Combimate

[chloeriches123]

Does anybody have experience of the combimate, are there benifits in plumbing it into an existing system?

Will it eventually clear scale from existing pipes?

Many thanks.

[Andy Hall]

This is a phosphate dosing system.

It won't soften water.

It will reduce scale deposition. I have not seem claims that it will redissolve existing scale.

A proper ion exchange water softener will soften water and reduce detergent costs. It will prevent scale deposition and will gradually dissolve existing scale.

[John Stumbles]

But they're really for different purposes. A phosphor-dosing system is to protect heating systems such as (as the name suggests) combi boiler heat exchangers) from scaling up. A water 'softener' makes hard water behave like soft water in respect of soaps and detergents lathering more readily (although it doesn't turn it into 'real' soft water: it just turns the calcium salts of hard water into their corresponding sodium salts).

Since limescale is, to a first approximation, insoluble in water neither phosphor-dosed nor artificially softened water will dissolve it readily, but it's possible that either will gradually reduce it (since it is probably soluble to a very small extent).

Some phosphor-dosing scale inhibitor devices have tiny waterways to get appropriate levels of dosing. Unfortunately these are prone to blocking with redeposited phosphor salts and become inefective until the waterways are cleared again. The Permutit types with a metal can of salt fitted into a chromed brass attachment to the pipework are prone to this. I have only come across one combimate and that seemed to have got into this state too: it still had some crystals in its chamber after many years suggesting that it wasn't dosing any more. Screwfix now do a 'whole house' dosing system which doesn't have tiny waterways and therefore shouldn't be prone to this problem. It's also a lot cheaper than other systems, as well as potentially able to treat a lot more water.

[John Rumm]

I have one. Not having taken the plate heat exchanger apart on the boiler I can't comment on how effective it has been so far other than to say it being going four years now without any problem in a fairly hard water area.

No, and it won't help with scale deposition resulting from evaporation, so sinks, shower screens etc will still rapidly acquire hard water marks after cleaning.

[chloeriches123]

[Doctor Drivel]

Showershine type of sprays prevents that.