New radiators filled to test for leaks, then drained. Are they now rusting away?

[axt]

Hello,

I have fitted half a dozen radiators to the downstairs of my house (all of them) amid various renovation work. The downstairs loop is fed from two 22mm risers from upstairs and there is a drain gate valve in the floor downstairs going outside (pipes downstairs all in the screed).

After fitting the rads, as I had done lots of tail work (different rad sizes to before) I thought it would be clever to fill it using a watering can down the two risers (they are open and unconnected awaiting me to do upstairs plumbing). This went fine, I left overnight, no leaks, opened gaye valve and it drained down. All bleed valves left open.

Now I am paranoid the radiators are rusting out as they have gotten wet and are now empty.

Am I worried about nothing, should I repeat this with some sort of inhibitor that will then be wasted in short order? Should I remove rads to air them out / dry? It may be a month or two still until rest of system is in service...

Many thanks for any suggestions.

 

[Madrab]

Depends, some rad manufacturers coat their rads internally, that's why it's always best to flush a rad/system when it's new. Were the rads filled right up?
In simple terms, could they have started to rust, unfortunately yes. To what extent would be hard to say. If there's a small one, take it off and flush it through and that should give some indication.

 

[axt]

They are standard Screwfix flowmasta (and one Stelrad). The instructions mandate a clean before use, which would suggest they do have some sort of coating - and I assume they were tested with fluid during manufacture?

I think I could repeat but fill right up with x100 inhibitor in the mix (they were only part filled to exercise the pipework), then when ready flush down, x800 clean and then fresh fill with x100 (to a then complete system)...

Every time I walk past one at the moment I imagine it being slowly eaten from the inside out by the tin worm!

 

[Madrab]

I'm sure they would have been quality pressure tested and then undoubtedly a rust inhibitor would have been added. Try and avoid x800, it's very aggressive and probably not needed, an X400 clean for a few days then flush, drain and inhibit would be more than enough I'm sure.

 

[axt]

Thanks, I am cracking on and hopefully will have more of the system ready sooner, but I still can't decide on filling these half dozen up with water/inhibitor mix for the time being.

I am sure as you say it would have had a flashing of inhibitors when made/tested, such that a quick slosh of water should not have much effect - though after the (instruction mandated) chemical clean and flush post install it probably would be vulnerable if not kept up with inhibitor...

 

[Madrab]

If it's relatively easy and straightforward to fill them with water and cleaner, flush them out and then refill with an inhibitor mix then it would be folly not to do it for at least peace of mind and and at most avoid any grief later on.

 

[Exedon]

They are standard Screwfix flowmasta (and one Stelrad). The instructions mandate a clean before use, which would suggest they do have some sort of coating - and I assume they were tested with fluid during manufacture

I've been round several rad manufacturing plants stelrad more than once!
The radiators are actually tested with compressed air then passed through a water bath look for bubbles lol.

 

[axt]

That makes sense I guess, how I would find leaks... Still not sure, I am hoping to just fill with x100 inhibitor for the moment to keep at bay, and then do a x300 clean / x400 clean later once more complete, then x100 again.

Hopefully 2 weeks of being moist and empty has not offended them too much...

 

[big-all]

i personally would think they will need months possibly even years before any actual start to structural decay [rust and rot] before that will be no more than a surface interaction causing the orange discolouration off the water
so my thoughts
going to fill within say 8 weeks zero action needed

 

[foxhole]

How could you pressure test your rads without any pressure?

 

[axt]

i personally would think they will need months possibly even years before any actual start to structural decay [rust and rot] before that will be no more than a surface interaction causing the orange discolouration off the water
so my thoughts
going to fill within say 8 weeks zero action needed

Thanks, that was the kind of reassurance I was after, but I still bought a bottle of X100 this morning and after sorting the tails for another downstairs rad that was going to wait until a room was plastered (I won't fit the rad though), I am going to brim the loop with inhibited water and leave it until it can join the rest of the system, as it may be another month or so until that is ready. Then a good flush and new inhibitor after that.

How could you pressure test your rads without any pressure?

True, it was also an effort to wash away flux residue, but in hindsight an entirely pointless activity, unless I happened to have a really bad soldered joint...