Jump to content
BANGKOK
Polarizing

Undersink water heater strong enough?

Recommended Posts

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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 by eyecatcher

Share this post


Link to post
Share on other sites
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 🤔

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites
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??

Share this post


Link to post
Share on other sites
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. 
 

 

Share this post


Link to post
Share on other sites

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.

 

  • Thanks 1

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites
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.

 

PrYp2DI.jpg

 

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 by Polarizing
add a clearer pic

Share this post


Link to post
Share on other sites
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

Share this post


Link to post
Share on other sites
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

PrYp2DI.jpg

 

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

Share this post


Link to post
Share on other sites
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.

 

Share this post


Link to post
Share on other sites

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

6B8A30C7-E1DF-4883-842E-D713CB270A20.jpeg

Edited by sfokevin

Share this post


Link to post
Share on other sites
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

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...