System flushing and refilling advice required

[Serval]

I’ve got at an s plan fully pumped system that I drained down recently to change some of the downstairs rads and also replace a few upstairs valves.

I say I’ve drained the system, however on the ground floor I only drained down the feeds to the three rads (fed from above) that I was changing so this will probably have partially drained the system.

When I drained down the system everything that came out was clear.
The feed tank in the loft however, was full of sludge and crap at the bottom so I manually bailed that out and cleaned the tank to avoid getting that stuff down the feed pipe.

Before the final refill and adding inhibitor and I’d like to flush the system out.

Can anyone advise if I’ve got the following tasks correct and in the right order to make a good job of it?


- leave both motorised valves latched to manual

-Refill, bleed and add some system cleaner

- Run the system for an hour or so to let the cleaner do its stuff

-Switch the system off

- hook up a hose to a downstairs drain point
( ill be using a rad valve or a rad tail drain tap drain as ive got no drain cock fitted)

- open valve or rad tail drain tap and allow the F/E tank to fill and drain from the opened valve in order to flush the system

- drain, refill top up with inhibitor

-bleed all rads

-switch motorised valves back to automatic

By the way Im a Diy’er some guidance from those with more experience/knowledge

Any advice welcome

Cheers

 

[Chuck]

Choose a product family (Fernox, Sentinel, etc.) and follow the manufacturer's instructions.

Put the cleaner in early in the filling process so it actually gets down to where it's needed. I would would expect to run the system for more than an hour, but do whatever the manufacturer recommends.

 

[jtsplumbing]

If system has never been done Add Fernox F5 and run for a week, drain when hot and give a good flush through then fill & pump around system and drain a couple of times then add a good inhibitor Fernox F1 wile system is filling don't just pore into tank after system is full, that what the jelly was in your tank.

 

[Serval]

Thanks both. Not sure when/if it was flushed. House is about 30 yr old and uve been here 2.

When you say run the system with f5 for a week do you mean actually run the CH for the week? Its not cold out side so could get a bit hot! Or can i do the equivalent with the t/stat set to low?

Also are those steps i noted for flushing/refilling ok?

 

[jtsplumbing]

Thanks both. Not sure when/if it was flushed. House is about 30 yr old and uve been here 2.

When you say run the system with f5 for a week do you mean actually run the CH for the week? Its not cold out side so could get a bit hot! Or can i do the equivalent with the t/stat set to low?

Also are those steps i noted for flushing/refilling ok?

With F5 you just need to run system for about 1hr a day the hotter it runs the better, then when ready to drain get system hot B4 draining

 

[Best]

You stated that you replaced some of the rads. Had the old rads that were removed any sign of black magnetite or rust coming out of them? When you simply drain a system, the water will usually run clean,- so ignore that.
Ideally, each rad removed (if very dirty) and washed out thoroughly, is good to get rid of most of the corrosion first.
The F5 will put magnetite into suspension, but keep the F5 in for a week, using system and drain when system very hot.
Flushing can be done really well using mains flushing with a full open valve to another hose, but tricky to do correctly and individual rads

 

[Serval]

You stated that you replaced some of the rads. Had the old rads that were removed any sign of black magnetite or rust coming out of them?

the old rads that i removed did have a small amount of black, ink like water that only came out when they were removed and tipped over to one side.

Flushing can be done really well using mains flushing with a full open valve to another hose, but tricky to do correctly and individual rads

Not sure i understand this bit....are you saying connect one end of a hose to an open valve, with the other end going outside to a drain.

Then get another hose, fed off the mains and connect to another valve in order to flush the system through?

 

[Best]

the old rads that i removed did have a small amount of black, ink like water that only came out when they were removed and tipped over to one side.



Not sure i understand this bit....are you saying connect one end of a hose to an open valve, with the other end going outside to a drain.

Then get another hose, fed off the mains and connect to another valve in order to flush the system through?

Sounds like your system is only moderately dirty. The F5 will do a good job, although I still prefer to wash rads out by removing them first, if straightforward.
It is highly risky to flush using mains water. Your heating expansion tank would need the vent and feed pipes plugged temporary to prevent open ends.
A hose from mains connected to one side of a rads valve and another hose joined to the opposite valve to a drain, with both valves open. But it needs flushed doing only one rad at a time and always maintaining a path for circulation.
Motorised valve to manual open, for each circuit being flushed.
If the F5 cleans well, just repeat filling and draining the system will also work

 

[Serval]

It is highly risky to flush using mains water.

I think ill pass on that option then as i dont think im ready for that one quite yet

 

[Best]

I think ill pass on that option then as i dont think im ready for that one quite yet

You are obviously very wise.
Most people think they can do it all.
Good to be cautious.
Problem with just gravity flushing is some parts of system will not flush and you would need to fill up system again, run pump for a while, then drain again. That's where mains flushing has the advantage of less time involved and better flush

 

[Serval]

If threes less risk of me inadvertently causing a problem, i dont mind if the job takes longer and is a bit effective. I reckon ill go with the slower, safer option.

when flushing will i have to attach a hose to a drain valve at each ground floor rad and flush from each rad one by one, refilling as i go around each one?