Has anyone got details of how I can do a comparison between using electricity and LPG?

We currently have 2 × 45KG bottles for LPG (town LNG not available). It powers the cooktop and hot water system (HWS). The HWS uses about about 10L/min, according to the rating. In our situation, LPG costs $1.54 per L.

We use a reverse cycle air con for heating of the house.

Water usage is normally two people having two reasonably long showers per day, once in the morning and once at night. Washing machine usage is normally cold water with the occasional warm or hot cycle.

We are going to replace the HWS (not big enough) and want to figure out which is better value. Solar is out because of the installation costs.

So how do we do the sums?

where is the house? I have instantaneous gas hot water. no pilot light. very efficient.

$15.40/minute seems a bit expensive for heating water

ChrispenEvan said:

where is the house? I have instantaneous gas hot water. no pilot light. very efficient.

Ah, sorry – ours does have a pilot light. A real pain when the bottle runs out and we have to restart it.

We’re south coast NSW.

We currently have 2 × 45KG bottles for LPG (town LNG not available). It powers the cooktop and hot water system (HWS). The HWS uses about about 10L/min, according to the rating. In our situation, LPG costs $1.54 per L.

——

Your cost is litres (liquid), I assume. I assume the usage is litres (gaseous). Otherwise, showers would cost $15.40 a minute.

stumpy_seahorse said:

$15.40/minute seems a bit expensive for heating water

The 10L/min is what the system is rated for and we are told that is too small for us… but I don’t think that is the actual usage rate.

Obviousman said:

stumpy_seahorse said:

$15.40/minute seems a bit expensive for heating water

The 10L/min is what the system is rated for and we are told that is too small for us… but I don’t think that is the actual usage rate.

how long on average does a 45kg cylinder last you and how much does a refil cost?

Obviousman said:

stumpy_seahorse said:

$15.40/minute seems a bit expensive for heating water

The 10L/min is what the system is rated for and we are told that is too small for us… but I don’t think that is the actual usage rate.

Ah, water flow rate, I guess again. Measure the flow through your shower head into a bucket.

>Otherwise, showers would cost $15.40 a minute.

4 ten minute showers a day would cost $224,840 a year.

Bubblecar said:

>Otherwise, showers would cost $15.40 a minute.

4 ten minute showers a day would cost $224,840 a year.

ERB is richer than a weather girl.

LPG costs $1.54 per L.

—-

Energy value of LPG @ 22MJ per L is…

Diesel @ 36MJ per L is…

Electricity @ 3.6MJ per kWh is…

stumpy_seahorse said:

Obviousman said:

stumpy_seahorse said:

$15.40/minute seems a bit expensive for heating water

The 10L/min is what the system is rated for and we are told that is too small for us… but I don’t think that is the actual usage rate.

how long on average does a 45kg cylinder last you and how much does a refil cost?

We are using about 15.8L per week, on average. That varies a little because when there are holidays the relos invade: that means an additional 2 adults and 2 young kids.

Actually, change that usage to 13L per week.

in the other house we have LPG – no pilot light, the water flow generates power to ignite the gas. better where you have town water , crappy water can bung the generator piece up. hard water probably bungs the heat exchangers up

when electricity falls over you still have hot water

don’t bother getting heat pump hot water systems, mine turned rusty and caught fire twice ( (DUX)

water not heated when not being used

over here the new instantaneous are all the go unless you opt for solar or heat pump solar.

ChrispenEvan said:

over here the new instantaneous are all the go unless you opt for solar or heat pump solar.

That would be LNG, not LPG… right?

i have bottle gas. so whatever that is. but townies go the instant route too.

I got a instant gas hot water system for the redoubt, works a treat, talked into it by the punters here.
However I don’t have two showers a day, washes off all the good bacteria leaving your skin vulnerable to attack by opportunistic greebles.
It’s well know that 97% of dermatologists only shower once a day max.

We moved from a house with an electric storage HWS into a house with instantaneous gas (from bottles, like you) and have found our electricity bill has dropped more than the cost of the gas. I would recommend you go that way.

You will also find that the cost of running suitable electrical wiring to your new electric HWS (or solar booster) will make it uneconomical to consider, although there are (were?) some nice rebates available for heatpump systems that may offset those costs.

Obviousman said:

stumpy_seahorse said:

$15.40/minute seems a bit expensive for heating water

The 10L/min is what the system is rated for and we are told that is too small for us… but I don’t think that is the actual usage rate.

Who told you it is too small for you? How does that claim stack up against your actual experience?

My younger sister has gas water and full gas central heating (extremely efficient, as I found on the recent holiday) but that’s mains gas.

Carmen_Sandiego said:

Obviousman said:

stumpy_seahorse said:

$15.40/minute seems a bit expensive for heating water

The 10L/min is what the system is rated for and we are told that is too small for us… but I don’t think that is the actual usage rate.

Who told you it is too small for you? How does that claim stack up against your actual experience?

One we had was rated 2.5x that and only just maintained hot water at shower + a tap.

Carmen_Sandiego said:

Who told you it is too small for you? How does that claim stack up against your actual experience?

The gas heater dude; I believe him. The water pressure when you use the unit is quite low despite us having normal water pressure. For example, the granny flat has a small electric HWS which is our ‘backup’ on occasion. When we run on the electric and not gas, pressure is fine.

Obviousman said:

Carmen_Sandiego said:

Who told you it is too small for you? How does that claim stack up against your actual experience?

The gas heater dude; I believe him. The water pressure when you use the unit is quite low despite us having normal water pressure. For example, the granny flat has a small electric HWS which is our ‘backup’ on occasion. When we run on the electric and not gas, pressure is fine.

pressure? or flow?

Flow, I suppose, but they are the same to me.

Obviousman said:

Flow, I suppose, but they are the same to me.

now you’re sounding like a plumber…

if the 10L/min you quoted earlier is the flow out of the HWS, that is very low.
household taps should be in the high 20’sL/min

if you want higher pressure, put a more restrictive shower head on, if you want higher flow, replacing the HWS would be a start, but if it isn’t the HWS, short of replacing the pipe with a larger diameter pipe, or adding a booster pump, it’s very difficult

Are you sure solar is too expensive? Admittedly I am in SE Queensland but my solar hot water saved me $400 in the first year of use.

OK, so your current gas HWS has a restricted flow-rate and you wish to upgrade it. If there is no power point near it, you will have to replace it with one that doesn’t need one. (This is a good idea, it sucks when your gas HWS doesn’t work when you lose power)

If you have a power point, it opens up the option of other types that need electricity that may be more reliable or have more options. Either way, replacement should be a quick no fuss affair.

If you are still thinking of solar but money is the only thing holding you back, then a new HWS now isn’t a waste – you could use it as a back-up system, making the solar HWS installation cheaper.