Phosphate doser questions

[Sponix]

I posted recently asking about "descalers" for combi boilers.

I spoke to my friend who has pretty much decided to get a "Fernox Quantomat". From what I can see it's suitable for whole house use as well as protecting the boiler.

What are the advantages to protecting the whole house instead of just the boiler? Scale build up only occurs on the hot side so is there any point protecting the cold water circuit?

Obvious disadvantages are that it'll cost more and the family will be drinking water with phosphates in it.

(fwiw, he's never had any problems with appliances scaling up.)

Unless anyone can see an advantage to whole house protection I'll recommend fitting it to the boiler only.

sponix

[John Rumm]

Limited in my experiance - it only has a big effect on scale precipitated out during heating. Since it does not soften the water the scale is still present in it and will be left on surfaces when the water evaporates. You may find that it reduces scale a little - but you will still get it on hard surfaces etc.

Remember however that many dishwashers etc will fill from the cold and do their own heating - so for that reason it is probably worth treating the whole house supply.

Things like the combimate use food grade phosphates and only add tiny amounts... they are not that expensive to run anyway - but you may want to avoid feeding the outside tap since that is where you may use a significant amount of cold water.

[Sponix]

From what I can gather it simply coats the insides of the pipes with phosphate which stops the scale from sticking. The scale is still there but doesn't stick.

Apparently some soft water areas have phosphate added by the water board. It coats the inside of lead pipes and stops the lead getting into the water...

It's never been a major problem from what I can gather. Appliances have failed for other reasons long before the scale has an effect.

Cost isn't an issue. What could cause problems is forgetting to check the device isn't empty!

sponix