Help! Tankless Water Heater in Hotel....

Hi Guys

I'm in the middle of designing and building a boutique 8 room hotel in Thailand. This will mean 8 bathroom sinks and 8 overhead - rain type showers that require a really good flow rate to give the desired rain effect when showering.

I am limited on space and want to keep electricity bills down so it looks like tankless electric water heaters are the way to go. (Gas heaters are not an option as there is no mains gas supply in Thailand).

I'm just wondering how many heaters I will need, what power rating etc to achieve a really strong flow for the showers... temperatures will be moderate as people generally take luke warm showers in a hot country.

The rooms are arranged in the exact same layout on 2 floors.

Not sure if this is relevant but the power supply in Thailand is 220v at 50 cycles/sec.

Any help would be massively appreciated as these Thai plumbers are great at the hands on stuff but not too good at working out the requirements first!

Thanks very much in advance.

Wax

Simple answer, you can't - you won't be able to supply that much water from instantaneous water heaters (such as the Redring Powerstream - look up specs on google)- they can deliver no more than electric showers. Even if you did manage to get enough electric into the building, running costs would be massive.

Probably the best way is for each room having a cylinder and 3kw immersion heater or may get away with one cylinder between 2 rooms etc,

you have not said what water pressure you are working with - whpes is right though, inline heaters will not do the job. Other options are to get a large linked set up, boosted off a pump (as i can guess that the water pressure in Thailand leaves something to be desired . . .)

You can work it out based on the flow rate of the showers and the length of shower to get your storage needs.

ie:10 litres per minute, 5 minute showers = 50 litres per shower

total = 400 litres of water.

This is a minimum really, as your showers may have a greater flow rate paricually if boosted with a pump. You need to know the avarage time people shower over there as well!

The electric need for inline heaters would be about 40 amp per room! 2 linked cylinders could have a 3k immersion in each, so that would only require approx 40 amp for the whole set up. Get the cylinders on a proper timer set up, and properly insulated to save as much energy as possible!

Good luck!

[QUOTE=waxmiracle;120138]Hi Guys

I'm just wondering how many heaters I will need, what power rating etc to achieve a really strong flow for the showers... temperatures will be moderate as people generally take luke warm showers in a hot country.

Funny old thing but when I lived in hong kong and visited lots of the counties in that area, I took long hot showers when I washed as the airconditioning was very effective. Only a thought based on real life experience

Thanks for the replies guys.... the problem that I have is space being at a minimum. There is plenty of space on the roof so it could be an idea to have a large tank up there and link that to all rooms... The advantage of having the tank exposed is that the ambient temperature in thailand is about 25 - 30 degrees C, hence the sun does part of the heating job for you....

or just thinking about having a cylinder with immersion in each room... how much space would that take up?

Cheers muchly

wax

in india they go with the roof mounted tanks - really huge ones!

This will give you the gravity pressure you require, and can be built on raised stands to give more pressure. Another trick I learnt by being in India is fo for a solar panel set up in a hot country and you will get all your hot water free! You will have to look at options over there but I am sure that the technology is out there. No other boiler/heater would be required most likely, but you would have a number of insulated storage cylinders that your hot water will go in, which would be roof mounted as well. The main issue would be making sure that the water doesn't get too hot, as it could get near boiling point off a panel in tropical sunlight!!!! Correct installation of thermostats/blending valves and saftey cutouts as the manufacturer will specify is essential.

Good luck.

solar panels does sound like a good choice, each room has its own system with solar panel and cylinder and have electrical heaters for heating if needed. Although you may need to base your showers on the maximum 15 minutes as some people do have long showers, you could have immersion heaters in the cylinders also for night time use.

Originally Posted by Avatar

The electric need for inline heaters would be about 40 amp per room! 2 linked cylinders could have a 3k immersion in each, so that would only require approx 40 amp for the whole set up. Get the cylinders on a proper timer set up, and properly insulated to save as much energy as possible!

Good luck!

Hi There,

Where do you get the 40 amps per room from? and how does that equate to the "40amp for the whole set up"

Surely a 3k immersion in each cylinder would require only a 16 amp fuse (if they have those out there?) 3000/220= 13.6 amps this is the design current for each heater.

40 amps was for inline heaters not immersion heaters and cylinders. 40 amp for the whole set up would be for cylidners all round.

Surely THailand being hot and sunny - solar with immersion backup would be the way to go. Could market the hotel as "eco" which is a good marketing point these days.

You can also get eco shower heads which don't use as much water but still give a good showering sensation.

Originally Posted by WHPES

40 amps was for inline heaters not immersion heaters and cylinders. 40 amp for the whole set up would be for cylidners all round.

Doesn't matter what type of heater if it's 3kw it'll still pull the above design current! And thats for each heater.

inline heater are 9kw +