If system is open vented (tanks in loft) isolate the cold feed to the expansion tank, open 2/3 port valves, cap off open vent and cold feed to heating system. (For combi boilers ignore instruction 1 & 14. Simply drain down then refill via filling loop)
Drain down heating system. Connect the powerflush onto the system either on flow and return of raditor feed (take off radiator) or connect via a pump adapter (isolation valves found either side of pump, shutoff and remove 4 bolts on pump head and take head only off, fit on pump adapter with 'o'ring and new set of bolts) Pump adaptors available from £42.
Connect hoses from heating system to flow and return on powerflush unit. Connect dump valves to discharge hoses which need to be run to a suitable draining point. The overflow on the machine can also be connected if you feel it is necessary. The cold water inlet needs to be connected to the mains water supply via a 1/2" hose (garden hose)
Open all lockshield valves and radiator valves, this will allow flow to reach all rads. Now fill the system via the powerflush cold water inlet to a position between the min and max shown on the unit. (Do not add chemicals yet) Vent off radiators as normal.
Ensure expansion cap is off and turn on powerflush machine to circulate the water. You can fire up the boiler to heat the water to help the sludge loosen up. (MAX 50C) Ensure you disconnect pump wiring first though or pump will be be working against the machine. Allow to circulate for a minimum of 10 minutes minimum. Use the flow reverser to change the direction of flow every few minutes to help loosen furthur particles.
After 10 Minutes open one dump valve and set flow reverser so that dirty water is being dumped from the system. While doing this open up the water inlet to the machine so you have dirty water being dumped and fresh water entering the system. This should be carried out until dumped water runs clear.
Now shut off the dump valves, add your chemical to the machine and continue to fill the system via the machine until max level is reached.
Flush again for minimum of 10 minutes with all rad valves still open not forgetting to regulary reverse the flow.
Now shut off all rad valves except one radiator (usually the furthest from the machine) and allow machine to flush that one radiator for minimum of 5 minutes, again remember to reverse the flow.
Work around the system on each individual radiator so your flushing each rad in turn. Once all are flushed re open all valves and flush the whole system for a furthur 10 minutes.
Now carry out the dumping process again as per instruction 7 again re filling with fresh water at the same time.
Once dumped water is running claer, close the dump valve and refill to max level. Now test the PH level of the water with litmus paper to test acid levels. The water PH needs to be around PH7 (Green litmus paper). If the water Ph level is to acidic add the neutralising crstals to the machine and pump water around system. Now test water Ph again and continue this process until Ph7 is obtained.
Now add your inhibitor (Fernox Etc) via the machine to ensure your system remains protected. Circulate system water for a furthur 5 minutes.
Now isolate the machine and disconnect it from the system. Remove the caps from the feed on the header tank and most importantly REMOVE CAP ON OPEN VENT as this could cause huge problems if left on.
Restore water feed to F+E tank and vent off all radiators and your central heating pump. Also re wire your pump if you disconnected it.
Your system has now been flushed and you can re light the boiler.
All in all this process on a 8 Rad system should take a minimum of 4-5 hours.
This process is far easier on a combi system as you have no vents to cap off and no 2 / 3 port valves to deal with. Make sure the filling loop is not connected to the boiler when flushing is carried out to prevent contanimation of the mains water.
If you would like to try a unit before you buy we hire out AquaMax machines from our Sittingbourne shop for £60 + Chemicals and will refund your £60 if you buy one within 7 days of hire. You cant say fairer than that!
Thank you for reading our guide. If you have any more questions please call us on 0845 489 0199 and we will be happy to help.