Hot Water Cylinder Replacement Options

I don't know why people are so keen on LPG.

Main selling point of instant gas systems is endless hot water. Given OP don't run out their current 180L 2kW cylinder (which would likely be replaced with a 3kW one, giving faster recovery), this isn't really a selling point for them.

Minor selling point is freeing up space in a cupboard (or eliminating the need for one to be included in a new build), and the ability to dial up a temperature rather than mix it.

I think many people who have changed from a low pressure cylinder to gas rave about the pressure etc, when a mains pressure cylinder would have done the same.

Gas instant does have some minor downsides. Generally the units last less long than a cylinder installed inside, some need reset after a power cut, and they struggle with low or highly variable flows (Had a washing machine at an old flat which would control water temp by pulsing. What torture if you were in the shower with the gas water heater trying to chase the pulses). Also if retrofitted with an external unit, the additional pipe run to get to the hot water cupboard can mean that it takes longer to get hot water to the taps. Generally they cost more too.

Resilience to power cuts seem over hyped too. As other have said, you would need an UPS or similar to run the unit. In NZ cities power cuts that run longer than the hot water in your tank will last are fairly rare, and it is possible to deal with not having hot water.

Generally 45kg LPG bottles works out similar or more expensive than a standard power user using an electric cylinder (more expensive based on my power pricing), so unless one is a low user, not much saving to be had. Also some power companies give cheaper rates to those with electric hot water (can be ripple controled).

Natural gas is a lot cheaper, but the last flat I lived in with it, the savings roughly matched the monthly connection fee. (also note that getting hooked up typically costs $600+).

Environmentally electric is better too.

OmniouS:

Thanks very much everyone for the feedback. Lots of excellent suggestions here to consider and ask the plumber about.

Due to the constrained install area and existing 500x500 (I think it was) drip tray, we wouldn't be able to fit in a Stainless Steel unit without reasonable renovations which we can't really do at the moment after recently painting the house. These units seem to be larger than their VE counterparts.

We have bottled gas available at the other side of the house (2 x 45kg) that just feeds into a gas fire at the moment. We could investigate utilising this for a gas water heater. The pipes would need to run a reasonable distance but I'll ask about it on Mon. We also have a gas feed on the street but note the comments about this being deprecated at some point.

The instant on electric heater sounds like a great option to replace the 45l cylinder when it dies - it's around 15 years old. Removing the small cylinder and plumbing the kitchen into the main one might be possible. It is quite nice having near instant hot water in the kitchen though which would probably change.

Good point regarding the wiring capacity for the cylinder. There is currently a single 16A circuit on the fuse board that's marked 'Water Cylinder'. Not sure if this is for both cylinders or just the main one. The switch to the cylinder is a modern PDL unit with a reasonable size cable coming out of it so hopefully that's promising. Thankfully it's reasonably close to the main fuse board so we could look to run a new cable if necessary. There is also a ripple control unit installed.

I also wouldn't mind some sort of IOT current monitoring device (clamp around the cables?) to add to our home dashboard and monitoring to alert on anomalies

Rheem makes a 180L, 490mm outer diameter Stainless steel cylinder.

Commented on gas above. I wouldn't look at it unless your power rate is above 20c/kwh

Would recommend keeping the 45L cylinder at this stage. The cost of it is sunk now. I would expect it to give another 15+ years service. Generally dedicated kitchen cylinders are only installed if it is a long way from your main cylinder (inconvenient and wasteful to leave the tap running while wasting for hot water.) Always painful to swap to a less convenient option, and cost of keeping that cylinder warm is likely covered by savings from not having to run the tap for so long to get hot water.

Might be good to get the plumber to swap out the sacrificial anode when they visit next, given your other cylinder failed quite young.

You would want to talk to a sparky before buying a instant water heater - They need a fat dedicated power wire from the main switch board, and there may not be enough power from the street to accommodate it.

The 16A breaker will be able to feed a 3kW cylinder if it is the only one. You could check to see if it is feeding the little cylinder yourself if you wanted. (turn it off, wait for it to run cold, then pop the 16A breaker, wait say 4 hours and see if you have hot water at the little cylinder if not. Main cylinder unlikely to run out in 4 hours)

rogercruse:

The plumber that replaced our original 180l cylinder for the 300l unit explained that there is little difference in the prices of hot water cylinders - that is, a cylinder that twice the capacity isn't twice the price!. He further explained that there is little value in the unwanted original unit.

If we had the space, then I would have opted to have both cylinders servicing our hot water needs.

Our new tank wasn't much wider and the additional capacity was accommodated by a increase in the cylinder length.

Takes a lot less material to build one 300L cylinder than two 150L cylinder's. A lot less surface area in a single bigger cylinder too, which means less standing losses (than two cylinders with the same combined capacity).

If 300L is insufficient (unlikely in a residential setting, unless you have a massive number of people or are doing something unusual like only using off peak or solar power, or feeding a central heating system with it), and one has space, cylinders up to 800L are available.

Bung

decibel

Jase2985

Kickinbac

lapimate

Kickinbac

Scott3

Mehrts