Central Water Heater Vs Individual Water Heater

[tangcoral]

I would like hot water in my 3 bathrooms and kitchen.

Was planning to buy 4 units when my contractor suggested I buy one storage tank instead.

The Stiebel unit ranges from 3500-6000watt. The storage tank unit uses 2500watt.

I like hot showers, but I am guessing the storage tank heater uses less wattage as it constantly warms the water while the smaller units are instantly heat the water.

I would imagine the cost to operate the storage tank unit would be more than individual unit as it is a warmer.

Am I misunderstanding how the storage tank heater works?

Which route should I go with?

the smaller units cost 5000-6000baht while the 80 liter storage tank cost 11,900

[bankruatsteve]

That's an interesting (to me) subject. I don't have answer but having lived in SE Asia for some years now and finding the electric on-demand shower units to be very satisfactory, I wonder why the "west" seems to need hot water being cooked in a tank at all times? Actually, I've had some US friends visit me and thinking they will change to the on-demand units back home. On-demand had GOT to be less expensive than keeping a tank hot all the time, doesn't it? And, the intial cost should be perhaps discounted to the ongoing cost of heating water that may/may not be used.

[Crossy]

I'd go with on-demand too, reasons follow :-

Never run out of hot water.

Lower plumbing cost (no need for miles of hot water pipes).

No wait for the water to run hot (with associated waste of water and energy).

Just heat what you need (a big plus in low consumption homes).

On the side of the tank heater:-

Lower power consumption (over a longer period) puts less strain on the supply for those of us on long feeders.

[electau]

On demand or instantaneous water heaters should not be larger than 20A single phase to minimise demand on the supply authority.

Storage type water heaters rated at 13.5watts per litre have the advantage of being connected by a time switch for heating at off peak periods (eg, 2300 to 0700hrs). They can be connected to off peak tariffs if available.

Storage type ( 270 litre) can be connected to solar collectors to heat the water, and a booster element can be switched in as required.

Generally a 270litre unit is suitable for the average residential dwelling with 2 bathrooms and kitchen.

Temperature settings for a storage type HWS should be 70C. Smaller 45litre and 135litre units are also available with wattage ratings of 1.8 to 3.6kW.

All units fitted with a thermostat, over temperature cut out (manual reset) and pressure relief valve.

　

[craigt3365]

I have a 3 bath house and was looking at buying 4 units, the other being for the kitchen. But the builder had me buy these Stiebel multi point heaters. He then hooked up 2 bathrooms together and then hooked up the kitchen and the other bathroom. So I only had to purchase 2. And so far, it is working out fine. Even when both showers are being used, there is plenty of hot water...not that much ever gets used here in HOT Thailand!

[katabeachbum]

on demand heaters use less electricity than hot water tanks. however they increase your max demand load substantially. so for a 4 point hot water house, I would first look at your

electric supply. If its a 15/45 amp, it will probably be sufficient to use 2 on demand hotwaters at the same time. I would install max 3500 watt heaters/16 amp. sufficient for a good warm shower. perhaps larger in the kitchen to get 60-70C.

the hotwaterstream from a tank is much more comfy/stable. for a 7 bath, 2 kitchen house 200liter tank works fine. reasons, water temp in is 25-35C, its installed in warm air 25-45C. In my homecountry we had 300liters for a 3 bath home, and due to water in at 5-10C and airtemp in tank room 10-15C we could run out of water. here it never happens. 2200 watt/10 amp is sufficient for 200 liter, making very low max demand. I use Fagor 200litres at 19.900 baht, no problems in 3 years

I have houses with both solutions, and absolutely prefere the tank solution. However cost can be higher due to hot water piping and faucets. Best piping seems to be PPR, a plastic material which can now be purchased at Home Pro, geen pipes. Copper corodes to quickly due to 2 reasons. Much minerals in water, and salt in sand used to build walls. Perhaps also the salt in the air in coastal areas destroys the copper pipes. Most hotels here in Phuket have replaced their copper pipes within 10 years. PPR lasts forever if they are not exposed to UV.

Hotwater tank should be set at more than 70C to avoid legionella, and of course 85C increases capasity of hot water

[powderpuff]

I use a storage hot water heater & I love it.

4 bathrooms 70 liters & have never run out. Many good points above but maybe some misconceptions too. A storage water heater is well insulated & thus is not "constantly" reheating the water. Another point rarely discussed is the massively better flow I can get through mine. Most instant heaters have a tiny (1/4 inch) pipe in which the water is heated. Hard to force much flow through that. Sure if you have a 6000 watt instant heater it will work well. But my 2500 watt Ariston suits my needs. One drawback is the lag - that is unavoidable.

In the West they can use gas fired instant heaters, much cheaper & more efficient, hard to find here.

[bazmlb]

I have a National 4100w instant unit and find it great, the funny part is they originally set it up a bit wrong, the box says it needs a 30A breaker, so they mount a 30A breaker on the wall next to it and run it back to the switchboard to a 16A breaker with every thing else for the second floor, about 3/4 on the dial the lights go out

Never been a fan of the storage units as your heating water for nothing most of the time.

I saw at Home mall the other day a solar unit on display that wasnt too expensive, using solar would help reduce the cost of running a instant unit a bit.

[Artisi]

Thoughts on central gas hot water heating unit would be appreciated as I am currently reviewing on-demand, electric storage, or gas.

[trogers]

Thoughts on central gas hot water heating unit would be appreciated as I am currently reviewing on-demand, electric storage, or gas.

Central gas hot water heating unit is just a fancy name for a boiler...

Thailand has been using it since the first turkish bath was built...

[lopburi3]

In the West they can use gas fired instant heaters, much cheaper & more efficient, hard to find here.

That's what they all were here 30 years ago - a lot of deaths because of them as not vented and cold season windows often blocked. They were overkill for the slight temperature increase required and I had to block three of the four jets on units here in Bangkok during the summer months.

I saw at Home mall the other day a solar unit on display that wasnt too expensive, using solar would help reduce the cost of running a instant unit a bit.

That would make sense if you don't melt your pipes. Just having a SS tank in direct sunlight a few hours heats the water considerably.

[PattayaParent]

with the individual multi point water heater units you need to have sufficient water flow through them for them to work so check out your water pressure and the units requirements first.

[lopburi3]

Below is the operating range of a typical Panasonic point of use water heater. At less than 1 psi pressure requirement do not believe most people would have a problem getting heater to activate.

Water Pressure

Min 0.05kgf/cm2 (.7112 PSI)

Max 3.87kgf/cm2 (55 PSI)

If the question is adequate flow for a good shower (subjective) that will require a higher pressure but not just to make the water hot.

[bazmlb]

I saw at Home mall the other day a solar unit on display that wasnt too expensive, using solar would help reduce the cost of running a instant unit a bit.

That would make sense if you don't melt your pipes. Just having a SS tank in direct sunlight a few hours heats the water considerably.

Especially if you paint it black.

[bazmlb]

with the individual multi point water heater units you need to have sufficient water flow through them for them to work so check out your water pressure and the units requirements first.

This morning I could only use half the pressure i normally use due to the tank water temp being so low, even with the 4100w unit it was not enough to heat a full flow shower.

[trogers]

with the individual multi point water heater units you need to have sufficient water flow through them for them to work so check out your water pressure and the units requirements first.

This morning I could only use half the pressure i normally use due to the tank water temp being so low, even with the 4100w unit it was not enough to heat a full flow shower.

This is the reason I only use 6kW units in all my condo units in Bangkok, for those few weeks of cold spells at the end of the year.

[lopburi3]

It is only a few weeks a year and I find no great problem in reducing flow for that time. If living upcountry might consider more than 3.5k units (if power were available) but in Bangkok feel smaller units are fine (and safer for normal use).

[craigt3365]

In the US, on demand systems are now the rage. I have 3 friends who built new houses 3-4 years ago and all have them installed. These are fairly "upscale" houses. But in one friends house, if you are in the shower, and somebody else turns on the hot water, look out! Instant cold.

My Mom's house has a tank. The guest bedroom is on the opposite side of the house from the tank. Takes like 3-4 minutes to get hot water. A total waste of energy. Even in the kitchen, it takes almost 1 minute.

I have the 6k watt heaters. Almost instant hot water. And if we are gone for a week, we don't have to worry about turning off the water heater. In the summer here, only the kitchen one gets used as the water is already hot enough for a shower!

[PattayaParent]

Below is the operating range of a typical Panasonic point of use water heater. At less than 1 psi pressure requirement do not believe most people would have a problem getting heater to activate.

Water Pressure

Min 0.05kgf/cm2 (.7112 PSI)

Max 3.87kgf/cm2 (55 PSI)

If the question is adequate flow for a good shower (subjective) that will require a higher pressure but not just to make the water hot.

turned down the water pressure to my bathroom 'cos the bum gun was too powerful and when I used the shower there was no hot water at all.

Then I remembered what the sales lady told me about water pressure needed for it to heat the water, re-adjusted the pressure and hey presto, instant hot water.

[PattayaParent]

In the US, on demand systems are now the rage. I have 3 friends who built new houses 3-4 years ago and all have them installed. These are fairly "upscale" houses. But in one friends house, if you are in the shower, and somebody else turns on the hot water, look out! Instant cold.

My Mom's house has a tank. The guest bedroom is on the opposite side of the house from the tank. Takes like 3-4 minutes to get hot water. A total waste of energy. Even in the kitchen, it takes almost 1 minute.

I have the 6k watt heaters. Almost instant hot water. And if we are gone for a week, we don't have to worry about turning off the water heater. In the summer here, only the kitchen one gets used as the water is already hot enough for a shower!

Then they should have been able to afford to put a multi point water heater in each bathroom plus 1 for the kitchen, not one for the whole house.

[sarahsbloke]

Central hot water tank with solar panels = cheap to run

Single electric showers = cheap to install

Unless you use vast quantities of hot water (bath, jacuzzi), I would go with the singles

[lopburi3]

turned down the water pressure to my bathroom 'cos the bum gun was too powerful and when I used the shower there was no hot water at all

.

They should all be fitted with a valve so you can adjust just the spray pressure. Some spray heads have adjustment but I prefer dedicated valve fixtures or just use an valve "T" and put another valve on the spray side of the "T". You can then adjust spray or turn of both it and toilet in the bathroom.

[craigt3365]

In the US, on demand systems are now the rage. I have 3 friends who built new houses 3-4 years ago and all have them installed. These are fairly "upscale" houses. But in one friends house, if you are in the shower, and somebody else turns on the hot water, look out! Instant cold.

My Mom's house has a tank. The guest bedroom is on the opposite side of the house from the tank. Takes like 3-4 minutes to get hot water. A total waste of energy. Even in the kitchen, it takes almost 1 minute.

I have the 6k watt heaters. Almost instant hot water. And if we are gone for a week, we don't have to worry about turning off the water heater. In the summer here, only the kitchen one gets used as the water is already hot enough for a shower!

Then they should have been able to afford to put a multi point water heater in each bathroom plus 1 for the kitchen, not one for the whole house.

Multi point heaters don't seem to be that popular in the US, regular "boiler" type heaters are the norm. These guys have a whole house, on demand heater system. First time I have ever seen that before. But I have not owned a house in the US for many years....so I am far from knowledgeable on this...

My bum gun is also way too strong. But it has a valve to reduce the spray pressure....a great relief!!!!

[PattayaParent]

turned down the water pressure to my bathroom 'cos the bum gun was too powerful and when I used the shower there was no hot water at all

.

They should all be fitted with a valve so you can adjust just the spray pressure. Some spray heads have adjustment but I prefer dedicated valve fixtures or just use an valve "T" and put another valve on the spray side of the "T". You can then adjust spray or turn of both it and toilet in the bathroom.

On my list of things to fix now that I encountered the problem.

[CM4Me]

Artisi,

I think the majority of Thailand's' lower income group are connected to the Government Electricity Grid via the cheapest means possible, i.e. a 5/15 Meter. For this type of supply they can run a small refrigerator, a couple of lights, a small TV & a small fan. Totally adequate for most of the year.

However, a 5/15 Meter supplies insufficient electricity to power an electric hot water heater in addition to those appliances listed above.

Consequently, particularly the further North one goes, gas water heaters (for those than can afford any sort of heating) is more of the norm.

Gas Water Heaters are efficient, economical, clean & safe (provided they are installed correctly).

By safe I believe the units should be either installed outside or, if inside, vented to outside.

I have a number of friends that have gas heaters & they swear by them. I have also stayed at a small resort in Tha Ton, where the manager said they were installed because 'not enough electricity'.

In CNX I have seen a number of makes & models for sale at the bigger outlets.

Edited November 5, 2010 by CM4Me

[lopburi3]

(provided they are installed correctly).

In my view they are not safe for use in Thailand where normal precautions are often not implemented. When I had in Bangkok used copper pipe supply which almost nobody had any experience with (clear plastic was the norm) and ran on outside of home (expect most would have run inside and risked a gas buildup in case of fault). On many occasions ignition failed or turn off was not complete at the unit and could have resulted in serious problems. I was aware of the need to never cover windows/vents but many people were found dead each year who did - even in the relatively mild weather of Bangkok. I would never use or recommend use of gas heater here. In the west central heaters of gas are common and safe. But there is no home gas supply here and such units are not normally used anywhere.

[Artisi]

(provided they are installed correctly).

In my view they are not safe for use in Thailand where normal precautions are often not implemented. When I had in Bangkok used copper pipe supply which almost nobody had any experience with (clear plastic was the norm) and ran on outside of home (expect most would have run inside and risked a gas buildup in case of fault). On many occasions ignition failed or turn off was not complete at the unit and could have resulted in serious problems. I was aware of the need to never cover windows/vents but many people were found dead each year who did - even in the relatively mild weather of Bangkok. I would never use or recommend use of gas heater here. In the west central heaters of gas are common and safe. But there is no home gas supply here and such units are not normally used anywhere.

What you say might well be true, but how many instant electric water heaters are installed correctly, for example, the earth wire screwed against the wall into a plastic wall plug, that's if they ever bother to run an "earth".

[lopburi3]

You run an earth to a ground rod or to your electric supply earth if you have one. A wall screw would not make a reliable ground plastic insert or not. But I do understand your point that electric service is often not done properly. Although not perfect I have not seen any electric units without a ELB/GFI protection.

My point is that gas can be a lot more risk in a closed area than electric. While it should only be one person in an electric mishap it could be a building and/or many in a gas leak/explosion or CO leak. So no reason to risk it now that electric heaters are available.

[CM4Me]

lopburi3, re your post #26

I agree in part with you in that Thais practice of installing a gas appliance (being cooktop or water heater) with the gas supply line being plastic is a disaster waiting to happen, as plastic does deteriorate.

However, if the supply line (from the gas bottle to the appliance) is copper tubing negates the plastic deteriorating problem. Here in CNX I have located a well equipped refrigeration / aircon spare parts specialty store that carries all the necessary copper tubing & accessories for gas instalations. In talking with one of the assistants he advises that they only use copper for installations in hospitals, large hotels / restraurants.

Modern gas water heaters manufactured by renown international companies are very safe (as previously stated if installed correctly), & also are now electrically ignited (by 2 x AAA batteries) which eliminate the old style 24/7 pilot lights.

[lopburi3]

I was not talking about tank type heaters (which are normally run from commercial gas mains) and had pilot lights in the past. My experience here, and I believe the general experience, has been with point of use units with no venting and piezoelectric ignition. These units were made by major companies such as National and the most common means to heat water here some 40 years ago (lord time flies) and at that time it was very difficult finding anyone to install copper even in Bangkok. I do understand that time has passed and that they do normally vent units today but I would still not want gas inside a home here when there are alternatives.