Flushing a two pipe direct return hot water system.

Call_Me_Al

I am replacing an old 80% efficeint boiler with a Triangle Tube Prestiege boiler. Do I need to flush the system before I install the new boiler? If so, How do flush an old piping system with take offs to each radiator? Any suggestions.

SWEI

Start with what we call a power flush, which is really just hooking the domestic water supply to one side of the heating system. Connect a hose to the other side and run that to a drain or outdoors. Flush until you see clear water coming out the hose. If you have zones or radiator valves, close them off and then re-open one at a time to direct as much flow as possible through each circuit.

After that, you pretty much need a purge cart or a pump, plus a bucket or barrel, preferably with some kind of a screen or filter in-line with the returning water from the system. Excellent hydronic cleaning agents are available from Rhomar or Fernox.

Is there any steel or iron in the old system? If so, I would add a magnetic dirt separator to the low point of the return line, just before it turns up to connect to the boiler return.

unclejohn

If you want to clean the system thoroughly use Fernox F3 cleaner after the new boiler is in place and run it through the system for a couple a days and then refill and bleed and run the system for maybe a 1/2 hour and flush and fill again