Mains Water Central Heating Flush

[Sonic70]

I am fitting a new radiator and central heating magnetic filter fernox omega tf1 and was going to do a mains water flush of the system. My question is that my filling loop for the boiler connects to the flow side, I will be turning off the iso valve on the return side of the boiler, do you think I will still be able to monitor the system pressure on the boiler dial while doing the flush as the filling loop is on the flow not the return side.

Victor

 

[oldbutnotdead]

Be careful- your dirty water that you will be flushing through has to go somewhere, you don't want it going through the boiler. Pressure during a flush- who cares?

 

[Sonic70]

as I'm fitting omega filter with valves on return pipe, I will just turn those valves off so water cannot flow via return to boiler. I am sure you have to keep pressure below 2 bar.

 

[oldbutnotdead]

If you are flushing then you'll need somewhere for the water to exit- before you fit your filter, sticking a hosepipe on the return would work, no way the pressure will get up to anything much with an open exit. Don't forget to flush the rads 1 by 1 to get all the crud out. Where did you get that 2 bar figure from?

 

[Sonic70]

I was going to use the drain dock next to one of the radiators but could use open exit as you say. I think I saw the 2bar figure on this forum somewhere where they described a mains flush.

 

[Madrab]

Do it all the times in flats. Identify flow and return on each rad. Make a piece of drain hose that will be long enough to stretch to a sink or toilet or similar. Get a couple of fittings that match the radiator valves. Easy for me of course as I have lots of them.
Shut off both boiler valves and empty a rad from the end opposite to the loop, then connect the hose to the opposite end from the loop and open the filling loop, once the water runs clear then move onto the next one.
If the loop's on the boiler then cut a fitting into the return where a valved mains supply could be connected.

Again, appreciate it's easy for me to do but not that hard if DIY savvy.

 

[Sonic70]

Rob,

Thanks for info. The way in doing it using the drain cock as the exit for water can you see any problems or should I use pipe where I'm cutting for omega filter as the drain point. Also do I need to monitor pressure.

Victor

 

[Madrab]

Yep no bother there but you really need know which (F or R) pipe the drain is on and then have the loop/mains feed on the other pipe. Once the system is fully drained, open the feed and run it through each rad in turn. Always have one rad fully open though at both ends to provide a continuous path for the water to flow through otherwise you could over pressurise the pipework, mains pressure dependent of course.

 

[Sonic70]

Cheers Rob, I will check the drain is on the return pipe. Most helpful once again.

Victor