Hot Water Cylinder

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cadman

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#1978753 16-Mar-2018 16:06

Usha:

Thank You for understanding, Gordy. We have been to Disputes' Tribunal, and they have asked us to provide them with a statement/report from a certified plumber to confirm that a faulty valve can increase the electricity bills. And, we are not even sure if any one would give us such a statement/report without a fee?

Seriously? The DT referee can't make the logical conclusion that a leaking HWC, which is the equivalent of leaving a hot water tap dripping, increases power use? Oh dear.

So, was your water also metered?

EDIT:

And why the Disputes Tribunal and not the Tenancy Tribunal? The Tenancy Tribunal decisions are all published for 3 years so it would have at least allowed future tenants the opportunity to easily see how slack this Landlord is with regards fairly urgent maintenance. I would have thought that the DT would have referred you to the TT, to be honest.

Bung

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#1980255 20-Mar-2018 08:27

cadman:
Critical question: How long was it between the time you advised the Landlord of the problem and him fixing it? If says he fannied about for 2 months, you have a reasonable claim for the period from the time he was notified to the time it was rectified. Otherwise, not so much as he couldn't have known.

Not only when was the landlord advised but was there any follow up. It seems that lots of things happen with the urgency that comes from the person that needs the action, the squeeking wheel.

Usha

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#1980336 20-Mar-2018 09:10

Sorry for a late reply. Below is a brief synopsis of what exactly happened in 2017.

April
After weeks of heavy rainfall, the garage roof began leaking incessantly.
Landlord advised that leaking point will be fixed, roof to be cleaned, painted and water channed re-adjusted.

May
Tradies cleaned the roof, but leak was not fixed (as per landlord's text message)
We (tenants) were overseas for 9 days.

June
We messaged landlord - Hot water constantly flowing out from the overflow pipe on the roof

July
We emailed landlord - Electricity and water bill has been on a rise since May 2017

August
We emailed (again) - Electricity and water bill has been on a rise since May 2017
21 Aug - A plumber visited the property to change the valve of the hot water cylinder

Since we have been in NZ for only 6 years, we did not know that we could ask the landlord to reimburse us with the charges we paid when the valve was faulty, i.e. May - Aug 2017.

In Jan 2018
We asked landlord to reimburse us with the excess that we believe was paid due to faulty valve.
They replied won't do so, and we went to Tenancy Tribunal (not DT, as per my previous post, sorry).

30 January 2018 - Mediation Meeting. No resolution

15 March 2018 - Tenancy Tribunal hearing, wherein the adjudicator asked us to prove that that the bills were high due to faulty valve, and wants us to submit written confirmation from plumber/electrician re the same.

Usha

10 posts

Wannabe Geek

#1980338 20-Mar-2018 09:16

From what we have read online and enquired with plumbers + general public, we have been advised that a faulty valve of a hot water cylinder leads to a high electricity bill, and water bill, too (at times).

Our household comprises of me an my partner only. Both of us are working Monday - Friday, 8am - 4pm.
On weekdays, we are out of the house from 7am - 5pm.

Our electricity bills have never been more than $100. Below is what we paid in 2017.

May = $155.44
Jun = $204.11
Jul = $291.79
Aug = $244.82

Our water bills have never been more than $45. Below is what we were billed in 2017.

May = $44.93 (estimated reading)
Jun = $66.86 (actual reading)
Jul = $54.41 (estimated reading)
Aug = $138.80 (actual reading)

Once the valve of the HWC was fixed/replaced, our bills went back to normal.

2017 - ELECTRICITY

Sep = $99.67
Oct = $95.68
Nov = $80.25
Dec = $69.23

2017 - WATER

Sep = $60.14 (estimated reading)
Oct = $31.22 (actual reading)
Nov = $60.14 (estimated reading)
Dec = $30.07 (actual reading)

Gordy7

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#1980348 20-Mar-2018 09:26

June
We messaged landlord - Hot water constantly flowing out from the overflow pipe on the roof.

Flowing... not dripping... That could easily use heaps of power... did you think to grab a photo or video...

Gordy

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Usha

10 posts

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#1980351 20-Mar-2018 09:29

No, Gordy. We did not take a video or photo, as the landlord told us that it is a normal thing.

However, we do have a photo of the stained floor due to the water falling down.

Gordy7

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#1980354 20-Mar-2018 09:32

Red flag... 'landlord told us that it is a normal thing'

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

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cadman

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#1980497 20-Mar-2018 14:01

Clearly you have a valid claim for both the excess water and electricity usage through the Landlord's slackness. Presumably you weren't in the house the year before? There would need to be some allowance made for the fact it was in the cooler part of the year if you were using any forms of electric heating such as electric blankets, electric heaters, so if you had the previous year's usage it would be better for comparison to that end.

It's certainly a bit disappointing that the referee isn't able to simply understand that using more hot water is obviously going to affect your electricity consumption - they used to be much better than that.

As an aside issue, were you also paying the full amount of the water bills as invoiced? A lot of people don't realise but fixed charges not related to consumption (i.e. annual wastewater charge) are not the tenants responsibility.

Aredwood

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#1980731 20-Mar-2018 21:41

Does your house have a smart meter? If so, ask your power company for all of the meter data. As smart meters record usage down to the 1/2 hour. You can see the element in the hot water cylinder switching non and off with that data. You can use it to prove that the cylinder is doing far more heating cycles due to the faulty valve.

cadman

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#1981260 21-Mar-2018 22:41

Aredwood: Does your house have a smart meter? If so, ask your power company for all of the meter data. As smart meters record usage down to the 1/2 hour. You can see the element in the hot water cylinder switching non and off with that data. You can use it to prove that the cylinder is doing far more heating cycles due to the faulty valve.

I'm not sure this is right. Our meters are't actually 'smart meters' but advanced meters. You'll be able to see a low resolution (½ hour intervals) of instantaneous usage but not specifically that of just the HWC since it's just bundled together with the other loads in the OPs case.

Aredwood

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#1981298 22-Mar-2018 01:00

cadman:
I'm not sure this is right. Our meters are't actually 'smart meters' but advanced meters. You'll be able to see a low resolution (½ hour intervals) of instantaneous usage but not specifically that of just the HWC since it's just bundled together with the other loads in the OPs case.

They almost certainly have quite a low baseload power consumption. So it is actually quite easy to tell the difference between the HWC element running Vs low drain items like the fridge + vampire loads. The trick is to look at times when no one is at home. Regular spikes indicate the element switching on for a reheat cycle. Once you figure out the time between cycles, and amount of power use per cycle, you can then calculate a total heat loss. When the valve was working properly, each cycle still uses about the same amount of power. But the gap between cycles will be longer.

cadman

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#1981437 22-Mar-2018 12:34

Aredwood:
cadman:

I'm not sure this is right. Our meters are't actually 'smart meters' but advanced meters. You'll be able to see a low resolution (½ hour intervals) of instantaneous usage but not specifically that of just the HWC since it's just bundled together with the other loads in the OPs case.

They almost certainly have quite a low baseload power consumption. So it is actually quite easy to tell the difference between the HWC element running Vs low drain items like the fridge + vampire loads. The trick is to look at times when no one is at home. Regular spikes indicate the element switching on for a reheat cycle. Once you figure out the time between cycles, and amount of power use per cycle, you can then calculate a total heat loss. When the valve was working properly, each cycle still uses about the same amount of power. But the gap between cycles will be longer.

The problem is in demonstrating, not simply claiming, that the load isn't simply electric heaters or cooking. Extrapolating out ½ hour blocks wouldn't cut it for me given the power bills increased by the amount they're saying. I think trying to offer that logic, to someone who doesn't realise that a leaking hot water cylinder can cause electricity usage to go berserk, would be pointless.

For that purpose, I'd compare the water usage figures first as that water consumption isn't as likely to be subject to a seasonal variation that would increase over the cooler months and show the clear correlation between that and the power bills.

Our water usage over the entire year - year-after-year - only varies by about 10% - higher in summer for watering the garden.

Just for demonstrative purposes, assuming incoming water temperature of 15°C and a thermostat setting of 70°C (high, but not that uncommon, particularly in larger household with small cylinders that may have been running out of hot water at times and this was done to compensate) and no losses, it will take 231kJ of energy or 0.064kWh to reheat 1L of water (1W is 1J/s, 1kW = 1 000W, so 1 000J/s x 3600s/h = 3 600 000kJ/h @ 1kW). So if you've got a leak of just 50L/day that's 3.21kWh/day or an extra ~90 minutes of a 2.2kW element on time or 96.25kWh/30 days going down the drain - probably $25/mth.

Worst case scenario: if a HWC 2.2kW element never switches off (i.e. the leak is so bad that is never actually gets to temperature) that will be 1584kWh/30 days or around $427/mth depending on your applicable tariff. That would correspond to 25kL of water use a month. But of course you'd actually never get that knife edge balance right between incoming water (replacing that which leaked) keeping the temperature just below the thermostat setting and still having hot water available at the tap - it'd probably only ever be warm water unless maybe you were away for a few days to give it time to catch up.

But in the OPs case we're talking an increase from $45/mth to $90/mth on water and $95/mth to $250/mth on electricity. $155 of electricity at say $0.27/kWh that's 574kWh. Or 9kL/mth - 300L/day - of extra water heating based on that. Assuming a water tariff of $1.50/kL incoming and $2.50/kL wasterwater (charged at @80% of incoming kL) that's $31/mth extra water - short ~$14/mth on your actual water bills.

So plugging in a more likely slightly lower 60°C thermostat setting. 1L of water heated to that lower temperature is now down from 231kJ/L to ((60°C - 15°C) / (70°C - 15°C) x 231kJ/L) = 189kJ/L.

Subsequently, water usage per month must go up to compensate for the lower energy required per 1L of water to achieve the same increased energy consumption noted on the bills, so by simple ratios (231kJ/189kJ) x 9kL/mth = 11kL/mth or ~360L/day. Water bills then are ~$38.50/mth based on the same guestimate tariffs. That's not too far off the $45/mth at all considering we don't even know the relative timings of the billing periods.

Now assuming a 2.2kW element heating an extra 360L/day, that's going to be an additional (189kJ/L x 360L/day) = 68 040kJ/day (18.9kWh/day). How long does it take for a 2.2kW element to deliver that? 18kWh /2.2kW = ~8½ hours. So 35% of every day the element is on solely for the purpose of heating the 360L of wasted water. During times the house is unoccupied that could be 10 minutes straight every ½ hour, 20 minutes straight each hour, or 40 minutes straight every second hour, or 30 straight minutes every 1½ hours, depending on the thermostat hysteresis.

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