Hi all, I went overseas for 5 weeks, and just got my energy bills.
Electricity usage went from daily average of 14kwH to 3kwH (fantastic).
Gas usage went from 83MJ to 63MJ.
It's not really a significant drop… I don't understand why.
We have gas cooktops, gas hot water, and gas central heating, obviously when we were away for 5 weeks we didn't use the central heating or cooktops.
Is it possible the hot water system was using all of that gas?
storage
If the unit is outside (especially over cold winter nights) then it will use plenty of gas keeping your water warm. You need to turn it off to save gas.
didn't think of doing it unfortunately.
Correct!
Hot water heating uses the most energy in any household.
Always turn off hot water when you are away for more than a few days.
Mystery solved
There's one issue with doing this.
The storage system will have a propensity to develop bacterial growth with the temperature drop. It's not recommended to turn the system off, nor to turn down the heating temp below the lowest appropriate temp to keep bacteria from developing.
he storage system will have a propensity to develop bacterial growth with the temperature drop.
But can't you turn on the unit when you back to a higher temp and kill the bacterial growth before usage? or it wont die and the bacteria lives forvever?
How about you turn off the water to the tank and empty the tank as well before you leave will the bacteria grow?
@cloudy: "Good questions! Let’s break them down:
Turning the unit back on and killing bacterial growth:
Yes, if you turn the hot water system back on and heat the water to a sufficiently high temperature (above 60°C), it can kill most of the bacteria, including Legionella. However, there’s a bit of nuance. While the bacteria can die at high temperatures, they might leave behind endotoxins (substances released when bacteria die) which could still be harmful, though the risk is generally much lower than living bacteria. Also, it takes some time at elevated temperatures to completely eliminate bacterial colonies.
Emptying the tank and turning off the water:
If you completely drain the tank and turn off the water supply, bacteria won't be able to grow in the absence of water. However, it's important to ensure that the tank is thoroughly drained. Any leftover water, especially in small crevices or low points in the tank, could still allow bacterial growth in those moist areas. When refilling the tank after returning, you’d want to heat the water back up to 60°C to ensure it is safe for use.
In summary, while turning the water heater back on to a high temperature can kill the bacteria, it’s better not to let it cool to unsafe levels for extended periods. Completely draining the tank can prevent bacterial growth during long absences, but precautions should still be taken when refilling and reheating the system."
@Oofy Doofy: hey you might be able to answer this for me.
last week water company did works. water was off for part of the day.
when it came back on the cold tap ran black with silt for 20 seconds or so, and air blasted out making a splash. each tap around the house did it. i thought i'd solved it once that was done.
a couple of days later i noticed the hot water was pouring brown. i'm guessing it got a full shot of silt and now the storage tank is contaminated.
I've had several showers to cold. i understand the storage continues to fill while drawing hot so never actually empties.
this morning after shower to cold, i ran the bath to full with the plug out so probably three bath fulls total, and i was still getting brown water.
any suggestions besides running it constantly until it clears?
edit : actually never mind. just tested and this morning's three bathtubs full seems to have done most of the work. only a little dirty now. wont be drinking from the hot tap this week, but showering and laundry will be a net gain again.
@Oofy Doofy: dunno about gas, but my indoor Sydney electric 80L storage tank I've turned off when going away for a while
I've estimated that just leaving it on unused might cost me about $2 per day in electricity - that was a while ago and prices have jumped so it could well now be $3 a day.
If so, if I deduct my daily service fee (about $1/day) then just keeping it on steady may account for up to two-thirds of my usage costs.
If anyone knows for sure I'd be interested.
@Hangryuman: No, unless your 80l tank has leak it will cost less than that when in use. $2 of electricity is around 6kwh and that's more than enough to heat a full 80l tank from cold. My 310l use maximum of 18kwh to heat from cold in the middle of winter and 9-10kwh daily now so no way your tank use half that just sitting idle.
@Oofy Doofy: One could isolate the unit and flush it with bleach before using it again or heat disinfect the unit.
If the unit is outside (especially over cold winter nights)
This is the most accurate answer, because this happened to me.
@ntt: Whatever you do, the gas is still being consumed.
I guess, building a small shed to stabilise temperature is a good effort,…because it can act like a greenhouse for the outdoor water heater.
Is your bill based on readings or estimated?
It says "Gas charges are based on an actual meter reading" on the bill
How about the previous bill?
This… your last bills are likely underestimates over winter.
Gas hot water still had to maintain heat in the system.
Just shows how little gas you use via the stove top and heater and how much the hot water system uses, and yep.
I'd be looking to convert to all electric as it cuts down significantly on supply bills.
I always thought the gas heating used the most gas , far out
It wasnt set on a timer was it?
no
It's storage heating that is bad in any possible way, not gas.
We no longer have gas heating, just gas hot water. With solar panels on the roof, I guess I just need to crunch the numbers to see how long it would take to pay off the cost of converting.
I’m surprise it’s not 69 years.
With solar panels on the roof, I guess I just need to crunch the numbers
If convert to heat pump HW it can be set up on a timer to operate off the solarPV. In theory that means no bills for electricity to operate the HPHW so the pay back should be the cost of the new system divided by your monthly gas bill for HW.
I'm only on gas for the instantaneous HW. Bill is ~$24/m or $288/yr. Last time I was quoted on a HPHW it was approx $3k so 11 years payback without taking into account inflation. 8 years if gas cost increases 10% every year. (or maybe I've calculated badly)
You must have a good gas plan and/or use very little?
$288/yr is less than my gas daily supply charge was!
@Giraffe: Obviously he's not included supply charge on that. Instantaneous hws uses little gas but if it's the last gas appliance in the house then daily usage charge should be included in the calculation.
Obviously he's not included supply charge on that.
Maybe don't assume. Supply charge included in calc. I'm on a great (legacy) plan & use very little.
Current usage is skewed because I'm only there half the week but based on last years usage when I was IGHWS and gas cooktop (used several times daily) of 11.5mJ/day. Gas cooktop is now inverter electric.
Supply charge (Sep 2024) = 30x$0.4303958= $12.92
Usage (HW&Cooktop) 11.5x30x0.0458944=$15.83
I did forget GST so make it $32 per month or $380/yr at current prices for HW + cooktop.
It's a bit higher in the dead of winter & lower in summer.
So yes, pay back is a bit quicker than what I stated.
little mermaids are on the house!@
You sure the readings are for the correct time that you were away?
bill period is for 58 days, of which 34 of them were absent from the house
bill period is for 58 days
You get billed on a 58 day cycle? That's an unusual period. I get read and billed every 90 days.
I've always been billed gas 2 month cycle.
Never 90.
Victoria standard gas bill period is 2 months.
Since in this period you had 24 days at home presumably ~83MJ then I think your 34 days were more like ~49MJ to get the average of 63MJ
Still seems high for just maintaining the heat, is it an old gas storage system? Do you know the star rating?
How was your trip
pretty good , watched 3 movies on the flight home… Mad Max Furiosa, Civil War (2024), and Unforgiven (1992)
Haha I was thinking I BLOODY BET this will be that scene from the castle (and will be disappointed if not)
Did you have beef wellington on the flight ?
lol you took a whole trip just for that? i could've watched those at home
Meter reading may not accurate (human error ). I always turn off central gas heating,hot water gas every time I go on holiday.
I tend to go overseas at least once a year for 3-4 weeks at a time. Longest I've been gone for is 3 months. Have noticed a drop in all utilities (gas, water, electricity). I thought we weren't supposed to turn off hot water systems as when the temperature drops there's a risk of legionnaires disease? Unless the entire system is drained dry and turned off? Instant gas vs gas hot water storage would have difference too - I imagine if you have gas storage it would have kept burning gas to maintain temperature.
you can turn it back on and let the system cook the water for some time before using it
That's what I would have thought you could do
63Mj per day? That is 17kWh, over 700W continuous.
Suggesting that is normal to keep storage hot is absurd.
Either hot water is constantly flowing out a leak, you left the central heating on, or the reading is incorrect.
63Mj per day
Don't be absurd. Over the billing period donkey.
Read again "ass".
" daily average of 14kwH to 3kwH (fantastic) Gas usage went from 83MJ to 63MJ."
You think 83Mj over a whole billing period before with central heating? Can you do arithmetic?
I can mathematical but I can't gas. Haven't had a gas bill in 20 years so I had no idea. Cheers big ears.
In colder areas, i.e. vic or tas 80MJ a day is about right for a billing period if you are using central heating and would be on the low side for quite a lot areas. So a drop to 63MJ average during the coldest months doesn't seem unreasonable. Would suggest his normal usage would probably be in the 100MJ range
@gromit: No, if there is central heating use everyday usage will definitely not lower than 100mj per day. Below that then OP must turn the heater on and off 15 minutes later.
that's what it says
Avg Daily Usage MJ 63.42
Avg Cost per Day $1.92
Have you checked the bill against the meter?
Or just check the meter over some hours now, without the central heating on.
That's a lot of gas!
That is not a lot. For a household with gas storage and cooktop that number is about average in Victoria. OP fail to mention that he went on holiday for 35/58 of those billing period so the calculation is compounded by the period he was still using gas. The drop in daily usage explains that, if he goes for holiday during that entire period then his daily usage would be lower, but there is no way to quantify that because who knows how much energy he use for ducted heating during the 23 days he was at home.
so was the bill $122 - or were there extra charges like supply charges that you would pay regardless of usage ?
The bill total was higher as the supply cost were included
But as described, the usage was very high
You were correct, there WAS a leak in the tank
Check the meter number on the bill actually matches your meter. They could have it mixed up with a neighbour.
They could have it mixed up with a neighbour.
or neighbour was coming over to use the gas.
You could have turned off the gas. So it will be 0 usage.
Heat Pump hot water time.
You have someone living in your roof, probably
australia is an expensive country.
How big is the storage unit? How old? What water temp do you have it set at (e.g. it's normally a dial from warm, hot or really hot).
Back when I had storage units, any trips more than a week, I would turn it off either at the unit or the gas mains. Not a big hassle to light it again when you get home, takes about 3 hours to heat up.
Apu exactly
Winter? If the days you were there were winter and you were using heating, the reduction might not be as great as you think between the preceding period where you might not of used heating, taken cooler showers and done less oven meals.
There was definetly no overlap on the days away across bills?
The heating usege/ water usage when at howlme was similar across periods? I.e no guests, no significantly colder/warmer periods?
Check your cylinder for leaks, check your water meter over a couple of hours woth no water usage to see if water is being lost somewhe re.
I would be turning off the cylinder and isolating water if away for any period greater than 2 days personally. Mainly for peace of mind, but with the added benefit of gas usage reduction.
what do you mean "not a signfiicant drop" it fell 25% in probably the most expensive high use time of year. Given hot water etc would still be on and the time you were here would likely be high usage, that seems like it is actually in line with expectations.
If we assume 10Mj/d standby on the HWC
OP was out for 59% of the period so the remainder 41% had usage ~80% higher.
Worth an investigation.
Likely a billing roll over or very high standby rate on the HWC through fault.
10MJ/d? that seems extremely optimistic, maybe that in warmer months. Always worth checking but the numbers really don't seem bad.
Are you also comparing bills from a different climate, ie were you away during a particularly cold period (ie more water heating), but the bill you’re comparing to was from a warmer period? How does the daily consumption compare to same period last year?
Also, if you go away for a few days, turn off all gas appliances, read the meter, then read it again when you get back … to check for gas leakage.
I'd definitely do a leak test if concerned. Not a. Big job to pay someone to do I think, but could be bigger finding any leaks if detected. Parents new build had a pipe just loose fit unsealed into an adjoining pipe and it just spewed gas 24/7. Nice.
It was actually hot water system tank leaking, not a gas leak
Your bill is still made up of a fixed (supply) charge regardless of whether you consume gas or not.
With gas prices increase l, what do people recommend I upgrade to save money? I'm not looking into solar. Choice between upgrading to hot water heat pump or heating split system or something else?
Most cases without solar, aim to get the max usable life out of what you have currently installed.
In the long term, heat pump hot water will save you money. How much depends on your hot water usage, gas price and the size and type of system you buy.
Depends what you have on gas and how much you want to invest vs how long you intend on living at the house?
I have gas hot water, gas central heating and gas cooktop, obvioulsy the heating is doing most of the gas usage, particularly during the cold months (the other 8 or so months of the year the gas bill is actually tiny) but to swap all that over is gonna cost a heap and it could be many years before I would get a return on investment.
I'm in the same boat. Was looking at hot water heap pump and seems warranty is a problem even for good brands. Split system seems to be a bit more reliable.
We were away for the whole July and our gas bill was $20 cheaper. It wasn’t $120 to $100. It was $200 to $180. We have instantaneous hot water too so there go figure.
The daily service charge is the problem.
I'm actually laughing. Please tell me what you think that massive device is doing while you're away
Got rid of gas completely about 6 years ago…. it's been great. The supply charges alone every year before you even use a cent of gas are ridiculous!
Everything electric- Evacuated tube solar water, boosted by electricity (rarely), solar panels, reverse cycle air conditioning, induction cooktop.
I'm saving thousands of dollars every year, and now that the solar panels have been completely paid off, it's cheap/free power most of the year.
Whether you believe in climate change or not, economically the decision is clear… get rid of gas!!
Yeah nah.
Gas (at a local price, not the USA retail back to us ripoff price) should have been the methadone between coal and fully renewable, but LNP w*nkers and CFMEU fkd it for all of us. If only sheep could comprehend a REAL class action, or better yet ,come election time, vote for the greater good.
Because you didn't turn off the things that were using gas
Gas storage hot water sucks! After moving into a new house in 1993, I discovered that the gas-heated hot water tank used loads of gas just to keep the pilot light burning. It's a huge waste. I realised that if I had only the pilot light on in mild-to-warm weather and turned off the main jet, the water would be hot again by the next evening. Only the pilot light was needed to re-heat the water I used. If I had the main jet on, the water would heat up quickly, but that gave me no benefit. The extra gas burned was wasted. I didn't need hot water again until the next evening. Since then, I've never kept the main jet on — even in winter. I turn it on just when I know I need to because the water isn't hot enough. (Not everybody can be bothered to do this!) I've saved masses of gas and $$thousands over the years.
When you go away on holidays it's perfectly safe to turn off the gas. It doesn't matter if bacteria have a ball while you're away. They probably won't, actually, because Legionella pneumophilia bacteria like to multiply in water between 25 and 42 degrees C. Your water won't take very long to cool to below that range (except in hot climates) and it won't matter if it doesn't, anyway. You just heat the water with the main jet to over 65 degrees C when you return, and the bugs are dead. They are non-spore-forming bacteria, so heat kills them — finished!
If you really want to save money, get rid of gas. Either do what I plan to do, which is to get a heat pump hot water system, or do what @UFO has done.
I also recommend induction cookers. They're fast and powerful compared with gas, but give you great control over your cooking from low power to full power. I've used both. Induction is streets ahead of gas, plus you don't suffer from toxic fumes and carcinogenic carbon nano-particles. Your health wins too. It won't be long before I ditch gas totally and never go back!
don't be stoopid homes
We are a major producer of natural gas. Shouldn't our gas bill be cheap?
Instantaneous hot water or storage?