Pump to boost low pressure in a condo?

[mran66]

Visited a friend who recently bought a condo which seems to have very low water pressure all the time. To improve the situation in bathroom, he had bought  a cheap booster pump from Lazada and simply put in water heater inlet line. It kind of makes it a bit better, but nothing comparable what e.g I have in my house with a Mitsu WP pump.

 

I was wondering whether the EP series Mitsu pump which has the flow switch in addition to pressure switch would work in his condo if installed right after the water meter, boosting the pressure in all rooms? What is the functional logic in EP series with the pressure and flow switches?

 

The small booster pump with (flow sensor/switch) logically works OK in his case - it simply starts if water starts flowing, keeps running all the time until flow stops for whatever reason. In his case the pump indeed should work like that i.e in case the condo water supply would be so bad that no flow at all without the pump running, the pump should not start at all. The pump should simply be a booster pump which only runs if there is something to boost i.e some flow (which start if a tap is opned and stops when tap closed). If zero water coming in from condo supply, pump should not start at all.

 

The WP pump I have would not work in his case, but would EP? If not, anything else suitable for his case?

[scubascuba3]

Don't you need a tank for pumps to work? condos don't have their own tank

[Artisi]

It is illegal to pump straight off the main supply, although saying that it is common practice in Thailand. 

 

The problem could be lack of water in the main, if insufficient water available at the pump, pumping won't necessarily fix the problem

[Muhendis]

5 hours ago, scubascuba3 said:

Don't you need a tank for pumps to work? condos don't have their own tank

Yes you certainly do.

The OP needs to instal something like a 200 litre tank then use a pressure pump to supply his faucets from it.

[NickyLouie]

12 hours ago, mran66 said:

 

The WP pump I have would not work in his case, but would EP? If not, anything else suitable for his case?

 

 

Run a proper pump from the water feed into the condo, it will maintain constant pressure when on.

 

 

[sometimewoodworker]

2 hours ago, Artisi said:

It is illegal to pump straight off the main supply, although saying that it is common practice in Thailand. 

While pumping directly off the incoming supple is certainly done, I would say rather then being common practice, it not uncommon. The point is that while some people do it the majority don’t, because apart from everyone knowing it’s illegal/against all supply rules, it is also inefficient and having the required tank avoids having no supply when the inlet is dry.

[Artisi]

21 minutes ago, sometimewoodworker said:

While pumping directly off the incoming supple is certainly done, I would say rather then being common practice, it not uncommon. The point is that while some people do it the majority don’t, because apart from everyone knowing it’s illegal/against all supply rules, it is also inefficient and having the required tank avoids having no supply when the inlet is dry.

on the estate I'm on of 150 + houses, more that 50% pump straight from the mains to their storage tanks when the supply pressure is low, there is normally sufficient water - just low pressure. This is not unusual throughout thailand, I've also seen many set-ups where they continually pump direct from the main.

Of course there is a very good reason why it's illegal - but that another story and has been discussed previously.

[mran66]

6 hours ago, scubascuba3 said:

Don't you need a tank for pumps to work? condos don't have their own tank

 

1 hour ago, Muhendis said:

Yes you certainly do.

The OP needs to instal something like a 200 litre tank then use a pressure pump to supply his faucets from it.

 

The condo, like many other if not most condos, have tanks on top. I dont know how the tanks have been connected to lines going to condos (pump inbetween or not). I assume water to condos come from the tanks, not city line directly, but pressure is too low.

 

Practically not possible to install own tank anyway without major piping rework incl breaking walls as cold water supply to rooms goes inside the walls to each room.

 

50 minutes ago, NickyLouie said:

Run a proper pump from the water feed into the condo, it will maintain constant pressure when on.

 

If put just normal pump with pressure switch, problem is if water supply dries out completely, the pump just continues to run until either temp protection stops it (like in Mitsu pumps), or it dies. May not be a likely scenario, however ideal system would be like the cheap booster pumps with flow sensor that controls the pump to work ONLY if there is water flow, just with higher capacity, comparable to e.g smaller Mitsu EP series.

 

Was just wondering if the Mitsu EP works like that as it has some kind of flow sensor, just dont know what/how it is used for.

[Muhendis]

1 hour ago, mran66 said:

I assume water to condos come from the tanks, not city line directly, but pressure is too low.

i guess there is a main valve somewhere which allows you to turn off the incoming water supply.

if you haven't done so already, make sure it is fully open.

It could be a flow problem rather than a pressure problem.

A way to check this would be to turn on a tap and then block the output with your thumb.

If, when you remove your thumb, the water gushes out briefly then you have plenty of pressure.

[saakura]

The high rise Bangkok condos that I have lived in (including the present one) all have a reasonably large reservoir on the ground level hidden away from sight. The water supply from the mains fills this reservoir all the time. A high level sensor has been fitted in the tank, so the handyman can close the main filling valve if it gets full (I have never seen that happening) Powerful pumps then take suction from this reservoir and pump it all the way up to water tanks at the top of the building (present condo I live in is 40 floors high, with the supply tanks on the roof).

Water pipes then lead from the roof tanks to individual units. The lower the floor, the better the pressure due to greater vertical distance which the water falls to. For the 36th-40th Floor, as the water pressure will not be so great due to shorter vertical distance, a special booster pump has been installed to boost the pressure in their lines.

[mran66]

10 minutes ago, Muhendis said:

i guess there is a main valve somewhere which allows you to turn off the incoming water supply.

if you haven't done so already, make sure it is fully open.

It could be a flow problem rather than a pressure problem.

A way to check this would be to turn on a tap and then block the output with your thumb.

If, when you remove your thumb, the water gushes out briefly then you have plenty of pressure.

 

Open and close main valve many times no impact. Asked from neighbors, it is a problem in the building everyone suffering. Why they have not fixed it no idea. Too many thai owners in the building I assume is the reason 

[mran66]

1 minute ago, saakura said:

The high rise Bangkok condos that I have lived in (including the present one) all have a reasonably large reservoir on the ground level hidden away from sight. The water supply from the mains fills this reservoir all the time. Powerful pumps then take suction from this reservoir and pump it all the way up to water tanks at the top of the building (present condo I live in is 40 floors high, with the supply tanks on the roof).

Water pipes then lead from the roof tanks to individual units. The lower the floor, the better the pressure due to greater vertical distance which the water falls to. For the 36th-40th Floor, as the water pressure will not be so great due to shorter vertical distance, a special booster pump has been installed to boost the pressure in their lines.

 

Correct, I am familiar with that.

 

The condo in question is has 8 floors. I don't know whether they have different supply for some floors or all in same pipe. Condo in question is 5th floor. 

[Muhendis]

24 minutes ago, mran66 said:

 

Open and close main valve many times no impact. Asked from neighbors, it is a problem in the building everyone suffering. Why they have not fixed it no idea. Too many thai owners in the building I assume is the reason 

Sounds like not much water in the storage tank and if that is the case a pump would be of little benefit. 

What would be of benefit would be to have a forceful word or two with the condo owner and tell him to do his job.

[mran66]

25 minutes ago, Muhendis said:

Sounds like not much water in the storage tank and if that is the case a pump would be of little benefit. 

What would be of benefit would be to have a forceful word or two with the condo owner and tell him to do his job.

 

Water tanks 4 floor levels above his condo so won't make much difference if they full or empty. 

Don't know how the situation in top floor vs his vs bottom floor. Maybe no pump at all in building to give pressure to units, only to get water up to tanks. 

 

He been talking to himself quite a bit about the issue;-) 

[Muhendis]

19 minutes ago, mran66 said:

 

He been talking to himself quite a bit about the issue;-) 

Perhaps he's worried about the police finding out about the prostitution racket he's got going on the 3^rd floor.............

 

22 minutes ago, mran66 said:

Water tanks 4 floor levels above his condo so won't make much difference if they full or empty.

Water pressure is dependant on quantity/weight of water in the tank. If the tank only gets a few centimetres of water in it every time it tops up there will be low pressure for everyone. The only pressure is whatever's in the pipe.

[mran66]

6 minutes ago, Muhendis said:

Water pressure is dependant on quantity/weight of water in the tank. If the tank only gets a few centimetres of water in it every time it tops up there will be low pressure for everyone. The only pressure is whatever's in the pipe.

 

Well, difference in head 12m empty vs say 14m full tank is 1.2 vs 1.4 bar. What is missing is like 1-1.5 bars so tank empty or full won't fix it. Only pump of some kind, either in his unit or in the condo water distribution system can cure this problem as far as I can see. 

[mran66]

21 minutes ago, Muhendis said:

Perhaps he's worried about the police finding out about the prostitution racket he's got going on the 3^rd floor.............

 

... He has paid his security contribution monthly so that's under control... 

[sometimewoodworker]

8 hours ago, Muhendis said:

Water pressure is dependant on quantity/weight of water in the tank. If the tank only gets a few centimetres of water in it every time it tops up there will be low pressure for everyone.

That is not how physics works.

The quality of water in the tank only governs the amount of water available, it has little to do with the water pressure available.

 

The hight of the water governs the pressure available. For each 10 meters of hight you get 1 bar of pressure.

 

If you have a column of water (the pipes) that connects to a tank whose base is at 10 meters above the tap you will have 1 bar of pressure when the tank is virtually empty. When full you will probably have about 1.15 bar of pressure (an insignificant increase)

 

The point I have not mentioned is that unless your supply pipes from the tank are about 37mm you will get friction losses and since most pipes are ½ inch these losses will be rather large, add in the 90 degree bends and you have problems.

 

Our house water supply is all 32mm PPR and bends are 45 degrees, so even though the tank is only about 7 meters above the taps we always have water available in a power cut, it is walking water not running, but we can always shower and clean the dishes.

 

[Muhendis]

9 hours ago, sometimewoodworker said:

That is not how physics works.

The quality of water in the tank only governs the amount of water available, it has little to do with the water pressure available.

Very true.

However, as every educated person who did physics at school knows, the weight/quantity of water acting on the tanks outlet pipe is what we are talking about.

If we imagine an outlet pipe of (say) 50mm internal diameter in the bottom of the tank, the column of water, also 50mm diameter, directly above that outlet is the only weight/volume of water to consider.

This was a given in my "Water pressure is dependant on quantity/weight of water in the tank." comment.

Thanks to STWW for pointing this out.

By the way,

The quality? of water in the tank.

I expect STWW intended to write Quantity........🙂

 

 

[sometimewoodworker]

2 hours ago, Muhendis said:

Very true.

However, as every educated person who did physics at school knows, the weight/quantity of water acting on the tanks outlet pipe is what we are talking about.

If we imagine an outlet pipe of (say) 50mm internal diameter in the bottom of the tank, the column of water, also 50mm diameter, directly above that outlet is the only weight/volume of water to consider.

This was a given in my "Water pressure is dependant on quantity/weight of water in the tank." comment.

Thanks to STWW for pointing this out.

By the way,

The quality? of water in the tank.

I expect STWW intended to write Quantity........🙂

 

 

Indeed I ment quantity, (thanks for the correction I didn’t proof reed the post) though with some village supplies quality, solids, in the water, can be a problem.

 

just to be clear a 1kilolitre tank with the surface at 5 metres above the outlet will give 0.5 bar irrespective of the outlet pipe size.

 

while a 1 litre tank with the surface at 20 meters above the outlet will give a 2 bar pressure again irrespective of the outlet pipe size. though a 5mm pipe will give horrendous friction losses when you try to use the water.

 

Fluid dynamics is a non intuitive science. Case in point, SWMBO was using a 1” 100 meter pipe from our pool pump to water the garden, when it needed to be replaced I bought a 2” pipe to replace it despite vehement protests from her that it was a bad idea. Now watering the same area of garden is about 3 times faster in part due to the larger area but also the dramatic reduction in friction losses. NB the pump outlet is 1”