Electric geyser electricity calculation, help required!

sasa110

Disciple
I've made a rough estimate of electricity cost of geysers, would appreciate if someone could correct them if wrong. Given my non-tech background, chances of them being wrong are on the higher side :ashamed:

My math on electric geysers:
1) small 1 litre instant, 3kw, takes 2 mins.
so, per run: 3Kw x 2 mins. Per month: 3 kw x 60 mins or 1 hr = 3 kwh.
1 khw costs around 4 Rs, hence Rs 12 monthly (run once daily)

2) 10 litre storage, 2kw, takes 10 mins:
so, per run, 2kw x 10 mins. Per month: 2 kw x 300 mins or 5 hours = 10 kwh.
1 Kwh = around 4 Rs, hence monthly cost run once daily = Rs. 40.

If run 'a' times per day, cost will be 'a' x above estimates. So, run 5-6 times daily, instant 1L thingie will cost 12 x 5 = 60 Rs. per month.

However, the stores are putting up a different cost calculation which I'm not scientifically capable of understanding. They are showing me charts similar to the one at the bottom of this page: Gas Geyser -

At least 2 of them are telling me that electric geysers bill upto 5-6 k a year to run for 2-3 people.:huh:

I have taken from this forum that gas geysers for 3 people need 1 LPG cylinder every 40 - 45 days. So roughly, cost per year would be 9 LPG cylinders @ Rs, 350 = Rs. 3200ish.

Would appreciate some expert input on the calculations of the electric geyser thing. If my calculations are correct, will go with the electric only. Thanks for reading.
 
A 100w bulb when run for 10hrs will consume 1 unit of electricity. So a 3kw electric geyser will consume 1 unit in 20mins. From this you should be able to calculate your electricity consumption per month. cost per unit x geyser usage in mins.

A gas geyser works out cheaper. We are using it in our home. One cylinder lasts almost 2 months for our household of 4 people.
 
I dont think running the instant geyser for 2 minutes is useful, unless you are making noodles or tea. Instant geysers are typically run for as long as you are consuming hot water. Which is about 10-15 mins. Storage type water heaters are run for 10-15 mins and then switched off. The stored hot water (15-25L depending on the capacity of the heater) is then used for bathing. You should observe how the 2 types are used differently. However, the running cost will be very similar as long as you are heating similar quantities of water in both. I prefer instant geysers because of a marginal efficiency advantage, reduced space utilisation and less waiting time. Are they cheaper too?

LPG heaters are cheaper only if you are running them off subsidised gas cylinders. This is illegal. There is also asphyxiation hazard if the bathroom does not have proper ventilation or the installation is not done properly.

Not sure if heat pump based designs are available/possible. Good designs can cut energy consumption to a third.
 
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