I like soft water (softened with a unit that uses salt) but I hear that the salt ruins boilers aluminium heat exchangers. Since most boilers do have aluminium heat exchangers, I find it odd that the manufacturers (Permutit, Prismermetic, etc) do not mention this. As far as I can gather, only one boiler maker (Vaillant) actually has a cast iron heat exchanger anyway. Is this danger over-stated? Or would I be foolish to go for an ordinary boiler. I was thinking of a Worcester Bosch combi. Thank you.
Boilers and water softeners
- Thread starter NickStone
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Vaillant have never had cast iron heat exchangers the newer ones are stainless steel. Others will come on and tell you why you cant put softened water through a boiler
NickStone said:
Softened water is ok in stainless steel heat exchangers but not in cast aluminium. If your boiler has a cast aluminium heat echanger then whenever you fill the system you will just have to put the softener on bypass to fill with hard water. Note most manufacturers warn of this in theri installation instructions.
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wow 
kevplumb said:wow
Their old one was a Vokera, about 10 years old. The only reason for replacing it was cos their insurers refused to warrant it anymore because of its age.
I was dubious as well, so I had to protect myself against all liability. Previously I had asked different manufacturers about this. They did not seem to be unduly concerened about electronic softeners but their chief complaint was the effect of salt on copper components within the boiler.
Anyway, I dunno.
Worcester use aluminium not stainless st. Call them or see the instructions.
Chlorides are very bad for many stainless steels, so if any come out of a water softener (from the salt) it could be a mess, depending which st st the mfr uses.
Chlorides are very bad for many stainless steels, so if any come out of a water softener (from the salt) it could be a mess, depending which st st the mfr uses.
You should not fill any heating system (primary side) with softened water.
The inhibitors are formulated for use with mains water and the amount of limescale in the initial fill is insufficient to cause any damage. Any make-up connections (connections to F&E float valve or to a combi filling loop) should be made to the upstream/hard water side of the water softener. There should be a negligible make-up demand.
The PSA recommendations for large (i.e., district) heating systems used to recommend the use of de-ionized water + inhibitor for make-up.
There should not be any chlorides discharged from the softener into the water supply. The resin changes calcium carbonates into sodium carbonates until the resin is depleted. The salt (sodium chloride) used in ion exchange water softeners is used to regenerate the resin. On regenerating with salt, the sodium is absorbed by the resin and calcium chlorides are discharged into the drain.
The inhibitors are formulated for use with mains water and the amount of limescale in the initial fill is insufficient to cause any damage. Any make-up connections (connections to F&E float valve or to a combi filling loop) should be made to the upstream/hard water side of the water softener. There should be a negligible make-up demand.
The PSA recommendations for large (i.e., district) heating systems used to recommend the use of de-ionized water + inhibitor for make-up.
There should not be any chlorides discharged from the softener into the water supply. The resin changes calcium carbonates into sodium carbonates until the resin is depleted. The salt (sodium chloride) used in ion exchange water softeners is used to regenerate the resin. On regenerating with salt, the sodium is absorbed by the resin and calcium chlorides are discharged into the drain.
>>>There should not be any chlorides discharged from the softener into the water supply. The resin changes calcium carbonates into sodium carbonates until the resin is depleted. The salt (sodium chloride) used in ion exchange water softeners is used to regenerate the resin. On regenerating with salt, the sodium is absorbed by the resin and calcium chlorides are discharged into the drain.<<<
Thanks, onetap. It sounds as though you're saying that water softeners that use salt don't allow the salt to get through to the boiler anyway, so wouldn't cause any damage? In that case, I've obviously been misinformed along the way, and don't really need to worry. Perhaps some cheap softeners don't do this, but I'd always go for a reputable make like Permutit.
Thanks, onetap. It sounds as though you're saying that water softeners that use salt don't allow the salt to get through to the boiler anyway, so wouldn't cause any damage? In that case, I've obviously been misinformed along the way, and don't really need to worry. Perhaps some cheap softeners don't do this, but I'd always go for a reputable make like Permutit.
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