Downstairs rads not coming on

[guilbert53]

We have a "normal" non-combi central heating system.

We have one rad in the downstairs hall with no thermostat. 3 other rads downstairs all with thermostats.

Upstairs we have 3 rads in each bedroom with thermostats, and a (new) heated towel rail in bathroom.

We have not set the central heating to come out automatically yet, but on our central heating control with have a "1 hour" button.

When I press this the upstairs rads come on, and the one in the hall with no thermostat comes on, but the other 3 rads downstairs initially stay cold.

After about 15 minutes the downstairs rads do eventually get hot. Not sure when this problem started.

At the moment we have a man who is replacing the bath and sink and tiling our bathroom and toilet but he says it is nothing he had done. He has replaced the rad in the bathroom with a heated towel rail.

We do have a hot water tank in the bathroom airing cupboard with all sorts of wires going to it but I have no idea if there are any central heating controls in the airing cupboard.

 

[MJN]

The system needs balancing. Check the archive/FAQ for details.

What's happening is that your upstairs radiators are presenting a lower resistance path to the flow of water. The recently added towel radiator could be compounding this given its greater bore size.

Only when these rads are upto temperture, and their TRV's start closing down, does their resistance increase such that the downstairs radiators start getting sufficient flow.

Balancing will cure it. If the problems only started following the installation of the towel radiator you could try throttling it back (i.e. closing the valve on the opposite side of the TRV).

Mathew

 

[ajrobb]

Sounds like another 'balancing' post. Have a look at:

http://www.draytoncontrols.co.uk/WorkArea/DownloadAsset.aspx?id=11815

//www.diynot.com/wiki/plumbing:faq:faq2

//www.diynot.com/forums/viewtopic.php?p=1772897