Solar geysers vs heat pumps: what's the better option?

What's the better option?


  • Total voters
    72

Kwaai

Well-Known Member
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Sep 23, 2012
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364
Hi all.

I'm planning to go for one of the above and find conflicting info about which is the better option of the two. I'd appreciate some advice on which route to take and who did the install.


Thanks in advance
 

Gordon_R

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Jul 5, 2009
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You don't need an opion poll, you need some facts. They are totally different technologies, and you need feedback from people who have used them.
 

swakop_toe

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Sep 17, 2013
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371
The house I now live in have both.
The standard Kwikhot Geyser and a heat exchanger.
Normal operation is as follows.
The Geyser is switched off at the DB with the heat exchanger pumping/circulating hot water through the Geyser keeping it at 55°C.

Should the heat exchanger fail, the Geyser kicks in.
The heat exchanger use/rated at 1.1kWH.
It is still more efficient than a geyser.

Edit: corrections.

For reference:
http://hydratherm.co.za/55-2/
 
Last edited:

ToxicBunny

Oi! Leave me out of this...
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Apr 8, 2006
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I have a solar geyser at home and during summer it is unbeatable... During winter I think the element probably kicks in once or twice a day.....

If I was to do the stuff again I would do the solar geyser with gas heaters for backup so that the element in the geyser could be permanently disabled.
 

ekske1

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Apr 22, 2017
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5,073
Hi all.

I'm planning to go for one of the above and find conflicting info about which is the better option of the two. I'd appreciate some advice on which route to take and who did the install.


Thanks in advance
Both for an optimal winter and summer combination.
 

Arthur

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Aug 7, 2003
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I chose a heatpump because a) I planned to run the house off solar pv, and b) didn't want to use a normal kettle element to augment the system on overcast/winter days, c) didn't want to worry about having enough hot water at night.

Heatpump gives 24/7 heating at a fraction of the cost per erg compared to a kettle element.
 

Marsie27

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Jul 21, 2014
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We put in a solar geyser system (retrofitted a solar panel to our existing geyser) in 2009 and had records of the previous 5 years. Our daily average for 2005-2009 years was 15.634 kWh per day, from 2010 till the end of last year was 10.558 kWh. Same average occupancy rate in both periods. Even in Cape Town's winter, there are very few days when we don't get at least some benefit, and in summer the geyser very seldom kicks in. Even with a fairly cloudy day today and 5.5 hrs of no electricity during daylight hours, there's enough hot water for bathing tonight.
 

RedViking

Nord of the South
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Feb 23, 2012
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40,371
/some irrelevant information

I don't know about South Africa. In NZ most use gas or solar hot water heaters. Do we get something like this in South Africa?

http://www.rheem.co.nz/solar-water-heaters/


They also use fireplaces (wetback) which circulates the water and heat it in combination with a water heater. I thought it is interesting to post here: http://www.level.org.nz/energy/water-heating/energy-sources/wetbacks/


A heatpump is like an Aircon, but it heats.....


/okay, now back to South Africa....
 

Hemi300c

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Dec 15, 2009
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If I was to do the stuff again I would do the solar geyser with gas heaters for backup so that the element in the geyser could be permanently disabled.[/QUOTE said:
This is the best option.
A heat pump still requires electricity so you screwed with load shedding.
 

Pineapple Smurf

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The house I now live in have both.
The standard Kwikhot Geyser and a heat exchanger.
Normal operation is as follows.
The Geyser is switched off at the DB with the heat exchanger pumping/circulating hot water through the Geyser keeping it at 55°C.

Should the heat exchanger fail, the Geyser kicks in.
The heat exchanger use/rated at 300W/hour.
It's very efficient.

For reference:
http://hydratherm.co.za/55-2/
300 Watts per hour ?
 

swakop_toe

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Joined
Sep 17, 2013
Messages
371
I never checked, took their word for it.
I was mistaken. Correct me if I'm wrong, but it appears to be 1.1kWH.
b71ac46978fe67ae573c35e6487ac557.jpg
 

Speedster

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May 2, 2006
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Like some others above I have retrofitted my geyser to solar and basically don't use any electricity to heat water from October through March. The rest of the year the element supplements the solar (using a geyserwise) to ensure I have enough hot water.

I can't speak for a heat pump, but have heard good things about them.

You might find this article interesting too: https://www.powersaving.co.za/upload/MTechNWUHeatpumpsvssolar.pdf. Remember that electricity costs have increased significantly since 2008 (and are likely to continue that trend), which obviously influences the results of such comparisons today.

Fortunately I was able to obtain my solar at a significant discount which made the choice a no-brainer for me.
 

Cius

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Jan 20, 2009
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Solar geysers I have heard require a lot less maintenance and hassle. The heat exchanger is essentially an aircon so far more moving parts to fail.

Payback period on the heat exchanger is faster though, however average life of a solar geyser is longer, and will cost less in maintenance. I have both as an option and am hoping to install a solar geyser this year sometime.
 

REAList_1

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Oct 12, 2011
Messages
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Heat exchangers have a lifespan and will need maintenance.
Install a 200l solar geyser.
Cloudy days will influence it off course.
 

Mista_Mobsta

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Jan 22, 2015
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Have had a 300L Close-Coupled Suntank Solar Geyser for the past 14 years. Inspect twice a year and ensure all the pipes and fittings are not leaking, install an outdoors UV resistant geyser blanket , check geyser PCV for excessive overflow and service once every two years or so. I have a geyser timer installed for the winter months but only use in the early morning for about 45mins on a 3KW backup element. Would install again for sure!

Only issues we have had was hail that damaged one or two of the panels but luckily it is covered under the building insurance as it's mounted to the roof.
 

dews

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Joined
Mar 10, 2011
Messages
374
I have a PV setup that powers the house.
I installed a throttler and set my geyser to about 1Kw, and a timer so that it can be powered by the solar panels.
It's therefore a solar powered electric geyser, however less efficient than what a real solar power geyser would be.
 

ToxicBunny

Oi! Leave me out of this...
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I have a PV setup that powers the house.
I installed a throttler and set my geyser to about 1Kw, and a timer so that it can be powered by the solar panels.
It's therefore a solar powered electric geyser, however less efficient than what a real solar power geyser would be.

Thats actually an interesting solution....
Might be useful to do to a normal solar geyser as well just to limit the power draw.
 

calypso

Expert Member
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Feb 10, 2009
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1,720
I have a PV setup that powers the house.
I installed a throttler and set my geyser to about 1Kw, and a timer so that it can be powered by the solar panels.
It's therefore a solar powered electric geyser, however less efficient than what a real solar power geyser would be.

As inefficient and wrong as it sounds, i also think this could be the most cost effective way of heating water. Solar Geysers and Heat pumps are a huge amount of cash which can rather be put into PV panels.
 

Pineapple Smurf

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I have a PV setup that powers the house.
I installed a throttler and set my geyser to about 1Kw, and a timer so that it can be powered by the solar panels.
It's therefore a solar powered electric geyser, however less efficient than what a real solar power geyser would be.
Same system as what i want, kind of.
https://www.sustainable.co.za/geyserwise-pv-solar-water-heating-kit-for-100l-geyser.html
I only need to power up my geyser at home at around lunchtime for 1 hr, this is more than enough hot water for a bachelor.
I too want to go PV as then the rest of the day i want my panels grid tied to an inverter to run fridge and other small stuff during the day.

So to have my panels switch over to the geyser i dont mind tricling off ESKOM in that short time.
Downside to system i want is it is a 900 Watt DC element which means it needs to run much longer than the std one in your geyser, but it is a simple installation and will work well in my case.

Anyways, i havent done any of this yet as i am only using R350 ESKOM a month so not too phased, longer i wait the more the prices drop in going Solar.
 
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