Cold radiators downstairs

[Rumble]

I've noticed over the past couple of days that when the CH comes on in the morning, the upstairs radiators get hot quickly, but the downstairs ones take ages to warm up and never get as hot as the upstairs ones.

I'm assuming that the system is sludged up and needs flushing out. I had a look at the DIYFAQ for heating, but there doesn't seem to be a section on a suitable procedure for flushing and I haven't done this before.

As the system hasn't been flushed out for a good number of years, I am planning to do this anyway, but is there something else I should look for as a potential fault?

System is S plan with conventional boiler and cylinder.

Thanks,

Rumble

[Set Square]

I assume that you have a bog-standard S-Plan - a single CH zone and HW zone - rather than an S-Plan-Plus with more than one heating zones?

If there *is* a separate zone for downstairs, its zone valve could be faulty - or its thermostat could be set too low.

If all the heating's in a single zone, it's probably just a case of needing to balance it. See the balancing FAQ at

[Ed Sirett]

It might be sludge but this would show as a large cold area at the bottom of the/some radiators.

Just as possible is that the down stairs rads are fed from upstairs (a common arrangement) and that the upstairs rads are easier to heat than the down stairs ones. This would be corrected by balancing, see main FAQ.

If you have TRVs on the rads as they close upstairs the downstairs ones come on.