Water tank height to provide adequate pressure under gravity

[David48]

water heater won't work with 1 bar!

The question was about using a shower under gravity flow due to power failures. You forget that without electricity the water heater will not work at all!

You heat your water ... luxury ... sheer luxury I say ...

Can I come and stay at your place please?

[Naam]

Suitable for a couple of toilet flushes, but not half a day of water consumption during a power blackout.

Not true. Pressure tanks can be sized to suit ones needs.

don't forget that the total volume of a pressure tank is not available as (per rule of thumb) actual water volume under pressure is only ~40%, e.g. a 200l pressure tank yields a maximum of 80l with adequate pressure.

[Naam]

Water level in tank, every 10 meters above tapping point gives 1 bar. 2 bar is acceptable.pressure. so water level in tank should be 22 meters above ground level. Be sure you use sufficient diameter tubing., and remove inside burrs!

Sent from my GT-I9300 using Thaivisa Connect Thailand mobile app

I think 1 bar works for a normal home, unless there is a rain shower...lol.

water heater won't work with 1 bar!

The question was about using a shower under gravity flow due to power failures. You forget that without electricity the water heater will not work at all!

touché!

[Naam]

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Thanks for the helpful and prompt replies.

It's back to the drawing board as I had not realised that the tower would need to be more than 10m high to obtain adequate pressure. Such a tower would be wholly out of place.

It looks like we need to consider the alternative of a back-up power supply.

In this regard any thoughts on how the inverter and battery option compares to a diesel generator with automatic changeover on loss of mains power?

How much it costs depends on what you want to run.. Just the pump? if so, how many watts is it, and what sort of runtime would a UPS need to supply? Assuming you just want to run the pump, I cannot see any diesel generator being cheaper than a charger/battery/inverter setup - either to install or to run.

We built a water tower with the bottom of the tank at 4mt. (13ft)

For anyone else thinking of doing something like this - check your pump specs carefully - most standard pumps won't like a tank head much higher than about 2M. Some will have an additional spring you can fit to increase the tank head height, but very few I've seen will like the 5M+ in this poster's garden.

I cannot see any diesel generator being cheaper than a charger/battery/inverter setup - either to install or to run.

BINGO!

power available automatically any time on demand. runtime based on pump wattage and installed battery capacity.

[BWPattaya]

The lowest point of my tank in the bungalow I used to live in, in the UK, was one metre above the highest outlet (a shower head). That was sufficient height. If you use a smaller tank then you could easily put it in the roof dpace so it won't be unsightly.

[Naam]

The lowest point of my tank in the bungalow I used to live in, in the UK, was one metre above the highest outlet (a shower head). That was sufficient height. If you use a smaller tank then you could easily put it in the roof dpace so it won't be unsightly.

that must have reduced you water bill considerably

[maximus101]

Why not use a ups for the pump. Decent models can have batterys added to give longer service. depending on pump and how much its used it may work out cheap enough

[gimbo2]

We also live on a farm and been through ALL the problems.

The soluation is easy.

Buy a small diesle powered generator.

PROBLEM SOLVED.

GIMBO

[steve73]

The lowest point of my tank in the bungalow I used to live in, in the UK, was one metre above the highest outlet (a shower head). That was sufficient height. If you use a smaller tank then you could easily put it in the roof dpace so it won't be unsightly.

...and if your roof space gets anything like as hot as mine does you'll get a hot shower...

A low height like this will only work if you have a very short run to your shower head, and you may need to drill out the holes for a reasonable shower. But you won't get much pressure from your bum gun, and flushing toilets often need higher pressure to refill.

[MW72]

As another post has pointed out, if there is a power cut then an electric shower will not work. Assuming we are talking about a shower providing cold water then you will easily get a shower with 0.5 bar or even less. This would mean the tank base being 5 metres higher than the shower outlet so the tank would have to be 7 metres high. You could lower but you will not have great pressure.

While storage tanks are great when the mains cuts off, they also present many other issues. The obvious one is getting access to maintain it. A fall from 5 metres would not be nice not to mention the possibility of Legionella.

[maderaroja]

Why not get a pressure tank? Cheap. Nothing unsightly. Problem solved.

Suitable for a couple of toilet flushes, but not half a day of water consumption during a power blackout.

Seems the traditional Thai way of having stored water in an urn works best, as this was the way of living before they even had electricity.

A pressure tank is small and will supply continuous pressure of the desired amount for as long as there is water in the storage tank.

[khunPer]

Based from pure experience only with my own 1100 ltr. water tank, placed at attic in 3-floor house:

3rd floor just enough pressure, but not a lot. Bottom of water tank is 3 m above floor level, and water level normally 1+ m in tank, so minimum 4 m total to top level.

2nd floor Okay water pressure, adding another 3 meters equals some 7 m from floor to water tank top level.

Ground floor fine pressure, adding another 3 m, equals around 10 m from floor to water tank top level, which is 1 bar.

Would think your water tank tower shall be minimum between 7 m to 10 m measured from floor level in house to average water level in tank.

Electric water heaters work fine on all floors, but at 3rd floor filters need to be kept clean not to reduce water pressure, so heater is not turning on. (I also have a solar panel water heating system, so electrics heaters are just boosters for instant hot water and during raining season with not enough sun.)

I see quite a number of Thai houses with a too low water tank tower and a booster pump installed, in which case you might save the water tower. I did want a (small) tank to prevent water from stop running during “black outs”, and as I also didn’t want a water tower – hardly space for it – the attic solution with limited height were the only option, but it does work. Discussed back-up battery power from inverter (eventually charged from solar panel), but at that time (5 years ago) I was told that either the inverter or the water pump would burn off – at least those inverters available locally in Thailand – believe inverters today are much better and can do the job. Alternative was a 12 Volt DC well pump, which were outstanding expensive.

Hope my information will be helpful.

[MW72]

Why not get a pressure tank? Cheap. Nothing unsightly. Problem solved.

Suitable for a couple of toilet flushes, but not half a day of water consumption during a power blackout.

Seems the traditional Thai way of having stored water in an urn works best, as this was the way of living before they even had electricity.

A pressure tank is small and will supply continuous pressure of the desired amount for as long as there is water in the storage tank.

Incorrect. A pressure tank will only supply a fraction of the water contained within it. As soon as you open the tap the pressure will start to drop. Water will be supplied until the pressure in the pressure tank reaches the same pressure in the storage tank which is atmospheric pressure. As a previous poster pointed out, you would be lucky to get 40% of the volume of the pressure tank.

Think of it like a party balloon full of air. If you take your finger off the neck the air will escape and it will deflate until it reaches atmospheric pressure. It does not get continually replenished by the atmosphere and continue to pump out pressurised air. It is the water pump that pressurises the pressure tank. Cut the power to the water pump and the water at pressure in the pressure tank is all you have left. The water storage tank cannot provide pressure.

[MrY]

Water level in tank, every 10 meters above tapping point gives 1 bar. 2 bar is acceptable.pressure. so water level in tank should be 22 meters above ground level. Be sure you use sufficient diameter tubing., and remove inside burrs!

Sent from my GT-I9300 using Thaivisa Connect Thailand mobile app

I think 1 bar works for a normal home, unless there is a rain shower...lol.

water heater won't work with 1 bar!

You can opt for a "boiler" instead of an instant water heater. It will also give you hot water for a few showers during a power cut. I bought one with a thermostat for 6xxx baht and set it so one couldn't get a skin burn even at full hot (still quite hot). I was also advised by the salesman that the full hot setting would eventually deteriorate the insulation. It's on it's 6th year now. I get my steaming hot showers and the wife loves the hot water for cleaning dishes and all.

[Mitker]

Don't know if the OP is still following the tread but if yes, here's our experience:

Our company is off the grid, running a generator only during working hours. We don't want to have an engine running at night, even if we have staff staying 24/7.

"tower": the water is stored in a tank around 5M above ground (2 levels scaffolding) and supplies water for the showers around 30m away (3/4" PE piping). Even if at the end it means only around 3M difference, it's still sufficient for a decent normal shower (not a Las Vegas style water pressure massage)

The main restriction i see would be the valve at the entrance of specific devices as dishwasher or laundry machines but we're talking here about dealing with power cuts and the requirements in inverters + batteries would not make them a reasonable solution

"inverter": for our electrical needs off hours, we convert 12V batteries source into 220V by a simple, cheap inverter that supplies enough for basic needs (TV, radio, lights, phone chargers - - not water heaters, air cons, irons or other heavy consuming equipments)

"hot water": a smaller, insulated, tank is connected to a PE pipe running on a roof section above the showers. It provides comfortably "hot" water up to the morning. Not a single electron needed at this stage. Don't try this water (unmixed) after a fully sunny day: far too hot for a shower

[richardrb]

A pressure tank which stores the water under pressure inside a membrane IS a viable option. While large pressure tanks are expensive, you would not need any power to get good pressure, up to 50 PSI depending on the pressure switch you install. They are available in many sizes, you need one larger than the amount of water you might need during an outage. If you power stays off for days, the cost of a large enough pressure tank may be too high. This is the typical design for well users in the US and Europe but is rarely done in Thailand. When sizing a pressure tank, it is important to know what the draw down is, that is the amount of water that is available before the pump needs to come back on to refill the tank. You want the pump to run at least one minute so you need to also know the output of your pump. There are many sizing charts online for pressure tanks, but most presume a steady supply of water. In your case, the larger the better.

Pressure Tanks are sold in Thailand sized from 8 litre t0 5000 litre (and larger if you have the baht), one web site that shows several brands is http://www.power.wrc.bz. I've attached a drawing of how this is typically installed in rural USA. Note, the diagram does not show any filtration but it can be easily added either before or after the tank. I would guess you would want something in the 300-1000 range, costing between 15,000 baht and 75,000 baht.

Richard

Edited July 23, 2014 by richardandjariya

[ingvar]

Bottom of tank to the highest fitting should be minimum 10 meters. This is the standard for most high rise buildings for the top most floor. 10m=1bar will still leave you a little bit dissatisfied especially when it comes to having a good shower, but for all other purpose it is sufficient.

[wichianburi1]

Thanks for the helpful and prompt replies.

It's back to the drawing board as I had not realised that the tower would need to be more than 10m high to obtain adequate pressure. Such a tower would be wholly out of place.

It looks like we need to consider the alternative of a back-up power supply.

In this regard any thoughts on how the inverter and battery option compares to a diesel generator with automatic changeover on loss of mains power?

Naam is, as so often, correct. Don't bother with a diesel generator. Not only are they rather expensive and require regular maintenance, but they are also noisy. Although I have a 5 kvA Generator, for my electrical backup system, I use two truck batteries, 200 Ah each, an 1500 Watt inverter and a 30 Amp battery charger. Unless you wish to buy sealed/gel batteries, make sure the batteries are always topped up with enough distilled water.

I recommend you permanently connect the battery charger to the batteries/inverter. To contain everything in one unit, I built myself a wooden cage on wheels for easy manouverability, and ensure the batteries are recharged whenever the electricity is back. Emergency electricity is supplied to fridge/freezer, lights, fan(s), water pump, PC, etc. Mind you, for safety reasons I use external extension cables and do not connect to the electrical safety box.

Good luck.

[Naam]

Why not get a pressure tank? Cheap. Nothing unsightly. Problem solved.

Suitable for a couple of toilet flushes, but not half a day of water consumption during a power blackout.

Seems the traditional Thai way of having stored water in an urn works best, as this was the way of living before they even had electricity.

A pressure tank is small and will supply continuous pressure of the desired amount for as long as there is water in the storage tank.

are you vying for the Gobble Prize in surreal physics?

[Naam]

Thanks for the helpful and prompt replies.

It's back to the drawing board as I had not realised that the tower would need to be more than 10m high to obtain adequate pressure. Such a tower would be wholly out of place.

It looks like we need to consider the alternative of a back-up power supply.

In this regard any thoughts on how the inverter and battery option compares to a diesel generator with automatic changeover on loss of mains power?

Naam is, as so often, correct. Don't bother with a diesel generator. Not only are they rather expensive and require regular maintenance, but they are also noisy. Although I have a 5 kvA Generator, for my electrical backup system, I use two truck batteries, 200 Ah each, an 1500 Watt inverter and a 30 Amp battery charger. Unless you wish to buy sealed/gel batteries, make sure the batteries are always topped up with enough distilled water.

I recommend you permanently connect the battery charger to the batteries/inverter. To contain everything in one unit, I built myself a wooden cage on wheels for easy manouverability, and ensure the batteries are recharged whenever the electricity is back. Emergency electricity is supplied to fridge/freezer, lights, fan(s), water pump, PC, etc. Mind you, for safety reasons I use external extension cables and do not connect to the electrical safety box.

Good luck.

a slightly more elegant solution is an inverter with a built-in charger. all my three systems have that feature but with the small disadvantage that a minimum charge of 2A is always applied. the latter means topping up distilled water is more often required because my power cuts are quite rare.

[weegee]

Thanks for the helpful and prompt replies.

It's back to the drawing board as I had not realised that the tower would need to be more than 10m high to obtain adequate pressure. Such a tower would be wholly out of place.

It looks like we need to consider the alternative of a back-up power supply.

In this regard any thoughts on how the inverter and battery option compares to a diesel generator with automatic changeover on loss of mains power?

Naam is, as so often, correct. Don't bother with a diesel generator. Not only are they rather expensive and require regular maintenance, but they are also noisy. Although I have a 5 kvA Generator, for my electrical backup system, I use two truck batteries, 200 Ah each, an 1500 Watt inverter and a 30 Amp battery charger. Unless you wish to buy sealed/gel batteries, make sure the batteries are always topped up with enough distilled water.

I recommend you permanently connect the battery charger to the batteries/inverter. To contain everything in one unit, I built myself a wooden cage on wheels for easy manouverability, and ensure the batteries are recharged whenever the electricity is back. Emergency electricity is supplied to fridge/freezer, lights, fan(s), water pump, PC, etc. Mind you, for safety reasons I use external extension cables and do not connect to the electrical safety box.

Good luck.

a slightly more elegant solution is an inverter with a built-in charger. all my three systems have that feature but with the small disadvantage that a minimum charge of 2A is always applied. the latter means topping up distilled water is more often required because my power cuts are quite rare.

Hi Naam....which one did you use and where did you get it ?

Another thing about this is, I want to try something like yours but connected to the Bore....to the tanks

[Naam]

Hi Naam....which one did you use and where did you get it ?

Another thing about this is, I want to try something like yours but connected to the Bore....to the tanks

getting them in Thailand is a problem. i imported mine from India but they are obviously Chinese made. whatever i found in Thailand did not have an auto-switch function (grid off / switch to batteries and grid back on / switch back to grid) nor a built-in charger.

what's the capacity of your pump?

[Naam]

these are the specs of the latest model (2400VA) i bought recently, price INR 7.750 = THB 4,200 which is extremely cheap.

[khunPer]

Hi Naam....which one did you use and where did you get it ?

Another thing about this is, I want to try something like yours but connected to the Bore....to the tanks

getting them in Thailand is a problem. i imported mine from India but they are obviously Chinese made. whatever i found in Thailand did not have an auto-switch function (grid off / switch to batteries and grid back on / switch back to grid) nor a built-in charger.

what's the capacity of your pump?

I bought a 1000 VA "Meind" inverter (made in) in Thailand with a built in charger – did not work very well, perhaps because of missing auto-switch-function or... – so after a while gave up with that unit.

[sawadee1947]

"If you're American or Canadian, 30 feet from the shower head to the bottom of the tank will give you 13 psi."

What's the difference if you're not American or Canadian?

Nor Americans either Canadians can do their mathematics. Did not learn much about science I suppose

[mike44]

Once again thanks for the helpful replies.

If I can find one in Thailand, it looks like a battery and inverter with auto on/off on power fail/restore is the way to go.

We have a water boiler and storage tank (not instantaneous water heaters) so, with a back-up power supply, we can continue to have hot water from the storage tank for some time during a power cut.

[Naam]

You can opt for a "boiler" instead of an instant water heater. It will also give you hot water for a few showers during a power cut. I bought one with a thermostat for 6xxx baht and set it so one couldn't get a skin burn even at full hot (still quite hot). I was also advised by the salesman that the full hot setting would eventually deteriorate the insulation. It's on it's 6th year now. I get my steaming hot showers and the wife loves the hot water for cleaning dishes and all.

If you set a water heater, (and special the ones what store water, like a boiler does) on a temperature that it does not burn you, the temp is maximum around 45 degrees celsius. That is the perfect temperature for legionella disease. I consider this advise as a very dangerous one!

Arjen.

Hot water storage cylinders that maintain a temperature of 60ºC throughout

the whole storage vessel for a period of one hour daily should achieve

satisfactory control of Legionella bacteria, in line with recommendations in

HSE CoP L8.

[MrY]

Resurrecting an old thread here, as apparently I had given some 'dangerous' advice.

 

Here's my old boiler setup explained;

 

I bought a [small] 30L boiler with advice from salesman not to set it full hot as this would deteriorate the insulation quite fast. Installed it at a location between kitchen and shower. Cranked it to max too see how hot it would get the water. After a few hours you could feel the outside of the tank was ever so slightly warmer than surrounding materials, and the the water coming out at the kitchen sink (closest tap) was 85C or so. Too hot in any case as I didn't want to invest in thermostatic valves and don't like burns. Then I set the thermostat to "E" (for 'Economy'?), ran the water until the heater light came on and went out again. Now below 50C. Not hot enough. A couple of small adjustments resulted in about 65C output (as I mentioned in the original post still quite hot) which, while hot enough for pots and pans, allows you to pull you hand away before getting scalded should you mistakenly stick your hand in the hot water. (This happens to me all the time. The wifey runs the hot water, turns off the tap without running a bit of cold water through, and the trap is set.) This happy medium lets her also take her long hot shower (steam bath?) first, but still leaves enough 'hot' water for myself.

 

Now as far as Legionella is concerned, that wasn't a consideration as virtually all water tanks in Thailand are in the temperature range to support bacterial growth, not just heated ones. The bacteria can be kept at bay with very low levels of continuous chlorination, but this is Thailand of course. Even though the water in our area is [occationally] treated, I chose to add bleach to my main water tank from time to time, just in case.

 

Hope this helps. Cheers.

 

   MrY