Fernox F4 - how long does it take to cure?

[magpieman]

We've had a new combi boiler and the pressure is dropping so much that we have to top up 3/4 times a day.

I had the people back who put it in and they said it was probably a leak in the old pipes which are under the floor. There are no visible signs of a leak but they recommended putting Fernox F4 in to try and seal the leak. I have done this and it has been in for a week with no discernible difference, the plumber said it may take 2 weeks to "cure", is he right or should it be sooner than that?

 

[warmadmax]

what's the pressure when it's cold? does it stay steady?

 

[magpieman]

It still drops when cold. I top up at night and next morning it's back to nought. If anything it's worse when cold.

 

[doitall]

Leak sealer will block the small water ways in the boiler and shouldn't be used.

You need to find and repair the leak.

 

[Terry lambert]

Leak sealer will cure small weeps, but i wouldn't use it to cure a leak, which is what yours sounds like.

It can take a couple of weeks to work.

What system did you have before, was another combi or a gravity system with tanks?

If it was a gravity system, you cannot expect the installer to take responsibility although he should be willing to help.

With a pressure drop that quick, I would be lifting floors on the ground floor to find the leak

 

[Terry lambert]

Leak sealer will block the small water ways in the boiler and shouldn't be used.

You need to find and repair the leak.

I've used it once, and I thought the same, according to Vaillant and fernox tech it just increases the water tension and reacts with air ( where the leak is) to seal it with no effect on the boiler.

I've had no call backs to the boiler so can only assume they are correct.

 

[magpieman]

Leak sealer will block the small water ways in the boiler and shouldn't be used.

You need to find and repair the leak.

The boiler is a Worcester and the plumber said they have asked the manufacturers if they could put Fernox in the system and Worcester said it was ok.

All the pipes are under solid floors so its difficult to trace.

 

[magpieman]

Leak sealer will cure small weeps, but i wouldn't use it to cure a leak, which is what yours sounds like.

It can take a couple of weeks to work.

What system did you have before, was another combi or a gravity system with tanks?

If it was a gravity system, you cannot expect the installer to take responsibility although he should be willing to help.

With a pressure drop that quick, I would be lifting floors on the ground floor to find the leak

It was a gravity one pipe system. I am not blaming the people who installed the boiler as they did warn me that sometimes leaks occur. I just wanted to know how long to leave it before taking further action. If it doesn't work it looks like they will have re pipe the whole system as that would be preferable to digging solid floors up.

 

[Terry lambert]

They should never have sealed a system in solid floor.

You could try putting perfume in the system and then run it for a few days and trace the smell, dig up repair.

I've never used a thermal imaging camera and so I am not sure if it would give you enough detail to trace the leak if you hired one, someone else might like to comment?

 

[ianmcd]

Thermal imaging camera is the answer to your problem, contact your house insurance you might be covered for this, wouldnt recommend hiring one unless you know what you are looking for but they are excellent in finding the problem that you have , stop adding leak sealer it doesnt work and will damage your new boiler

 

[Phill Peck]

Where abouts in the country are you

Local to me there is a company called munters who specialise in finding damp etc

They are not cheap but they are very good and have certainly saved my customers money in the past by finding leaks