Author Topic: Gas geyser VS Solar geyser  (Read 336 times)

Offline 1200GXman

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Gas geyser VS Solar geyser
« on: July 01, 2020, 09:50:41 AM »
Hi all
I am planning on doing a complete kitchen overhaul sometime next year. I told the wife that the next project will have to be the geyser to try and save money with electricity.
2 of my friends installed gas geysers at their homes and are very happy with the savings and convenience of hot water on demand.
I had long hours thinking over the 2 options mentioned in the subject and here are my concerns below:

Solar is only as good as long as there is sunlight. We use geysers too late in the afternoon to benefit us. Maybe if I increase the tank size to 200L it might have a better effect. Some inputs would be appreciated.

Gas is relatively cheap but for how long into the future.
I read and heard the gas powered geysers needs to be maintained which involves cleaning the tubes, etc

What are your thoughts and experiences?
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Offline DACMan1

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Re: Gas geyser VS Solar geyser
« Reply #1 on: July 01, 2020, 10:03:38 AM »
Both have advantages and disadvantages. For most people gas is best - the maintenance is simpler. With solar, having electricity backup, it is hard to tell if it does not operate efficiently anymore. It is also hard to tell if it has been installed properly (for the same reason). I personally prefer solar as mine runs completely without any electricity (I do switch it on, maybe 3 weeks a year in peak rain season), so I know when it stops working.

If you can install one of those solar geysers with the tubes going into the tank - that would be the best low maintenance option. But definitely go for a bigger geyser. I think the guideline is 50l geyser per person in the household for electric. My recommendation would be double that for solar.

Offline 1200GXman

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Re: Gas geyser VS Solar geyser
« Reply #2 on: July 01, 2020, 10:42:06 AM »
It is a 4 bedroom house with 4 people but one never knows what will happen in the future with our economic climate.
One of the parents might come and stay with us if the pension doesn't pay enough anymore. I have seen it many times so far. So I like to predict for myself possible scenarios just to be prepared.

Quote
I think the guideline is 50l geyser per person in the household for electric. My recommendation would be double that for solar.
That would mean a 500 Liter water tank!!
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Offline markc

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Re: Gas geyser VS Solar geyser
« Reply #3 on: July 01, 2020, 11:01:05 AM »
Gas geyser VS Solar geyser.

Very interesting topic. I also want to do this. I also can't decide, so following with interest.

Offline Pax

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Re: Gas geyser VS Solar geyser
« Reply #4 on: July 01, 2020, 11:21:36 AM »
Our kitchen is gas powered - stove and hot water. We have 2 x 19Kg gas bottles (me and my tendency to overkill) and need to fill up one so about on 6 -monthly basis. My house was built in 2016 and save for new batteries for the igniter, the gas heater has never stopped working 100%. It sits outside too and a little'house' was built around it to protect from the elements as far as possible. It is cheap and convenient with instant hot water as the pipe to the tap in side is a mere 500mm. The initial capital lay-out was also a positive - much less than any other system.

Our 2 bathrooms are fed with a solar system. The electrics kick in when the water temp goes below 45 degrees. I have actually never seen it go below 48 degrees and in mid summer temps show up to 85!. So, also convenient and cheap to run, but not to install, but it made more sense because one uses a lot more water in the bathrooms than in the kitchen, so I thought a reservoir of hot water would be better.

Online rodga

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Re: Gas geyser VS Solar geyser
« Reply #5 on: July 01, 2020, 11:26:24 AM »
I have a 300l solar geyser (flat panel) that the house came with. The problem is when you use say a 100l then it gets filled with 100l of cold water lowering the temp in the tank, so it needs to be heated up again. It also takes a long time to heat up fully in winter and the last few weeks we had the element doing the work probably 90% of the time. If i had to redo it, this is what I would do. 200l solar with glass tubes (with electric element) and gas heater as a top up. This will allow instant hot water and no wastage when waiting for the hot water from just the geyser (gas needs to installed close to where it needs to be used to limit cold water waste). I believe you can set the gas geyser to only kick in if the water coming though is below a certain temp. Winter you will have hot anytime. If you run out of gas you can use the element - in normal operation it wont be switched on at all. Im not sure if ti will actually work as I think, but I will look into it in more detail when I need to redo my system.

Offline 1200GXman

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Re: Gas geyser VS Solar geyser
« Reply #6 on: July 01, 2020, 11:36:04 AM »
Quote
If i had to redo it, this is what I would do. 200l solar with glass tubes (with electric element) and gas heater as a top up.
This would become too expensive for me unfortunately.
My friend's gas geyser install was R16 000. So if I add a solar geyser also which is in my eyes totally overpriced, it would in total come out to over R30 000 for the setup.
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Offline MeTsU

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Re: Gas geyser VS Solar geyser
« Reply #7 on: July 01, 2020, 02:09:15 PM »
In for the sub.  We haven't started looking at options yet, but certainly need to start considering it.  About 4 months ago we installed a gas hob with 9kg bottle, going well so far.

Offline 1200GXman

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Re: Gas geyser VS Solar geyser
« Reply #8 on: July 01, 2020, 02:15:46 PM »
Kitchen is going to also have a gas top. So my idea was as first option to go with a gas geyser and run gas to the geyser and to the stove.
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Offline markc

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Re: Gas geyser VS Solar geyser
« Reply #9 on: July 01, 2020, 02:32:14 PM »
I think gas is the way to go. If you look at Solar costs you are looking at R23K. Payback will take years.

Offline 1200GXman

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Re: Gas geyser VS Solar geyser
« Reply #10 on: July 01, 2020, 02:34:59 PM »
Quote
I think gas is the way to go. If you look at Solar costs you are looking at R23K. Payback will take years.
I agree. Thus the reason posting on this forum to get other people's opinions. I am just concerned about the stories I heard of maintenance that needs to be done.
Apparently it is lime that cakes on the inside of the pipes that needs to be cleaned.

« Last Edit: July 01, 2020, 02:37:08 PM by 1200GXman »
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Offline chrisc

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Re: Gas geyser VS Solar geyser
« Reply #11 on: July 01, 2020, 02:53:49 PM »
We have a 20-tube evacuated tube collector and a PV-powered 12 volt pump to help circulation.  There is also a Daikin heat-pump which has a 1100 watt motor

In 320 days of the year, even in winter as long as there is sunshine, the water heats up to 55 degrees by 3.00 in the afternoon.   The heat-pump is controlled by a Geyserwise and set to come on at 12.00 and off at 5.30pm.  This caters for 40 of the remaining days

About 5 days a year, when the temp is below 10 deg, the heat pump is a bit slow (it is 28 years old) so I have a switch that turns on the 3Kw electric heater.  This heats the water by 1 deg every 5 mins, so a 2-hour heat up makes it 25 deg warmer.  I find that when the water is up to 50 deg this is enough for a hot shower

There is also a PV installation with batteries, of course nothing to do with water heating, but ensures we don't operate in the dark during load-shedding

Our electricity costs in the past 6 months are about R650 a month

I'm considering replacing the heat-pump.  The unit are about R15k for a 4Kw device
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Offline Curlycat

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Re: Gas geyser VS Solar geyser
« Reply #12 on: July 01, 2020, 05:46:45 PM »
ChrisC your setup is good but rather expensive.

I am partial to heat pumps. Solar only in certain areas. Gas is good, BUT it has to be specced right.

Solar - EV tubes are much more efficient than flat panels. EV tubes are more forgiving on installation requirements (In addition, flat panels gather dust - so there is the added cleaning/efficiency issue. They must be correctly installed to work properly) if something damages the panel - you need to replace the whole panel. Tubes, just the damaged ones.
The solar systems with the tubes going into the cylinder is an indirect system that is mainly used in areas where frost occurs. (Not to be confused with the low-cost solar systems, where the geyser has no element/no electrical connection. These are used in RDP houses, etc and are low-pressure systems only) In Cape Town, we do direct systems. Indirect systems can only be placed on the roof, whereas a direct system - the cylinder can be placed inside the roof cavity and only the panels/tubes on the roof, or everything on the roof.

Gas geysers' biggest drawback is not a big enough flow rate geyser was installed. Make sure you use an accredited gas geyser installer!!! Many people have died from carbon monoxide poisoning where a gas geyser was installed inside a bathroom, not according to standard. Apart from that, they are great, if you have gas.

Heat pumps great - a bit noisy. They rust if you get metal ones on the coast. Choose a plastic one if you live at the sea.

Each application needs an individual evaluation, the pro's and con's compared. Get an experienced guy and an honest guy to advise you on your particular needs.



« Last Edit: July 01, 2020, 05:48:56 PM by Curlycat »
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Offline AudioEars

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Re: Gas geyser VS Solar geyser
« Reply #13 on: July 01, 2020, 06:13:59 PM »
Hi
I had a 300l sun tank indirect solar geyser installed ... total waste of money plus has to be serviced , glycol top up and in winter not at all viable
I now have a gas hob for cooking and a gas geyser
With the gas prices regulated by the government the prices have stabilized ( there is talk of a big gas deposit off the cost off Mozambique for future peace of mind?)
I probably save about R500.00 a month on electricity having the gas geyser(Eskom supply will only get worse)
It is a drag to have the bottles refilled and swopped out but usually last 3 months, cooking and hotter usage
Hope this helps
Regards Andrew

Offline Mat

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Re: Gas geyser VS Solar geyser
« Reply #14 on: July 01, 2020, 06:44:06 PM »
I run gas geysers for hot water in the house. I have never had a major problem- except when guests are in the shower and the gas runs out. I have 2  x 48kg botles for the bathrooms with a manual switch over valve between them (36l geyser). Another 48kg supplies a smaller geyser(12l) for the kitchen and wash area. The gas hob runs on its own gas bottle. I also routed the pipe work so that I can switch back to normal geysers if needs be. An important issue would be to look at the plumbing from the heyser to the end points. Older houses have large diameter pipes, many of which are in the walls. The piping through the geyser system is normally much smaller in diameter. This causes pressure problems in showers specifically. Another consideration would be to run new plumbing directly from the gas gyeser to the end point. This will save water and gas and you will have the benifit of almost instantaneous hot water- pressure will also be good. All in all, my experience has been very positive. You can regulate the flow rate and burner intensity separately to achieve what you want. I  lower the burner intensity in summer. We never run out of hot water


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