Dirty water - how to flush out a hot water cylinder?

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jonathan18

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#191603 10-Feb-2016 08:53

We've had issues with brown water for a while, and it's been confirmed it's not the supply or the pipework itself, but is limited to the hot water - which apparently means it's crud build-up in the cylinder.

In an attempt not to have to replace the cylinder, we'd prefer to be able to somehow reduce the crud to an acceptable level - the plumber suggested purging the cylinder, which I'm yet to do, but the issue will probably still remain given the outlet for doing this is about 15-20cm above the bottom of the cylinder, so much of the sediment will remain below the outlet level and therefore will be untouched.

Can anyone advise how we could go about significantly reducing the level of sediment? I know there are plumbers on here eg @Aredwood?), and I was hoping they and other members may have some ideas.

I was thinking of purging it as suggested, then filling it just a bit to disturb the sediment before purging it again, and then repeating a few times.

Thanks for any ideas!

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#1488550 10-Feb-2016 09:01

Would you really be happy with knowing there's less cr*p in your hot water, rather than virtually none? Cylinders are in the region of $1200, plus fitting. Hot water is regularly used for cleaning you, your cutlery, and sometimes in kettles and such.

jonathan18

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#1488575 10-Feb-2016 09:18

timmmay:

Would you really be happy with knowing there's less cr*p in your hot water, rather than virtually none? Cylinders are in the region of $1200, plus fitting. Hot water is regularly used for cleaning you, your cutlery, and sometimes in kettles and such.

At this point in time - yes! We're just embarking on a fairly costly house spruce-up, so an additional $2k or so (it's gas so not as cheap as electric) really isn't something we need right now.

If we can't make a sizable dent in the crud, we will of course look at replacing; at that point we'd contemplate whether we switch to an electric cylinder, given we now only use gas for hot water and cooking (hob). Speaking of which - can most existing gas hobs be converted to run off LPG? Ours is a hob attached to the (electric) oven; it's an Indesit (not a brand or model I'd have chosen...).

Stu

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#1489656 10-Feb-2016 11:52

Ours has a flush pipe right at the bottom, under the cylinder, with a plug at the end which is outside the house. Was perfect for emptying the cylinder when we replaced it at the end of last year. Looked to be ~40 years of crud flushing down the drain!

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Stu

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#1489659 10-Feb-2016 11:54

For the gas hob, it's usually a matter of having the brass jets replaced with a different size. Must be done by a suitably qualified tradie apparently.

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jonathan18

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#1489666 10-Feb-2016 12:02

Stu:

Ours has a flush pipe right at the bottom, under the cylinder, with a plug at the end which is outside the house. Was perfect for emptying the cylinder when we replaced it at the end of last year. Looked to be ~40 years of crud flushing down the drain!

Yep, that placement makes total sense! Why ours is 15-20cm from the bottom is anyone's guess, as its placement ensures we can't fully drain it. (I guess the only issue with placing the flush pipe under the cylinder as in your case is increasing the likelihood of it becoming blocked, and also of access to clean it out if this happens?)

Googling the issue suggests that my plan to refill partially and empty (and repeat) once it's been initially drained appears to be the most commonly recommended approach.

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#1489675 10-Feb-2016 12:07

The new cylinder also has inlets on the side like yours. I guess for use when there's a concrete floor? No idea why it'd be used if there's one in the bottom.

Would it be cost effective to remove the cylinder, flush it and put it back in?

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jonathan18

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#1489676 10-Feb-2016 12:10

Stu:

The new cylinder also has inlets on the side like yours. I guess for use when there's a concrete floor? No idea why it'd be used if there's one in the bottom.

Would it be cost effective to remove the cylinder, flush it and put it back in?

Are you thinking that removing it would allow it to be tipped on its side, hence the crud to be drained more directly out of the hole? Certainly an idea worth asking of the plumber (though I assume would need disconnecting the gas as well as water?) - cheers!

timmmay

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#1489678 10-Feb-2016 12:12

Cut the top off, get in there with a spade?

gzt

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#1489684 10-Feb-2016 12:28

Ask your plumber to flush it. Don't ask how, they know how! : ).

For diy, look at draining it through the inlet. On inspection of the inlet sequence you may find it has a two way installed for that purpose already.

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#1489688 10-Feb-2016 12:31

Remember there may be contributing factors like an old failing Ajax delivering built up cruft into the cylinder.

PhantomNVD

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#1489828 10-Feb-2016 16:24

And if replacing it, go straight to Califont, and save a fortune on keeping 100+ litres hot all day everyday 🤔

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Stu

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#1489856 10-Feb-2016 16:32

jonathan18: Are you thinking that removing it would allow it to be tipped on its side, hence the crud to be drained more directly out of the hole? Certainly an idea worth asking of the plumber (though I assume would need disconnecting the gas as well as water?) - cheers!

Yes, the gas would have to come off as well. Would mean you could drain it and shove a hose into it to give it a good clean out (this cylinder needs an enema!)

Depends on cost, though. By the time the plumber/gas fitter have disconnected and reconnected it, the only thing missing is a new cylinder, so maybe just get it replaced!

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#1489863 10-Feb-2016 17:01

We also have an old cylinder with the raised outlet. I assume the reason is similar to the elbow in kitchen drains, to trap rubbish so it doesn't plug the system. I have no idea if this would work, but one possibility might be to get a short length of narrow hose or tubing that would fit into the pipe (any hardware store), duct-tape it to a vacuum cleaner attachment, and vacuum out the crud. Of course you should use a vaccum cleaner that doesn't mind getting wet.

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Fred99

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#1489885 10-Feb-2016 17:59

Stu:

For the gas hob, it's usually a matter of having the brass jets replaced with a different size. Must be done by a suitably qualified tradie apparently.

My gasfitter just gave me jets to DIY (put me in prison, flog me, cancel my insurance, report me to the SPCA in case I gas my cat etc etc). In that case the standard jets were a bit small for the wok burner, so went up a couple of sizes with strict instructions that the flame must still be blue on full output, tinge of yellow means it's generating carbon monoxide which might kill you, and soot which will make a mess. There should be replacement jets for LPG in the plastic bag with instruction manual. IIRC the socket needed is an odd size - can't remember, 6.5 mm perhaps. Useful to have the tool to remove them for when they get blocked and need cleaning in future.

Stu

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#1489901 10-Feb-2016 18:32

I'd do it myself also. Not qualified to advise anyone else to do the same though, so won't.

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