Topping up heating system

Luckysasha

Ok bear with me please. I have one rad in the house that won't heat properly. Cold on the top warm on the bottom. All my research is pointing towards sludge or some kind of blockage in the rad itself. So after being let down by a couple of plumbers I have decided to have a look at it myself. So when I turn off the two rad valves and take the rad off and flush it out etc is there anyway of checking good flow at the valves before I rehang the rad. Can I simply open the two valves in to a bucket to check flow. Do I need the heating on to do this I.e. Have the circulating pump running? Also when I rehang the rad will I open the vents before I open the valves or let the rad fill first the bleed it. One valve is a TRV so does it matter which valve I open first. Now when all that is done will the system top itself back up with water. I have a 1/2" pipe from the tank in the attic going through a wheel valve which is fully open at the minute. After the valve is two one way valves pointed away from the tank. The 1/2" pipe continues down and is tee'd into the 3/4" pipe that leaves the bottom of the coil in the cylinder. I have an expansion vessel out beside the boiler but there is no pressure gauge fitted on the system. Is this normal?

K.Flyer

Cold on the top, hot on the bottom is Air in the rad. Open the vent screw on the top of the rad to release air until you get some water and close the screw again.
Hot on top of the rad and cold along the bottom is usually Sludge.

agusta

Luckysasha wrote: »

Ok bear with me please. I have one rad in the house that won't heat properly. Cold on the top warm on the bottom. All my research is pointing towards sludge or some kind of blockage in the rad itself. So after being let down by a couple of plumbers I have decided to have a look at it myself. So when I turn off the two rad valves and take the rad off and flush it out etc is there anyway of checking good flow at the valves before I rehang the rad. Can I simply open the two valves in to a bucket to check flow. Do I need the heating on to do this I.e. Have the circulating pump running? Also when I rehang the rad will I open the vents before I open the valves or let the rad fill first the bleed it. One valve is a TRV so does it matter which valve I open first. Now when all that is done will the system top itself back up with water. I have a 1/2" pipe from the tank in the attic going through a wheel valve which is fully open at the minute. After the valve is two one way valves pointed away from the tank. The 1/2" pipe continues down and is tee'd into the 3/4" pipe that leaves the bottom of the coil in the cylinder. I have an expansion vessel out beside the boiler but there is no pressure gauge fitted on the system. Is this normal?

Leave the rad that is not heating properly turned on.turn off all the other radiators and balance valve for the cylinder and see how the rad works then

Luckysasha

Have tried everything suggested so far so my next step is to flush the offending rad hence my questions

Pete67

You have a 'semi sealed' system. It should refill when you are venting air, however it is quite common for the check valve(s) to stick closed, as there is usually very little pressure to open them due to the tank being only a few feet higher than the valves. Personally I would change it to a mains filled, fully sealed system.

When you vent the radiator do you get a steady stream of water under pressure from the vent once all the air has been released, or do you get a little air and then nothing? Your problem does sound like air rather than sludge. You don't say what type of boiler you have, most gas boilers have a pressure guage on the front panel somewhere.

Luckysasha

Thanks Pete. It's an oil boiler floor mounted in the shed. A sime ar4 to be exact. All it has on the front is a temp gauge and a knob with a diagram of a heating coil I presume. The tank in the attic is approximately 6 foot higher than the check valves. It's a bungalow. When I open the bleed screw on the offending rad I just get water straight away. No Air whatsoever. The water has good pressure but is crystal clear. Is the fact the water is clear means no sludge I wonder. There is a rad in the sitting room a little further away so the offending rad is not even the last one on the system

MeeMoo

I had a similar issue recently . I call in 3-4 plumbers , all of them giving different options ( valve is gone - from boiler, another one to put an extra tap before cilinder , and so on ) .

At the end we had to change all the pipes for heating , it was black and mudd. Now all radiators are working .
Good luck to sort your problem as soon as possible! 😉