Water Pressure

[robertsonmartin]

Hi All, I hope you can offer some advice on how to maintain water pressure at a decent level.

My water pressure from the street is generally quite good ranging from 200kPa - to slightly over 300kPa. (2-3bar / 30-45psi). However, on occasion it drop down to a trickle when there is probably a pipe break or work being done on the main.

I would like a constant pressure regardless of the street main pressure (if possible). My house is on one level with two bathrooms / showers (hot water side from a electric storage heater).

What is the optimum pressure to have in the house? Obviously I don't want to break any pipes due to too high a pressure but would like as good ass possible for the showers. When my pressure is 300kPa the shower is good, would 400kPa (4bar / 58psi) be acceptable or too high?

My setup is basic, mains into a filter and then into the house. If pressure goes completely then I have an underground tank and pump that can be used until the mains returns but this is only an emergency backup.

I don't really want to have a pump kick on everytime I open a tap because of noise and unnecessary electricity usage (I'm not being cheap, just green ) .

I have heard that pressure vessels can be used to maintain pressure when street pressure is low but don't really know how they function or how they are piped up. This is where I need some help. I guess the pressure tank is a water buffer that maintains a pressure on the top on it and that that pressure is maintained with a booster pump that only cuts in when it reaches a low pressure threshhold, or am I way off the mark?

Any help as to pressure tanks setup would be most appreciated, piping diagrams etc, recommended pumps, brands etc.

Thanks in advance to all.

Martin.

Reason for edit - max house pressure allowed.

Edited July 24, 2009 by robertsonmartin

[tjo o tjim]

From the street, provide a check-valve so that water can only flow one way, and in to the compression tank. Tap for your underground tank before the check-valve.

[kamalabob2]

In rural Buriram I had a local "pump shop" who actually sell/install/maintain "village water systems" and "hospital/hotel/business" water tank/pump systems do the design and installation of our water pump, filter, tank and now pressure tank system. The labor and parts from this sort of "pump shop" cost far less than Home Pro and the free "after the sales" service is valuable. I would suspect that most all areas of Thailand have similar shops, your Thai spouse would have to ask around. It is NOT village guys maintaining village water systems, it is real pump shop staff would be my guess.

The metal pressure tank is widely available in Thailand and it insures that all of our 3 point under the counter water heaters work. With a properly installed pressure tank you MINIMIZE or eliminate unnecessary usage of the electric water pump. There is no excuse for a pump activating every time you turn on a water tap in your home. The noise, cost and wear and tear on the electric water pump is far greater than the initial cost to have a tank such as our S.W.K. 500 liter pressure tank.

We have a two story home and initially I took the "no pressure tank" option from the Pump shop. It took about one day of cold showers on the 2nd floor to realize why they had suggest I consider the S.W.K. 500 liter pressure tank which comes with a SquareD control device. That SquareD device failed, but the shop did an immediate new replacement.

[robertsonmartin]

In rural Buriram I had a local "pump shop" who actually sell/install/maintain "village water systems" and "hospital/hotel/business" water tank/pump systems do the design and installation of our water pump, filter, tank and now pressure tank system. The labor and parts from this sort of "pump shop" cost far less than Home Pro and the free "after the sales" service is valuable. I would suspect that most all areas of Thailand have similar shops, your Thai spouse would have to ask around. It is NOT village guys maintaining village water systems, it is real pump shop staff would be my guess.

The metal pressure tank is widely available in Thailand and it insures that all of our 3 point under the counter water heaters work. With a properly installed pressure tank you MINIMIZE or eliminate unnecessary usage of the electric water pump. There is no excuse for a pump activating every time you turn on a water tap in your home. The noise, cost and wear and tear on the electric water pump is far greater than the initial cost to have a tank such as our S.W.K. 500 liter pressure tank.

We have a two story home and initially I took the "no pressure tank" option from the Pump shop. It took about one day of cold showers on the 2nd floor to realize why they had suggest I consider the S.W.K. 500 liter pressure tank which comes with a SquareD control device. That SquareD device failed, but the shop did an immediate new replacement.

Hi KamalaBob2,

Thanks for the great information.

Is the pressure tank before your storage tanks or after? Do you have a piping diagram of how it all connects up?

I have a pretty good guy who installs filters / water systems but he didn't seem too clued up on the pressure tank idea and talked about having the pump kick on everytime whereas I'm thinking the same way as you in that I don't want the pump running when I open a tap.

What pressure does your system work at?

Cheers,

Martin.

[kamalabob2]

I do not have a diagram. The pump shop did the "back of napkin" plans and they worked. In our case the Hitachi WM-P400 EX Inverter water pump comes on RARELY to put water INTO the S.W.K. 500 liter tank. The water flows OUT of the pressure tank with PSI of between 15 and 45. I watched the OKURA pressure gauge on top of the metal tank this morning. It is normally at 15psi, and water runs in the home. After an extended time, often more than two hours, the pump will go on for a SHORT period and the PSI on the metal tank will rise to 50psi, fall quickly to 45 psi and stay there for a while. It then drops down to 15psi. This level of PSI activates under the counter 3 point water heaters on both ground floor and 2nd floor of our home.

There is a Square D controller model number 9013 FSG-2, made in Italy, installed on the side of the metal tank. The pressure tank is the final item water goes through in our "pump house". Water comes through 4 different filters, into two different 2000 liter storage tanks, through the Hitachi Inverter pump, into the S.W.K. pressure tank and then into several pipes to various rooms in the home and pool house.

I would think a "pump shop" in your town or nearby City would be very familiar with pressure tanks. our pumps do NOT come on at night when people use the bathrooms. I sit outside for two meals a day and it is a rare day I hear the pump activate. The pressure tank really can keep up with a home with too many showers, too many sinks, a washing machine, dish washer, pool, etc..

The water for our garden does NOT go through this pump and filter system. Garden faucet water supply is diverted near the municipal water meter so that water does not use up the "consumables" in the water filters.

[robertsonmartin]

I do not have a diagram. The pump shop did the "back of napkin" plans and they worked. In our case the Hitachi WM-P400 EX Inverter water pump comes on RARELY to put water INTO the S.W.K. 500 liter tank. The water flows OUT of the pressure tank with PSI of between 15 and 45. I watched the OKURA pressure gauge on top of the metal tank this morning. It is normally at 15psi, and water runs in the home. After an extended time, often more than two hours, the pump will go on for a SHORT period and the PSI on the metal tank will rise to 50psi, fall quickly to 45 psi and stay there for a while. It then drops down to 15psi. This level of PSI activates under the counter 3 point water heaters on both ground floor and 2nd floor of our home.

There is a Square D controller model number 9013 FSG-2, made in Italy, installed on the side of the metal tank. The pressure tank is the final item water goes through in our "pump house". Water comes through 4 different filters, into two different 2000 liter storage tanks, through the Hitachi Inverter pump, into the S.W.K. pressure tank and then into several pipes to various rooms in the home and pool house.

I would think a "pump shop" in your town or nearby City would be very familiar with pressure tanks. our pumps do NOT come on at night when people use the bathrooms. I sit outside for two meals a day and it is a rare day I hear the pump activate. The pressure tank really can keep up with a home with too many showers, too many sinks, a washing machine, dish washer, pool, etc..

The water for our garden does NOT go through this pump and filter system. Garden faucet water supply is diverted near the municipal water meter so that water does not use up the "consumables" in the water filters.

Thanks again Kamalabob it is making a lot more sense now. I have pretty good idea in my head of what I would need to do but I will contact a local pump shop, like you say, for them to give me a drawing and a quote. I'll be able to throw a few questions at them now without sounding too thick.

Mart.

[JimmyGreaves]

Hi there

How did you get on with your final design?

[stgrhe]

What is the optimum pressure to have in the house? Obviously I don't want to break any pipes due to too high a pressure but would like as good ass possible for the showers. When my pressure is 300kPa the shower is good, would 400kPa (4bar / 58psi) be acceptable or too high?

If you have the blue plastic water pipes they come in three different classes for a maximum pressure of 4, 8 and 12 bar respectively, so it all depends on the type you are having.

[robertsonmartin]

Hi there

How did you get on with your final design?

Haven't had time to do it yet, but the plan is to hook it all up like the attached diagram.

System_Setup.pdf

[stgrhe]

Hi there

How did you get on with your final design?

Haven't had time to do it yet, but the plan is to hook it all up like the attached diagram.

Is there a reason why you have opted to put the filter on the pressure side? I would have taught the filter had better be installed before the tank in order the limit sediments to being build up in the tank.

[tjo o tjim]

Is there a reason why you have opted to put the filter on the pressure side? I would have taught the filter had better be installed before the tank in order the limit sediments to being build up in the tank.

You would have to run the pump more frequently then given the pressure drop across the filter. The schematic is the easiest way to make it work reliably.

[stgrhe]

Is there a reason why you have opted to put the filter on the pressure side? I would have taught the filter had better be installed before the tank in order the limit sediments to being build up in the tank.

You would have to run the pump more frequently then given the pressure drop across the filter. The schematic is the easiest way to make it work reliably.

I do not follow what you are saying. The water from the main supply passes either the filter/softener unit or flows directly to the tank. This is on the pumps suction side and the pump would have no or little influence over the pressure from the main supply or any eventual pressure drops across the filter/softener unit if the latter is fitted before the storage tank as I would see it. Please correct me if I am wrong.

[robertsonmartin]

There is no particular reason why the filter is after the pressure tank except that if any maintenance needs to be done on the pump / pressure tank then i can still have filtered water into the house through the bypass line (this is how it is connected at the moment, into the filter direct from the meter. The underground tank / pump just a backup incase mains fail completely).

The water is pretty clean so there wouldn't be much of an accumulation of sediment etc in the pressure tank. The pressure to the filter will also be dampened a little by the pressure tank (kind of like a capacitor).

The design is just in my head at the moment. Any good suggestions with valid reasons to do if differently are most appreciated, hence the original post to get some information from the people who have done this kind of thing before.

Cheers, Mart.

[stgrhe]

The reason for my questions Mart is that I am in a similar situation like yours but with a difference because my water will be coming from a well and well water here in the Hua Hin region tend to have a fairly high level of calcium, thus hard.

The engineer for my house is a very competent person but he seems to be a bit week on the design of the water supply part. Being an engineer myself, although in electronics, I tend to question things when I am not fully convinced of the solution. I have briefly discussed the issue with a company i Khon Kaen and I realise that it is much more to it than what I first taught. For the moment I a searching for specialist company in the Hua Hin region that can do a proper design as I do not like the idea of having things redone because of poor function. It had better be right from the beginning.

I will follow this thread and see what you are coming up with.

[tjo o tjim]

You have pressure drop across any filter; letting city water pressurize the bladder tank is the cheapest way to maintain pressure, as you are not constrained as much by flow rate. You can "charge" the bladder slowly as long as you have proper discharge flow.

Robert is missing some check valves on the pump side.

[robertsonmartin]

I fully agree with you Stgrhe in that it should be done right first time. I am an Oil / Gas Instrument guy so have a pretty good feel for this kind of thing although usually on a bit of a larger scale and more commissioning over design.

A very good point from tjo in that to minimise the pump running I should connect the city main also to the discharge of the pump. My city water pressure is up and down but I might as well utilise it when it is "up" to reduce pump useage, the max I've seen on the city line is 45psi which is what I would like the system to permanently run at.

Modified diagram now looks like this (purple line added). I've added a check valve on the discharge from the pump but could also be placed in the purple line. Comments welcome.

System_Setup_rev_2.pdf

[stgrhe]

This is my preliminary design although it is not fully complete yet and it also still needs to be discussed with a specialist in the field.

I will be using a Grundfos pump with integrated pressure tank and pressure switch, either model CH4-40PT or CH4-50PT. The sprinkler pump has not been chosen yet. The filter and softener will be an automatic and integrated unit from Masterpure type M7 Auto. This unit does the back wash automatically as set.

Since I will be installing a MagnaPool I will be able to use the back washed water for the garden although it should be mixed with fresh water at a ratio of 5:1. My intend is therefore to collect the back washed water from the pool and the rain water, collected by the gutters, in a separate tank.

[Artisi]

I fully agree with you Stgrhe in that it should be done right first time. I am an Oil / Gas Instrument guy so have a pretty good feel for this kind of thing although usually on a bit of a larger scale and more commissioning over design.

A very good point from tjo in that to minimise the pump running I should connect the city main also to the discharge of the pump. My city water pressure is up and down but I might as well utilise it when it is "up" to reduce pump useage, the max I've seen on the city line is 45psi which is what I would like the system to permanently run at.

Modified diagram now looks like this (purple line added). I've added a check valve on the discharge from the pump but could also be placed in the purple line. Comments welcome.

Ensure that you use a good quality NRV otherwise you could end up pumping back into the incoming supply.

[tjo o tjim]

Modified diagram now looks like this (purple line added). I've added a check valve on the discharge from the pump but could also be placed in the purple line. Comments welcome.

You need it in both places, I think. On the pump it prevents overflowing your tank from city water pressure and on the purple line it keeps you from hitting the city water supply.

Has anybody ever seen double check-valves or reduced pressure backflow preventers in Thailand? If you are pressurizing above city water pressure you might need the double-check... but I'm just a sparky.

[bkkbill]

Modified diagram now looks like this (purple line added). I've added a check valve on the discharge from the pump but could also be placed in the purple line. Comments welcome.

You need it in both places, I think. On the pump it prevents overflowing your tank from city water pressure and on the purple line it keeps you from hitting the city water supply.

Has anybody ever seen double check-valves or reduced pressure backflow preventers in Thailand? If you are pressurizing above city water pressure you might need the double-check... but I'm just a sparky.

I don’t see why you would need a double check reduced pressure back-flow preventer because of pressure above city supply. The reason for using them is for cross contamination in the event of negative pressure. Don't think you would find one in Thailand. Your right on the need of a check valve on the purple line as the pump would create a loop with the storage tank and in a no pressure situation drain the tank into the municipal water supply.