Generating Hot Water For Bathroom

[simon43]

I've just started to build a small hotel in Phuket. My inrention was originally to use solar water heaters to provide the hot water for the showers in each room. (I wasn't keen on using instant hot-water heaters because of their high purchase price and high running costs).

However, I can't really use the solar heaters now because of some issues in mounting them in the correct orientation.

So I need to look at other options. My immediate thought was to use what is comon in the Uk. That is, an insulated water cylinder which is supplied with a cold water feed from my cold water holding tank on the water tower, (supplied via pump from our well). The hot water take-off is at the top of the insulated tank, as well as an open vent in case of dangerous pressure build-up. (The open vent pipe goes back to the cold water holding tank as an 'overflow', but should never actually be used if the system is working correctly).

The actual hot water is generated by an imersion heating element in the insurlated tank. This has a thermostat, so only heats and maintains the temperature of the hot water.

Is this type of system used in Thailand, or would my system (well-proven in the UK), be condemned by the local authorities? Any other alternatives as a means of providing a relaible supply of hot water?

Thanks - Simon

[GuestHouse]

The cheapest method is to heat the hot water as you use it. You only heat what need to heat.

Have you considered placing a water storage tank where it will be heated by solar heat (raising the temperature a few degrees and then using this to feed the water heaters?

Every bit of solar heat would then reduce elctricity use.

[Morden]

Simon,

I've neither seen nor heard if a UK style water heating system in LOS.

As Guesthouse says, an external storage tank will allow its contents to warm up nicely and an electic on-demand heater will bring it up to shaving and nut-scalding temperatures. Siemens do a heater for about Bt8,500. For a hotel, you might need to install one in each bathroom.

Edited April 8, 2006 by Morden

[lopburi3]

Tank type water heater are available here and Home Pro have a number of models. But they are mostly used in hotels of tourist class upwards I believe. This requires the extra plumbing/dual faucets that a heat at point of use heater avoids.

In Phuket you do not need much heat rise so a normal home wall unit should work well. They only draw electric power when in use and only to the extent of heating required so reading 3.5KW is not the way to judge. They almost never will be used at that capacity and only be used when needed. If you use tanks in the sun the water already will be at almost hot level anytime it is not raining.

[Gary A]

Guesthouse has the right idea. Your tower tank more than likely sits in the sun so paint the tank flat black and use the on demand shower water heaters. It pays to buy the better ones that actually have a thermostat built in rather than the three setting cheapies. The good ones heat the water to the thermostat setting regardless of the temperature of the inlet water. The water in the tower tank will get a lot warmer than you think. If you can't paint the tank throw a black mesh cloth over it. The kind of mesh that they use to shade plants.

[Farma]

The UK style water heater you describe sounds the same as commonly used in Australia and other countries. Rheem is a major maker in Australia.

If you do go the water tank route, I suggest you purchase a tank that has vitreous enamel lining and anode to prevent any corrosion caused by the well water you intend to use. It will save you in the long run. The anodes are replaced every few years if I recall.

A quick scan on the web suggests the “on demand" water heaters are the most economical to run.

[Digger]

No experience of solar heating but I have gone through a lot of instant water heaters trying in vain to get a balanced water temperature. The upshot is that I have ditched using the Siemans water heaters described earlier for showers. Overall I would suggest:

for sinks, assuming your having a hot water supply, fix a Siemens multi unit, the smaller 6kw I think is ample and copper pipe it through to about 4 sinks. The amount of hot water people use in bathroom sinks is minimal and these work fine for that.

For showers, just stick with a one feed instant shower heater - i.e it only takes a single feed from the cold water supply. You dont need to buy expensive mixer taps (i.e 2,000 baht a time) and the thing is easy to replace if it goes wrong. I have latterly used 3.5kw Panasonic water heaters in my showers and they have worked the best. They have a rotary dial to set the temperature and cost about 4000 baht each. I used to use the Siemens units for showers but the balancing was always hit and miss - one second cold, next hot, then cold again - getting the balancing is not easy and I used expensive Grohe taps with a temperature controller. Its also more economical as your not needing to pay so much for the heater and also all the copper piping you need to run in the bathroom as well as the cost of the faucets - basically the shower comes with its own hose and you just need a simple cotto on/off tap which costs 200 baht.

[bino]

If the rooms are going to have aircon, you may consider using the aircon condensers to generate hot water. I saw this system working at Chaweng Buri resort in Samui, and I was impressed.

There were a couple of threads on the subject- I can only find one now....

http://www.thaivisa.com/forum/index.php?showtopic=40256

Hope this helps.

[lopburi3]

No experience of solar heating but I have gone through a lot of instant water heaters trying in vain to get a balanced water temperature. The upshot is that I have ditched using the Siemans water heaters described earlier for showers. Overall I would suggest:

for sinks, assuming your having a hot water supply, fix a Siemens multi unit, the smaller 6kw I think is ample and copper pipe it through to about 4 sinks. The amount of hot water people use in bathroom sinks is minimal and these work fine for that.

For showers, just stick with a one feed instant shower heater - i.e it only takes a single feed from the cold water supply. You dont need to buy expensive mixer taps (i.e 2,000 baht a time) and the thing is easy to replace if it goes wrong. I have latterly used 3.5kw Panasonic water heaters in my showers and they have worked the best. They have a rotary dial to set the temperature and cost about 4000 baht each. I used to use the Siemens units for showers but the balancing was always hit and miss - one second cold, next hot, then cold again - getting the balancing is not easy and I used expensive Grohe taps with a temperature controller. Its also more economical as your not needing to pay so much for the heater and also all the copper piping you need to run in the bathroom as well as the cost of the faucets - basically the shower comes with its own hose and you just need a simple cotto on/off tap which costs 200 baht.

The only time I have had the misfortune to use that Siemens unit was in a middle class hotel in Chiang Mai about 10 years ago and I hope to never come across another one. Scalding hot or cold and almost impossible to control. Thought it was the unit and changed rooms but next room not much better. Did figure some way to get it to work after many tries but was not impressed. Although I guess it did heat the water good. Not sure if it was water pressure problem or what but can not believe a major company product would be this bad and actually sell so there must be a reason.

[elkangorito]

I've just started to build a small hotel in Phuket. My inrention was originally to use solar water heaters to provide the hot water for the showers in each room. (I wasn't keen on using instant hot-water heaters because of their high purchase price and high running costs).

However, I can't really use the solar heaters now because of some issues in mounting them in the correct orientation.

So I need to look at other options. My immediate thought was to use what is comon in the Uk. That is, an insulated water cylinder which is supplied with a cold water feed from my cold water holding tank on the water tower, (supplied via pump from our well). The hot water take-off is at the top of the insulated tank, as well as an open vent in case of dangerous pressure build-up. (The open vent pipe goes back to the cold water holding tank as an 'overflow', but should never actually be used if the system is working correctly).

The actual hot water is generated by an imersion heating element in the insurlated tank. This has a thermostat, so only heats and maintains the temperature of the hot water.

Is this type of system used in Thailand, or would my system (well-proven in the UK), be condemned by the local authorities? Any other alternatives as a means of providing a relaible supply of hot water?

Thanks - Simon

In no way compare the UK with Thailand. The rules, codes & the weather conditions are worlds apart.

If you have more than 3 persons in your household, it makes sense to use stored hot water. The storage tank size can be easily calculated. I'll give an example;

providing a 'non-water saving' shower head is used, about 200 litres per person per a 10 minute shower is used. If all people use the shower one after the other & assuming that the total water volume used is 50% hot water, then about 200 to 300 litres of hot water shall be used (maybe less in Thailand due to the warmer weather). Subsequently, a minimum 250 litre hot water service (HWS) is prescribed.

Heating this water is not a problem in Thailand. For some reason, you seem to think that you must face solar arrays in a certain position for them to be able to work. This is not so...especially in Thailand. The yearly ambient (& average temp) is about 32 degrees celcius so whether the sun is directly upon the solar panel or not, the water will always be 'not cold'. Also, the storage tank must be insulated. 'Glass' hot water tanks are cheap & last a long time (especially if not at high mains pressure. Thailand does not use high mains pressure like western countries do).

Effective & cheap solar panels can be black matts placed upon the roof (swimming pool heaters used in the Southern Hemisphere). These matts have tubes running through them & require a small circulating pump, to pump the heated water from the matts to an insulated storage tank. These pumps are very cheap to run & last many years (Grundfoss) if installed out of the weather. A possible problem is that the matts will 'spring a leak'. The next best thing & also the 'ultimate' solution is to employ a copper solar array (see Solarhart or Rheem, Australia). These systems will outlive you.

In Thailand & contrary to popular belief, there is no need whatsoever to use electricity to heat water, provided you are prepared to make the necessary modifications to your abode.

I can see no reason why a solar hot water system can't be easily & effectively used in Thailand for a household of 6 to 8 persons, provided you have an appropriately sized storage tank.

By the way, an instantaneous hot water heater is VERY expensive if more than 2 people use it. See the above paragraph. If you don't believe me, I will be happy to do the maths for you.