Instantaneous Gas Hot Water & LPG

[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.

[DJ’s Timber]

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.

[ian]

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.

[Wrongwayfirst]

[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

[Beardy]

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.

[Wrongwayfirst]

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

[Jasethebeginner]

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

[woodPixel]

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 (https://www.popularmechanics.com/science/a34372005/solar-cheapest-energy-ever/) It may help you think about the prices of electrons in the next few years (cheap!!!)

[woodPixel]

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.

[artful bodger]

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.

[malb]

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.

[q9]

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.

[justonething]

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.

[Chris Parks]

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.

[ian]

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 | (https://www.bosch-thermotechnology.com.au/au/en/ocs/residential/hydropower-1001934-p/)
I'm sure other makers have similar systems

[ian]

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.
I thought that is what I said :? It was definitely what I intended to convey.

liquid withdrawal for high energy requirements -- e.g. a car, instantaneous hot water
gas vapour for low energy requirements -- e.g. cooking

[Beardy]

I thought that is what I said :? It was definitely what I intended to convey.

liquid withdrawal for high energy requirements -- e.g. a car, instantaneous hot water
gas vapour for low energy requirements -- e.g. cooking

How can it be different when the same bottle and gas line is feeding both / multiple appliances?

[ian]

How can it be different when the same bottle and gas line is feeding both / multiple appliances?
as I understand LPG systems, there are two types
1. vapour is drawn from the top of the LPG tank -- e.g. for a bar-b-que -- and passes through a largish hose to reach the appliance.
2. liquid (under pressure) is drawn from the bottom of the tank and passes through a small tube to reach the device -- car engine or water heater. Liquid withdrawal relies on a tube inserted to access the liquid at the bottom of the LPG tank.


as far as I know you won't find both systems on the same LPG cylinder. But, hey, I could be wrong.

[Wrongwayfirst]

LPG vapour (gas) is what is needed and burned through every household gas appliance.
LPG liquid is what a car requires and the big thingy on the carburettor puts what is needed into the engine to make it work. (As you can tell automotive is not my field:U)

so the gas bottle that you connect to your house (45kg or bulk bottles ) have the tap on the top and draw the vapour off to burn. Same goes for a 9kg BBQ bottle, tap on top draws vapour to burn and yes you can connect these to the house as it is same connection.

LPG bottle the shop uses to fill your bottle has tap on top but inside is a tube that runs to the bottom which draws the liquid into your bottle. When filling the ‘filler’ undoes a bleed screw on the side of your tap to let air/vapour escape. When white gas comes out the bleed screw this is liquid turning to gas and your bottle is full again.

LPG bottle a fork lift uses is on its side and when put on forklift it has a gauge that is in the up/top position there is a tube inside that runs to the “bottom” to withdraw liquid.

LPG bottle in a car is sideways (so it fits easier) also has inside a tube which draws liquid from the bottom.

car and fork lift bottles have their own unique threaded connections so people do not connect car bottles to houses and vice versa.

theoretical: if you turn a House 45kg gas bottle upside down (and have all the right connections) you can fill your BBQ bottle. Don’t try this at home. I think I was told that the liquid comes out at minus 35 degrees and if you fill enough gas bottles without gloves on you will get burned and it hurts like hell and yes once is enough.

cheers:U

when you boil the kettle and pour it over your BBQ bottle, you run your finger from bottom to top to see how full your bottle is. What you are doing is ‘feeling’ how much liquid there is left. Finger feels the cold at bottom (liquid area) when your finger starts to feel warm this is the area where vapour starts. Note when the bottle is nearly empty there is not a great temperature difference as not enough liquid to cool through bottle. On a nearly full bottle sometimes no finger required as you can see condensation line on the bottle.

[DJ’s Timber]

When my instant heater was installed, the plumber had to install a new line from the LPG Vapour bottles which is bigger, normal line is 1/2” or 12mm, new line is 3/4” or 19mm.

[Beardy]

as I understand LPG systems, there are two types
1. vapour is drawn from the top of the LPG tank -- e.g. for a bar-b-que -- and passes through a largish hose to reach the appliance.
2. liquid (under pressure) is drawn from the bottom of the tank and passes through a small tube to reach the device -- car engine or water heater. Liquid withdrawal relies on a tube inserted to access the liquid at the bottom of the LPG tank.


as far as I know you won't find both systems on the same LPG cylinder. But, hey, I could be wrong.

I haven’t seen anything like that here
They are plumbed the same way as being on natural gas except your pipework goes back to your chosen bottle location.
There is only one line running from the bottles and you branch off to whatever appliance you choose to connect. The pipework needs to still be sized accordingly to ensure sufficient gas flow for the said appliance

[fxst]

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 | (https://www.bosch-thermotechnology.com.au/au/en/ocs/residential/hydropower-1001934-p/)
I'm sure other makers have similar systems

This is the system I use and never had a problem. We have had lpg stove and instant heater for over 40 years and the savings are definitely worth going this way.

[Pete57]

I alway thought solar with gas instant hot water system in series made sense - to me. If solar hot water is not hot enough, gets a bit of extra heat added as it passes through the instant hot water system. Not using hot water, not using gas either.

when I did some research a few years ago, solar systems had mostly electric boosters to keep the hot water hot if solar not getting it to temperature. Not using hot water, electric booster still keeping water in tank hot I.e using electricity just in case I need hot water.

maybe I am missing something, but seemed like a simple system.

[Beardy]

Here is a pic of my gas setup, you can see the 19mm gas supply line in the centre under the regulator going to the various appliances

[Chris Parks]

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 | (https://www.bosch-thermotechnology.com.au/au/en/ocs/residential/hydropower-1001934-p/)
I'm sure other makers have similar systems

I have read some pretty poor reviews of the Bosch heaters but there must be happy owners as well.

[rrich]

There is one other thing that you need to consider. Should you ever get natural gas where you are, the water heater, space heater and kitchen will require different a orifice. Smaller due to more energy being in the natural gas. it is just a little brass thing that is very inexpensive. However if your water heater doesn't have an interchangeable orifice you'll have to change the the whole unit.

[malb]

There is one other thing that you need to consider. Should you ever get natural gas where you are, the water heater, space heater and kitchen will require different a orifice. Smaller due to more energy being in the natural gas. it is just a little brass thing that is very inexpensive. However if your water heater doesn't have an interchangeable orifice you'll have to change the the whole unit.

What you say is true, the two fuels use different sized orrifices. Here in Oz a lot of appliances come from the distributor configured for one fuel but with a set of orrifices for the alternate fuel included so that the unit is convertible in the field. If the purchaser is lucky, the installer leaves the alternate set in the appliance housing (room heater or HWS) or hands them over to the owner, so they are available if a conversion is required at a later time. I get the feeling that for the east coat of Oz, the gas supply situation fairly stable, i.e. the only expansion of the natural gas network will be in new estates being developed close to existing NG serviced areas, and ares removed from the NG network will continue with LPG.

[malb]

Here is a pic of my gas setup, you can see the 19mm gas supply line in the centre under the regulator going to the various appliances

Supply line size is a function of what your potential peak load is. If you are running gas cooking or heating as well as HWS you need larger feed pipes to maintain appropriate flow and pressure to all appliances should they all need to operate at the same time. Cook would not be happy if the oven goes out because someone wants some hot water to wash their hand, or the gas heater kicks in.

DJ mentioned that they had to upgrade his feed pipes when he converted to instantaneous gas, that in itself suggests that the plumbing was in place to supply other appliances and was sized to suit that demand, but needed updating for the additional demand.

[Beardy]

Supply line size is a function of what your potential peak load is. If you are running gas cooking or heating as well as HWS you need larger feed pipes to maintain appropriate flow and pressure to all appliances should they all need to operate at the same time. Cook would not be happy if the oven goes out because someone wants some hot water to wash their hand, or the gas heater kicks in.

DJ mentioned that they had to upgrade his feed pipes when he converted to instantaneous gas, that in itself suggests that the plumbing was in place to supply other appliances and was sized to suit that demand, but needed updating for the additional demand.

19mm is the standard for most installations, when we have fitted two instant HWU on a house we have had to upgrade the line to 25mm

[Enfield Guy]

Do you have 3 phase power? Steble Eltron do a continuous flow unit which is the ducks guts. No flue, indoor install, no bund, uses mil amps when not running, can service more than one point.

I had one installed in my creative space when I bought my premises. The unit takes up next to no space. About 600 x 200 x 100. I have it mounted in the cupboard beside the bathroom.

well worth looking at me thinks.

[Chris Parks]

I do have three phase but in the past instantaneous heaters were always condemned as being expensive to run though they were of the small storage type. It is an option though and worth looking at.