Hot water tank degenerative disease

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Re: Hot water tank degenerative disease

Postby jules » Mon Jan 16, 2017 4:28 pm

... and thanks Smurf. Ruling out the element is helpful.

I've turned the thermostat down to 60 already though I'm not sure that the "too high setting" works in with the 12 month progressive degeneration.

The "pump at night" will be investigated. It seems to be doing the right things during the day in that it only turns on if the panels are 5 degrees warmer than the tank. I've never observed it to turn on when the tank is warmer than the panels but it's not out of the question.

No research for a few days as I'm back in my natural environment :)

Jules
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Re: Hot water tank degenerative disease

Postby davidg » Mon Jan 16, 2017 9:48 pm

jules wrote:I will work out if that's something I can look at, or if it's a situation for calling in another electrician with special tank skills.


Check valves are the domain of plumbers they are installed to stop water moving, lets say "backwards or in reverse" if dirt or grunge stop them closing properly or they stop sealing properly then they will allow water to flow in "reverse" where its not wanted to do so.
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Re: Hot water tank degenerative disease

Postby jules » Tue Jan 17, 2017 8:39 am

Check valves are the domain of plumbers


Yes, good point. Hot water tanks straddle an electrician/plumber divide. It seems to be ok for an electrician to replace a sacrificial anode but perhaps that's because it's an anode :D ?

I'll do some tests this weekend if I've got time and there's a hot day. I want to measure the power used overnight to heat water that's already hot. What doesn't add up for me, is that even with the power off the water is still very hot [as should be the case] but it doesn't seem to be cooling down in the way you might expect if syphon cooling was occurring.

I'll take some tank temp. readings from the tank computer controller as well.

Thanks again davidg
Primary system: .8KW Trina panels; Plasmatronics PL40; 1,000Ah VRLA 12X2V battery bank; 1.7KW Selectronic inverter

Veteran system, semi retired: 6 X 55W Solarex 12V panels; Fangpusun CC; 6 X 2V, 35 year old 550Ah lead acid flooded cell batteries.
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Re: Hot water tank degenerative disease

Postby tytower » Tue Jan 24, 2017 7:14 pm

Someone been playing with the thermostat setting? Turning it up or is it corroding and increasing its resistance somewhere or stuck on full heating ? maybe the element is shorted to ground and the power is just going to ground through some sort of corrosion created resistance like the thermostat maybe mica strips used. ?

Leave the power off . That will soon sort it out
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Re: Hot water tank degenerative disease

Postby davidg » Tue Jan 24, 2017 11:15 pm

tytower wrote: Turning it up or is it corroding and increasing its resistance

If that was the case then the element would heat more slowly.

tytower wrote:maybe the element is shorted to ground and the power is just going to ground through .......

That's ridiculous if that was really occurring the circuit breaker would trip due to an excessive increase in current demand.
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Re: Hot water tank degenerative disease

Postby jules » Wed Jan 25, 2017 8:12 am

Thanks for the input tytower.

The power has now been off for about three weeks and it isn't being missed at all :D

Because the problem has been progressive, the solution will have to be something that can degenerate slowly. At the moment, the anti-syphoning valve is looking like the most likely culprit and we're waiting on a professional to check that out. Like all of these things, there could be a compound problem of course. That always adds to the challenge!

Someone been playing with the thermostat setting?


Not in this case but this event [and a comment from smurf above] has made me think. The element controlling thermostat was set to 70C. I've brought it down to 60C but the solar thermostat is quite separate. A setting of 70, particularly in summer, will tend to have electric power doing what solar energy would do by itself if the power wasn't being directed to. Winter might be slightly different but I'm wondering if 60 isn't going to be fine year round.
Primary system: .8KW Trina panels; Plasmatronics PL40; 1,000Ah VRLA 12X2V battery bank; 1.7KW Selectronic inverter

Veteran system, semi retired: 6 X 55W Solarex 12V panels; Fangpusun CC; 6 X 2V, 35 year old 550Ah lead acid flooded cell batteries.
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Re: Hot water tank degenerative disease

Postby davidg » Wed Jan 25, 2017 8:24 am

jules wrote:Winter might be slightly different but I'm wondering if 60 isn't going to be fine year round.

You will loose less heat and therefore less energy running at 60C, it's still hot enough to kill legionella.
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Re: Hot water tank degenerative disease

Postby jules » Thu Jan 26, 2017 11:13 am

Adding to the mix ... the good householder has trawled back through her records only to find that at a key moment in this saga the electrician replaced the thermostat, which leads to several possibilities:

1. At the time the thermostat was replaced [12 months ago], the temp could have been re-set to 70 rather than 60. Even if this is the case it still seems the power being used is too high [referring back to Gordon's post about the amount of heat produced for the the power being used]

2. The wrong thermostat was installed, or it was installed incorrectly, or it just isn't doing its job.

3. There's more than one problem.

4. Why do I do all my own work at my house [not the house in question here] and never call in "professionals" ;) ? The first resort of scoundrels seems to be, if the problem is too hard, the equipment is "old" and should be replaced. Yes, that was one suggested solution to the problem.
Primary system: .8KW Trina panels; Plasmatronics PL40; 1,000Ah VRLA 12X2V battery bank; 1.7KW Selectronic inverter

Veteran system, semi retired: 6 X 55W Solarex 12V panels; Fangpusun CC; 6 X 2V, 35 year old 550Ah lead acid flooded cell batteries.
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Re: Hot water tank degenerative disease

Postby tytower » Thu Jan 26, 2017 9:06 pm

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Re: Hot water tank degenerative disease

Postby tytower » Fri Jan 27, 2017 8:03 am

Jules wrote:35 year old 550Ah lead acid flooded cell batteries.


WoW , how did you keep them going that long ? Whats your secret?
That would put them back in the days almost of each cell being tar sealed in a very hard case and replaceable.
Last edited by tytower on Fri Jan 27, 2017 8:04 am, edited 1 time in total.
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