Reducing limescale

[Wagas]

Anyone have a recommendation for a filter of some kind that that connects to the incoming mains and reduces limescale build up in the house? Preferably a small unit that doesn't require electricity. Thanks

[Jeremy Harris]

There's only one way to remove limescale from water, which is to remove the calcium and magnesium ions from the water, so that calcium and magnesium carbonates cannot form. There are two ways to do this, using an ion exchange resin, which swaps the calcium ions for sodium ions, or use reverse osmosis.  The latter isn't well suited to volume water supplies, so that really leaves ion exchange.  There are a multitude of different ion exchange systems around, that differ mainly in terms of physical size, whether they uses electricity or not to control the valves and regeneration process and the type of salt they use.  The smaller units that don't need electricity are the Kinetico and the Harvey (both of which licence their technology to other companies).  We have a Harvey and have found it to be reliable and effective, and it's supposed to have some advantages in its water metering system over the Kinetico, but I believe these are probably a bit marginal.  Both are compact units that can fit (just) in a kitchen cabinet if need be, although we have ours in the services room.

 

There are lots of other devices that claim to reduce the impact of limescale, using magnets, special catalytic elements, etc, but these don't actually remove anything.  There is some limited evidence that they may slightly change the nature of the carbonates that precipitate out, making them less prone to sticking to stuff, but my own preference is to just remove the limescale completely.  Some of the water conditioning devices that are marketed are simply snake oil, and use pseudo science to make them sound as if they are doing something magical.

 

Finally there are phosphate dosing hard water treatment systems.  These can work very well to stop limescale sticking to things, as although they don't remove it, they do reduce the impact it has on things like washing machines and dishwashers.  They have the advantage of being cheaper to buy then something like the Harvey or Kinetico units, but they do need topping up with phosphate balls, that can be more expensive than salt.

[oranjeboom]

@Wagas Have a read here. Some entertaining discussing on some 'revolutionary technology'

 

 

[Temp]

@JSHarris has pretty much covered the options.

 

Beware there are numerous gadgets on the market, some for very high prices that are best avoided. The Advertising Standards Authority has ruled many times on the claims made for clip on magnetic, electronic or fairy crystal based gadgets that claim to be able to soften water and remove limescale.  The general rule appears to be that in the UK such gadgets cannot claim to soften water unless they remove the calcium/magnesium.

 

https://en.m.wikipedia.org/wiki/Magnetic_water_treatment

 

"Magnetic water treatment is regarded as unproven and unscientific".

 

 

[richi]

I'm now two years into my whole-house Combimate installation (which reminds me: It's time to buy new phosphate balls). I'd call it a qualified success.

 

In a hard water area like this (north Hampshire), it makes it easier to clean the taps and things. The calcium doesn't stick, nor make crusty deposits. It's not magic, but it's a lot less bulky and expensive than a softener.

 

Running costs: The phosphate-ball refill costs £25/year. Perhaps £50 if you used enough water to justify replacing them twice a year. £0 in waste water for regeneration, of course.

[Mr Punter]

I have fitted Combimates in new builds.  Quick to install and they don't take up much room.  The only issue is if you leave them with the phosphate balls and don't use any water the stuff breaks down and you risk clogging the system.  You can take them out if you plan to be away for over a month.

[Temp]

Am I right in thinking the Combinate just passes water over the balls? If so you might be able to make one from a water filter and refill balls for a less than they charge for the device.

Edited September 7, 2019 by Temp

[Jeremy Harris]

3 minutes ago, Temp said:

Am I right in thinking the Combinate just passes water over the balls? If so you might be able to make one from a water filter and refill balls for a less than they charge for the device.

 

Pretty much, yes.  Our boiling water tap came with a phosphate dosing unit, that was just a replaceable cartridge filter that contained phosphate balls. 

 

Probably worth an experiment to see if just sticking some of these balls inside a clear water filter housing would work.  Might be an idea to plumb a ball valve bypass around it, so that the flow rate over the balls could be adjusted, as it might work better, or use less phosphate, if the flow over the balls is adjusted to be just enough to stop limescale sticking to stuff.

[PeterW]

4 minutes ago, Temp said:

Am I right in thinking the Combinate just passes water over the balls? If so you might be able to make one from a water filter and refill balls for a less than they charge for the device.

 

You can buy a standard 10” filter that does that already. 

 

https://www.wiltec.de/nw-790-g-siliphos-cartridge-silicate-phosphate-binder.html

[Jeremy Harris]

4 minutes ago, PeterW said:

 

You can buy a standard 10” filter that does that already. 

 

https://www.wiltec.de/nw-790-g-siliphos-cartridge-silicate-phosphate-binder.html

 

 

I have a couple of refillable water filter cartridges that are identical to the one in that link, minus the phosphate balls.  I use mine to hold silica gel, as an air dryer on our ozone system.  The empty cartridges are cheap and easy to refill, so I keep one in use and another in a sealed plastic bag ready to swap over (I rejuvenate the silica gel granules by gently baking them in the oven).

 

The cartidges I have are like these: https://www.ebay.co.uk/itm/10-Refillable-Water-Filter-Cartridge-Refill-with-DI-Resin-Carbon-Polyphosphate/302974549259?epid=1448362502&hash=item468ab0bd0b:g:GXEAAOSw~RVaGEds

 

They fit a standard water filter housing.

[MrMagic]

@PeterW - what kind of flow rates would you get through a single 10" polyphosphate cart? I've been looking at the spec sheets but they all seem to omit flow rate.

 

Essentially I have my main incomer split, one goes to feed the combi for DHW, the other provides the 'cold' feed to the rest of the house... I'd have to install (at least) one 10" filter on each feed... any ideas if that would inhibit the flow much?

 

Simple (tightarse) moneysaving - £250+ on a pair of combimates or £50 on a couple of 10" filters and poly refils.

[tonyshouse]

Tony’s secret way ro reduce lime scale build up

 

in kettle, always empty completely immediately after boiling, allowing water to cool slowly maximises scale build up.

 

applying this to hot water cylinder - run at constant temperature, I use 50C and have done all my adult life. 24/7 365

 

alternatively get a water softener, beware of snake oil products there are a LOT out there 
 

 

[SteamyTea]

I don't have a secret method to reduce lime scale build up, I just live in Cornwall.

[Temp]

9 hours ago, MrMagic said:

@PeterW - what kind of flow rates would you get through a single 10" polyphosphate cart? I've been looking at the spec sheets but they all seem to omit flow rate.

 

Essentially I have my main incomer split, one goes to feed the combi for DHW, the other provides the 'cold' feed to the rest of the house... I'd have to install (at least) one 10" filter on each feed... any ideas if that would inhibit the flow much?

 

Simple (tightarse) moneysaving - £250+ on a pair of combimates or £50 on a couple of 10" filters and poly refils.

 

I was also considering making one.  The holders are normally designed for 10"*2.5" carts but there are "jumbo" versions which are 10"*4.5" and double length 20"*2.5" both of which should have less resistance to the flow.. You could also use two in parallel to boost flow rates.

 

Example Pair of jumbo carts but these are in series..

https://www.finerfilters.co.uk/finerfilters-10-jumbo-high-flow-double-water-filter-housing.html?gclid=CjwKCAiAjMHwBRAVEiwAzdLWGInx_E8xNuP2QWESQWLjyT4U34xkTcn-z_OkEJy3LD7bNA7lyMnwehoCq8kQAvD_BwE

 

Haven't yet found a jumbo size refillable cart but haven't looked hard as other projects are going to keep me busy for quite a while.

 

Some water filter holders have/haven't got brass thread inserts which seems to affect the price a lot.

 

[Jeremy Harris]

In my experience, the flow restriction from the filter housing, even the standard small 10" one, is very low, 99.99% of the restriction comes from the filter cartridge.  The refillable inserts that fit the 10" filters also have a very low flow restriction when empty, and I'd guess that the restriction around the polyphosphate pellets will be pretty small, as they are fairly large, with big gaps around them.

 

I'd be inclined to get a standard 10" housing, one with 3/4" BSPF fittings and a clear lower part, plus a clear, refillable media cartridge, and see how it goes.  I doubt you'll notice any pressure drop through this.  I think you may have to rig up a bypass, anyway, to be able to get the dosing right.  I don't think you want all the water to flow through the polyphosphate beads, just enough to get the right dose.  A simple bypass across the filter, with a ball valve, would probably be enough to adjust things, but you might also need another valve to restrict the flow through the cartridge a bit.  I believe that the clever stuff in the Combimate is mainly the bypass arrangement that gets the dosing right, so I would expect a home brew system to need a bit of trial and error to get set up.