How frequently should I need to balance my radiators

[Martino]

Had a look around the many posts on radiator balancing but didn't see an answer to this question, so....

How often should you need to balance radiators?
Reason I ask is this - had system powerflushed and balanced Jan 2009. For the rest of that winter all rads lovely and hot. Winter 2009/2010 rads lovely and hot again. This winter just gone, the rad at the end of the system gone back to being tepid (would get up to warm if heating on for a few hours and no hot water on; otherwise wouldn't get beyond tepid).
All other rads OK (got one that maybe takes a few minutes longer to get up to heat but otherwise OK).
The tempertaure seems pretty even over the rad once it gets up to the heat it seems to want to go to so no obvious signs of air (bleeds OK) or sludge.
This rad was cold/tepid prior to the flush & balance so is obviously the problem one in the system.

Should I expect to need things balancing again so soon?
Thanks,
Martino

 

[simond]

Should not need doing unless you - or someone else -tamper with the lockshield valves.

Are you turning the boiler stat right up in the winter?

 

[45yearsagasman]

Agree with simond. Once flushed and set up a system should be ok for years.Maybe another issue such as a pump problem,Very hard to say without being there.

 

[Martino]

Thanks Guys,

Not touched any lockshields.
Bolier has 'high/low' switch. Is on high during winter.
Nothing has changed and nothing is different as far as I know, rad just lost it's heat from one winter to the next.
I usually run system with pump (replaced when flushed/balanced) on speed 2. Tried it for couple of days on speed 3 but that made no difference to the "guilty" rad.

Martino

 

[muggles]

Air in the rad??

 

[Martino]

Don't think so. The heat it has seems constant over the whole surface area and I've tried bleeding it several times and get water out straightaway with no obvious sign of air in it.

 

[ianniann]

Nothing should change, but just for more info close off a couple of radiators closest to the boiler. Remember how much you have to turn them so you can set them back again. If this makes the last radiator heat up properly then something has slightly reduced your pressure or flow. Might not be this since turning the pump up didn't help, but you might as well try. If turning all the other rads off doesn't help then there is something blocking flow to that last rad that wasn't blocking it last year.

 

[bengasman]

Once a system is balanced correctly, it never needs adjustment.

A lot of powerflushes are not done correctly.
You don't know if the system was balanced properly afterward.

1. Check ph of system
2 Check performance of pump