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Mako

Laundry needs hot water

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I'm trying to help my sister to get her laundry more energy efficient. We've sorted out her electricity spikes which catapult her into very high tariffs (800 amps available) and we are now looking at hot water. PV solar is on hold for now (salesman had convinced her she would save hundreds of thousands) as most of the energy is consumed at night and the unit charge is under R1.00/unit off peak. (this is in George)

Water is currently heated by a donkey boiler and stored in a 800L bath type tank which I have just insulated along with the circulation and delivery piping. (this has been uninsulated for 18 months) The wood used to fire the boiler is free (furniture offcuts) but needs to be trimmed before it fits the boiler. This means a noisy chainsaw (changed to an electric chainsaw the moment the petrol job needed repair) and labour to do the cutting and handling. Most hot water is consumed at night so storage at a high temperatures is needed. The washing machines wash at 40C and blend cold in to control temps. Water is from a borehole.

So the plan is to go with EV tubes into a manifold and simply circulate the tank water with the donkey taking up the slack at night. It would be a low pressure system fed by a circulation pump with the return line terminating above the water level in the tank so that the system can drain when not in use. The huge roof is east / west with a 20 something degree pitch and the peak is about 9 meters above ground. I don't know how many tubes I would need but for the description I'm using forty as I need to understand the best practice configuration.

What I do know is that to extract the maximum heat from the tubes the manifold shouldn't be too long as the water heats up it is less efficient at extracting heat from the downstream tubes. So this means a number of manifolds connected in parallel eg 4 x 10 tubes or 2 x 20 tubes etc. Parallel means a decent size pump to ensure circulation through all manifolds and the tops should all be on the same level to avoid uneven flow. The simplest install is east west and same pitch as the roof. Is this feasible or should the tubes be tilted up more? Should we go north facing?

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the notorious

I. Am. Going. To. Send. A. Email. To. Someone!!!

I can NEVER get those low tariffs ... ever.

Need a drink!

Ok, calmness prevails, back to the matter on hand. I am all for EV tubes. Our geyser has been hot and not bothered with no help whatsoever from Eskom due recent water rationing being in effect in Cpt.

Even before our new norm, EV tubes, if warm water usage is adjusted, can negate Eskom completely.

Expensive, hell yes, but if user manners are adjusted, they can pay for themselves quickly. Took me less than 24months to settle them way back in 2012 or some such.

One quirk we stopped, was using warm water for washing machine. Pipes where to long, so we changed the soap for cold water, problem sorted.

Lately, rainwater is all that is used, so there is now even less chance of hot water. :-) 

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Commodore 64
18 minutes ago, The Terrible Triplett said:

I can NEVER get those low tariffs ... ever.

1.07 peak tariff. Our LifeLine tariff isn't even that low. Then again, if I had to guess, George likely has a connection fee and this might be ex-VAT, so the actual cost once you add that in is likely a tad higher.

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MR PENN

Joburg Off-Peak tariff if on Time of Use billing structure is 84c in summer and 89c in winter. I am sure CoCT will have something similar.

It sounds great until you see the Peak tariff;

  • summer = 134c 
  • winter = 308c!!!

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MR PENN

The TOU tariff above has fixed monthly costs excess of R500/month before any usage, I am on prepaid with total costs below R500 per month.

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MR PENN
7 minutes ago, pilotfish said:

I am sure CoCT will have something similar.

Just checked CoCT tariff's - no luck on TOU:angry:

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the notorious

We reached about R2.32 per kWh, then we got PAYG. 

Now we are on R1.61 per kWh and I am holding the fellow house dwellers in line simply by saying that if the meter is out of units, search for N ... as in "NOT My Problem"!

Once SWAMBO and once her female "langhaarhuisdier" got worried, ONCE, and each bought units ... I was floored.

Rest are ducking and diving ... I am a patient 'N' fellow. ;)

See, the "requests" are simple:
1 - Use power wisely.
2 - Switch off at the wall if not in use.

Got the house down to +-110w between 12am-7am, Eskom, with batteries carrying about +-45w 24/7, to keep them active.

Have a add-hoc peak of 220w during this time due to an older fridge, just not enough justification to buy a new A++ fridge ... yet ... for the old folk.

Therein my hindrance ito cost vs ROI to go bigger with solar, as most of the power is used after hours because for some reason CoCT is unreasonable ito going grid tie, feeding back to use at night. Must send Cyril a email on the matter.

If CoCT comes with a fixed connection charge, identifying me as a ideal candidate, then I will have a serious reset ito point of departure.

And IF there is a 30% increase on top of that, it will become a matter of principal to go "off-grid", bit for bit.

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Commodore 64
14 hours ago, pilotfish said:

winter = 308c!!!

Geeez, now I understand why "Scheduled charge/discharge" is such a much wanted feature. Fwiw... it's coming soon on planet blue. You will be able to charge (from the grid) at low-tariff times and discharge again at peak time.  At over R2/kwh price difference, with a good set of lithium ions... you'll pay for them pretty quickly.

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MR PENN

Yes - Time of Use is not a common tariff but it is available, if you are able to shift loads then it is definitely worthwhile.

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The wizard

I use to hire a farm that had TOU tariff and the pumps use to switch on in the evening at about 9pm. and off at 6am and on at 10am and off again at 5:30pm.

We had a very funny incidence due to the TOU. switching. I had hired a new shearing team and we arrived at about 6 pm  and they offloaded their kit into a vacant house and settled in for the night. Shearing is back breaking work and although I and many of my staff can shear a sheep we are not nearly as efficient as professional shearers and a professional shearer can probably shear a sheep in a ¼ of the time it would take me to shear a sheep. They are hard working - hard drinking men not to be trifled with. Even the cops grudgingly give them some respect.

After supper the shearers were retiring two two to a room and a pump started. The underground water on the farm is very sulphurous  and the water stinks (smells of rotten eggs) but is good for irrigation. The team captain had to separate two men, blades drawn, as the one had accused the other of farting. Meanwhile the malfeasant odour was actually wafting in from outside  through the open window. The two men were still laughing the following morning when they related the story to me.

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