On Mar 4, 5:34*pm, "Clot" wrote:
Ray wrote:
We have a boiler/radiator system in our six-unit apartment building.
We have been flushing it -- I think it might be called "draw down" --
once a week.
But I get mixed advice on how often we should do this, and how long we
should let it flush each time.

Any guidance welcome.

Living the other side of The Pond and reading this site quite frequently,
I;m under the impression that central heating systems on the Left Side are
usually different to those we use.

Do you mean this sort of system powered by gas, oil or solid fuel - coal/
lumber?http://www.gasapplianceguide.co.uk/c...ng_systems.htm

If so, then frequent bleeding could assist rusting! It would draw in fresh
oxygenated water. What is common for such a system here is to add an
inhibitor to a new system to prevent corrosion and sludge build up and then
drain every few years. We can purchase fluids here to help flush the system
for this process, then wash through with fresh water, then refill adding
inhibitor, (the cost of the process from recollection is circa $40,
excluding my time of about two to three hours).

My current system that I have had from new in a new build house has been up
for almost 25 years and I've flushed it just 3 times in that time - if my
memory serves me well! No leaks, no problems apart from assisting the
circulatory pump to wake up in The Fall some years.

I have a 60 yr old steam system, flushing it weekly meaning a few
gallons, is fine, oxygen boils out almost 100 % on the next cycle