On 15 Sep 2004 15:15:34 -0700,
(Lobster) wrote:

(adder) wrote in message . com...
"IMM" wrote in message ...
"Aidan" wrote in message
om...
What is the best inhibitor to use in this sort of system anyway? I was
going to get some more Fernox MB1 but it's a bit pricey (£19/4l).

No idea, I don't know what's in any of them. I use Fernox or Sentinel.
Corrosion is cheaper, in the short term..

Sentinel X-100 is far cheaper and just as good.

Some of the old combined pressure hot water & heating (i.e. the hot
water tank acts as a pressure vessel for the heating) types you're not
allowed to put inhibitor in because of possible contamination of the
potable water.


OP back again...

I'm now a bit confused as to which inhibitor I can use in my combi
system. I was going to buy one of those injector kits, but found a
Fernox one in B&Q for £26 so thought it was worth looking into
further, particularly when you can buy a 1L bottle of el cheapo Protex
stuff from Screwfix for only £3.59. What's the difference?

I gather Fernox and Sentinel are the brands to go for, for whatever
reason, and note that on Screwfix's site (http://tinyurl.com/3l4ow),
Sentinel X400 is stipulated as being for indirect systems (combis are
direct, right? ie no h/c water storage, all water at mains pressure?)
whereas the Protex one isn't. Does this relate to potable water
issues as mentioned above? Have I *got* to buy the cheapo stuff, or
go to B&Q for a whopping £26 kit?

I've used Fernox products - originally MB-1 but more recently
Superconcentrate gel and Alphi-11 in various systems for over 25
years. I have never had sludging problems at all.

Ergo, I know that these products work.

I am certainly not going to fret over trying to save £20 every few
years when the risk factor in products that are unknowns and may or
may not be good in the long term is many thousands of pounds.

When a chemical is specified as being for indirect systems it refers
to those with a cylinder where the indirect aspect is because the
heating of it is via a coil. Therefore the primary and secondary
water never come into contact.

A combi is a different arrangement where a separate heat exchanger
inside the boiler warms the DHW directly. Again the two sets of water
are kept apart.

Sentinel have a good reputation as well. I would not attempt to
save a few pounds by buying an unknown brand with unknown means to
test its effectiveness. The saving is far outweghed by what is at
stake.


..andy

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