Cold Rad after balancing

[tabz2003]

One of the radiators in my house has not worked for a long while. With the summer on its way out and winter approaching i thought i would have a go at fixing it.

The central heating is all newly fitted (3 years old) with a worcester combi boiler. I find one of the inlet pipes is hot and other cold with the radiator only becoming luke warm at the top.

I removed the radiator and flushed it out with a hosepipe, it was clean and there was no masses of sludge. With the radiator of i opened both valves and water seemed to be coming out at a good pressure from both sides.

Reapplied the radiator problem persists. I then read on the forum about balancing the radiators. I turned all other rads off and left the faulty rad valves open after 20 minutes the rad was 90% hot (cooler at the bottom) and the once cold inlet pipe was now hot but not as hot as the other side.

Although the problem is 90% better the bottom of the radiator still is not as hot as the top and i feel when i open the valves for the other rads the problem will reoccur.

Any ideas what this could be are the valves faulty? is there an air lock in the system? should i change the rad?

Many thanks sorry for the long post

 

[D_Hailsham]

Water flows through the rad from one pipe to the other and on the way it gives off heat. So the temperature of one pipe will always be colder than the other. The hotter pipe is called the flow; the other is the return. TRVs and wheel valves are normally fitted to the flow end; the valve at the other end (normally with a plain cover) is called the lockshield valve and is used to balance the rad.

Read How to balance a CH system

 

[tabz2003]

Thanks for your reply

from your reply do you think i need to balance the CH system or is there a fault somewhere?

tabz

 

[gigz]

If it works with the other rads off it will probably just need balancing properly. Close the lock-shield valve down a bit at the hottest (or first from the pump) rad then second hottest etc, there's no cut and dried way to get them all spot on but with patience you can get them as near as dammit.

 

[D_Hailsham]

If the top of the rad is cold, it usually means that there is air in the rad. So it needs bleeding.

This should be done with the system off (CH and HW) and the water cold. It's probably best to do all rads. Start with those on the ground floor.

Just closing down the lockshield valve a bit will have no effect on the balance; the working range of a LS valve is from closed to about one and a half turns open.

 

[doitall]

A very common problem with cold rads this time of year if the TRV's closing because the room is up to temperature.

You may be looking for a fault that doesn't exist.

Take the TRV heads of and try it.

 

[thfc191]

if the rad is colder at the bottom possible sludge and if cold at the top needs bleeding , and re balancing