The everlasting HWC

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neb

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#317449 16-Oct-2024 12:21

When we moved into the Casa de Cowboy we inherited the existing HWC, which AFAIK is a 1986 Rheem (it's covered in cylinder wrap so can't easily check). I don't know if they did some special run that year but it seems to be indestructible, it's so well insulated that we thought it had been switched off because we couldn't feel any warmth on it until we ran the hot water and realised it was running. Given its age it feels like we should do something about replacing it, but there's been no problem with it so far, and I asked a plumber friend whether there was a danger of it suddenly releasing its contents and he said that happened but was extremely rare.

Should we be worried? Having said this, Mother Neb's HWC is a 1975 Rheem and still going strong, apart from bleeding heat like crazy.

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#3298052 16-Oct-2024 12:55

I read somewhere that HWC's supposedly have a lifespan of 8-12 years lol and there is a lot of chatter around about them bursting/leaking. Not sure if this chatter has been amplified by the likes of the "Cylinder Guy", but our Rheem installed with the house 20 years ago, to this day looks brand new and works fine.

I posted this thread about continuous hotwater, thinking i'd be wise to replace our 20yo cylinder with something else before it bursts/leaks when we're not there - but now I'm not so sure. I think water quality has a lot to do with longevity in terms of corrosion.

Possibly like most things nowadays, older gear like this was built to last and newer gear with a more limited lifespan.

It would be interesting to hear from any GZ'ers who've had a HWC burst/leak on them and the age/type of cylinder and area/water quality.

richms

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#3298059 16-Oct-2024 13:03

Hard water is what kills them. NZ doesn't really have much of that so they last a very very long time here.

Richard rich.ms

Jaxson

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#3298079 16-Oct-2024 13:57

Well this did happen to us and flooded the house good and proper.

I would simply say, look out for any symptoms of rust. At the first sign of brown water in the bath/sink etc, get it replaced asap!

dimsim

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#3298084 16-Oct-2024 14:16

Jaxson:

Well this did happen to us and flooded the house good and proper.

I would simply say, look out for any symptoms of rust. At the first sign of brown water in the bath/sink etc, get it replaced asap!

Was this in a hard water area and approx how old was the cylinder?

BlargHonk

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#3298089 16-Oct-2024 14:33

Our one from 1986 started leaking recently and we got it replaced. Luckily it just started dripping and didn't dump all the water at once. See my post history for more details. Got an outdoor 300L cylinder. The best thing was putting it on a timer and using Contact's 3hrs free power each night. We are now getting ~50% of our total power usage free during this three hour window.

Jaxson

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#3298121 16-Oct-2024 16:12

dimsim:

Was this in a hard water area and approx how old was the cylinder?

Hard water means you're getting it out of the ground.
I'm in Palmerston North and it's a mix. Mostly from a dam in the hills but there are some bore sites contributing to the network.

Typically hard ward leads to premature electric elements, not sure on it's impact on actual cylinder failures.

Ours was a gas unit in a hallway cupboard.
When it let go the water supply kept trying to top it up, so it's a dump of the contents plus a continual hose running inside your house until it is identified.
Sucked well and truly. Plumber to isolate the cylinder itself so we could then turn on water for the rest of the house again.
Cold showers, dehumidifiers running for a week to dry the place out, carpets stretched etc.

Ultimately we replaced with a gas instantaneous unit outside.
Freed up the space inside to hold our suitcases but we lost a drying cupboard in the process as it no longer had any additional heating.

About 25 years old I'd say. 07 ish new and failed a few years back.
If there's any rust / brown water, get onto it asap. Do not muck around.

SomeoneSomewhere

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#3298124 16-Oct-2024 16:18

Stainless and copper (low pressure only) cylinders generally last a long time.

Vitreous enamel is highly variable; if the paint/enamel layer fails, then the underlying steel will start to corrode. Steel corroding expands into rust, popping off more enamel and exposing more steel.

They should have a sacrificial anode that corrodes instead of the cylinder, and is replaced on a regular basis. No-one ever replaces these so the cylinder does not last long once the enamel fails.

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tweake

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#3298131 16-Oct-2024 16:40

a lot of the early copper ones where thick copper which lasts a long time. not so much these days.

one of the worse things is many old cylinders where never installed on a pan, so they leak straight on the floor. if the floor is covered it can be hard to see the leak. afaik the normal failure mode is pinhole leaks. that also can be hard to spot.

Eva888

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#3298133 16-Oct-2024 16:51

There is also the power savings to consider with a new tank. Our very old one downstairs was unnoticeably seeping water so was being replenished with cold and therefore heating up a lot more of the time.

neb

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#3298136 16-Oct-2024 16:57

Yeah, that's the problem here, and it's a chipboard floor so will turn to mush if it leaks. There's a LoRA leak detector sitting right next to it for just this reason, although I'm not sure what I'd do if there was a large sudden leak, thus the inquiry to a plumber friend a while back where he said that particular style of failure is quite rare.

Having said that, it's most likely any quantity of water big enough to be a concern would exit via the access panel the builders put in the ceiling of the downstairs bathroom that the cylinder sits above and drop into the sink there... wonder whether it's worth installing a 10mm hole there to help it go that way?

roderickh

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#3298137 16-Oct-2024 16:57

Another consideration to upgrade - we had a low pressure copper hwc, and upgraded to SS external tank - heats more efficiently, higher pressure and also mounted outside - so obtained some cabinet space back.

Sharesies referral

neb

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#3298138 16-Oct-2024 17:00

How does that work at night when the temperature outdoors drops to low single digits or worse? Unless it's phenomenally well insulated you're going to lose a lot more heat than one sitting a a steady 20 degrees or so indoors.

tweake

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#3298144 16-Oct-2024 17:07

neb:

How does that work at night when the temperature outdoors drops to low single digits or worse? Unless it's phenomenally well insulated you're going to lose a lot more heat than one sitting a a steady 20 degrees or so indoors.

thats why i dislike external tanks. its not to bad with heat pump hot water because of the low cost of heating.

richms

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#3298146 16-Oct-2024 17:17

neb:

How does that work at night when the temperature outdoors drops to low single digits or worse? Unless it's phenomenally well insulated you're going to lose a lot more heat than one sitting a a steady 20 degrees or so indoors.

They are well insulated. The pipes not so much. At a friends house if you turned off hot water for a minuite or 2, then ran it again it would be nice and warm till the part that was in the pipe outside and cooled down came thru and you would get a blast of cold.

Richard rich.ms

tweake

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#3298190 16-Oct-2024 19:25

richms:

They are well insulated. The pipes not so much. At a friends house if you turned off hot water for a minuite or 2, then ran it again it would be nice and warm till the part that was in the pipe outside and cooled down came thru and you would get a blast of cold.

define "well insulated". i've seen claims that its "meets spec..." but they all look like very thin amount of insulation. remember that an indoor hwc also has the insulation of the house around it. also the pipes should all be insulated, including the cold as you don't want that to freeze.

the other thing is has anyone actually tested it? i bet no home owner has ever tested it. people assume its well insulated.

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