Vaillant 418 s53 & s7 after New radiator

[rbranco]

Looks like it's crud/limescale in the Hex, last night the boiler started kettling really loud.
Will be draining down tonight, replacing the broken pump gate valves with ball valve as they don't close and I think one is not opening all the way, cleaning the F&E tank, putting in cleaner x200 then after it's been drained again putting in some x200 & x100.
10 years since any real work was done so it's just all come to the top now.

 

[dilalio]

so it's just all come to the top now.

The bottom more likely

 

[rbranco]

Pulled pump apart and found that the impeller had loads of magnetite stuck, i've cleaned it all out and now the pump is pretty much inaudible even on fastest setting (yes it is moving).
Found one of the pump gate valves was only half open, would not go any further due to sludge/magnetite buildup so they were both changed for ball valves instead.
Cleaned the F&E tank out, put isolation valve for tank near the boiler so I dont have to venture into the loft each time I want to drain the system.
I still think that the ABV is not working as it should to maintain the correct flow to the boiler, reducing from 22mm->ABV->15mm then back to 22mm is affecting the return flow as it does not matter what I set the ABV too the return never gets anywhere near the temp that comes out of the boiler. I suspect differential pressure is playing a part here or just flow rates, even at max flow on the 15mm it will be way less than the 22mm is flowing and it would nearly drown out the hot water.
Still hearing rattling though the pump and am putting that down to pieces of magnetite going though the system or being dislodged. I opened pump again and found more bits stuck.
The boiler seems to no longer start kettling just over 60c like it was doing before.
The magnaclean is picking loads of crap up so this system was really packed.
Still some way to get this system back to the best performance, ile have to get a friend in to replace the pipe between the abv though to rule that out.

 

[John D v2.0]

Glad you worked it out. I'm sure youryo getting too worked up about that 15mm pipe, should be plenty for the boiler unless it's a 30m run or something.

 

[rbranco]

Glad you worked it out. I'm sure youryo getting too worked up about that 15mm pipe, should be plenty for the boiler unless it's a 30m run or something.

,

I may be, looking at the install guide again for the boiler it states minimum 15mm.
There is still some restriction I think as I've had to range the boiler to 11kw to stop it overshooting and triggering overrun and also set the max flow temp to 80c.
Pump possibly undersized?

 

[dilalio]

Air or crud in the boiler/system from the drain down and refill. Can you bleed the boiler? Have you bled the pump?
Try those then check pump is spinning freely then drain down again and try and flush things through. Did the F&E cistern have a load of Shyte in it when you drained?

Ahem!

 

[rbranco]

Ahem!

The crap in the pump and gates was magnetite, also the F&E tank does not feed from the bottom, its about 5cm up so the crap settles at the bottom and does not all flow down hopefully. Old systems are a faf.