the Central heating system is running at the top temperature but the radiators don't get hot in the middle?

Question

i have already bled all of the system all the radiaters are new and all the valves are new..

Answer 1

At first all points to sludge but as you say the rads are new so it must be circulation. You don't say as to what kind of boiler / system you have. First make sure that the pump is turned onto full output. ( switch on the side of the pump.) If its conventional tanks /cylinder fully pumped and the diverter valve is operating OK then it may be that the bypass valve is open to much, this is situated in the vicinity of the pump and diverter valve and is connected between the pipe just on the outlet side of the pump and a return usually the bottom connection on the cylinder.
Next look at the temperature setting on the cylinder thermostat, if this is set too high then it may be never getting up to temperature and switching over to fully central heating. setting should be 55'
To save time turn the cylinder thermostat down so only the central heating side is operating. Do the rads work OK now ?
If still no improvement, turn some of the rads off dose this improve the situation? if so, change the pump, if its a big system 12 or more rads, 3 floors, pump and cylinder in the loft then fit a 6mt. pump.
If you have a combi boiler then I would have thought you would have other problems as well so I'll forget that at present.

Answer 2

Merry Christmas Mate,
When you bleed your radiators, you must not have the pump running as this just pushes the air all around the system, turn heating off & after doing so then start bleeding the radiators from the upstairs and work down, also make sure the valves on the opposite ends of the radiators from the control valves or thermostat valves are all open halfway or more, these just have white pull of covers or are held on with a philips screw.
Hope this helps. Remember Without The System Running.

Answer 3

Sounds like an airlock in one of the pipe lines.

I have this problem ocasionally and I discovered a means of getting around this.

I have a hot water boiler heating system with a total of three circuit paths for heating. When it seems like it isn't circulating in one of the paths, this is what I do;

I manually add water into the line (usually set at 12 psi) and as it increases in pressure, I open/close several valves to push water through the lines and back out one of the spickets, I open it partially, to keep pressure in the pipes at around 35-40 psi for about 5-10 seconds then stop adding water into the line and slowly close the spicket until the psi is around 5-10 psi.

Doing this 2-3 times gets most of the air out of the line.

In about 1-2 days later, I do that again but only once and this takes care of that problem.

Also having the heat on high creates more steam and less water in which air eventually builds up in the system over time and soon causing an airlock. I keep the temperature below 200F and it works fine.

Answer 4

sound´s like they might have some air inside . did they leave you a small key with your radiator´s, if not a small coin should do , get a jug put under the valve then with the coin open the valve you will here the air escape , then when you think the air has all been let out , close the valve, do this to all the radiators , hope you get it fixed Merry Christmas, dont worry if some water comes out that´s normal, switch off the heating and try again

Answer 5

You need to bleed the radiators, because there is air in the system. Make sure that the pressure stays above 1 by topping up while you bleed the system.

Answer 6

interior the boiler is one or 2 pumps. One for the nice and comfortable water and one for the heating. The heating you could have a velocity administration on it. turn this to positioned 3 and the subject could be cured. examine if the utmost radiator interior the gadget is warmer and perhaps warm throughout. despite if this is then examine that the pump is working. in case you have thermostatic radiator valves see that the valve on the different end (the lock preserve) is totally open. despite if this is not then open it. terrific of positive fortune. happy Christmas.

Answer 7

you have to bleed all of the radiatots properly with a key .Try opening up the valve on the end of the radiator. get the pump checked.

Answer 8

Have you tried closing some of the radiators off, to give you max flow through a radiator, and see then if they get hot all over. once you have resolved the problem, you must add a bottle of the treatment to your expansion tank, prevents corrosion, and air build up

Answer 9

Worth checking that there is sufficient pressure in the system after bleeding them. Might need to top up.

Answer 10

But did you drain the radiators and flush them out? Sounds like a pile of sludge in them - are they very old?