On Demand Hot Water Heater

[sirineou]

I am sure the subject has being covered, but we all know about TVF's search function. so aside from direct advice , links to appropriate threads will also be appreciated.

So I am building a new house in Khon Kaen (link ti thread at:https://www.thaivisa.com/forum/topic/1003921-new-build-in-khon-kaen/where I document my process ) 

A Friend of mine who has also build in the area and has done a good job, advised me that the  On demand  hot water heater I chose should not be any less than 6000w. (I know very litle about water heaters in Thailand). I looked at the Home Pro website (they seem to have the most comprehensive user friendly site)  and  6000w was the biggest I could find, and there were not many of them. The price difference between the different power was not so great to make price an issue, they are all relatively the same. So what should be looking at? are there other criteria than Wattage? 

  For The most part  it will be just me and my wife using it, and I do like hot water.

Thank You

[r136dg]

Since you emphasized your like for hot water, 6kW units for sure. If you have decent water pressure & can get good volume to the shower head, a 4.5kW unit may not heat the water enough for you. You'd have to turn the volume down for a real hot shower.

We're using Stiebel Eltran & manzuma in are bathrooms with absolutely no complaints, but no doubt there's other good brands out there.

They do pull some amps so it's critical you get the right gauge wiring & mcb's on those circuits! Crossy or another authority on that will be along to sort you out there.

[Crossy]

Mazuma do an 8kW unit https://www.homepro.co.th/product/260931

 

BUT, big water heaters use lots of power, 8kW equates to 36A, a significant chunk of the regular 45A electricity supply.

 

If you do like hot water at high flow rates, have a look at the gas water heaters, very effective and no strain on your electricity  supply.

 

[sirineou]

43 minutes ago, Crossy said:

Mazuma do an 8kW unit https://www.homepro.co.th/product/260931

 

BUT, big water heaters use lots of power, 8kW equates to 36A, a significant chunk of the regular 45A electricity supply.

 

If you do like hot water at high flow rates, have a look at the gas water heaters, very effective and no strain on your electricity  supply.

 

 Thank you Crossy, Unfortunately I am not there , We are in the process of starting a new project at NYC next month and I am stuck in the minutia of logistics planning so I could not come.. Wife is en route and will be there in a few hrs. Unfortunately she is not very technologically minded, so I don't want to  involve her in anything complicated. So I think Electric will be the way to go.

I was able to also find an other thread concerning   Water heaters and it seemed that the consensus seemed to lean towards Siebel or Panasonic.  What would be your choice between those two if you had to choose between them, and any particular models?

You say, Standard 45 amp supply , I am embarrassed to say that I have not discussed the Electric supply issue with the builder  .In the US a 100 amp box is standard , 45 amp sound undersized. 

The house is two bedrooms two baths, living room kitchen,  There will be three A/C units, (two about 1200 btu one about 1800 btu, electric cook top . The downstairs  is all open except a bathroom, in the future I might put another bedroom

there. Plenty of lights everywhere including two flood lights for the yard.

I dont have the contract with me to see what is included, wife has it with her and she is on a plane right now.  Will ask her as soon as she gets there.

You can view the build  there:   http://:https://www.thaivisa.com/forum/topic/1003921-new-build-in-khon-kaen/where I document my process )

 

Edited November 26, 2017 by sirineou

[sirineou]

 ^^^

Doing a crash course on the subject now,  LOL by reading some of the treads in the electric subforum

seems like in Thailand most will have a 15 45 amp system , which I assume since I have not asked for anything special (electric not being my specialty)  is what I will be getting.

 

[Crossy]

Don't forget we are 220V here, so your 15/45 which will likely have a 50A incoming breaker is good for around 11kW.

 

A quick and dirty maximum demand calculation:-

 

Aircon totalling 42k BTU - 4kW - 18A - (assume a 30% duty cycle) = 9A

2 x 6kW water heaters - 12kW - 54A (assume only one active at once) = 27A

Electric cook top - 6kW - 27A - with diversity (10A + 30% full load) = 19A

 

Major loads = 55A. That cook top is taking you into 30/100 supply territory before considering all the other (small) stuff. A 30/100 may or may not be available in your area, time to talk to PEA, fancy cooking with gas?

 

We have a similar load (but gas cooking) on a 15/45, whilst our 50A incomer has never opened on overload we have come pretty near when all the bedrooms are occupied with family, and the supply has obviously been stretched, see my thread on AVRs in the electrical forum.

 

[eyecatcher]

We have a stiebel multipont 6kw feeding three showers at our spa and its had virtual continuos use for 7yrs.

So i bought another for the house just for the pleasure of a great shower and washing up in hot water.

Its been fine also though in hindsight i should have used a bigger diameter pipe to the sink since the green hot pipes are a tad smaller than the blue.

 

[klikster]

I know you are talking about demand heaters, but:

 

On our build about 5 years ago I opted for a wall mounted (outside on terrace) Siebel Eltron. It makes ALL the hot water I need for my showers (wife seldom uses).

 

One reason I went this route is because of the water+electricity mix in an indoor appliance.

 

Power bill for 200 sqm house with 2 - 26K BTU A/C, outside lights, water pump, washer, dryer, big fridge,  etc., etc. seldom exceeds Bt 3,000.

 

Note: 2 A/C, dryer, big fridge are inverters.

[Crossy]

@klikster I assume you are talking about a tank type heater (Stiebel-Eltron is a manufacturer), these are an excellent way of getting your maximum power demand down. 

 

Up to 150L of hot water for a power consumption of only 2kW.

 

https://www.homepro.co.th/product/1016384

[klikster]

Just now, Crossy said:

@klikster I assume you are talking about a tank type heater (Stiebel-Eltron is a manufacturer), these are an excellent way of getting your maximum power demand down. 

 

Up to 150L of hot water for a power consumption of only 2kW.

 

https://www.homepro.co.th/product/1016384

Yes, should have written "tank style", but mine is a vertical mount

Edited November 27, 2017 by klikster
unsure about capacity

[sirineou]

I spoke with my builder  and he said he will call PEA concerning 30/100 and  will talk to my wife about extra costs  ( our contract calls for   45 Amp service ,

A Hot water tank would be nice . but I plan to be away from home a lot after I retire, ( spend some time at out property in Florida, and with family in italy and Greece) so an On demand Hot water Unit, I think would be more practical. 

[lopburi3]

On 11/27/2017 at 5:29 PM, sirineou said:

I spoke with my builder  and he said he will call PEA concerning 30/100 and  will talk to my wife about extra costs  ( our contract calls for   45 Amp service ,

A Hot water tank would be nice . but I plan to be away from home a lot after I retire, ( spend some time at out property in Florida, and with family in italy and Greece) so an On demand Hot water Unit, I think would be more practical. 

Why?  Did you understand the 220v rather than 110v?  Volts x Amps = Wattage (power).  So with twice the voltage you only need half the amperage (and much smaller wire).  The normal 15/45 service should be fine for you (it will handle a lot more than 45amps for normal short periods).  I run a six bedroom home (five water heaters - washer/dryer - 3 20cf refrigerators and 2 5cf - 5 air conditioners - 7 TV's - I do use gas for cook top but have 3 electric ovens and 2 microwaves, water cooler, toaster, water pump and there are normally 8 or 9 people living here.

[Crossy]

4 hours ago, lopburi3 said:

Why?

Because his calculated maximum demand, even after diversity is 55A.

 

A 15/45 would likely be just fine, but if a 30/100 is available let's do the job right.

 

2 x 6kW water heaters and a 6kW cooktop, a potential 18kW just there = potentially 81A (it's never going to actually be that which is why we apply diversity).

 

 

[lopburi3]

23 minutes ago, Crossy said:

Because his calculated maximum demand, even after diversity is 55A.

 

A 15/45 would likely be just fine, but if a 30/100 is available let's do the job right.

 

2 x 6kW water heaters and a 6kW cooktop, a potential 18kW just there = potentially 81A (it's never going to actually be that which is why we apply diversity).

 

 

Admit did not see your post for some reason (not having a great success reading forum today as jumping all over the place trying to load ads) so was taking it as one water heater and from size of rooms believe the air conditions should also be smaller and probably not cooling most of the time.  Normally I would 'be prepared' but hate to paint a target on a house upcountry by it being the only home in area with 30/100 service (very visible to any potential thief).

[Crossy]

Big on-demand water heaters and the electric cooktop really are the killers. Cooking with gas and 3.5kW water heaters and you're more than happy on a 15/45.

 

We've had our 15/45 up to 65A but by then the supply was down below 185V (having started at >220V).

 

[KKr]

As an alternative you could consider a solar heat collector.
During the last two years, I used my backup, an electric on demand water heater, just TWO days. 
Roof is SW, so installed two collectors (on South one would have sufficed probably), and a 240 Liter tank. Installed a temperature control, and thermostatic shower taps so we do not waste water for temperature mixing
Users usually two, sometimes four and so far 240 liters was sufficient hot water.
Also, to have real hot water available in the kitchen sink I consider a big advantage.

 

Edited December 1, 2017 by KKr

[sirineou]

Solar heat is a great Idea, we just came from a vacation in Greece and you could see them on every roof top,

in fact , in the one in the background they have covered part of it with a piece of carpet  because, I was told, they get too much hot water.

Because there are so many used there, they are very inexpensive , I was told they start at 800 euros.

I think they are much more expensive in Thailand. How much did your system cost?

Between , our home in NY and in Florida, and friends and family all over the world. (Greece, Italy , Australia,) when I retire , we plan to do a significant amount of traveling, so a low maintenance, in demand hot water system is more desirable for as right now, but just as soon as  our "friends and family" get tired of as visiting, and start turning the lights of and locking their doors in the hope we go away, (which should not take too long LOL) . and we don't travel as much as we plan to do, I will certainly look into it.

 

  

Edited December 1, 2017 by sirineou