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In particular Im trying to understand the Mitsubishi pumps, there seems to be two types

 

  1. Automatic pump
  2. Constant pressure pump

 

Im confused by this...

 

If you turn on a tap, naturally the water pressure drops in the pipe and the automatic pump comes on, it comes on automatically, but the constant pressure type would also come on as the pressure in the pipe has dropped.

 

So what’s the difference?

 

Logically the constant pressure pipes makes sure the pressure within the pipe stays at a constant pressure, where as the automatic pump does not do this.

 

Ive had showers here with the water pressure drops and drops, then suddenly bursts back to life, so I'm guessing this is the automatic pump which only comes on when the pressure gets below level. Then it turns on and the shower gets a bit extreme for a moment, then the pump turns off, and the shower slowly drops in pressure until the cycle restarts.

 

So why would anyone use the automatic pump?

 

What situation do we use each pump for?

 

For a shower Ive seen so many bungalow resorts use the automatic pump, but should they actually be using the constant pressure pump?

 

Any shared insights into these two types of pumps much appreciated!

 

Specifically, in the house Im building, for the mains water coming in from my 4000L tank, should I use a constant pressure pump?

 

And in the UK we use the "bar' system for pressure, but these pumps don't mention this, so how can i compute the "bar pressure" a particular pump will provide?

Edited by STD Warehouse
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Just as an example, I downloaded this spec sheet for Mitsu WP Series pumps.  It's from the Malaysian site http://mitsubishielectricmalaysia.com/products/water-pump/q3/water-pump-specs.pdf  but at least it's in English.

 

There is a table that gives the ON/OFF/MAX pressures in kg/cm2 (just about the same as bars)

 

If you download the spec sheet for the model that you are interested in you should find similar information.

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The "automatic" pumps have an air bladder and a tank while the constant pressure do not. If feeding direct to your pipes, the constant pressure is better. If used to fill a tank, the automatic is better.

 

Both are automatic and both will work fine in either application. The constant pressure are much touchier, so every time there is a slight pressure drop they will cycle on. The bladder in the automatic allows more water to flow before the pressure drops enough for the pump to cycle on. 

 

If you have a slow leaking toilet, the constant pressure will cycle on and off ten times for every time the bladder type cycles once.

 

 

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1 hour ago, doctormann said:

Just as an example, I downloaded this spec sheet for Mitsu WP Series pumps.  It's from the Malaysian site http://mitsubishielectricmalaysia.com/products/water-pump/q3/water-pump-specs.pdf  but at least it's in English.

 

There is a table that gives the ON/OFF/MAX pressures in kg/cm2 (just about the same as bars)

 

If you download the spec sheet for the model that you are interested in you should find similar information.

Thanks, will look, very helpful

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58 minutes ago, Yellowtail said:

The "automatic" pumps have an air bladder and a tank while the constant pressure do not. If feeding direct to your pipes, the constant pressure is better. If used to fill a tank, the automatic is better.

 

Both are automatic and both will work fine in either application. The constant pressure are much touchier, so every time there is a slight pressure drop they will cycle on. The bladder in the automatic allows more water to flow before the pressure drops enough for the pump to cycle on. 

 

If you have a slow leaking toilet, the constant pressure will cycle on and off ten times for every time the bladder type cycles once.

 

 

Thank you, that explains a few things!

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