So I am considering instant water heater systems, in Indonesia.
Here electricity is typically low amperage (household supplies start at 450W, then 1100W, then 2200W), and there's a strong incentive to avoid high power consumption appliances (because you may also need a generator to back it up, as the power is unreliable)
I was recently in Malaysia and tried a power shower (http://www.midea.com/my/consumer/kitchen_bathroom/instant_water_heater/201505/t20150525_180326.shtml) in a hotel, which was 3800W. This, as mentioned is more than the entire electricity capacity of most houses in Indonesia. It gave a pretty good shower.
Now here in Indonesia they sell electric and gas heaters.
One common model is a Paloma 5 litre (I think this means 5 litre/minute flow rate) gas heater.
According to Paloma's website:
the flow rate is based on 25C heating above input (so here, with 20C input, you'd get 5 l/minute of 45C water)
They say a kitchen tap is 4l/minute, and a shower 8-10l/minute. So the 5l is only sufficient for a kitchen tap, not for a shower.
According to these data:
the 5l water heater has a gas consumption of 10.5 kW. That's more than double the 3800 W of electricity that I used to shower with in Malaysia.
So what is the explanation:
- some difference between x,000W of water heating capacity between gas and electricity
- my 3800W shower actually wasn't very powerful, I just got used to terrible low water pressure in Indonesia and it seemed good in comparison
- some difference between the way the shower pumps water and a simple water heater which then obviously requires a separate shower?
- something else?