Balance central heating

[kev999]

Hi,
I need to balance my C/Heating system after changing many rad valves and taking the rads off and flushing them.
I have found a couple of web pages that explain how. It's just one says flow and return should be about same temperature, the other says there should be an 11 degree difference.
I have just had a new condesing oil Greenstar Worchester 25/32 boiler fitted.
Which if any are correct?

 

[gasandoilman]

are you sure it needs balancing ?
Have you kept the boiler in the same position as before?

has your problem just started since new boiler removal of reds e.c.t.?

You may have an air lock in the pipe work not the top of rad where you bleed it..

Whats the symtoms you have if some rads not hot enougth check return pipe to rad if not hot turn off all other rads and leave just that on to see if it breaks air lock..

 

[Bahco]

Read post 2 and 8 HERE

 

[kev999]

Problem has only started since new boiler fitted and work on rads done.
I have it zoned now, one upsatairs, one downstairs.
Only just had the Boiler done so I'm still playing with it.
When I put Downstairs on one radiator is cold,(flow and return pipes cold) it used to work fine, I played with the rad valves shutting off a couple and that got that one working and made a different one go cold at flow and retun also.
Does that sound like an airlock?
On the balance thing, Which pipe is hotter by 12 degrees, flow or return?

 

[D_Hailsham]

one says flow and return should be about same temperature,

Which site said that? If they did, they do not know what they are talking about. If there is no difference between the flow and return temperature, then the radiator has not given out any heat.

the other says there should be an 11 degree difference.

That's more like it, although condensing boilers may work better with differentials up to 20°C. The important thing is that the differential is the same for all radiators.

On the balance thing, Which pipe is hotter by 12 degrees, flow or return?

It's obvious, if you think about it If you apply heat to water, the temperature rises; if you extract heat from water, the temperature drops. So, in the case of a radiator, the return must be colder than the flow.

As you have a shiny new boiler, I assume you have a lot of shiny new TRVs. If so, then Drayton provide useful instructions on Balancing TRVs