Water Tower & House Supply

Anything to do with the subject of water or plumbing. Any type of well (hand dug wells, drilled wells, etc.), plumbing (but not swimming pools) or any other discussion related to water.

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Water Tower & House Supply

Postby lblake32 » Mon Oct 06, 2014 10:30 am

I've recently moved into a new build house in Phuket and I'd be grateful for comment and advice on my water supply system. I've found it near impossible to get reliable technical information on this subject.

I have a deep bore-hole which pumps to a 3000 Ltr tank on a water-tower. The base of tank is 8 Mts above ground level and the tower is about 30 Mts from the entry point to the house. I thought this would provide good pressure to three upstairs bathrooms but I was mistaken as only a weak dribble comes from the showers, not enough the switch on the heaters. The builder said I needed a pump and he installed a Mitsubishi WP-305QS near the house. The supply line from the tower is 40mm and reduces to 25mm just before the pump.

The pump just pulses on/off when any tap or shower is open and it will not run continuously. I screwed down the pressure valve adjustment until the pump would run continuously but this raised the pressure to the point that the bum guns and some valves started leaking. Thinking the switch was faulty, I bought a new one which was pre-set to the pump specs and now it's back to pulsing on/off. I've tried to understand the instruction document that came with the pump but this is only available in Thai so I'm not sure if I understand correctly. For example, one diagram (2) shows a storage tank at ground level and seems to suggest that high water level should not be greater than 2 Mts. Also there is a reference to a spring in the check valve - should it be used or not? One more thing - the builder made a pump bypass but only fitted a check valve whereas I would have thought a stop valve would be necessary and lower pressure water from the tower joins the pumped output. Could this create turbulence and stop the pump ?

I can see that many people experience the pulsing problem but so far everyone seems to be pumping from a well, not a tower. I"m begining to think this is the wrong pump for this setup because there is a static head from the tower and the pump has no need to suck. I'm ready to throw the thing out and start again but I'd like to know that it will work next time.

Regards
Les
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Re: Water Tower & House Supply

Postby Sometimewoodworker » Mon Oct 06, 2014 12:53 pm

You have a well pump. And what you need is a constant pressure pump specially if you have heated showers. They are the EP series. The WP series are not recommend for instant hot showers.

Though you might be OK with a booster pump.
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Re: Water Tower & House Supply

Postby Klondyke » Mon Oct 06, 2014 7:44 pm

Les, Once you have got the Mitsubishi pump you do not need the water tower. You can feed the pump from a tank that is on the same level with the pump. Then you can save the power pumping not so high.
In your situation once the tower is available, perhaps you can keep it as a back up during a power outage. Or, if easy possible, use the tower only for the ground level installation. Then, for the 2nd floor to install a smaller tank and run the pump only for that.
When the water system is not so easy to divide, even for the whole house you can have the same small tank - 1,000 L is enough - for a sudden larger demand you will always get the backup by the water tower.
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Re: Water Tower & House Supply

Postby Ians » Mon Oct 06, 2014 8:17 pm

First up, what is the difference in water level of the water tank,(say half full) and the outlet of the shower heads, this might account for the low pressure at the shower heads?

PUMP:
If the pump is feed by an overhead tank 8 meters above the pump, you don't really need the Mitsubishi WP-305QS, what would have been a better arrangement is a basic centrifugal pump which a pressure tank and pressure control valve or a pressure / flow sensing switch arrangement. However, I'm not sure without thinking a bit more about the Mitsubishi WP-305QS with 8+ meters on the inlet side of the pump - gut feel is should work and if its pulses on/off it possibly means that the pressure difference between the shut off point and the start point is too close together, possibly the standard pressure switch is not the correct one or the pressure tank is "water-logged".

Question: how long has the Mitsubishi been installed and running - and has it pulsed from the initial installation?
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Re: Water Tower & House Supply

Postby lblake32 » Tue Oct 07, 2014 7:07 am

Update:

I replaced the check valve with a gate valve and it made no difference. I drained the pressure tank (again) and the pump still pulsing. Then I thought some more about the replaced pressure valve - it was not OEM and it's two wire electrical supply was by spade connectors whereas the original wires were soldered. What if the switch had fixed polarity ? I changed the spades and no more pulsing. It seems that the pump was trying to run from the maximum pressure setting and of course it would immediately switch off. In Thailand, it's 50/50 which way you connect the plug to the power outlet and I wonder if many of the pump pulsing problems are cause by incorrect polarity ? I'm not qualified to answer.

Thanks to all for your helpful advice. It's good to know I can get support when needed.
Regards
Les
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Re: Water Tower & House Supply

Postby Ians » Tue Oct 07, 2014 11:23 am

Interesting solution and worth thinking about further, good detective work on your part.
Assume the "pressure valve " is the pressure relay that you replaced.
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Re: Water Tower & House Supply

Postby lblake32 » Tue Oct 07, 2014 3:58 pm

Yes, I should have called it the pressure switch but I'm sure "relay" is more correct.
Regards
Les
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Re: Water Tower & House Supply

Postby Sometimewoodworker » Tue Oct 07, 2014 5:13 pm

lblake32 wrote:Yes, I should have called it the pressure switch but I'm sure "relay" is more correct.
Regards
Les

Pressure switch is the correct term, at least accordion to Mitsubishi. :)
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