Replacing our hot water cylinder... options

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10 years 7 months ago #35986 by kiwilassee
Our current low pressure hot water cylinder was installed in 1981 and we are renovating our bathroom shortly (October), so it seemed a good time to replace our 32yo system (with the 25yr lifespan we're probably pushing it).

Some background info...
- two adults (however, we are hoping to start a family soon)
- 2 x 5000 gallon concrete tanks with pump (didn't run out last Summer, which was a drought!)
- currently no bath but getting one with bathroom reno in October
- one bathroom, two toilets
- septic tank
- in next year will add Thin Tank under house for greywater
- we will be buying Methven All Pressure tapware for our new bathroom

Currently, we don't have issues with ...
- water running out
- pressure of water (shower is fine and rinsing thick hair is no problem)
- getting cold in shower (do make an effort to put dishwasher and washing machines on timers but never had problems with someone turning on taps in kitchen or bathroom whilst someone's in the shower, which in one year of living there, must have happened a few times inevitably!)

To be honest, there's not really a problem with our current system but as it is 32yrs old, it does seem like a ticking time-bomb. So we figure these are our options and the pros/cons as we see them...

1. electric system - low water pressure
2. electric system - mains pressure
3. heat pump system - low pressure (probably with Econergy)
4. heat pump system - mains pressure (probably with Econergy)
5. gas hot water

(from what we've read on solar, it's still far too expensive and still needs a lot of topping up with electric, so for us, it's not really an option yet).

1. MAINS ELECTRIC: PROS
- more hot water through the taps
- no change in temp when someone else turns on the water elsewhere in the house (not currently a problem)
- better with a bath

1. MAINS ELECTRIC: CONS
- 10 year lifespan
- will use water faster and could therefore run out of tank water and have to buy water

2. LOW PRESSURE ELECTRIC: PROS
- 25 year lifespan
- less water than mains therefore cheaper (is this right?)

2. LOW PRESSURE ELECTRIC: CONS
- may get worse pressure with new bathroom (a big unknown?)

3. MAINS PUMP: PROS
- cheaper water heating
- hot water faster (claims their website anyway!)
- more hot water through the taps (ie. mains pressure)
- no change in temp when someone else turns on the water elsewhere in the house (not currently a problem)
- better with a bath than low pressure
- supposedly adds capital value?

3. MAINS PUMP: CONS
- 15 year lifespan
- will use water faster and could therefore run out of tank water and have to buy water
- more expensive to install

4. LOW PRESSURE PUMP: PROS
- cheaper water heating
- hot water faster (claims their website anyway!)
- supposedly adds capital value?

4. LOW PRESSURE: CONS
- 15 year lifespan
- more expensive to install

5. GAS: PROS
- cheaper water heating
- cheaper to install than replacing your HWC
- frees up space where your HWC
- control of temperature and quantity via a control panel (good for filling the bath)
- shower will never run cold (unless you run out of gas which shouldn't happen)
- option to add gas cooking

5. GAS: PROS
- unsightly appendage to your house
- not instantly hot when you turn the tap on (may take longer for the water to run hot when tap is turned on)
- have to remember to fill up gas bottles (and they're big so quite a bulky job)

And now for some questions...
- any comments/feedback/additions to the pros/cons above?
- will we need to change our kitchen and laundry tapware? (no idea what they are currently)
- will we need to change/upgrade our pipes?

Thanks, in advance :-) and sorry for the long post!

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10 years 7 months ago #470535 by igor
If the current hot water cylinder is not leaking or giving trouble in any other respect I would leave it alone. It may continue to function for many years. You can bet that the new one you buy will not last as long as the old one already has. When the time comes to replace the cylinder it is a simple task that should not require the alteration of any other pipework in the house.
There is no need whatsoever to change any of your other tapware. Similarly the pipework should be fine also unless it is damaged and leaking. Do not let anyone sucker you into replacing systems that are in good working order just because they would like to sell you new stuff.

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10 years 7 months ago #470554 by kindajojo
we had to replace our hot water cylinder and found that a solar system was the best option because:
1 we had to get a new cylinder anyway.
The edwards system could be mounted on the roof with the solar panels, so we actually gained a storage cupboard.
The solar was not optimal because of the orientation, but was then connected to a wetback and solar panel, with an electrical base giving hot water supplement in winter and summer.
Not sure on the current costings but we have ours up for 8 years with no problems.

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10 years 7 months ago #470576 by Murray100
Our H/W cylinder split about 2yrs ago and we replaced with gas after similar analysis. Some comments on your pro & cons:

Control panel - not needed, just use the cold tap as before. Costly and unnecessary.

Unsightly - a bit, but not bad with a good installer.

Time to heat - MUCH better than HWC. Pretty much instant.

HW Pressure - extremely good and no running cold if another tap is turned on.

One small downside - all but the lowest flow units have inbuilt electric pumps and electric igniters so dependent on power. Some low flow units have flow of water igniters but were not recommended

The biggest problem we had was the minimum exhaust to window distance.

Gas filling - no issue, the supplier comes around every so often with a tanker & long hose. No need to touch the tanks.

Pipes / Taps - no changes required.

The tank space has come in handy!

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10 years 7 months ago #470607 by max2
When we built we installed a greenglo tank www.greenglo.co.nz/ in our ceiling cavity. Our wetback on the fireplace is connected to it.

We hope to install solar at some point but were weighing up the pros and cons of generating our own power rather than just worrying about hot water. Either or, at least we can also connect the solar to it if and when we install the roofing tubes.

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10 years 7 months ago #470623 by kiwilassee
Thanks all for the comments... all very helpful and gives us lots to think about.

Great timing, just got the latest Consumer Report and there's an article on Solar Water Heating... saying not yet a good option!

www.consumer.org.nz/reports/solar-water-heating

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10 years 7 months ago #470631 by blimeyvicki
We just replaced out hot water system with Gas.
We bought the house 4 years ago and a couple of months later the cylinder sprung a leak. We had to have a new one custom made as the tank was made to lie on its side and had a wet back attached to it. 2 years later that tank sprung a leak. Had to get it fixed and the supplier wouldn't stand by his warrantee as he said we had hit it with a hammer (?????). Another year later it springs another leak. Cue me throwing a massive tanty and throwing out cylinder (literally) and having gas installed.

Yay! Love it. Gas man comes around when we ask and swaps tanks. Never ending hot water, much faster to tap than it used to be and much better pressure. Only downside is a much higher water usage :( Lower power bills though!.

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10 years 7 months ago #470632 by igor
How do you have higher water usage BV? You ought to be using less through not wasting a lot while waiting for the tap to run hot. If the pressure is higher you just need to turn the tap on less far.

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