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Electric Hot Water Heater?


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#1 Beardog

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Posted 2008-12-07 16:54:07

I just got a 6 month old Fujika Model FS-60 from a friend.
It is a multipoint showing 4 taps used . That is the exact number sinks tubs & showers it will use.
there is no thermostat control on it. all plumbed units will have hot & cold faucets off the unit.
The reason he replaced it was he said it heats water so hot it boils your skin off your bones. Even with hot & cold faucet to control the heater it gets to hot.
There is an automatic thermostat off the hot leads & has only 2 poles from it.
Does anyone know a test for the thermostat unit before I put it into use?
The only portion that is a concern is the shower. I want the bathtub to be hot & the sinks as well.
Seems odd that a new unit out of the box would be direct instant hot & no shutoff when it reaches a certain temp.
If it is supposed to be this way is there something to limit the amount of heat accept the faucets in the shower.
It was stated that it gets to hot & was to difficult to compensate with the cold water.
I have no clue as I am used to either a gas or electric U.S. system that compensates or can be adjusted. The site is in Thai & I don't see any adjustments. Thanks for the help! :o
Barry

#2 kamalabob2

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Posted 2008-12-07 18:10:57

Perhaps on Monday you could phone the manufacturer in Bangkok at 02-749-5199. They MIGHT be able to send you instructions in English, give you a valid e-mail address to send them questions and MAYBE they have staff who can understand English who you can ask questions and get valid answers. The web site of Fujika Electric did not function in English when I attempted to click the TH/EN button.

#3 Gary A

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Posted 2008-12-07 18:26:00

I have a friend who has a similar unit. Quite frankly it really stinks. The water gets VERY hot and when you turn on enough cold water to make it comfortable, I think the cold water actually back feeds into the heater and the pressure switch shuts it off resulting in COLD water. I find it impossible to have a decent shower and usually end up with a cold shower rather than get scalded. If there were a way to adjust the heater temperature it would probably be fine but there is no adjustment.

#4 Crossy

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Posted 2008-12-08 09:11:07

These simple heaters have no thermostat pre-se just a safety cutout that operates somewhere around 80oC (bloody hot). They simply get the water as hot as the flow rate will permit, more flow = lower temperature attained.

You could try:-
  • Looking if the safety cutout is adjustable, but remember it's not intended to work as a thermostat and so may fail quickly.
  • A thermostatic mixer tap (not cheap).
  • If you suspect back-feeding into the heater add a non-return valve in the outlet (no idea if this would work, just a thought).
  • Maximise the flow though the heater to reduce the temperature it attains.
  • Insert a 50A 600V rectifier diode (it will need a heatsink) in series with the heater element to reduce the power available by supplying half-wave rectified mains.
Or my personal favourite, ditch the thing or at least relegate it to heating water for taps only and not the shower.

If you're a hobby electronics enthusiast why not make a 'super' lamp dimmer with a BTW67-600 (50A 600V) TRIAC for continuous power adjustment, you could likely modify a regular lamp dimmer with a bigger TRIAC. Not sure I'd bother.

Edited by Crossy, 2008-12-08 09:28:19.


#5 Beardog

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Posted 2008-12-08 09:40:47

Thanks guys,
I think a 2nd shower heater probably the easiest way to go. the other 3 taps can be scalding no worries.
Crossy can I run 2 heaters into one 32 amp breaker as I won't ever use them at the same time. Or hardly use much hot water at that rate except for 2 weeks a year in cold season. It will be nice to have hot water to clean dishes & get out of a 5 year camping mode cycle. Fujika's tele# is in Thai & ends up taking you into the twilight zone.
Thanks for the input!

Edited by Beardog, 2008-12-08 09:48:56.


#6 Crossy

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Posted 2008-12-08 09:55:38

Crossy can I run 2 heaters into one 32 amp breaker as I won't ever use them at the same time.

Welllllll, it would contravene UK (and probably Oz) codes but yes, you could run both off a single breaker. Turning the two on together would simply drop the breaker.

You should really run a separate cable and install a second breaker. If you do decide to extend the existing wiring please use a decent ceramic connector block (the plastic ones tend to melt at high currents).

#7 Beardog

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Posted 2008-12-08 13:03:05

Thanks again Crossy,
It will be a new install with 6 mm wire to the 6000w & 2.5 mm to the shower heater. & Grounded!

#8 Crossy

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Posted 2008-12-08 13:26:54

It will be a new install with 6 mm wire to the 6000w & 2.5 mm to the shower heater. & Grounded!

Unless cost is a significant issue I'd run 6mm2 (or at least 4mm2 good for 5kW or so) to the shower too, just in case you decide to upgrade the heater in the future. It would be a real bind to find the 3.5kW shower unit hasn't quite got the oomph and have to replace your wiring too.

Also-

Unless you use 6mm2 for both you must NOT (that's NOT) use the same breaker to control both heaters, the breaker must be sized to protect the smallest cable connected in the circuit.

And-

Please ensure the heaters are protected by an ELCB :o

Edited by Crossy, 2008-12-08 13:36:52.


#9 Beardog

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Posted 2008-12-08 15:50:36

Your the man Crossy,
Will follow your recomendation. The run is not much for the shower to go a heavier guage.
Last project had no water heater or ac this one will & be built correctly. Do you think I can safely tie the 6mm with a 4mm & use one circuit or just get another breaker?
Appreciate all your comments as well as the other good advise.
To You All!!!!!

Edited by Beardog, 2008-12-08 15:53:55.


#10 Crossy

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Posted 2008-12-08 16:01:45

Do you think I can safely tie the 6mm with a 4mm & use one circuit or just get another breaker? If you have space install a new 25A breaker for the 4mm2 run to the shower. It would be unsafe to have the 4mm2 protected by a 32A breaker so if you have to use a single breaker you must use 6mm2 for the full run.



#11 Beardog

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Posted 2008-12-08 18:20:45

Do you think I can safely tie the 6mm with a 4mm & use one circuit or just get another breaker? If you have space install a new 25A breaker for the 4mm2 run to the shower. It would be unsafe to have the 4mm2 protected by a 32A breaker so if you have to use a single breaker you must use 6mm2 for the full run.


Thanks again Crossy! :o

#12 Gary A

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Posted 2008-12-09 11:10:24

I have 4 SQ. MM wire running to my water heater. The heater has a 20 A breaker on the outside bathroom wall and another in the breaker box itself. It was designed for a 3500 watt heater. The 3500 watt heater just wouldn't do the job in the wintertime. I replaced it with a 5500 watt model. So far neither of the breakers have tripped. The water is not scalding but warm enough to be comfortable.

#13 Beardog

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Posted 2008-12-09 14:30:58

I have 4 SQ. MM wire running to my water heater. The heater has a 20 A breaker on the outside bathroom wall and another in the breaker box itself. It was designed for a 3500 watt heater. The 3500 watt heater just wouldn't do the job in the wintertime. I replaced it with a 5500 watt model. So far neither of the breakers have tripped. The water is not scalding but warm enough to be comfortable.



Thanks for the advice. The cost isn't much different. I am not sure if I would need much more than 3500 in the Pattaya area. The water just needs to be a tad over luke warm on the shower.
But you gave me great advice on the Kawasaki Boss & your advice is always welcomed in my book!





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