I am thinking of getting another water pump with external pressure tank in addition to the one that is already installed to the main house.

I want it to solely feed my bottom floor outdoor shower.

I plan to install possibly install 8"-12" square rain shower head as I want it to pour not trickle.

Anyone can shed some light on what I should be doing as I was thinking I need the pressure to be high yet don't want to risk bursting any main house pipes.

I have heard grundfos are known to high water flow. Is the one with the small tank on top what I need?

Can I split the outlet pipe from the main water tank to feed both water pumps?

Does my plan make sense or there another way around to successfully have high water pressure without affecting main house pipes?

Edited September 18, 201015 yr by tangcoral

No need to increase pressure, only flow. Pressure over 2,8 bar will blow most pvc pipes, even 13,5, within weeks

For a large rainshower, a Mitsu 305Q feeding shower only should be sufficient at 6xxx baht. Desire more flow, Grundfos (with tank on top) from 12-18 k baht. Read the spec on flow, to see the differences.

Thinking of it, for rainshower only, you could just use a simple pump without pressure sensor and tank, 2-3k baht, and an electric switch for on/off.

LOL. I am running 5 bar pressure at my condo. It wails.

As to your questions.

Yes one suction is fine. Should be ideally 1 inch & not less than 3/4.

Personally I would run a dedicated pipe from my new high pressure high volume water pump to my rain head shower.

But that's just me.

Grundfos pumps are great.

This Masterfow pump is one horsepower (750 watt). About 1/2 the price of grundfos, does not need expansion tank & is fully adjustable.

Edited September 18, 201015 yr by powderpuff

Do not forget a larger diameter floor drain to match the high pressure 1-inch discharge.

3/4 inch discharge is plenty.

I am forcing a lot of water through 1/2 piping & hot water heater.

Thank you for your inputs.

Edited September 18, 201015 yr by tangcoral

No need to increase pressure, only flow. Pressure over 2,8 bar will blow most pvc pipes, even 13,5, within weeks

The blue PVC sold at hardware stores is usually made by Thai Pipe Industry Company. This pipe usually comes in three "working" pressure ratings based on pipe wall thickness of 5 kg/cm2 (a.k.a., 5 bar) which is 72 psi, 8.5 bar which is 123 psi, or 13.5 bar which is 196 psi. Most water pumps like the Mittsubishi WP, EP, CP series usually have an upper end pressure setting ranging from 1.8 bar (smaller pumps) to 2.8 bar (larger pumps). The bar/pressure rating is printed on the pipe.