Boiler issue - suspect good cleaning required and advice needed

Hi all,

Just joined this forum.
I have a Potterton Suprima boiler (with upgraded PCB) which is causing me trouble...
Just as background info, it has been serviced by BG, pump and electric valves and water tank all replaced recently.
The heat in the rads is very low to a point where i usually turn upstairs off to have a little bit of heat downstairs. BG want to change the whole system, whilst i contacted Potterton who told me i should hang on to my boiler as long as possible as most parts are still available.
Yesterday, my boiler went into lock out (red light flashing every second). I tried to reset it many times and it failed, or ran a little bit and then lockout again, until it eventually seems to start (with green and orange lights flashing at regular intervals) by lowering temp on both boiler and water tank.
Now i suspect one of the issues is that i have a lot of sludge in my system. I tried to vent the rads yesterday as i thought maybe there was air in it and when water started dripping, on one of them it was very black. BG also told me that my system was likely very dirty but they only do power flush with new boiler (of course...)
So my question is, should i attempt using something like Ferndox DS40 or X800?
Also, after using these products, they say "The system must be drained down and flushed several times with fresh water until the water running to drain is clear." (On Ferndox)
Can anyone tell me exactly how the system is drained and flushed several time? Is it just by opening the little drain valve outside my house and let the water run for a bit or is it something more complicated than that? If so, can i do it myself?
Thanks

Excellent flushing guide here Lars -

//www.diynot.com/diy/threads/how-to-flush-a-heating-system-with-mains-water.38902/

Thanks Madrab. I have to say I am not sure I understand that part (for the Open vent instructions):"The main modification required is to isolated the F&E tank and open vent, otherwise the mains water would simply rush up to these points and run out the overflow pipe. This isolation is usually done by disconnecting the feed pipe fro the F&E tank and temporarily joining this to the Vent pipe, with the addition of an isolating valve. The valve is closed when flushing through other circuits, but opened to allow flushing through the feed and vent pipes. But do not attempt to run the boiler with this cross connection in place."
I have a valve that i can turn off next to the F&E, I am not sure that's what they are referring to.
Also, the draw valve I have outside my house has a lot of pressure when i open it, almost feels like it has water from mains coming out. Is that normal?
I'll check if there's another drain valve somewhere...

And I was looking forward to a thread about a Lars boiler!

I am not sure that I would agree with the BG diagnosis of a dirty system.

Odd too if they really told you that they don't power flush old systems. They do ( if you have £800 to spend ).

Tony

Agile said:

And I was looking forward to a thread about a Lars boiler!

I am not sure that I would agree with the BG diagnosis of a dirty system.

Odd too if they really told you that they don't power flush old systems. They do ( if you have £800 to spend ).

Tony

Click to expand...

What would cause you to not agree with the system being dirty if the water is black, somebody who has actually seen it saying its dirty and the fault symptoms pointing toward a mucky system / clogged blocked pump?

Bg won't flush microbore on manifolds or 8mm pipe, they have been insurance based for years now and advice has to be spot on.

Of course words have an important meaning. "BG also told me that my system was likely very dirty"

But BG have replaced his pump! I would not have expected them to waste time replacing a pump on a "very dirty" system as that's just not going to last very long.

The OP only said the water was very black when he started to bleed a rad. That is often the case with a dead leg effect at a bleed point. But it is not necessarily in indication of the condition of the whole system.

He has not yet said that its microbore!

Hi Agile, sorry i'm not sure what microbe is...
I have started the system yesterday again and it ran for a bit, so I get hot water, rads work (bot super hot but warm) upstairs but stone cold downstairs.
I checked the pipe coming the downstairs rads to see if they were getting hot near the thermostat as i figure if hot water was getting there it would get hot but again stone cold but one, one the kitchen that get warm at the top but cold at bottom.
And again, this morning boiler locked out.
I'm thinking of trying to drain my system tomorrow and refill see if that helps. Any thoughts?
Another bit of info (no idea if that's relevant) if that when the boiler works, there's a hissing sound in the rads, even when they are turned off. I think this is fairly recent.

Thanks for help

what is the size of the pipework to your radiators?

22mm I believe. Its a pretty standard 3 bed house, 10 rads, 2 x 2 way valve (I think its called S plan configuration)

Right, here is the outcome of this week end's fun...
- I decided to try and drain my system, in case there was a block somewhere
- took most downstairs rads out and gave them a good flush with hose outside. Lots of black water coming out. couple of rads have rust near the valve.
- refilled the system, bled rads, starting downstairs.
- Also drained from drain valve next to boiler as i read somewhere that there could be air in the boiler (especially as sometime there is gargling/kettling noise). There was indeed the sound of air for a minute or so then it stopped.

Turned heating on again, with all rads fully open on both end.
Upstairs became hot (some more than others), downstairs cold.
I then closed all the hot ones and the downstairs ones started to be hot again (hooray i thought!)
It ran like that for a couple of hours.

Unfortunately my boiler then locked out again :-S. I pressed the rest button for more than 10 seconds to get the diagnostic and the red light flashed 5 times, which apparently means overheat.

Any idea would be much welcome!

Thanks

I would never advise fully draining a system unless essential.

Did you bleed the pump ?

Open any air vents? Particularly any near the cylinder?

Tony

An overheat suggest the boilers heating the water up, but it's not getting out of the boiler properly. You've drained the rads, but I suspect that there's muck in the pipes that's getting shifted along, so unless you can flush the pipes, you may not get much further. As the rads get hot for a couple of hours, it suggest the pump is okay, so unless there's something dodgy with the boiler - difficult to test unless onsite, I stick with the crud in the pipes, and now the rads again, option,

The gurgling sound in the boiler for about a minute was the automatic vent working. And the hissing sound in the rads, is most likely the water running though them. You just don't tend to notice it until there's a problem your're trying to diagnose.

Did you put any cleaner in the system, before draining it down.

Once you've got the system flushed out a bit more, you need to tackle the rads. Having opened and closed the rads, you've upset the balancing of the system, so you need to start each rad off at about a half turn, and then open them up, or close them down fractionally till they are all heating up evenly.

Do you have something that looks similar to a small can, made of copper with 3 or 4 pipes coming out of it, probably in the airing cupboard near the cylinder. It'll be fitted in the pipework before the pump if present. If so, try a magnet on it and see if it sticks.

If you don't have such an item, its still worth trying a magnet on the pipework around the pump, and see if the magnet attracts anywhere. A magnet will not attract to copper or any other non ferrous metal, but it you find its being drawn to copper pipework, this is a sure sign of sludge build up inside the pipework at that point.

How many times did you empty the system, and then refill it - or was it just the once. Remember to add inhibitor when you've finished all the work

Thanks all:
To Agile's questions: yes i bled the pump. Pump seems fine. Not sure what you mean by air vents though. Are you referring to the ones on the rads? I bled those (starting from downstairs) and also bled the one near boiler. The gargling and banging I had in boiler seems to have gone since, so that's that!

Other than that, I also have a drain pipe near the HW cylinder. I havent' touched that one.

To Hugh: yes, I have that above the pump. So basically in airing cupboard, I have a pipe going up to that (from boiler I believe), it also has 2 pipes coming down (from loft tanks I believe) and one pipe going down to a T junction with one valve on each side.
And yes its that metal round box that the BG guy said if was probably dirty. However, the pipes going down from it get hot so i suspect its not completely blocked???

And finally, I drained only once this week end (took long enough, that with cleaning the rads!).
before that, I put X400 about 4 weeks ago.

If its the round metal box being clogged, is there anything I can do? Should I give it another dose of X400 or similar and drain again, see if that helps?

Thanks

Laurent