New electric hot water cylinder vs gas cylinder, or infinity?

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duckDecoy

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#288862 28-Jul-2021 14:25

My office mate has an external gas hot water system that is 20 years old and on its way out. He needs to replace it with something and is looking for advice on the options.

It will need to be installed in the same place, so it wont result in any longer or shorter pipes. Heat pump cylinder is out of the budget (the recommended ones look to be 8k+)

Are there any advantages or disadvantages to a gas cylinder vs electric cylinder?

An infinity gas system is a possibility too, but there are comments on the web that you will notice a delay for the hot water to turn up. I am unsure if that delay is a general feature, or if it is because people repalced an internal cylinder with an external infinity and there is now a longer pipe run. Does anyone know if infinity systems would add a noticable hot water delay if installed in exactly the same spot?

EDIT: heating and cooking are also on gas, so he cannot consider dropping gas as a cost saving.

cshwone

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#2751228 28-Jul-2021 14:48

I have always had gas Infinity systems in the three houses I have lived in in NZ. All have been pretty consistent with only a few seconds until we get a hot flow. Comparable to the time it takes from a hot water tank really.

Batman

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#2751335 28-Jul-2021 15:03

The govt wants to get rid of gas

duckDecoy

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#2751336 28-Jul-2021 15:08

Batman: The govt wants to get rid of gas

Yes, that is on his mind. But will they? And if they do, when is it likely to happen.

wlgspotter

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#2751340 28-Jul-2021 15:37

duckDecoy:

An infinity gas system is a possibility too, but there are comments on the web that you will notice a delay for the hot water to turn up. I am unsure if that delay is a general feature, or if it is because people repalced an internal cylinder with an external infinity and there is now a longer pipe run. Does anyone know if infinity systems would add a noticable hot water delay if installed in exactly the same spot?

EDIT: heating and cooking are also on gas, so he cannot consider dropping gas as a cost saving.

I've had the Infinity (piped) gas system for 2 of the houses that we've lived in NZ, the others being electric hot water tank. The infinity system was already installed when we moved into the houses, so we used them outright from the moment we've moved it. In general, you can notice a slight delay in the infinity system, sometimes up to 10 maybe 15 secs, as the system have to light up and heat hot water on demand. The good bit of course is that you will never run out of hot water, especially if you have a large household. Overall we quite like the infinity system especially since you could control the temperature easier with a control panel typically located around the kitchen and/or bathroom areas.

For the other houses, it was an electric hot water, including out current place. Actually, our current place uses solar panel on the roof to heat up the hot water, with electric as backup (I usually need to turn on the electric heating element for about 6-7 months in a year, the other times I could just rely on solar heat alone). Personally, I find electricity somewhat cheaper for us (there are only 2 of us living in the household) compared to gas, and that would have been a big consideration.

If your mate already have gas widely used at home, then there are definitely synergies/benefits in going the gas path, "ignoring" the fact that perhaps the Govt may get rid of gas - as you indicated will they, and if so, when...?

Edit: Corrected typos and grammar

jonathan18

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#2751342 28-Jul-2021 15:45

I moved from an internally located gas HWC to an infinity system about seven years ago (at a guess); I initially had similar fears but these were assuaged by advice received here (there’ll be an old thread on this).

One of the best decisions we made, and wish we’d done it ages before. We were in a similar position - an older HWC cr@pping out - and one thing we noticed was a significant reduction in our gas bill, I assume due to a mixture of the inefficiency of the old cylinder plus the inherent benefits of heating just in time.

In our case there’s a slightly longer delay in the water turning hot as the best location to mount the system was not near where the HWC had been, but it’s not significant or terribly frustrating - given your workmate’s HWC is already external, I’d imagine it could be installed in the same place so this won’t be an issue.

What you may be referring to is that the heating takes a few seconds to kick in, so (for example) if getting in the shower soon after someone else there’ll be a jolt of cold(er) water once that bit makes its way through the pipes. Not a biggie in my opinion, and you soon get programmed to expect or avoid it.

We didn’t bother going with any of the controllers, and I don’t regret that at all.

Edit: Here’s that earlier thread, and it was in Oct 2016 so less than five years ago:
https://www.geekzone.co.nz/forums.asp?forumid=141&topicid=204543

Batman

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#2751347 28-Jul-2021 15:54

duckDecoy:

Batman: The govt wants to get rid of gas

Yes, that is on his mind. But will they? And if they do, when is it likely to happen.

depends on who's in power (govt). i dare say yes based on vehicle examples.

acc to this 2025 https://www.stuff.co.nz/environment/climate-news/124626848/the-end-of-bbqs-or-a-load-of-hot-air-the-proposed-ban-on-natural-gas-connections

tripper1000

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#2751359 28-Jul-2021 15:58

Is the subject property on bottled gas or reticulated gas?

Something to add to the equation is that if you switch away from reticulated gas for hot water, the remaining consumption (cooking, heating) can be too low to warrant keeping gas due to the monthly charges. Not so much of a problem for bottles because you can change to owned bottles to get away from the monthly rent.

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duckDecoy

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#2751360 28-Jul-2021 16:03

tripper1000:

Is the subject property on bottled gas or reticulated gas?

Something to add to the equation is that if you switch away from reticulated gas for hot water, the remaining consumption (cooking, heating) can be too low to warrant keeping gas due to the monthly charges. Not so much of a problem for bottles because you can change to owned bottles to get away from the monthly rent.

Mains gas, and yes we've discussed that. he's not sure how much he uses for heating so doesn't know how to determine if the bottles would be viable.

Scott3

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#2751363 28-Jul-2021 16:09

More information is really required to work out which is more cost effective. Key bits;

Is the gas connection piped or bottled. (piped natural gas is about 1/3rd the price of 45kG bottles of LPG, but comes with a $30 monthly fee)
Is the household on a low or standard user power plan, and is it somewhere in the country where power is expensive or cheap. - My standard user power connection costs about the same as LPG in 45kg bottles, so no cost saving going that route.

If they are on natrual gas, and given the monthly fee is sunk as they need it for cooking and heating, going the natural gas route would be much cheaper to run.

If they are on LPG and a standard user power plan, it will be about break even.

If they are on LPG and a Low user power plan, LPG will be cheaper.

I have an (inside) electric cylinder here (mains pressure), 25+ years old and still going sweet, Pressure cranks, that the 180L is heaps for my household.

If I was to go gas I would probably for a tankless setup. Generally these are pretty sweet. Physically small, No standing losses, ability to easily adjust temp via controller etc.

They do have some quirks. - if you want to leave a hot tap trickling for some purpose they won't be able to feed hot water to it. And they will chase around frequently changing hot water demand (had a washing machine that would do warm via pulsing the hot at a flat with a tankless gas heater. Hell if you were in the shower at the same time. Note they have less lifespan than an inside electric cylinder. If you get 10 - 15 years out of one you have done well.

That said nothing wrong with gas cylinders. They generally reheat faster than electric cylinders, but I imagine would be otherwise similar. Never had one myself.

duckDecoy:

Batman: The govt wants to get rid of gas

Yes, that is on his mind. But will they? And if they do, when is it likely to happen.

Draft report this is based on is here:

https://ccc-production-media.s3.ap-southeast-2.amazonaws.com/public/evidence/advice-report-DRAFT-1ST-FEB/ADVICE/CCC-ADVICE-TO-GOVT-31-JAN-2021-pdf.pdf

Talking about no new as connections from 2025 (bottles and natural gas), and a ending the supply of natural gas to houses in 2050.

Senecio

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#2751367 28-Jul-2021 16:15

We have infinity gas hot water system and there is no noticeable delay in hot water delivery over cylinder hot water systems. Our infinity system is directly outside our laundry and bathroom and when I want hot water in there it is almost instantaneous. There is a delay in hot water to the kitchen but that's ~20m pipe run to the other end of the house and would be there no matter which type of hot water system we used.

Zeon

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#2751369 28-Jul-2021 16:16

Gas will be around for a LONG time yet, even if the country has to start importing it like we now do with coal.

Considering all of the connections etc. will be there it could be easiest/cheapest to use the same setup he had previously. If he gets electric he will need to probably run new cables etc.. so there are electrician fees to consider there?

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Scott3

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#2751370 28-Jul-2021 16:16

duckDecoy:

Mains gas, and yes we've discussed that. he's not sure how much he uses for heating so doesn't know how to determine if the bottles would be viable.

As per my above comment, if the connection fee is a "sunk cost" regardless, going natural gas for this is the economic solution.

6c/kwh for natural gas vs 18c/kWh for standard user power, or 30c/kWh for low user power...

Not too bad environmentally either as the marginal unit of power generation in NZ is often gas or coal, and much better to burn the gas directly in a 90% efficient water heater, than to run it through a 35 - 50% efficient power plant and 95% efficient power grid...

If the situation changes in 10 - 15 years, a tankless water heater will be approaching end of life anyway...