Power fluctuations - electric supply

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Nereus
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Re: Power fluctuations - electric supply

Post by Nereus » Fri Jun 02, 2017 10:57 am

I should just sit back and watch, but that is not how I am!
....also check every joint you can to make sure air is not getting into your line between pump and house, or between tank and pump.
It is not possible for air to enter the plumbing system AFTER the pump. If there is a leak some where on the pressure side of the pump it will cut in and out as the pressure bleeds off without any taps being open.

It IS possible that air is entering BEFORE the pump, but as it has been posted that it is a surface tank, then the leak should be obvious if the piping is exposed.

Most of these small domestic pumps are what is termed "shallow well pumps". Many of them are not designed to have a "flooded" suction head. It is more than likely that it needs to be drained of all water, the pump primed and bled of any air in the actual pump, and restarted.

You should of made it clear at the start that "air" is also present at the other outlets.
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Re: Power fluctuations - electric supply

Post by Geko » Fri Jun 02, 2017 1:47 pm

I would definitely try priming the pump to remove air.
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Turn of power, fill small pump tank with water, screw cap on, start pump vent off air through cap loosening slightly, you may have to stop the fill pump and vent a few times, eventually the air should no longer vent. when this happens vent water out of your system by opening all taps.

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Re: Power fluctuations - electric supply

Post by PeteC » Fri Jun 02, 2017 2:23 pm

Name Taken wrote:
Fri Jun 02, 2017 10:33 am
prcscct wrote:
Thu Jun 01, 2017 3:22 pm
....also check every joint you can to make sure air is not getting into your line between pump and house, or between tank and pump. We had that problem and the water spit like an angry snake and screwed up the operation of the heater. Once the air leak discovered and fixed, all was fine. The problem is it is a bi^%h to find where the air is getting in. I was lucky as it was an elbow joint coming out of the in ground tank on the way to the pump and the first stop on my line search. Pete :cheers:
Thanks for the reply Pete.
I think that's more than likely what is causing the problem, an air leak in the plumbing/pvc pipework somewhere.
Nereus is right concerning pump to house. I was suffering grass cutting heat stroke and no beer in frig syndrome yesterday. :mrgreen: Pump to house you're just going to get a water leak and perhaps low pressure at the outlet...plus pump running when it shouldn't be. On the tank to pump side in my case, the elbow female end was only up 2mm and it caused all the problems. The original plumber hadn't glued the joint and it had gotten knocked from time to time and worked its way loose. Let us know when you find the answer. Pete :cheers:
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Re: Power fluctuations - electric supply

Post by Name Taken » Sat Jun 03, 2017 9:58 am

Geko wrote:
Fri Jun 02, 2017 1:47 pm
I would definitely try priming the pump to remove air.

compressors_0018_Layer_4.jpg

Turn of power, fill small pump tank with water, screw cap on, start pump vent off air through cap loosening slightly, you may have to stop the fill pump and vent a few times, eventually the air should no longer vent. when this happens vent water out of your system by opening all taps.
The water under the cap in the picture is full to the top and it has always been full.
What is strange is that I have found that if I open 2 taps at the same time the water flow stabilizes and becomes constant and consistent(no surging) but if I open only 1 tap the water surging problem comes back. :?
And as I said before the water surging problem only happens when the tap is opened a little bit not when the tap is fully opened and the water is flowing strong.

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Re: Power fluctuations - electric supply

Post by Nereus » Sat Jun 03, 2017 1:54 pm

What is strange is that I have found that if I open 2 taps at the same time the water flow stabilizes and becomes constant and consistent(no surging)
There is nothing strange about it! With 2 taps open there is no pressure build up to operate the pressure switch, just a continuous flow of water.

I have posted what the problem is. This only started after you had the system open to install the new heater right, if what you are posting is correct?

Isolate the both power and water supply if it has a valve on the supply tank outlet.

At the bottom of the big pump tank where it sits on the ground, there will be at least one drain plug. Remove the plug and allow ALL the water to drain out. NOT the priming chamber on top of the pump! Turn the water supply back on, plug the pump power back in and see what happens. It should run until the pressure builds up in the system and cuts out. Then go and run some water out of a couple of other taps until it is clear. It should cycle on and off as it did before you changed the heater.
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Re: Power fluctuations - electric supply.. and pump hydraulics

Post by laser » Sat Jun 03, 2017 4:59 pm

It could have been helpful providing some technical information. Else, it's like trying to catch a black cat in a dark room, and maybe in the wrong house. I reckon I know what the likely cause is, but to suggest a reasonable/simple fix need to know more.

Which/what 'Hitachi' pump do you have?
http://www.hitachiconsumer.com.my/produ ... alogue.pdf

There's a rough design sketch in the brochure. You probably can describe what are the differences between the design illustration and your system. Like you might have an above ground tank connected to the pump through the top of tank, or through a side connection located around the bottom of the tank. The pipe lengths would be different, too. How many floors and units (taps, showers, toilets, irrigation hose etc) the building has?
And something else not shown there: are there isolating valves (inlet and outlet sides of the pump unit) - typically ball valves that open/close with a 90 degree turn?

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Re: Power fluctuations - electric supply.. and pump hydraulics

Post by Name Taken » Sun Jun 04, 2017 9:33 am

laser wrote:
Sat Jun 03, 2017 4:59 pm
It could have been helpful providing some technical information. Else, it's like trying to catch a black cat in a dark room, and maybe in the wrong house. I reckon I know what the likely cause is, but to suggest a reasonable/simple fix need to know more.

Which/what 'Hitachi' pump do you have?
http://www.hitachiconsumer.com.my/produ ... alogue.pdf

There's a rough design sketch in the brochure. You probably can describe what are the differences between the design illustration and your system. Like you might have an above ground tank connected to the pump through the top of tank, or through a side connection located around the bottom of the tank. The pipe lengths would be different, too. How many floors and units (taps, showers, toilets, irrigation hose etc) the building has?
And something else not shown there: are there isolating valves (inlet and outlet sides of the pump unit) - typically ball valves that open/close with a 90 degree turn?
The Hitachi Water Pump Model Number is WM-P150XS
The above ground water tank that I have is connected to the Hitachi Water Pump through a side connection at the bottom of the water tank. The house is only floor(single story) and it currently only has 3 taps. The pipe length from the water tank to the water pump is about 4-5 feet I guess.
Yes, there are isolating ball valves on both the inlet and outlet sides of the pump.

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Re: Power fluctuations - electric supply

Post by Geko » Sun Jun 04, 2017 1:05 pm

The system you have described seems pretty normal with the type pump you identified.

One other thing that could be a possible cause of your problems is a faulty non-return valve (if fitted). Some household water supply systems are installed here with a second supply line to the house direct from the mains water supply as shown in the diagram.

My system is as shown but has an isolation vale after the NRV, which I keep closed as I have filter system fitted before the main tank and I don't want unfiltered water getting into the house direct from the mains supply.

Sure the system as shown in the diagram is for a clean mains water supply, where the tank and pump are used as a back-up, maintaining the household supply if the mains water pressure falls below the setting of the pumps pressure switch, the non-return valve prevents water from the pump back feeding the mains supply. (Sure some expert will tell me I'm wrong).

If you have a system as shown in the diagram and can isolate the NRV try doing that to see if the problem stops, if you cannot isolate the NRV open it up and see if it internals look ok or replace only a few baht.
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Re: Power fluctuations - electric supply

Post by NOKYAI » Sun Jun 04, 2017 1:24 pm

Well, I'm learning a lot from all of this, thanks guys!
Now semi retired 60:40 Thailand: UK ( seems to be working well)

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Re: Power fluctuations - electric supply

Post by Name Taken » Mon Jun 05, 2017 8:27 am

Nereus wrote:
Sat Jun 03, 2017 1:54 pm
What is strange is that I have found that if I open 2 taps at the same time the water flow stabilizes and becomes constant and consistent(no surging)
There is nothing strange about it! With 2 taps open there is no pressure build up to operate the pressure switch, just a continuous flow of water.

I have posted what the problem is. This only started after you had the system open to install the new heater right, if what you are posting is correct?

Isolate the both power and water supply if it has a valve on the supply tank outlet.

At the bottom of the big pump tank where it sits on the ground, there will be at least one drain plug. Remove the plug and allow ALL the water to drain out. NOT the priming chamber on top of the pump! Turn the water supply back on, plug the pump power back in and see what happens. It should run until the pressure builds up in the system and cuts out. Then go and run some water out of a couple of other taps until it is clear. It should cycle on and off as it did before you changed the heater.
No, the water surging problem started when I replaced the Mitsubishi water pump with the new Hitachi water pump which you can read about on page 1 of this thread.
The new Stiebel Eltron shower heater works great and thankfully it's strong enough to heat the water even with the surging problems which I still think is caused by the water pump. The Panasonic shower heater was too weak to heat the water because of the surging problem and I replaced it with a Stiebel Eltron shower heater.
Some farang in Thailand is very likely to have the same or similar problems with the their water pump in the future that I am having now, so I think it's important that the information posted in this thread is as truthful and accurate as possible.
And I did not see any drain plugs anywhere on the bottom of the pump.
Last edited by Name Taken on Mon Jun 05, 2017 9:03 am, edited 1 time in total.

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Re: Power fluctuations - electric supply

Post by Name Taken » Mon Jun 05, 2017 8:34 am

Geko wrote:
Sun Jun 04, 2017 1:05 pm
The system you have described seems pretty normal with the type pump you identified.

One other thing that could be a possible cause of your problems is a faulty non-return valve (if fitted). Some household water supply systems are installed here with a second supply line to the house direct from the mains water supply as shown in the diagram.

My system is as shown but has an isolation vale after the NRV, which I keep closed as I have filter system fitted before the main tank and I don't want unfiltered water getting into the house direct from the mains supply.

Sure the system as shown in the diagram is for a clean mains water supply, where the tank and pump are used as a back-up, maintaining the household supply if the mains water pressure falls below the setting of the pumps pressure switch, the non-return valve prevents water from the pump back feeding the mains supply. (Sure some expert will tell me I'm wrong).

If you have a system as shown in the diagram and can isolate the NRV try doing that to see if the problem stops, if you cannot isolate the NRV open it up and see if it internals look ok or replace only a few baht.

1381833443-2-o copy.jpg

images.jpg
Then why are they called constant pressure water pumps? If there was constant pressure then there wouldn't be any surging, right?
There is no mains water supply out here and it will probably be another 100 years before we get a main water supply system in our area. :laugh:

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Re: Power fluctuations - electric supply

Post by Nereus » Mon Jun 05, 2017 10:49 am

I new damn well that I should have kept away from this!

ALL of these types of water pressure systems have to have an "air cushion" that provides the pressure. You cannot compress water, so the pump shifts a volume of water into the holding tank against a certain volume of air, which is compressed and builds up pressure. As in ANY enclosed system the total pressure in the system is reflected on to all parts of that system, it is basic physics. The pressure switch is connected so that it senses this pressure, and is set to stop the pump. When you draw water off the system the pressure will start to drop until what is termed the "differential pressure" setting is reached, whereby the pump is switched on again and the cycle repeated.

In earlier, and probably some current bigger systems, the holding tank was fitted with a rubber "bladder". The water is stored on one side of the bladder and the air on the other side. BUT, the big difference with this type of system is that the airside has to be pre-charged and maintained to a given air pressure. They are more reliable and maintain pressure more accurately and usually have a bigger reservoir tank that allows for a bigger drawdown before the pump has to run again. Apart from that they work on the same principle as your system.

With the small types of pumps used here, and many other places, there is no "bladder" to separate the water and the air. From being empty of water to start with and only atmospheric air pressure, the pump moves water into the tank and starts to compress the air. It will continue to do that until such time the total pressure reaches the pressure switch set point and the pump stops. Draw off some water and the pressure drops below the differential setting and the cycle repeats.

The point here is that the reservoir tank HAS to have a space for air. That is why I suggested that you drain the tank and start again. HOWEVER, I also posted that these pumps are called "shallow well pumps", which means that they are NOT designed to have a "flooded" suction head from a surface tank. The constant head of water from your surface tank can allow the water to flow through the pump and "flood" the reservoir tank, eventually resulting in no air space to build up pressure. I have found that Mitsubishi pumps do not have this problem, but I am not sure about Hitachi, but as the problem appears to have coincided with the replacement of the pump, it is more than likely they are susceptible to this problem.

The drain plug I referred to may be hidden under the plastic stand the unit sits on so it is not obvious.

You have posted that the pump is a "constant pressure" pump. I have not seen them here but then I am no longer directly involved with the things. I will post a link to a site that shows the difference. On both of the examples shown you should note the air space in the reservoir tank, albeit one of them is shown inverted.

http://www.cyclestopvalves.com/simple/home.php
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Re: Power fluctuations - electric supply

Post by Name Taken » Mon Jun 05, 2017 12:03 pm

^Thanks for taking the time to post that Nereus and thanks for the weblink, that was informative.
:cheers:

So it looks like both the Hitachi water pumps and Mitsubishi water pumps have problems and I guess I'm stuck between a rock and a hard place. :laugh:
I think I will just stick with the Hitachi water pump for now. :laugh: :|

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Re: Power fluctuations - electric supply

Post by Geko » Mon Jun 05, 2017 1:25 pm

'Name Taken' sure the guy that solves your problem deserves a few beers.

So the pump you have is like the one shown in the video attached yes? It has no tank attached to the pump body but a pre-charged Nitrogen filled accumulator (the thing the guys are changing), sorry the video is in Thai but the pump seems to be working intermittently faster than usual indicating the accumulator has lost its pre-charge, they install a new accumulator which appears to solve the problem. I know your pump is new but shit happens.

One last attempt from me to solve your problem would be to fit a new accumulator.

I'm not sure if you can check if the original accumulator has lost its pre-charge by sticking a blunt stick inside the entry hole and see if you can detect any resistance from the Nitrogen filled bladder, then again I would not be sure how much resistance to expect to find in a full, partially filled or empty bladder.

Good luck and hope you solve your problem soon.

[url]

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Re: Power fluctuations - electric supply

Post by Nereus » Mon Jun 05, 2017 3:55 pm

I guess that the following is the type of pump that you have? In which case it does not have a reservoir tank and should not get flooded.

http://www.hitachiconsumer.com.my/produ ... alogue.pdf

If it is like the one posted by Geko then I have to wonder why the complete accumulator has t o be replaced. The size of that accumulator means that you could only draw off about a cupful of water before the pump has to run, and presumably it will keep running while any water is being used. I suppose that is why they are calling it a constant pressure pump.

The bladder has the same function as an air cushion in a tank type of pump. If it is ruptured then the pump will not work correctly. Usually accumulators such as that can be recharged, providing the bladder is intact.

Piece of crap if you ask me!
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