How many hot-water geysers are sold each year?

[AndyD]

I don't know how accurate you need your answer but from the WHITE PAPER
ON RENEWABLE ENERGY November 2003

Solar Water Heating: Domestic solar water heating is currently about 1.3% of the solar energy market. Residential consumption of electricity in 2000 amounts to about 32 846 GWh (2.83 Mtoe). Assuming that some 30% of total domestic electricity consumption is used for water heating and that 60% of this electricity can be replaced by solar energy by using a hybrid solar-electric water heating system, then the potential savings for urban residential households come to 5 900 GWh (0.508 Mtoe) (Fecher et al, 2003). This is about 18% of urban residential consumption which is equivalent to a large coal-fired power station (900 MW). There is thus considerable scope to increase the application of solar water heating,

So 32 846 GWh per annum (8760 hours) = 32 846 000 000 kwh per year total residential consumption.

If as they say 30% is water heating then 9 853 800 000 kWh is water heating load.

This is where the assumptions begin but lets assume that every geyser is on average 3.5 kW and it's actually heating for 5 hrs each day, then its consumption will be 17.5 kWh of power per day. Equates to 6387.5 kWh per annum.

Divide 9 853 800 000 kWh total water heating load by 6387.5 kWh per geyser and it gives you the number of HWC's as 1 542 669 in total.

Add to this that the number of HWC's might be increasing at 5% per annum and the figures were from 2003 then in 2010 it would be nearer 2.17 million cylinders.

There's several areas for inaccuracies in this figure. Firstly Eskoms initial hot water load estimates could be bulls**t, secondly the average geyser power was something I pulled from thin air working on the principal that a 4 kW geyser is the cheapest to purchase so the majority will be 4kW, thirdly the annual increase in the number of homes with hot water is only increasing at 5% per annum. If the innacuracies all compound in one direction then I wouldn't be surprised if this figure is 20% off the mark.

[desA]

I don't know how accurate you need your answer but from the WHITE PAPER ON RENEWABLE ENERGY November 2003

So 32 846 GWh per annum (8760 hours) = 32 846 000 000 kwh per year total residential consumption. Ok. I'll add in some bracketing numbers for estimating purposes.

If as they say 30% is water heating then 9 853 800 000 kWh is water heating load.
Let me bring in "Options for resisential water heating", Harris A., Kilfoil M, Uken E-A. Table 1, source provided for electrical water heating, suburban = 45.9% (15 076 314 000 kWh); township = 30.2% (9 919 492 000kWh); informal settlement 18.0% (5 912 280 000 kWh). Let's concentrate on suburban only, for now.

This is where the assumptions begin but lets assume that every geyser is on average 3.5 kW and it's actually heating for 5 hrs each day, then its consumption will be 17.5 kWh of power per day. Equates to 6387.5 kWh per annum.
3.5kW - good. Take 3.5h per full heat-up, 5h is good-enough then considering some residual hot water remains.

Divide 9 853 800 000 kWh total water heating load by 6387.5 kWh per geyser and it gives you the number of HWC's as 1 542 669 in total.
Let's work in the modified suburban number 45.9% => 15 076 314 000 kWh / 6387.5 kWh/geyser = 2 360 284 HWC's

Add to this that the number of HWC's might be increasing at 5% per annum and the figures were from 2003 then in 2010 it would be nearer 2.17 million cylinders.
Working on suburban number => 3.32 million cyclinders

There's several areas for inaccuracies in this figure. Firstly Eskoms initial hot water load estimates could be bulls**t, secondly the average geyser power was something I pulled from thin air working on the principal that a 4 kW geyser is the cheapest to purchase so the majority will be 4kW, thirdly the annual increase in the number of homes with hot water is only increasing at 5% per annum. If the innacuracies all compound in one direction then I wouldn't be surprised if this figure is 20% off the mark.
I've added in the bracketing figures to give us a spread.

Thanks so much. I owe you a few cases of your favourite beverage. Stunning work.

Ok, let's work in the following:
1. SA geyser elements are generally designed on a 3.5h recovery, from cold to hot - based on the geyser element kW & volume.
2. The new geysers will factor in:
2.1 New homes
At 5% growth p.a => 108 500 to 166 058 new HWC's pa;
2.2 Replacement geysers.
At say 10 year lifespan, annual replacement ~ 217 000 to 332 000 p.a.
At say 15 year lifespan, annual replacement ~ 144 667 to 221 333 p.a.
3. New geysers p.a. ~ 253 167 to 387 391 p.a (conservative estimate, 15 year lifespan) / 325 500 to 498 058 (10 life span)

I've worked these into your figures above. We can bat these around further, if you're keen. I hope my calcs are in line.

Looks like a good business to be in.

[AndyD]

I think your life expectancy figure of 15 years might have been accurate with the old copper cylinders.

The new galv cylinders with the annodic protection are lucky to last 6-8 years. The problem is that nobody, and I mean nobody ever replaces the annodes every year as specified by the manufacturers. The annodes are sacrificial and once erroded the cylinder starts to corrode rapidly.

A perfect example of built in obsolescence if ever there was one.

[desA]

^ A very valid point. Thanks for that.

Exactly, who ever thinks to maintain their geyser. No wonder the big geyser manufacturers are building larger factories. Food for thought.

I saw in your quote, this nugget:

Assuming that some 30% of total domestic electricity consumption is used for water heating and that 60% of this electricity can be replaced by solar energy by using a hybrid solar-electric water heating system,

Did this estimate materialise?
In reality, what would the solar percentage of the total geyser market be?

What percentage of the market would move over to a heat-pump, if these were reasonably priced, affordable & with a lifespan longer than the geyser itself? Expected energy savings around 70-80% on water-heating.

[AndyD]

Did this estimate materialise?
In reality, what would the solar percentage of the total geyser market be?

If you would like some bedtime reading you can try these;

24-market-survey-of-swh-in-sa-final-report


AN HISTORIC OVERVIEW OF CONTROLLING DOMESTIC WATER
HEATING

Market Survey of Solar Water Heating in South Africa

DOE Solar Water Heating Plan/Framework

DEMAND CONTROL UNIT SUPPORTING THE NEW DUAL ELEMENT HOT
WATER SYSTEM

If you're after some specific publication or report/whitepaper try a few strings to focus a google such as 'intitle' and"index.of", you'd be surprised what's not tied down on many of the servers.

[desA]

If you're after some specific publication or report/whitepaper try a few strings to focus a google such as 'intitle' and"index.of", you'd be surprised what's not tied down on many of the servers.

Sorry, I'm a bit stuck on this. Can you perhaps explain this a little further? How would a typical search string look?

[AndyD]

There's a beginners guide here

[desA]

Thanks so much. This opens up a whole new world.

[wynn]

Which link is that?

Sorry I misplaced the url but search CEF anyway because they have researched hot water systems repeatedly and must have a figure somewhere that will give you some idea of the number of geysers in RSA

[desA]

Thanks wynn. Much obliged.

[AndyD]

Well I was inspired by this thread nearly six months ago and decided that if I was ever going to cut my electricity consumption by the 60% goal which I set myself then I was going to have to convert my HWC to a solar/electrical hybrid.

The great news is I've finally done it...reduced my consumption by 60% that is. Only thing was that what started out as a solar/electric hybrid geyser project actually ended up as a home made heat pump/electrical hybrid.

The solar conversion gave me plenty of problems (I won't bore you with the details) but the actual amount of heat input from solar was very disappointing, mostly due to Cape Town climate. Eventually I binned the solar system and tried a home built heat pump retrofit instead using begged and borrowed refrigeration components and a home made copper heat exchanger. I finished the installation three weeks ago and have now finished sorting out a few teething problems. It's early days but so far I haven't had a cold shower. There's still a minor snag with high head pressure tripping but it's working fine as our only hot water source.

For the first time at the beginning of this month I now fall under the low consumption bracket with my electrical consumption and I even got free units when I bought my batch of electric units this morning. If I now include my free monthly units that means I have actually reduced my electric costs from what would be R1440.00 per month to around R600.00 per month. Not bad for a family of four.

I promised myself a new TV when I achieved the goal so I'm out shopping tomorrow morning.

[desA]

Well I was inspired by this thread nearly six months ago and decided that if I was ever going to cut my electricity consumption by the 60% goal which I set myself then I was going to have to convert my HWC to a solar/electrical hybrid.

The great news is I've finally done it...reduced my consumption by 60% that is. Only thing was that what started out as a solar/electric hybrid geyser project actually ended up as a home made heat pump/electrical hybrid.

The solar conversion gave me plenty of problems (I won't bore you with the details) but the actual amount of heat input from solar was very disappointing, mostly due to Cape Town climate. Eventually I binned the solar system and tried a home built heat pump retrofit instead using begged and borrowed refrigeration components and a home made copper heat exchanger. I finished the installation three weeks ago and have now finished sorting out a few teething problems. It's early days but so far I haven't had a cold shower. There's still a minor snag with high head pressure tripping but it's working fine as our only hot water source.

For the first time at the beginning of this month I now fall under the low consumption bracket with my electrical consumption and I even got free units when I bought my batch of electric units this morning. If I now include my free monthly units that means I have actually reduced my electric costs from what would be R1440.00 per month to around R600.00 per month. Not bad for a family of four.

I promised myself a new TV when I achieved the goal so I'm out shopping tomorrow morning.

Jolly good show.

Watch out for the high-pressure side of things. I suspect that you'll run through a few compressors, if you aren't careful. Please also take extra care that you don't burst a condenser tube at the top end of the heating run. You'll likely blow your geyser to smithereens.

When you're in the market for a really nice, high-efficiency, ultra-safe heat-pump, give me a call. I'm busy getting all my supply ducks in a line in terms of my new product line-up for SA. I'd expect a 80-90% reduction on your water-heating costs.

[AndyD]

Watch out for the high-pressure side of things. I suspect that you'll run through a few compressors, if you aren't careful.

The refrigeration side is a little tricky, especially not being a fridge engineer. That said I'm learning by the day.

The high side tripping usually happens with water teperature approaching 50 degrees C or over. I'm a little worried because the ambient attic temp is fairly low at the moment, I think the tripping may become more coimmon with higher summer attic temperatures.

I've now installed an auto reset HP switch, the manual reset was an annoyance. I've also ended up with a fairly complex three thermostat arrangement so the heating 48 degrees and over (up to 55degrees final temp) is done only by the electrical element. 30-48 degrees is heat pump only. If the temp drops below 30 degrees then both systems kick in. I'm probably going to replace the analogue thermostats with a PID controller which can look at the temperature change trends of the water. I'm hoping that a PID control will improve efficiency as well, I must just source a suitable offering. Finally the largest expense so far was replacing the standard fan unit with a much higher efficiency EBM unit which is also considerable quieter.

Touch wood...so far no compressor failures. I have been keeping a close eye on the superheat figures and playing it on the cautious side.

When you're in the market for a really nice, high-efficiency, ultra-safe heat-pump, give me a call.

If I ever need one I'll contact you but I'm going to percivere with my home made galoppie for now.

I'd expect a 80-90% reduction on your water-heating costs.

At the moment I've only been data logging the power consumption for a week but it's reduced the hot water power consumption by around 52%. Even with my planned improvements I'll I doubt I'll get close to 80%, I'm optimistically aiming for 60% savings in electricity consumption. If I factor in my free monthly units which I'm now qualifying for then I can make that figure a little higher.......but that would be cheating me thinks.

[desA]

What is your refrigerant?

[AndyD]

What is your refrigerant?

134A, Electrolux GP14TB comp.