Looking for air-over-water pressure tank

phaholyothin · November 18, 2021

I recall seeing a discussion a year or two ago where people were extolling the virtues of their pressurized water tank system. I can't find any such discussion when I search.

The tanks I see on Lazada and Home Pro are all plastic or resin and I doubt they have the structural integrity to be pressurized. Can anyone recommend a dealer for such a system? My new place is just three BR and two people, so a 500 liter tank ought to be good enough.

Thanks.

sometimewoodworker · November 18, 2021

You will need a way to introduce the water under pressure into the tank, you are unlikely to have a water supply that can do that so you need a pump.
The pressure tank will only supply about 45% of its total volume before the pressure will drop low enough to require the pump to kick in.

sizeable tanks are expensive most probably over 7,000 Baht for a moderate sized one.

Nobody uses them as a storage tank and pump is less expensive (about the same cost as just the presse tank by itself) and does a better job since the full volume of the tank is available to the house.

TLDR a large pressure tank is not a good idea.

sezze · November 18, 2021

1 hour ago, sometimewoodworker said:

You will need a way to introduce the water under pressure into the tank, you are unlikely to have a water supply that can do that so you need a pump.
The pressure tank will only supply about 45% of its total volume before the pressure will drop low enough to require the pump to kick in.

sizeable tanks are expensive most probably over 7,000 Baht for a moderate sized one.

Nobody uses them as a storage tank and pump is less expensive (about the same cost as just the presse tank by itself) and does a better job since the full volume of the tank is available to the house.

TLDR a large pressure tank is not a good idea.

100% agree , small pressure tank is ok , large pressure tank is not only very expensive , but also dangerous in case of failure ( hence the expensive reason) . You can make your own ,with larger diameter pipes , but anything containing more then let's say 50l will become a problem .

VocalNeal · November 19, 2021

A conventional water pump has its own pressurized tank!

Crossy · November 19, 2021

Yeah ^^^, I'd just go with a conventional tank and a pump with an integral pressure tank.

A 500l pressure tank = a potential bomb!

Muhendis · November 19, 2021

I have a flat panel solar closed hot water system fed from the cold water pressure pump via an NRV (check valve). I added a small pressure tank just for the hot water. The thought being that there needs to be a bit of independence between the hot and cold. I got my 10L bladder tank from a local water filter company in Buriram for about 1,500 Baht. Main hot water storage is 200L stainless easily good for a few bar.

In my opinion it is always better to use a diaphragm/bladder tank because, in the case of no rubber barrier between water and air, loss of water equals time spent recharging the air in the tank also the barrier serves to prevent water absorbing the air and the associated pressure drop over time.

Yellowtail · November 20, 2021

23 hours ago, Crossy said:

Yeah ^^^, I'd just go with a conventional tank and a pump with an integral pressure tank.

A 500l pressure tank = a potential bomb!

No more dangerous than an air compressor when you think about it, a little messier perhaps...

That said, it makes little sense because (as woody pointed out) you have to pump water into the take, and you'd still have a pretty wide pressure variation unless you regulated it down,

I think the better solution may be tank>constant pressure pump>buffer air-over-water air-tank>regulators>points-of-use.

Once I get decent roof access this what I plan to do.

bbko · November 23, 2021

On 11/18/2021 at 8:52 PM, phaholyothin said:

I recall seeing a discussion a year or two ago where people were extolling the virtues of their pressurized water tank system. I can't find any such discussion when I search.

This one?

sezze · November 27, 2021

On 11/20/2021 at 4:52 AM, Yellowtail said:

No more dangerous than an air compressor when you think about it, a little messier perhaps...

That said, it makes little sense because (as woody pointed out) you have to pump water into the take, and you'd still have a pretty wide pressure variation unless you regulated it down,

I think the better solution may be tank>constant pressure pump>buffer air-over-water air-tank>regulators>points-of-use.

Once I get decent roof access this what I plan to do.

No it is much more dangerous . It is the volume which is the issue . A bike tyre exploding is only a pff .., a car tyre is a boom , and a truck tyre creates a huge mess already . The larger it gets the larger the havoc it causes . In industry pressure tests are always done with liquid and not with gas , because in case of fail , the pressure with water is reduced fast , with gas it is a explosion .

Do not use any kind of pressure tank which is not supposed to used that way , you won't believe what hazards are there ( and it already killed many people in the past!! ) .

Yellowtail · November 28, 2021

6 hours ago, sezze said:

No it is much more dangerous . It is the volume which is the issue . A bike tyre exploding is only a pff .., a car tyre is a boom , and a truck tyre creates a huge mess already . The larger it gets the larger the havoc it causes . In industry pressure tests are always done with liquid and not with gas , because in case of fail , the pressure with water is reduced fast , with gas it is a explosion .

Do not use any kind of pressure tank which is not supposed to used that way , you won't believe what hazards are there ( and it already killed many people in the past!! ) .

I understand that a gas charged tank is generally more dangerous than is a liquid charged tank, but what does that have to do with what I said? I said an air over water system (which the majority of people in Thailand have) is no more dangerous than an air-compressor.

How is an air over water system more dangerous than an air compressor?

Incidentally, it's been at least 40 years since I over inflated a bicycle tire, but I don't remember it going "pff".

Muhendis · November 28, 2021

1 hour ago, Yellowtail said:

Incidentally, it's been at least 40 years since I over inflated a bicycle tire, but I don't remember it going "pff".

Lucky b'ger.

I had quite a few of them.

Yellowtail · November 28, 2021

1 hour ago, Muhendis said:

Lucky b'ger.

I had quite a few of them.

While I am in indeed lucky, not sure that my good luck has to do with it...

sezze · November 28, 2021

6 hours ago, Yellowtail said:

I understand that a gas charged tank is generally more dangerous than is a liquid charged tank, but what does that have to do with what I said? I said an air over water system (which the majority of people in Thailand have) is no more dangerous than an air-compressor.

How is an air over water system more dangerous than an air compressor?

Incidentally, it's been at least 40 years since I over inflated a bicycle tire, but I don't remember it going "pff".

Because a 500l tank is much larger then a 30-50 l tank of a compressor . The air is compressed , even if it is by water , the danger is the 500l .

You do not have to over inflate a tire , driving over a stone or similar and it can blow up , giving the pfft .

Yellowtail · November 28, 2021

2 hours ago, sezze said:

Because a 500l tank is much larger then a 30-50 l tank of a compressor .The air is compressed , even if it is by water , the danger is the 500l .

You do not have to over inflate a tire , driving over a stone or similar and it can blow up , giving the pfft .

I understand that a 500l tank is larger than a 30-50l tank, but my my last air compressor had a 1,200 liter tank.

You're hilarious.

MrJ2U · November 28, 2021

On 11/18/2021 at 8:52 PM, phaholyothin said:

500 liter tank ought to be good enough

Why not get a 2000 liter tank?

Its not much more.

500 liters doesn't go far, especially if there's a lady or two in the house.

What are you talking about pressurized tank?

Do you mean pressurized water pump so you can have a descent shower?

sezze · November 28, 2021

19 minutes ago, Yellowtail said:

I understand that a 500l tank is larger than a 30-50l tank, but my my last air compressor had a 1,200 liter tank.

You're hilarious.

1200l air compressor , that is not your home setup . The price of it will be according . This will show you the difference . +30y of experience working as process operator in chemical industry , working with pressures of <1 mbar abs to 300 bar . I do know what i am talking about . I might be hilarious , but at least i try to give people honest advice and do tell them about the danger involved .

Yellowtail · November 28, 2021

26 minutes ago, sezze said:

1200l air compressor , that is not your home setup . The price of it will be according . This will show you the difference . +30y of experience working as process operator in chemical industry , working with pressures of <1 mbar abs to 300 bar . I do know what i am talking about . I might be hilarious , but at least i try to give people honest advice and do tell them about the danger involved .

Why is it it when people are unable to answer a question or explain their position they always fall back on their many years of experience, as if it means anything to anyone.

Again, please explain how is an air over water system more dangerous than an air compressor?

sezze · November 28, 2021

5 minutes ago, Yellowtail said:

Why is it it when people are unable to answer a question or explain their position they always fall back on their many years of experience, as if it means anything to anyone.

Again, please explain how is an air over water system more dangerous than an air compressor?

It is not and i never said it was .

https://www.lazada.co.th/products/stellar-30-800w-str-30l-oil-free-air-compressor-30l-i305532962-s529780589.html?spm=a2o4m.searchlist.list.6.45f27076bVAD3y&search=1

This is a normal home air compressor .

And this is not , while they certainly do exist , any size and any pressure you want .

The difference is the volume as i explained . Both might be the same pressure , but they certainly give different effect in case of failure .

In case of a 500l tank , that is meant to be a pressure tank , is fine , but the price will be expensive . I am not scared of a bottle being pressurized to 5 bar , but i am scared of a homemade 500l tank being pressurized to 5 bar . A small bladder tank will work for all normal purpose , and is cheap . If you want a bit larger , you can even put 2 ,3,... in the system .

sometimewoodworker · November 28, 2021

11 hours ago, Yellowtail said:

I said an air over water system (which the majority of people in Thailand have) is no more dangerous than an air-compressor.

The air over water system that is usual in Thailand varies from around 500ml to a maximum of around 10 litres with the vast majority being under 2 litres, with quite low pressure. I have never heard of a small air/water system bursting, I have herd of several compressor air tanks bursting sometimes with nasty injuries as a result.

Get a large air/water tank failure & it has the possibility of equally nasty injuries.

Yellowtail · November 28, 2021

48 minutes ago, sezze said:

It is not and i never said it was .

https://www.lazada.co.th/products/stellar-30-800w-str-30l-oil-free-air-compressor-30l-i305532962-s529780589.html?spm=a2o4m.searchlist.list.6.45f27076bVAD3y&search=1

This is a normal home air compressor .

And this is not , while they certainly do exist , any size and any pressure you want .

The difference is the volume as i explained . Both might be the same pressure , but they certainly give different effect in case of failure .

In case of a 500l tank , that is meant to be a pressure tank , is fine , but the price will be expensive . I am not scared of a bottle being pressurized to 5 bar , but i am scared of a homemade 500l tank being pressurized to 5 bar . A small bladder tank will work for all normal purpose , and is cheap . If you want a bit larger , you can even put 2 ,3,... in the system .

I'm sorry, when I said that an air over water system was "No more dangerous than an air compressor when you think about it, a little messier perhaps..."

And you responded with: "No it is much more dangerous . " I thought that's what you meant.

So we agree that an air over water system is no more dangerous than than an air compressor, yes?

Yellowtail · November 28, 2021

9 minutes ago, sometimewoodworker said:

The air over water system that is usual in Thailand varies from around 500ml to a maximum of around 10 litres with the vast majority being under 2 litres, with quite low pressure. I have never heard of a small air/water system bursting, I have herd of several compressor air tanks bursting sometimes with nasty injuries as a result.

Get a large air/water tank failure & it has the possibility of equally nasty injuries.

So we agree that an air over water system is generally no more dangerous than than an air compressor, yes?

sezze · November 28, 2021

10 minutes ago, Yellowtail said:

So we agree that an air over water system is no more dangerous than than an air compressor, yes?

As long as the volume is the same yes , agreed .

sometimewoodworker · November 29, 2021

10 hours ago, Yellowtail said:

So we agree that an air over water system is generally no more dangerous than than an air compressor, yes?

No.

As the systems differ in the critical aspect of water (a corrosive liquid) being always present by design in the air/water design, but not present in anything like the same volume in a compressor, also the point that water in a compressor is going to have few to no extra contaminants as it’s condensation.

With the water in an air/water system containing whatever happens to be in the ground or mains water, this is virtually certain to have an interesting amount of extras.

Is it possible to build a tank with sufficient internal protection to avoid these problems? Of course it is, if you are willing to pay the price. Is is possible to have an air/water system that holds a similar energy potential to a compressor system and is as safe? Of course it is.
Are the large pressure vessels that can support that in safety easily available at a reasonable price? I don’t think so, I have never seen them.

How much more than an air pressure vessel are they? Again they are esoteric so I would be guessing but some multiple of the air tank given that the use case for them is tiny compared to air pressure tanks.

if you have information on the availability to consumers, cost, and construction of them it would be of interest.

NOTE they would have to be tanks of several hundred litres capacity to be relevant, not the tiny ones in use on domestic pumps

Yellowtail · November 29, 2021

7 hours ago, sometimewoodworker said:

No.

As the systems differ in the critical aspect of water (a corrosive liquid) being always present by design in the air/water design, but not present in anything like the same volume in a compressor, also the point that water in a compressor is going to have few to no extra contaminants as it’s condensation.

With the water in an air/water system containing whatever happens to be in the ground or mains water, this is virtually certain to have an interesting amount of extras.

Is it possible to build a tank with sufficient internal protection to avoid these problems? Of course it is, if you are willing to pay the price. Is is possible to have an air/water system that holds a similar energy potential to a compressor system and is as safe? Of course it is.
Are the large pressure vessels that can support that in safety easily available at a reasonable price? I don’t think so, I have never seen them.

How much more than an air pressure vessel are they? Again they are esoteric so I would be guessing but some multiple of the air tank given that the use case for them is tiny compared to air pressure tanks.

if you have information on the availability to consumers, cost, and construction of them it would be of interest.

NOTE they would have to be tanks of several hundred litres capacity to be relevant, not the tiny ones in use on domestic pumps

So when you said: "The air over water system that is usual in Thailand varies from around 500ml to a maximum of around 10 litres with the vast majority being under 2 litres, with quite low pressure. I have never heard of a small air/water system bursting, I have herd of several compressor air tanks bursting sometimes with nasty injuries as a result." you were just being argumentized?

In any event, I think we understand the systems differently.

Incidentally, as I understand it, the primary cause of compressor tank failure is corrosion, and the vast majority of water tanks are steel.

sezze · November 30, 2021

This discussion keeps going and going while we not moving further ahead . What i mean is : any system for normal operation , home or even hotel use , does not need a 500l pressure tank . In case of really needing one , well then it is something very special , and he needs a serious amount of cash , since this is not a home build system and his system needs to be calculated and constructed by specialized companies . He then not have to ask us about it , but asks the specialized company if and why he needs it and if there is a safer/cheaper solution . So what does he need, looking at the OP question is just nothing more then the standard home system , which does have a tank 500-2000l , standard . Costing from 1000-10000 baht , no pressure , and a automatic pump with pressure switch and BLADDER tank . The pump and bladder tank can be of choice , but even a smaller pump of 250watt will do

AKA

https://www.lazada.co.th/products/hitachi-wmp-150-200-250-300-350-xx-series-10-i2939349763-s10785575259.html?spm=a2o4m.searchlist.list.59.72d74f03WDnug9&search=1

and or similar , going from 800baht ( not recommend, motor quality can't be good imho opinion) to 10.000 baht at the really high end range .

These pumps normally got bladder tanks inside already , not have to do anything , water in /pressure water out . simple easy not expensive. Most houses ( all foreign owned ) houses got that system . Not difficult neither expensive and nothing dangerous to worry about .

I am all for finding home build solutions for over-expensive systems but in this case , it is a clear simple answer .

sometimewoodworker · November 30, 2021

15 hours ago, Yellowtail said:

So when you said: "The air over water system that is usual in Thailand varies from around 500ml to a maximum of around 10 litres with the vast majority being under 2 litres, with quite low pressure. I have never heard of a small air/water system bursting, I have herd of several compressor air tanks bursting sometimes with nasty injuries as a result." you were just being argumentized?

No at all. The OP was postulating a very large (500 litres and over) air over water system. That is what has been talked about

incidentally you probably meant to say argumentative since argumentized is an obsolete word and is the wrong tense even then.

And no I was not being argumentative but factual. The small air over water pressure tanks fail with pinholes (well tank versions) or fail with the bladder not working (constant pressure versions) but I have never heard of one bursting. That however is irrelevant to a very large domestic system. Very large domestic systems are dangerous, extremely expensive, and I’ve never heard of one being installed in Thailand (that doesn’t mean nobody has got one of course but if there is one it’s never been posted)

They may exist in large commercial installations but then the cost of the tank needing to be in the tens of thousands or hundreds of thousands will be justifiable by the ROI.

On 11/28/2021 at 10:27 AM, Yellowtail said:

I said an air over water system (which the majority of people in Thailand have) is no more dangerous than an air-compressor.

You introduced the tiny pressure tank systems that are not relevant to a 500 litre system except as a feeder to it.

On 11/28/2021 at 7:48 PM, Yellowtail said:

my my last air compressor had a 1,200 liter tank.

So if comparing a very large compressor tank to a standard domestic (usually under 1 litre tank) then since it’s chalk and cheese the tiny tank is probably safer than the large tank, in part because the wall thickness of the small tank (accumulator in Mitsubishi constant pressure systems) is effectively vastly greater for the contained pressure than your large compressor tank.

15 hours ago, Yellowtail said:

In any event, I think we understand the systems differently.

Certainly as the OP was trying for an air over water system that is around 5 to 10 times larger than your big compressor tank while you are talking about tiny air over water tanks that are 1/1200 to 1/2400 the size of your compressor tank.

15 hours ago, Yellowtail said:

Incidentally, as I understand it, the primary cause of compressor tank failure is corrosion, and the vast majority of water tanks are steel.

The only pressure tank I have seen in a shop that was remotely of the size talked about by the OP (it may have been between 200L and 500L I didn’t check the volume) was stainless steel and AFIR was more expensive than most pump + storage tank combinations

Incidentally I’ve just checked and the cost for a large pressure vessel in China is about 28,000 Baht, so economical? No, not for domestic use.

https://aqualeader.en.made-in-china.com/product/kNFEloOyNXhd/China-500-Liter-Vertical-Pressure-Vessel-Expansion-Tank-with-Replaceable-Bladder-Membranes.html

Yellowtail · December 3, 2021

On 11/30/2021 at 7:52 AM, sometimewoodworker said:

No at all. The OP was postulating a very large (500 litres and over) air over water system. That is what has been talked about

incidentally you probably meant to say argumentative since argumentized is an obsolete word and is the wrong tense even then.

And no I was not being argumentative but factual. The small air over water pressure tanks fail with pinholes (well tank versions) or fail with the bladder not working (constant pressure versions) but I have never heard of one bursting. That however is irrelevant to a very large domestic system. Very large domestic systems are dangerous, extremely expensive, and I’ve never heard of one being installed in Thailand (that doesn’t mean nobody has got one of course but if there is one it’s never been posted)

They may exist in large commercial installations but then the cost of the tank needing to be in the tens of thousands or hundreds of thousands will be justifiable by the ROI.

You introduced the tiny pressure tank systems that are not relevant to a 500 litre system except as a feeder to it.

So if comparing a very large compressor tank to a standard domestic (usually under 1 litre tank) then since it’s chalk and cheese the tiny tank is probably safer than the large tank, in part because the wall thickness of the small tank (accumulator in Mitsubishi constant pressure systems) is effectively vastly greater for the contained pressure than your large compressor tank.

Certainly as the OP was trying for an air over water system that is around 5 to 10 times larger than your big compressor tank while you are talking about tiny air over water tanks that are 1/1200 to 1/2400 the size of your compressor tank.

The only pressure tank I have seen in a shop that was remotely of the size talked about by the OP (it may have been between 200L and 500L I didn’t check the volume) was stainless steel and AFIR was more expensive than most pump + storage tank combinations

Incidentally I’ve just checked and the cost for a large pressure vessel in China is about 28,000 Baht, so economical? No, not for domestic use.

https://aqualeader.en.made-in-china.com/product/kNFEloOyNXhd/China-500-Liter-Vertical-Pressure-Vessel-Expansion-Tank-with-Replaceable-Bladder-Membranes.html

You're nothing if not long winded. In any event, all I said was that an air-over-water system was no more dangerous than an air compressor, and nothing you've said refutes that.

sometimewoodworker · December 3, 2021

1 hour ago, Yellowtail said:

You're nothing if not long winded. In any event, all I said was that an air-over-water system was no more dangerous than an air compressor, and nothing you've said refutes that.

Same cost and size tanks, absolutely not.

air over water tanks that cost much more than double I agree.

Yellowtail · December 6, 2021

On 12/3/2021 at 3:23 PM, sometimewoodworker said:

Same cost and size tanks, absolutely not.

air over water tanks that cost much more than double I agree.

Thank you.

kamalabob2 · December 7, 2021

I have purchased three "pressure tanks" for my own home starting in 2008. 300 liter and 500 liter. The problem, even with water that flows through 5 filters in line and is then stored in large Diamond Brand water storage tanks, is UNLESS you buy the more expensive stainless steel pressure tanks, they will rust out. I no longer have a "pressure tank" for household use. I am 100% satisfied with my Mitsubishi Super pump which has a tank and the power to delivery excellent water pressure in three full ensuite bathrooms on a second floor and three restrooms and two kitchens on a ground floor. I have a pressure tank smaller system pulling water from a smaller plastic tank for lawn sprinklers. There are plenty of pressure tanks sold in Buriram and in similar water pump stores in Thailand. If a store sells "Mitsubishi Super Pumps" (not home Pro, not Thai Watsadu) they might stock water pressure tanks. Lazada might not be the least expensive place to buy a Mitsubishi Super Pump. I prefer to buy from an established retailer who has a real team to install my water pumps.

https://www.buriramhome.com/buriram-three-car-garage/