Thread: Instantaneous Gas Hot Water & LPG

Can’t remember exact savings but when I did mine, think I worked it out to like saving about $400 per year on electricity and extra gas usage is like one 45kg bottle a year for me.

Mind you I’m the only person living in the house and I like long showers.

Originally Posted by Chris Parks

Can anyone here relate their experience with LPG & Instantaneous gas hot water.
snip
We do have LPG for cooking so installation is not needed apart from running to the heater.

what size of delivery line do you have from the LPG cylinder?
my understanding is that LPG gas used for BBQs is drawn as gas from the top if the cylinder. For creating hot water, you need considerably more, so a liquid withdraw cylinder is a must. Which type of system do you have?


We upgraded our [town] gas system to include a kitchen and instantaneous water heater 20+ years ago. Our "problems" included that the original gas supply line necked down to 1/2" immediately it entered the house -- necessitating a new line from the house wall to the kitchen, the external gas points we had installed when the kitchen was replaced were marginal for running the Rinai instantaneous water heater.
The hot water dollar savings in under two years paid for the purchase of the instantaneous water heater and its installation. I don't recall if we took advantage of a AGL promotion.

NOTE
you will need to ensure that the system you buy is configured for liquid withdrawal LPG operation.

[QUOTE=ian;2214332]what size of delivery line do you have from the LPG cylinder?
my understanding is that LPG gas used for BBQs is drawn as gas from the top if the cylinder. For creating hot water, you need considerably more, so a liquid withdraw cylinder is a must. Which type of system do you have?


Incorrect
LPG (liquid petroleum gas) when filling a bottle you fill the empty cylinder with liquid. When connecting the cylinder the liquid is at the bottom and you withdraw the vapour from the top. In a car you have the exact same gas and filling method but you withdraw the liquid from the bottom for use.

natural gas (town gas) is low pressure and a larger main is required. LPG (bottle gas) is at a higher pressure and thus uses a smaller pipe size.
cheers

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I have instantaneous on lpg but can’t give you any $ numbers as are still on the first bottle.

The other option you could look at is a heat pump, off peak is not an option for new homes anymore.
Seeing as though you have lpg already setup I would think that would be your best option.

Originally Posted by Chris Parks

Can anyone here relate their experience with LPG & Instantaneous gas hot water. We have an old off peak system which while it hasn't died yet but be getting towards the end of its life and I have always wondered if the LPG alternative would cost a lot extra to run than OP electric or maybe even less. We do have LPG for cooking so instalation is not needed apart from running to the heater.

yes gas will be cheaper to run I didn’t respond earlier as I have been out of that area too long and don’t have cost comparison.
a 45kg gas bottle has about 2000Mj capacity and your hot water unit will use between 100 and 200Mj per hour depending on size. This is not exact but a guide as the heater will ramp up or down depending on flow of water temperature etc but you can calculate rough cost.
instantaneous has a flue boosted by an electric fan so if the hot water unit and the new unit are in the same place your electrician will need to install a power point as well as the plumber changing the pipes and gas. If the power goes out you will have no hot water - no power = no fan and no electronic ignition.
cheers

We went from an electric storage system to an instantaneous gas system. Not long after we went Solar. Should have gone solar from the outset. I fell for the reduced costs line but with a teenage daughter who thinks 20 mins is a short shower and long pipe runs to the various hot taps it really wasn't cheaper.

If Solar is an option I would go that way.

Jase

Yes. Plonk on a dirty great solar accumulator regardless if you use gas or electric.

In a country where the sun is .... a problem... it seems weird we don't utilise it.

I was only just reading this: Solar Is Cheapest Energy: Renewable Energy vs. Fossil Fuels Cost It may help you think about the prices of electrons in the next few years (cheap!!!)

Interesting this should be mentioned... had my Good 'ol dad up for a few days this week (had his cornea replaced!)....

We were talking about country living (he's in the sticks) and the gas dude comes every three months to pop on another bottle. I think he said it was ($45 a month?)... so 3x45 (135-ish).

Seems like a decent price. He lives solo.

Had one of the instantaneous gas water heaters for several years now. We get the gas delivered in those largish gas cylinders (approx1200mm tall). The electricity bill dropped by much more than the gas costs so have been very happy with it.

We had natural gas storage hot water and a gas hotplate in Melb until we moved to Alex 5 years ago. Old house has a Bosch 26l/min instantaneous on 2 x 45kg cylinders with auto changeover. I am prone to getting grotty and wife is OCD so there is a lot of washing being done with a mix of hot and cold water. For all hot water for a 2 person house we were getting 3 months from a 45kg cylinder (currently $120).

In the new house, we had 2 x 20L/min units installed, one for ensuite and kitchen, the other for laundry and 2nd bathroom, again fed from 2 x 45kg cylinders and an auto changeover. We opted for the twin heater system too minimise the amount of piping that had to be cleared of cooling water every time you open a hot tap. Similar number of showers and washing, but we seem to be getting about 4 months per cylinder now.

Can't compare the economics of electricity vs lpg instantaneous because its 38yrs since we had an electric storage system, but LPG instantaneous has definitely been cheaper than natural gas storage was five years ago, and I doubt that NG has gotten cheaper in that time.

Note that with LPG, you pay annual rental on the cylinders, in our case about $60 per pair per annum. Our local agent replaces empty bottles within a day or two of placing an order, the delay is not an issue as we have the auto changer and an alternate cylinder so an effectively uninterrupted supply provided that we check to flag on the autochanger about once a week during the periods when a bottle may become exhausted.

Instant gas is all there is in Japan. Works well, but there's no funny laws about limiting output to 40C. Can push 95 if we so desire. Energy broadly cheaper than in Aus, so hard to give you a comparison, and our gas and electric bill are combined in any case. But I'd put it as close to the shower as possible, and if there is too much distance, put a second near the kitchen.

Originally Posted by Chris Parks

Can anyone here relate their experience with LPG & Instantaneous gas hot water. We have an old off peak system which while it hasn't died yet but be getting towards the end of its life and I have always wondered if the LPG alternative would cost a lot extra to run than OP electric or maybe even less. We do have LPG for cooking so instalation is not needed apart from running to the heater.

Had a bit of experience. We decided on LPG instantaneous because on our holiday house because we didn't want to pay the supply charge for natural gas for the occasions that we are down there. 1KG of LPG has a heat capacity of 49MJ, or 13.6 Kwh.

At Bunnings, 8.5 KG of bottled LPG cost $27, and it contains 115.7 Kwh and based on an electricity tariff of 28c per kwh, it will cost about $32.4 to buy the same amount of energy. So you are ahead slightly with LPG. But in some places, there is off peak tariff for hot water systems.

Unlike a storage HWC, there is no heat loss with an instantaneous hot water while it is on standby, which could be around 20 to 30%. I decided to have two of the 8.5Kg bottles, because I can go and swap for another one at Bunnings while the other one is in use. One thing to bear in mind is that hot water uses a lot more gas than cooking. It is not that convenient having to buy gas every week.

A consideration is that we only pay 10c per Kw for off peak and we do have 7.5Kw of solar on the roof but no roof space for a solar water heater. Many years ago we had a Siddons heat pump HWS (I think they were the pioneers of heat pump HWS) and it worked well but eventually died and became very inefficient when a house next door was built and it was in shade all the time. A tip for LPG installations, I handed back one 45kg?? bottle and fitted a 20kg bottle in its place which is enough to bridge the time it takes to get another large bottle and saves a few dollars for bottle hire. For cooking only a large bottle lasts us over 12 months as a rule.

Chris
If you are worried about power interruptions at the house, Bosch do an instantaneous unit that relies on water flow to ignite the burner. Might be an option for you. HydroPower | Hot Water | Products |
I'm sure other makers have similar systems