I have just removed a radiator for decorating and recently had a partial
drain down to replace a 3 way valve. I am now wondering what to add into the
system. I have used Fernox and Sentinel X100 in the past. I guess the system
is now a bit deficient of additives.
Worcester Heatslave Highflow Combi
Each fed by single end flow / return valves
System fitted 1988 (probably the last house to use the dual Yorkshire
Pipe 6mm microbore
The system seems to be working well.
I would like an additive that will dissolve any sludge and keep it in
suspension. I don't really want to clean / drain / flush as this adds lime
into the boiler. I intend to add whatever is recommended into the radiator
that I will be refitting before I open the valves.
Any suggestions / recommendations?
If it's all working OK and the water is reasonably clean - i.e. a
straw colour from the inhibitor; then I would be inclined to add more
if it's due and leave alone.
If you want to add something via the radiator, there are gel versions
of Fernox in a tube that can be injected through the vent.
With an empty radiator you can do this a little at a time, stopping to
let the air out. Then close the vent and open the valves. Vent as
There are flushing agents by both of these manufacturers, but you need
to really flush the system and add the material and run hot for a few
days. Then you drain and flush and finally refill with fresh
I wouldn't worry about the impact of flushing on the boiler. Each
time you fill you are talking about the scale from maybe 100 litres of
water. Unlike a HW cylinder where several times this amount per day
may be going through, this is not going to have any noticeable impact
on the heat exchanger.
To email, substitute .nospam with .gl
Don't worry about hard water. As the water is not continuously replaced
there is only a finite (and small) amount of calcium in the water. The water
softens very quickly as a undetectable layer of limescale forms around the
system. You only really get limescale on the primary side if you keep
topping up (manually or automatically, depending on the system) which
introduces new calcium over time.
Flushing the system would be a very good idea.
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