Virtually new radiators failing one by one

Hi Ken.

I've no idea what's causing the water flow from the expansion pipe - I think you'd need to provide a lot more info on that, such as type of system, photos of pipe layout (around the boiler, hot cylinder, pump location, valves, pipes leading up to the loft etc), but if there is hot water being ejected regularly out the exp pipe, landing in the tank mixing in a constant supply of air, and this is being circulated around your system, I think I can guess why your rads have rusted.

And - really - your plumber SHOULD be able to work out what's causing this exp water flow.

How old is the rest of the system (apart from the rads)? And what else was changed at that time?

 

Other useful info would be:
Did the original radiators leak? (why did you have to change them?)
Did you have the expansion overflow problem with the original radiators?
What make of new radiator?
How long between purchase and fitting - especially with the fitting caps removed?

diymostthings

 

I assume you mean the pipe hanging over the tank; not the overflow pipe which goes outside the house.

In either case, you should not get a constant flow from the pipe.

If it's the pipe hanging over the boiler: it's called pump-over and is usually due to the pump at too high a setting. It could also be due to the expansion pipe not going up high enough before it bends over. (The top of the bend should be 450mm above the water level.)

You can also get pump-over if the expansion and feed pipes have not been connected to the boiler circuit correctly or if there is a blockage.

If it's the overflow pipe: the water level in the tank is too high. It should not be more than half full when the boiler water is up to temperature.

In either case, a competent plumber/heating engineer should be able to diagnose the problem.

If water is going out of the overflow, that would explain why the rads are going rusty: you will have lost all your inhibitor by now.

 

Hi Ken
A powerflush will help clear a lot of the debris from your system but probably not any blockage you may have probably in the cold feed / open vent area. To be certain the best solution is usually to cut out and remake it. You could even consider a magnetic filter in the return pipe near the boiler as another preventative measure, something like a Magnaclean Pro 2.
The probable cause of the rapid corrossion is due to the pumping over adding oxygen to your system which in turn accelerates the process of decay.
One solution which may or may not be possible dependant upon the condition of your system would be to convert it to a sealed system, by adding an expansion vessel suitably sized to suit and a filling link. If like you said the boiler is in the garage and you have a cold main supply nearby it shouldnt be too hard a job. The old Baxi Solo's are suitable for that kind of system.
What this would be achieving is eradicating the pumping over issue as the F&E tank becomes redundant thereby not allowing excess air into the system.
May be worth a chat with your plumber see what he thinks.

 

Hmm, good point - if the old and the new rads have corroded as badly as they clearly have, then there will be a shed-load of gunge in your pipework. A partial blockage is oner good reason why water is forced up an expansion pipe.

It's a viscous circle (you know what I mean...)

What boiler do you have fitted?

 

The expansion pipe and the cold feed (that's the one coming out of the bottom of the small tank) should both connect, about 150mm apart, to the pipe from boiler to the pump. If you have a magnet, check the pipes around the junctions. If it shows any attraction, it means the pipes are blocked.

Can you post a pic showing the pump and the above junction?

 

He has a Baxi Solo 2 one of the better Baxi products back in its day, easy install fantastic to service.

 

You used to be able to buy a fitting (expansion box?) that you connect the cold feed to then take the expansion off it and over the tank which stops the pump over (I've not seen one for a long time) they where very popular with early fully pumped systems.
I've seen many different methods over the years (some very inventive) of curing the "pump over" (Tom knows a really good one) however, non of which you would ever find in a plumbing manual!!
Tappy,

 

Are you thinking of the Aerjec? They are still available. The problem is that most of them are not installed correctly.

 

And if you get that little bit of solder in them, a life time of rattle

 

Good point indeed.

If 4 out of 11 rads have corroded right through in only 2 years (that's some corrosion), then the remaining rads must be pretty darned close to doing so too.

What often keeps these rads from finally leaking is the coating of sludge on the inside! So, a good power-flush could easily cause quite a shower...

If you reckon you can get them replaced under insurance cover, then absolutely go for it.

Copper piping is usually ok; if anything it's the odd fitting that could fail (tho' I don't think a power flush itself will do that.)

Keep us posted.

 

a few options dependant on costs really.

Powerflush, repipe problem pipework, replace any failed rads
Powerflush, seal the system/ remove problem pipework, replace any failed rads
powerflush, replace all rads, seal system / remove problem pipework
fit an new system
sell your house and let somebody else sort it

 

So your doing a bit of what I sugested back on the 20th May still believe if you convert the system to a sealed system you will have no further issues.

 

Agree.

 

And when you pressurise your sealed system to 1 bar+, the other rads will definitely blow