Hot water service

I'm pretty sure my HWS has a small leak in the bottom.
I've been told by a friend that I can get a small HWS that heats as you need it.
I had a small gas one of these at the last place I rented.
The one my friend is recommending comes with a government rebate, I don't get this the supplier does, I just get a cheaper
heater. I did a quick search and found that I have to sign over something to the supplier.
my first question is to anyone that knows, is gas cheaper than electric to run or do I get another HWS to replace the one I have.

I don't know how else to describe this.

We use an instant gas water heater and its a cheap option to a storage system, why pay to heat water you're not using? I would suggest go for a gas system
Pete

Go for the best and get a gas boosted solar system.

Yes there is other hot waster systems that have cheaper running costs on a day to day basis but keep in mind the cost to buy one of these systems and more so fitting one to an existing house.
It can start getting expensive when you are chopping up paths and gardens etc to run gas to your heater point and likewise retrofitting solar
The most economical system to have might still be to just replace the current one you have, particularly if you do not consume a lot of hot water

People often get caught up in all the sales hype and spend more money on the infrastructure than it can possibly save them over the items life.

I went though this change over some years ago.
Traps for the unwarry
1. if you are on town gas, make sure the supply is large enough. (the pipe on our original gas supply didn't have the capacity to run, a heater, cook-top and instant HW system, so we needed to upgrade the supply.
2. ideally the water connection is very close to the usage point -- we were lucky in that the bathroom and kitchen were close together so plumbing the HW in at a common point was feasible.

3. if on bottled gas, there is a big difference in efficiency between liquid withdrawal and gas withdrawal.

Here in the US, the gas would be cheaper. However we are almost universally on natural gas. I've been told that LP or propane gas is more expensive.

The instant type of hot water heaters (Here in the US) require a larger supply pipe for the gas. If your house is over a basement or crawl space the installation of the larger gas supply can be easy. If your home is on a slab it could be a nightmare.

A quick check (Home Depot) showed a 220 volt / 18KW unit delivering 4+ gallons (over 16 L) per minute. That works out to close to 80 amperes capacity. That is one heck of an electrical requirement considering my A/C only draws 40 amperes max.

Thanks for the replies guys

If you have access to three phase power then there is a continuous flow electric available from Stebel Eltron. No bund, no flue, very small, highly efficient and comparable in terms of price. Worth looking into. I have one in my creative space that powers my shower. Highly recommended. No connection,just a happy owner.

Primarily, I would be concerned about what you have available to fuel a replacement first, likely prospects being electricity, Natural gas, and Liquid Petroleum Gas. The cheapest option overall would be to replace like with like, i.e an electric storage with an electric storage or gas storage with gas storage. That is because the infrastructure (water plumbing, gas plumbing, electrics) are in place and should only need minimal modification to connect to a similar unit. A change of unit type e.g. gas storage to gas instantaneous would require a more extensive modification because each service connection would be in a different location.

When we built our first home 35 years ago, Natural gas was readily available at the site and used internally for hotplates and a wall furnace, so we opted for a natural gas storage system. At that stage the primary offering used an enamel coated (inside and out) tank and a huge burner underneath. At about 10 years, this started to leak in the base of the tank, primary issue being that the burner rating is so high to achieve short term recovery that it causes stress cracks in the enamel coatings and allows rust to start up and dissolve the thin metal of the tank. We persisted with the steel tank unit for a couple of years as a very good friend was welding up the holes as they appeared. (We had acquired an identical unit with the same issue on the roadside, so would have the unit running on 1 tank and the second tank either being patched or on standby to swap in as soon as the running tank failed. Ran on this method for a couple of years till both tanks were beyond patching, got to the point where I could dismantle the unit, swap tank and reassemble the unit in a couple of hours. These heaters use a pilot light to ignite the main burner so there is always a small flame burning gas.

When both tanks were beyond it, we finally upgraded to a unit with a SS tank. This unit did away with the issue of tanks rusting, and could heat the water to a higher temperature and use an internal mixer unit to temper the output water to usable temps by mixing very hot water and cold water in appropriate proportions. We generally left the thermostat at moderate temps and mixing off as we were a 2 person household, but occasionally used higher temps and mixing if we had a number of guests. We had no issues with the SS tank unit for 20+ years, and the inherited family property has had one for 27 years, needing only a replacement thermocouple a couple of years ago ($25 and an hour to diagnose, purchase and install).

The house we are in now has a Bosch 20l/min LPG instantaneous, and for the 2 of us supplies all of our hot water requirements for one 45KG bottle of gas ($120) every 3 months. We run 2 bottles in place with an auto change over unit, so contact our gas retailer once we have emptied a bottle and they deliver a full one, install it, and take the empty away. We pay about $55 per year rental for the bottles, which are owned by our gas wholesaler. We have no issues with the system other than some outlets are a long way from the heater and we need to run a fair bit of water through the pipes to get hot water as the lagging on the old pipes has failed and water in the pipes cools quickly. We are building a new house at the moment and this will have two such heaters and much better plumbing insulation, so we have very short pipe runs from heater to outlets and should save on waste water getting hot water through the pipes. These modern units are computer controlled and use electronic ignition, no gas pilot light but they need a power point for the control and ignition system but use minimal electricity.

If the current system is electric storage, I suspect that any change in system type will be fairly expensive, as you would need to substantially upgrade cabling to go to an electric instantaneous system, or upgrade or install from scratch a gas installation to go to either gas storage or gas instantaneous. In any of these three scenarios, I would anticipate the overall changeover to be two to four times the basic cost of the HWS, once supply upgrade works are included.