Fernox Leak Sealer and Usage

Hi All,
I have a Worchester Highflow 400 boiler which is losing pressure of around a bar every couple of weeks. I have wooden and some tiled flooring on the ground floor where i suspect the problem may be (as i can see nothing on ceilings anywhere) and would at least like to try this stuff before i go ripping up floorboards and destroying tiling.

We have 2 floors and a converted loft above that with a radiator in it, i intended to use the Fernox leak sealer by draining water from the system so that radiator empties, injecting the Fernox into this radiator (i presume through the bleeding valve - is that right?) then filling up the system with water again and running.

I cant inject it at the inlet valve next to the boiler as im no plumber and it would involve disconnecting pipes etc so i presume injecting it into the top most rad would be the best move.

One other thing i wanted to ask, i have cold spots near the bottom of nearly all the radiators although some are worse than others, i've previously taken of the topmost radiator (the one in the loft) and flushed it through with a hose, quite a bit of dark filthy water came out, no clumps or rusty stuff though.

Im assuming the topmost radiator should be the best so i fear for the ground floor ones.

Would you recommend a powerflush? British Gas suggested a price of around 600 quid (we have 9 rads). Are there other who would provide this cheaper and are they as reliable?

Thanks - lots of questions i know.

The Fernox leak sealer is worth a try, it worked on my Grannies system it has never lost pressure for over a year now.

A powerflush would be worth it but not by BG, you can also clean it yourself if you like; by removing each radiator and flushing out with a house.

Is your system properly balanced?

Hi,
Thanks for the reply, does the method for using the Fernox i suggest sound correct?

An if not BG who would you recommend? What type of companies would do a power flush? I have a plumber who lives around the corner is he worth a try?

As for balancing, no its not been checked and i have that in mind, but that to my knowledge would only prevent hot water from reaching the top rad quicker not cause colder spots in the middle of a radiator down the stairs.

The way you suggest to put Fernox in is correct, you will probably need to bleed radiators after its been circulating for a few hours, starting from highest rad.

As for the cold spots, what colour is the water in your system?

Thanks

When the radiator is isolated and draining the water runs clear to begin, near the end of draining though it starts to run black. Then after unmounting the radiator and flushing through with a hosepipe a lot of black, dirty water was produced.

This is on the raditator at the top of the house, in the loft, furthest away from the boiler.

Incidentally, i just thought, if it was a powerflush that was needed, could this put excess preassure on the pipes and cause a bigger leak?

I don't think powerflushing could cause a bigger leak, IIRC powerflushing is circulating a large volume of water through the CH system, not at high pressure.

You could flush out all radiators, then inject Fernox cleaner F3 and circulate as advised in instructions, drain system, refill and drain, finally add Fernox protector F1 and refill.

Before trying the above get the leak repaired to prevent losing chemicals.

Have you checked the PRV is not leaking?

If you have black sediment, you can loosen and flush it out using a mild cleaner like Sentinel X400 (which you leave circulating for 4 weeks or so with the heating running). If you can afford an extra £100 and do simple DIY plumbing you can add a Magnaclean and I guarantee you will be amazed and delighted to see how much black sediment it traps (it is a device that you fit on a pipe and it carries on working for years)

The black material is caused by corrosion of your metal radiators. This may be either the cause or the result of the leak and the fresh water which has been repeatedly added, bringing in dissolved air and washing out whatever inhibitor might have been present.

Wow,
Thanks for the info guys, excellent stuff.

The Magnaclean looks like a great product, the only issue is the "simple DIY pluming", im not really that confident about doing this to be honest, dont get me wrong i'd be happy to give it a shot but never having done this before, being middle of winter and the wife etc , im sure you understand.

I could get the kit and have it installed for me though, given the amount of sediment that came out it could be an excellent investment over time. (It looks like you can remove the filter by unscrewing the and cleaning this too - is that right?)

Regarding the Sentinel X400, would i insert the cleaner, run it for several weeks and then empty the system via the external valve on the back of the house, outside (is this the PRV, preassure release valve?, that David mentions?), then refill the system and empty again for good measure? Or would this bring the sediment to the boiler?

I suppose that would then be a good time to install the Magnaclean?

Once again, many thanks guys, great advice.

Hi again, i just wanted to add that i put in the Fernox, last night and topped up the pressure then bleeded the top radiator again although i think i may go round and test the rest.

However i noticed that between myself topping it up and the misses having a bath the reassure dropped by about .3 - 4 of a bar.

Now the water was cold initially when i topped it up so i'm not sure if pressure would increase or decrease when heated or if there may be some sort of leakage when the hot water is ran for extended periods of time.

As we regularly have showers etc could this be a cause of the issue?

Any ideas?

IIRC if pressure drops when you draw HW is caused by a holed plate HE. Hopefully a RGI will be here soon to advise you.