Circuit Breakers - Household Hot Water System - One for the electricians

[101RRS]

One for the Electricians or is it Plumbers

I have a large 400l off peak hot water system. It has a top element and a bottom element - my understanding is that the bottom element is connected to the off peak system and the top element is connected directly to power and is set to a lower temperature than the bottom one. I believe the system is heated off peak via the bottom element but if some reason temp goes down like when all the hot water is being used up the top element kicks in and heats the water irrespective of the offpeak system.

So when the system is normally used within its capabilities (400litre for 2 people - means all the time) the top element rarely kicks in.

Recently the circuit breakers (20amp) (not earth leakage) for the hot water system have been popping. Looking at the bottom element - after clearing all the redbacks away looks all OK.

The top element connections shows evidence of arcing but not all the time. I cleaned everything up and sprayed with WD 40 and after one loud bright arc it settled down and seems to be working OK - I guess the WD40 has removed any moisture that may have been creating a short. I guess ultimately I need someone to get out and replace the connection box etc (plumber or electrician) or what ever is needed, however I am away from home from this afternoon.

So after all that - can I simply disconnect power from the top element (making all the precautions etc) and still get hotwater just based on the bottom element heating away on its off peak cycle?

Thanks

Garry

[Lemo]

Hey Garry,
Yes you can

Should be wired like one of these?

https://www.aulro.com/afvb/images/imported/2018/05/60.jpg

Do you have two supplies to the heater?

Craig

[Lemo]

Can you take some photos for us?

[Vern]

You can, you need to join the 2 nuetrals at the top thermostat, this will by pass it.

[101RRS]

Hi Craig - thanks for the response - yes I guess it is one of those. Here are pics of the two control boxes - there are two active wires coming into the bottom control box - the closest goes straight to the top.

139905139906

Bottom unit to the left and top unit on the right - pics are actually upright but the process tips them over.

It is shorting where the two red wires are on the top unit - crackles a bit and may pop but not straight away power can be on for hours before it pops the circuit breakers - I assume water is leaking in from the tank (no visual evidence though) but and slowly shorting until the short exceeds 20 amps and pops the circuit breakers.

Craig - actually I am leaving now to head to Belmont as that is where my family comes from. By any chance do you live with that family of Landrovers (RR, and D2s) that are on the highway opposite the High School?

Hi Vern - thanks I am not an an electrician and only have basic knowledge so not sure how to do what you suggest.

I am out of time so - the pics will not right themselves, on the right hand pic I have disconnected the brown active power wire and isolated it with shrink tube, I have removed the blue neutral wire and isolated it and left the silver earth in place. I am assuming that with only one person in the house until I get back home, the bottom off peak element will heat the water enough.

When I get back I will get my neighbour who is an electrician to have a look and if the themostat heating unit can be replaced insitu -great if a new water system is needed - that is bad $$$$$$$.

Thanks

Garry

[Vern]

On the top thermostat you need to join the blue and clear wire, just put them under the same terminal. Then remove the element wires from the thermostat and tape them up. Now only the off peak bottom element will work.

Or juat replace the top element, all fixed! Quite easy, turn the power off to the unit, turn the water off to the unit, drain a good 50L or so out, remove element, fit new element, turn water back on, let fill, turn power back on.

[trout1105]

When my electric storage heater started to play up a few years ago I got rid of it and fitted an instantaneous gas HWC.
No problems with power outages, No running out of hot water, No maintenance, No anodes to replace and on top of all that it is far cheaper to run than my old electric HWS [thumbsupbig][bigrolf]

[101RRS]

Well with the top element disconnected there is not heating at all - not even off peak.

Electrician time when I get back home - the person still at home is not liking cold showers in the cold Canberra mornings - was -1 the other day.

[PhilipA]

When my electric storage heater started to play up a few years ago I got rid of it and fitted an instantaneous gas HWC.
No problems with power outages, No running out of hot water, No maintenance, No anodes to replace and on top of all that it is far cheaper to run than my old electric HWS

It's horses for courses.

In Avoca there is only bottled gas. a friend has an instantaneous gas HW system and it uses a 45KG cylinder at $140 every six weeks for 2 people.


This accords with my calculations which I did 10 years ago when I had to replace my old system.

My 350L off peak for
2 people costs about $27-30 per quarter to run. At an initial capital cost of $800 and life of >10 years , There is nothing that even comes close in lifetime cost. The last one in my house lasted 21years AFAIR and I have mine on the lowest thermostat setting.

My biggest fear is that in future there will be no off peak as they are busily destroying coal fired power stations.
BTW , I would be happy to hear of any recent developments that change this calculation. I recently looked at a new type of electric instantaneous made in Melbourne with AFAIR a "flash" type heater , but I would need 2 to run the shower.
Regards Philip A

[trout1105]

a friend has an instantaneous gas HW system and it uses a 45KG cylinder at $140 every six weeks for 2 people.

That sounds really excessive.
Our system is hooked up to a 9kg bottle and this will last 6 weeks and that's with 2x showers a day for 2 of us and doing the dishes etc.
We don't use hot water in the washing machine, Maybe that is why we don't use as much gas.
We had an electric storage HWS originally But we got sick of replacing anodes and elements that got eaten away by the harsh bore water here, The Instantaneous gas heater doesn't have a problem with the calcium build up or corrosion that the old tank did and we never run out of hot water except when the gas bottle runs out (which I normally cop).
We paid about $700 for the unit and it came with a 10 year warranty, I doubt that an electric storage system comes with that sort of guarantee.

[PhilipA]

The Instantaneous gas heater doesn't have a problem with the calcium build up or corrosion that the old tank did and we never run out of hot water except when the gas bottle runs out (which I normally cop).

I was camping at Millstream Chichester and there was a gas instantaneous at the camp kitchen.
It was completely blocked by the calcium in the water as I found from the tech sent to fix it.

I also met a bloke there in a 80 series who had a genuine radiator fitted 1 year earlier which sprung a leak in a core. He lived in Karratha . Obviously the dealer had used tap water to fill it!

The water over there is certainly full of Calcium Carbonate.
So be wary of the Calcium.

I did the calculations on my situation based on manufacturer grams per hour etc and found bottled gas to be incredibly expensive to operate.
Don't even mention those evil heat exchanger thingos which now seem to have disappeared without trace. I cannot have solar as my roof is in shade for about 4months.
Regards Philip A

[Lemo]

Hi Craig - thanks for the response - yes I guess it is one of those. Here are pics of the two control boxes - there are two active wires coming into the bottom control box - the closest goes straight to the top.

139905139906

Bottom unit to the left and top unit on the right - pics are actually upright but the process tips them over.

It is shorting where the two red wires are on the top unit - crackles a bit and may pop but not straight away power can be on for hours before it pops the circuit breakers - I assume water is leaking in from the tank (no visual evidence though) but and slowly shorting until the short exceeds 20 amps and pops the circuit breakers.

Craig - actually I am leaving now to head to Belmont as that is where my family comes from. By any chance do you live with that family of Landrovers (RR, and D2s) that are on the highway opposite the High School?

Hi Vern - thanks I am not an an electrician and only have basic knowledge so not sure how to do what you suggest.

I am out of time so - the pics will not right themselves, on the right hand pic I have disconnected the brown active power wire and isolated it with shrink tube, I have removed the blue neutral wire and isolated it and left the silver earth in place. I am assuming that with only one person in the house until I get back home, the bottom off peak element will heat the water enough.

When I get back I will get my neighbour who is an electrician to have a look and if the themostat heating unit can be replaced insitu -great if a new water system is needed - that is bad $$$$$$$.

Thanks

Garry

Hi Garry,
No not me, unfortunately I only own one LR!
Craig

Good idea about the helping hand!
Should be just an element replacement?
If you disconnected the top element and now no hot water it could also be the bottom ones been stuffed for a while as well and just heating off the top??

Craig

[101RRS]

If you disconnected the top element and now no hot water it could also be the bottom ones been stuffed for a while as well and just heating off the top??

Craig

You could be right there. However on reviewing the pics again I see that the neutral wire does not go straight to the bottom element but to the top where the thermostat is and it then returns to the bottom element- I disconnected it at the top so I effectively disconnected power on the neutral side to the entire system [bigsad]. Maybe I should have better understood what Vern said. Also on thinking about it more I should have just disconnected the red wire on the bottom end of the thermostat at the top so power would be isolated to the top element and not the bottom. If I had more time when I did it I would have sussed that.

Anyway not my worry at the moment as I have hot water here in Belmont while my flatmate has cold water in Canberra - I bet he is starting to get a bit stinky.

Cheers

Garry

[Vern]

You could be right there. However on reviewing the pics again I see that the neutral wire does not go straight to the bottom element but to the top where the thermostat is and it then returns to the bottom element- I disconnected it at the top so I effectively disconnected power on the neutral side to the entire system [bigsad]. Maybe I should have better understood what Vern said. Also on thinking about it more I should have just disconnected the red wire on the bottom end of the thermostat at the top so power would be isolated to the top element and not the bottom. If I had more time when I did it I would have sussed that.

Anyway not my worry at the moment as I have hot water here in Belmont while my flatmate has cold water in Canberra - I bet he is starting to get a bit stinky.

Cheers

GarryThat is why i said the neutral wires at the top thermostat MUST be joined, that's the only way to complete the neutral circuit if by passing the top element.
The neutral wires are switched via the top thermostat.

[PhilipA]

On 30/7/2018 I bought a new Robertshaw thermostat model CS9610N from Reece for my Hardie Dux 315L single thermostat model which runs on controlled 1. Paid $51 which is a lot I now find.
Yesterday water is cool again.
I checked element resistance at about 11.5 Ohms and to earth about 10Mega Ohms.
So I assume the element is OK.
I removed the thermostat and I have continuity at room temperature between terminals 3 ( neutral) and 4( element) but no continuity between 1(active) and 2 (element). The excess temperature button had not popped.

Am I correct in assuming that at room temperature there should be continuity?

I adjusted the cutout temp and tested but no difference, and pressed the disc in but no difference.
This is expected but I think there should be continuity at room temperature as the device is just mechanical thing that should not depend on power , as it only depends on the disc distorting to open the contacts at the set temp, in my case 60C.
Urgent help needed as SWMBO is not impressed.
Regards Philip A
I am wondering if the thermostat has failed or no ripple for the last two nights.
BTW, I have the thermostat at my computer and just manually tripped the over temp button by pressing on the disc. It disconnects the neutral side.