Undersink water heater strong enough?

[Polarizing]

Hi diy people, this job is probably out of my diy scope, so I don't know if it's the right sub to ask.

 

My current situation is as follows: I have a shower with only cold water, my waterheater was next to my shower. A 4500w unit, it heats up the water fairly well, but it reduces the flow significantly, to the point I don't enjoy my shower. The unit broke some time ago. My shower probably has one pipe supplying the water.

 

So the good thing is that I want to renovate my bathroom, so the first thing is to tackle the flow and the hot water supply. I want to run another pipe with a undersink waterheater to the shower. The problem is, I don't know wheter 4500w is enough for a waterheater, the water will be mixed by a shower mixer valve. My ultimate question is, will 4500w be strong enough to be mixed with, to have an enjoyable shower? Actually I am looking to copying the shower water supply setup of those Ideo condo's (ideo mobi/ bluecove). OR should I upgrade to a 6000w, is it easy to have that installed with the wiring etc?

 

Let me know if you know something about this! I will probably buy a panasonic, rinnai or stiebel eltron.

[sometimewoodworker]

Your question doesn’t have enough information to give an answer.

 

if your on Doi Inthanon the answer is definitely no at this time of year.

 

What is an enjoyable shower? How big are your pipes? Do you have a pump? What is your cold water temperature? What hot temperature do you want? Do you want a water tank? Do you want instant hot water? etc.

 

our cold temperature at the moment is around 17 degrees, it gets up to over 34 degrees in the hot season.

[eyecatcher]

I have a 6kw Stiebel multipoint feeding my shower and my kitchen sink.

With the morning temps as they are now my mixer tap is on its maximum hot setting and I often wonder what exactly is a 3.6kw or 4.5kw heater able to do now.

 

Now, my kitchen sink is a good 7m away and floor below but found that by the time the water came thro hot enough to wash dishes, that they had already been done under the open tap.....so I dont even allow hot water to run to the kitchen now.

In hindsight, I would have had a separate heater under the sink on a very short run to ensure veryhot water is achieved.

Edited December 13, 2019 by eyecatcher

[Polarizing]

1 hour ago, sometimewoodworker said:

Your question doesn’t have enough information to give an answer.

 

if your on Doi Inthanon the answer is definitely no at this time of year.

 

What is an enjoyable shower? How big are your pipes? Do you have a pump? What is your cold water temperature? What hot temperature do you want? Do you want a water tank? Do you want instant hot water? etc.

 

our cold temperature at the moment is around 17 degrees, it gets up to over 34 degrees in the hot season.

haha I am in bkk, i just measured a pipe and I couldn't see it clearly but its around 25mm-30mm probably standard size, no pump and no water tank and would be last resort because i have read that in a condo its quite a hassle to install and have the management to be okay, i guess my water temperature is around 20 degrees celcius. I am looking for a tankless electric undersink water heater. I would define an enjoyable shower as one that have an okay flow within the 40-45 degrees celcius range. I don't know exactly what I find the most comfortable, but I like it a bit hotter than most people. As it goes higher, I don't care much if it is low flow.

18 minutes ago, eyecatcher said:

I have a 6kw Stiebel multipoint feeding my shower and my kitchen sink.

With the morning temps as they are now my mixer tap is on its maximum hot setting and I often wonder what exactly is a 3.6kw or 4.5kw heater able to do now.

 

Now, my kitchen sink is a good 7m away and floor below but found that by the time the water came thro hot enough to wash dishes, that they had already been done under the open tap.....so I dont even allow hot water to run to the kitchen now.

In hindsight, I would have had a separate heater under the sink on a very short run to ensure veryhot water is achieved.

Do you live in a condo? Did you have to replace the wiring for the install of the 6kw? That only works with a 3phase right? My sink is 3meters away from the shower, I wonder if that is close enough for a 4,5 to work ????

[Chazar]

youll  need  6mm (might get away with 4mm)  cable for 6kw and 32a  breaker anything less and  youll  be able to warm  yourself  on the cable

[Polarizing]

32 minutes ago, Chazar said:

youll  need  6mm (might get away with 4mm)  cable for 6kw and 32a  breaker anything less and  youll  be able to warm  yourself  on the cable

I am aware of the cable upgrade, is that just swapping the cable out to a bigger one? How do I upgrade the breaker??

[mogandave]

5 hours ago, Polarizing said:

I am aware of the cable upgrade, is that just swapping the cable out to a bigger one? How do I upgrade the breaker??

 

Assuming the breaker you’re taking about is close to the shower heater, it’s likely the wires feeding the breaker that need to be upgraded. 
 

I like a real hot, hard shower and have a 5,300w shower heater. For most of the year the 5,300 is great. This time of year it’s pretty good. 
 

 

[Crossy]

What size are your existing wires and breaker?

 

The "normal" 2.5mm² cable on a 20A breaker is good for up to about 4500W, 4mm² on 30A will serve to about 7kW. You could squeeze an 8kW and 40A on the 4mm² if the cables are already there but if pulling new it's time for 6mm²  (for new I would just install 6mm² and be future proofed). All are assuming single-phase.

 

Replacing the breaker is a case of removing the old unit (could just be plug-in) and installing a new one.

 

If you're replacing the breaker it would be wise to use an RCBO (which has earth leakage protection) if you don't already have a Safe-T-Cut or similar device.

 

We are in northern BKK, in a house mind, our 8kW Redring is just hot enough for me with a decent flow at this time of year, I turn it down to 5kW during the hot season.

 

[sometimewoodworker]

As Crossy has said for your comfort level year round you need an 8kW unit (that can be turned down) on 6mm single phase power supply.

[Polarizing]

1 hour ago, sometimewoodworker said:

As Crossy has said for your comfort level year round you need an 8kW unit (that can be turned down) on 6mm single phase power supply.

Yeah sounds like if I am going to installing new wires, maxing it out is the right thing to do. haha

1 hour ago, Crossy said:

What size are your existing wires and breaker?

 

The "normal" 2.5mm² cable on a 20A breaker is good for up to about 4500W, 4mm² on 30A will serve to about 7kW. You could squeeze an 8kW and 40A on the 4mm² if the cables are already there but if pulling new it's time for 6mm²  (for new I would just install 6mm² and be future proofed). All are assuming single-phase.

 

Replacing the breaker is a case of removing the old unit (could just be plug-in) and installing a new one.

 

If you're replacing the breaker it would be wise to use an RCBO (which has earth leakage protection) if you don't already have a Safe-T-Cut or similar device.

 

We are in northern BKK, in a house mind, our 8kW Redring is just hot enough for me with a decent flow at this time of year, I turn it down to 5kW during the hot season.

 

 

So I just took a picture because I am not that familiar (aka complete noob) in this field and I am just googling the info bit by bit. Adding a photo would be easier to tell what I am required to do ????

 

edit: I dont have existing wires under the sink, Only have existing wires in the shower which I will be pulling out probably. I don't know what size but I assume they are 2.5mm2 since the heater is 4.5kw

2 hours ago, mogandave said:

 

Assuming the breaker you’re taking about is close to the shower heater, it’s likely the wires feeding the breaker that need to be upgraded. 
 

I like a real hot, hard shower and have a 5,300w shower heater. For most of the year the 5,300 is great. This time of year it’s pretty good. 
 

 

The wires feeding the breaker? So incoming wires? That sound like a lot of work isnt it?

Edited December 14, 2019 by Polarizing
add a clearer pic

[Chazar]

1 hour ago, Crossy said:

What size are your existing wires and breaker?

 

The "normal" 2.5mm² cable on a 20A breaker is good for up to about 4500W, 4mm² on 30A will serve to about 7kW. You could squeeze an 8kW and 40A on the 4mm² if the cables are already there but if pulling new it's time for 6mm²  (for new I would just install 6mm² and be future proofed). All are assuming single-phase.

 

Replacing the breaker is a case of removing the old unit (could just be plug-in) and installing a new one.

 

If you're replacing the breaker it would be wise to use an RCBO (which has earth leakage protection) if you don't already have a Safe-T-Cut or similar device.

 

We are in northern BKK, in a house mind, our 8kW Redring is just hot enough for me with a decent flow at this time of year, I turn it down to 5kW during the hot season.

 

I  can see the time when all electric vehicles are the norm and thats  going to be hilarious in Thailand with their electrics.................bell wire  will charge my Tesla no honest it  will....rapid  charge to

[Chazar]

49 minutes ago, Polarizing said:

Yeah sounds like if I am going to installing new wires, maxing it out is the right thing to do. haha

 

So I just took a picture because I am not that familiar (aka complete noob) in this field and I am just googling the info bit by bit. Adding a photo would be easier to tell what I am required to do ????

 

edit: I dont have existing wires under the sink, Only have existing wires in the shower which I will be pulling out probably. I don't know what size but I assume they are 2.5mm2 since the heater is 4.5kw

The wires feeding the breaker? So incoming wires? That sound like a lot of work isnt it?

depends if they are  buried or you want them  buried or overhead,mine are  buried and in  hdpe  conduit a  metre down

[Crossy]

10 minutes ago, Chazar said:

depends if they are  buried or you want them  buried or overhead,mine are  buried and in  hdpe  conduit a  metre down

 

I think our OP is in a condo ????

 

From his board photo he should be good to go. Replace or add a suitable breaker to the ELCB protected side of his board, run 6mm² 3 core (or 3 singles in conduit) to the new heater location. Hook it all up and enjoy hot showers.

 

[sfokevin]

You might think out of the box...

I replaced my master bath hot water point with a hot water tank (see below)... For my install I placed the tank in the attic just above the shower area but many can put it on the outside wall, under counter or above the toilet as you usually see in Vietnam... The unit only need wiring for 1,200 watts (it just has a plain wall plug and we rewired the old wiring into new receptical box in the attic... I chose a 50l as this seemed to suit our needs (two people/showers)but you can get larger units 

 

https://www.homepro.co.th/c/PLU0502

Edited December 14, 2019 by sfokevin

[eyecatcher]

10 hours ago, Chazar said:

youll  need  6mm (might get away with 4mm)  cable for 6kw and 32a  breaker anything less and  youll  be able to warm  yourself  on the cable

Yes a 6mm2 cable is recommended, I was planning on 6 but my experienced sparky said 4mm would be fine. And yes its perfectly adequate.

Absolutely no smaller though, a 2.5 used on a 3.6kw unit willnot support a 6kw unit

[Polarizing]

2 hours ago, Crossy said:

 

I think our OP is in a condo ????

 

From his board photo he should be good to go. Replace or add a suitable breaker to the ELCB protected side of his board, run 6mm² 3 core (or 3 singles in conduit) to the new heater location. Hook it all up and enjoy hot showers.

 

Thanks, but can you explain a little bit what my electrical panel specs are and what you see and how you know I am good to go? This way I will learn more about my condo :)) btw is it diy doable? ????

1 hour ago, sfokevin said:

You might think out of the box...

I replaced my master bath hot water point with a hot water tank (see below)... For my install I placed the tank in the attic just above the shower area but many can put it on the outside wall, under counter or above the toilet as you usually see in Vietnam... The unit only need wiring for 1,200 watts (it just has a plain wall plug and we rewired the old wiring into new receptical box in the attic... I chose a 50l as this seemed to suit our needs (two people/showers)but you can get larger units 

 

https://www.homepro.co.th/c/PLU0502

 

I love this out of the box idea, however I got a custom ceiling and it is already closed so running it from the balcony would not be possible anymore, and putting it in my fairly small bathroom would be clunky! Love to see when people are getting ideas from other countries and implementing it!

[Crossy]

51 minutes ago, Polarizing said:

Thanks, but can you explain a little bit what my electrical panel specs are and what you see and how you know I am good to go? This way I will learn more about my condo :)) btw is it diy doable? ????

 

OK.

You have a 50A main breaker (the big one on the left), that will limit your total load to just over 50A (11kW).

You have an RCD (labelled as ELCB) in the middle of the board, this will be protecting the breakers to it's right from earth leakage (electric shock). You should run your heater from this side of the board.

 

You have space to add a new breaker to the right of the existing ones. Size it to suit the new cable and water heater as earlier posts.

 

It is certainly DIYable but if you are re-modelling the bathroom then your contractor ought to be able to run the new cable and fit the breaker.

 

[Polarizing]

2 hours ago, Crossy said:

 

OK.

You have a 50A main breaker (the big one on the left), that will limit your total load to just over 50A (11kW).

You have an RCD (labelled as ELCB) in the middle of the board, this will be protecting the breakers to it's right from earth leakage (electric shock). You should run your heater from this side of the board.

 

You have space to add a new breaker to the right of the existing ones. Size it to suit the new cable and water heater as earlier posts.

 

It is certainly DIYable but if you are re-modelling the bathroom then your contractor ought to be able to run the new cable and fit the breaker.

 

Thanks a lot! I will probably be going with a Stiebel eltron DHC 8 EC, given I have read that their customer service and product is quite good here. Unless someone say otherwise... Can you point me to where and which breaker I have to buy? (looked around a bit but confused me a lot haha) Contractors will have the cable available right?

[Crossy]

Your contractor should be able to source the cable, he'll probably want to use 4mm², tell him you want 6mm², if using singles or a separate ground wire it should be a minimum of 2.5mm².

 

Use a 40A breaker or whatever is the closest value available.

 

Can you post a photo of the board with the lid off (great care please) so we can determine the exact type of breaker needed.

 

[Polarizing]

14 minutes ago, Crossy said:

 

 

Can you post a photo of the board with the lid off (great care please) so we can determine the exact type of breaker needed.

 

You mean removing the 4 screws and opening it right?

[Crossy]

18 minutes ago, Polarizing said:

You mean removing the 4 screws and opening it right?

 

Yes, please turn off the main breaker first.

 

But be aware that there are still live bits inside (they should be finger proof, but TiT).

 

EDIT Poking around in the Siemens catalogue, you need breaker type 5SJ6140-7SC, it's a DIN mount breaker so other manufacturer's units should fit but it's always best to go with a single type.

[Polarizing]

42 minutes ago, Crossy said:

 

Yes, please turn off the main breaker first.

 

But be aware that there are still live bits inside (they should be finger proof, but TiT).

 

EDIT Poking around in the Siemens catalogue, you need breaker type 5SJ6140-7SC, it's a DIN mount breaker so other manufacturer's units should fit but it's always best to go with a single type.

https://imgur.com/gallery/QH6QENc (can you see the this link?) managed to shoot some pics without shocking myself haha.

[Crossy]

2 minutes ago, Polarizing said:

https://imgur.com/gallery/QH6QENc (can you see the this link?) managed to shoot some pics without shocking myself haha.

 

Yup, those worked ????

 

Looks a decent job, your man should be able to drop a new breaker at the far right (remove the red sleeve from the bus-bar first), take the neutral from the bar just to the right. Ground comes from the bar far left with all the green wires on it.

[Polarizing]

35 minutes ago, Crossy said:

 

Yup, those worked ????

 

Looks a decent job, your man should be able to drop a new breaker at the far right (remove the red sleeve from the bus-bar first), take the neutral from the bar just to the right. Ground comes from the bar far left with all the green wires on it.

Looking at this.. I wonder a bit, can you correct me if I am wrong? The blue and white headed black thick cables under the main breaker  are cables from outside feeding the whole box. The other big black cables do the same thing. The blue(live), white (neutral) and green(ground) goes to my appliances. With the 6mm2 installed, I should see 3 "number 9" cables connected next to number 8 (depends on whether he labels them ofcourse) which are thicker than the other bluegreenwhite cables. Correct? ????

Edited December 14, 2019 by Polarizing

[Crossy]

9 minutes ago, Polarizing said:

Correct?

 

Sort of.

 

The fat cables entering the bottom of the 50A breaker are your incoming supply. The other fat black cables are internal distribution of the big amps, don't worry about them.

 

If your man actually applies numbers (yeah, right) you should end up with a number 9 live on a breaker next to the blue 1-4 (right hand side breakers), a No.9 neutral next to the white 1-4 and a green No.9  with all the other greens.

 

I do wish our man had numbered the cables

[Polarizing]

20 minutes ago, Crossy said:

 

Sort of.

 

The fat cables entering the bottom of the 50A breaker are your incoming supply. The other fat black cables are internal distribution of the big amps, don't worry about them.

 

If your man actually applies numbers (yeah, right) you should end up with a number 9 live on a breaker next to the blue 1-4 (right hand side breakers), a No.9 neutral next to the white 1-4 and a green No.9  with all the other greens.

 

I do wish our man had numbered the cables

Thanks Crossy, got so much out of this forum! yay!!

[Crossy]

Just now, Polarizing said:

Thanks Crossy, got so much out of this forum! yay!!

 

Even if you don't intend doing it yourself, it's always handy to know what your man should be doing so you can "guide" him ????

 

Sadly, our Thai friends are very good at finding "shortcuts" which work most of the time, until they don't and someone dies ????

 

[Polarizing]

30 minutes ago, Crossy said:

 

Even if you don't intend doing it yourself, it's always handy to know what your man should be doing so you can "guide" him ????

 

Sadly, our Thai friends are very good at finding "shortcuts" which work most of the time, until they don't and someone dies ????

 

Thats so true and so sad indeed. Sadly, have to play mr supervisor everytime they renovate XDXD

[SNUMAND]

10 hours ago, sfokevin said:

You might think out of the box...

I replaced my master bath hot water point with a hot water tank (see below)... For my install I placed the tank in the attic just above the shower area but many can put it on the outside wall, under counter or above the toilet as you usually see in Vietnam... The unit only need wiring for 1,200 watts (it just has a plain wall plug and we rewired the old wiring into new receptical box in the attic... I chose a 50l as this seemed to suit our needs (two people/showers)but you can get larger units 

 

https://www.homepro.co.th/c/PLU0502

Look good,but what does it do to the pressure of the water ? does it stay the same or ...

[sfokevin]

32 minutes ago, SNUMAND said:

Look good,but what does it do to the pressure of the water ? does it stay the same or ...

No pressure loss at all!