On Thu, 27 Mar 2008 16:01:05 +0000, Andy Hall wrote:

On 2008-03-27 15:44:36 +0000, said:

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.

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.

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 Stumbles

Bob the builder / it'll cost 'yer
Bob the builder / loadsa dosh