Filling a Drained System after extended time

[Leaky1]

I had to drain my Central Heating system down to remove radiators/decorate etc. Unfortunately it has been drained down for far longer than expected due to certain delays, 12 months now.

I plan to flush each radiator manually before refilling, but should I be concerned about the rust that and sludge that will have accumulated in the radiators and pipework even after flushing through?

The system is a gravity fed system with open tanks in the loft and a modern-ish (2009) Glowworm heat only boiler. It does not have a filter on it.

I am worried about powering up the system again and the pumping lots of crap round the system and maybe damaging the heat exchanger.

Should I be concerned? What steps, if any, should I take to mitigate any issues?

 

[Mottie]

Perhaps it’s now time to fit a magnetic filter on the return to the boiler before filling it up?

 

[Madrab]

Depends on the condition of the system when you drained it. If it was nice and clean then they may have some rust in them. Fill and flush them with hot water if poss till clear, from both ends. Inhibit well.
You may have to go back to the system a couple of weeks/month in order to check system water. If it's redding up, then cleaner in and run for a few days and flush it again till clear.

And yup, get a filter on it if there isn't one.

 

[Leaky1]

Sounds like a good plan.

I assume it is best to get the filter connected before filling and flushing the system at all?

Any recommendation on filter brand? I know magnaclense crops up everywhere with marketing but what do people recommend on here? Or is it one of those "can of worms" questions.

 

[Mottie]

I fitted one of these to my system after a recommendation on here. Easy to fit and works well.

https://www.mrcentralheating.co.uk/...MIzaCW37Cj4QIVp5PtCh1PiAvQEAQYAiABEgKM0PD_BwE

 

[Leaky1]

Looks like a good one, I think I have seen recommendation for that before.

Looks easy enough to fit, might as well do it myself.

From what I can see, it should be fit on the return pipe just before the boiler.

As I have a heat only boiler, I assume I do not have to consider the location of the pump, with it being in a separate location to the boiler.

 

[Mottie]

I don’t think it matters where the pump is. I have mine fitted on the return right next to my boiler. My boiler is in the loft, my pump is downstairs in the airing cupboard.

 

[ianmcd]

doesnt matter where the pump is, just fit it on the return where access is easy to clean it

 

[Leaky1]

After a bit of reading, should I be concerned that the valves on the Fernox Omega are not full bore?

Will that cause issues with a open vent heat only system?

 

[Mottie]

If you’re concerned about that, fit the one without valves. That’s the one I have, not that I was concerned about that, just didn’t think I’d need them.

 

[Leaky1]

Ahh, I thought that makes it more difficult to flush and clean the magnet out, i.e you have to drain the system to clean it.

But, looking at their videos, I assume this is the scenario sans valve:

I assume another option is to fit my own 22m full bore valves before and after the filter.

 

[Madrab]

If you're worried, fit a couple of 22mm lever valves either side of the filter they really are just about essential for trouble free servicing and dosing.

 

[Mottie]

I’ve never seen that before. What I do with mine is switch the boiler off, remove the magnet and give it 10 seconds or so to allow any metallic particles to sink to the bottom of the filter then I open the drain valve and let it all out. I have a sealed system so it comes out under some pressure which I just top up afterwards. I couldn’t see why I should have fitted isolation valves either side of the filter unless I was going to be regularly dismantling it - with my boiler being fitted in the loft, my filter is fitted to within a foot of the highest part of my system so if it did need removing for whatever reason, I wouldn’t have much water to drain off.

 

[Leaky1]

Yeh, A full bore lever valve on each end seems a doable/sensible solution if I want to make it easier to service. Just a bit more work to install.

@Motman 's solution probably works just as well though. Although without cutting of the return pipe I wonder if there would be enough pressure to properly flush it through on an open vent system.

Another question, it may seem silly, but if you don't fit these every day I just wanted to check.

With this being a Heat Only boiler on an open vent system, unlike a combi or maybe system boiler, the return pipe comes down into the boiler from above. I think I am correct on that.

Nearly all the installation examples for these devices are for combi boilers, with the pipe coming from below going into the boiler above. In this instance when installing, the flow direction on the filter connection points up.

I assume if the return on a heat only boiler goes into the boiler from above, the arrow direction should face down. Am I correct?

I also assume while the arrow faces down, this does not affect the orientation of the filter itself.

 

[Mottie]

As long as it is fitted with the arrow in the direction of the flow, the filter housing can be correctly aligned by loosening the knurled ring collar on the housing and orientating the housing to the correct position. It can even be fitted on a pipe running at 45°.

Like this: