Central Heating Radiator Problem

[squirrel_hunter]

I have a slight problem with my radiators not heating up. I have heat at the top, but not the bottom.

First the set up: A new build development, first time the heatings been on. There is one radiator in the hall that is controlled straight from the boiler (no control on it) the house thermostat is also in the hall. The idea is that you set the house temperature here and then can turn up/ down the other radiators as required.

The radiators in the bathroom (towel heater types) and the radiators in the other rooms (normal radiator types) all were not heating up very well. So I bled the air from the system. This solved the problem with the bathroom ones but not the others.

I've tried re-bleeding a number of times but no luck. These radiators are nice and warm at the top but not at the bottom. A google gives hot at the bottom and cold at the top, and cold in the middle but not cold at the bottom. I've tried playing with the other knob on the bottom, but all I get is hissing from it and not any difference in temperature from what I can tell, unless I'm doing it wrong.

So the radiators are hot at the top, cold at the bottom, whats the diagnosis?

[Dave20046]

Full o' sludge?

[Dave20046]

Did you use an inhibitor before the summer/ever?

?? If they are hot at the top then water must be passing through them, the top will always get hotest first, then the rest of the rad will get warm if left on long enough, unless they are sludged up, but as it is a new system this would not be the case. Is it a pressurised system, if so is the water pressure about 1.3 bar.

[squirrel_hunter]

Not sure if its a pressurized system, but the boiler is around that Bar, there is a green zone on it and the needle is at the top of it.

Ok so yeah it is a pressurised system, AS we are waiting for a reply it could be that the system requires balancing, by turning down the rads that get hot, thus forcing the water through the other rads, to balance you turn down the other side with a spanner or grips, ie not the side with the thermostatic valve on that side is left on, ie at no 4 say, then turn the other side all the way off, then open it slightly about 1 full turn, you will hear when the water starts passing through, you can do this on all the rads, the theory being the rads closest in the system to the boiler will require less flow, and the farther away they are then obviously they will require more flow. ALSO YOU MAY NEED THE PUMP SPEED TURNING UP.

Ok mate i'm gonna say it's either the pump need turning up, some you can some you can't, may or may not be on the boiler, or it's the balancing. Is it a combi boiler, ie do you have a hot water cylinder?

I concur, if bleeding isn't doing the shizzle, it probably needs balancing.

Try turning off completely a couple of rads and see if that changes anything.

I presume the hall one is the bypass?

Hold on a cotton picking minute, it's a new build? Get the builders out to look at it!!!
Should've been set up properly when it was installed.

have you considered Dell or a Mac?