area. Can't be used. Same for side. Only front patch or roof is available. Besides, it's done.