Radiators are warm but not hot?

Question

Firstly....yes I have bled all of the radiators, and there was only one in the house that had any air in it.
Other checks;
- Boiler is heating the water very hot ok
- Pump is running ok
- Pipework from the pump is very hot
- Copper pipe entering the radiators is very hot

- However, the radiators are only tepid

Any ideas what I should check next?

Answer 1

sounds to me as though you have a bad case of sludge. your pipes slowly decompose over time along with your radiators and they form a sludge. This causes blockages and may lead to pin holes and leaks. you could do with a power flush/ jet flush, can be costly but is worth while rejuvenates your pipework and radiators improving efficiency in the heating of your house, your system does not need to work as hard to heat the house thus less gas consumption. Sentinel have some good information on this as they make the chemicals for the cleaning and inhibitors to stop it happening in the future. I know a company that could sort this for you PGS 0800 3284169

Answer 2

How hot is the water leaving the radiators? If that water is quite hot, then check the systems pressure gauge and see if there is positive pressure. Take into account that a column of water will give a positive pressure at a gauge at the bottom, and you need enough pressure to have positive pressure at the highest radiator in the system. Usually, there is an automatic fill valve that keeps pressure at a certain point, but that can get stuck over the summer and not keep the pressure up. Also, the expansion tank may become waterlogged, or if it's a diaphram type, the diaphram may be ruptured.
Hot water systems usually work at about 15psi.
Did you get water out of the radiators you bled?

Answer 3

Radiators Not Hot

Answer 4

You have an airlock in the radiators that the bleed screw won't release. Get a spanner which is the right size to undo the big nut on the radiator valve, and get something to catch the water underneath the valve. Slighty undo the big nut and let the water trickle out. let it run until you feel the water is hot, then retighten the nut and see if this improves the heat. You may have to do this more than once. mstart on the radiator that is furthest from the boiler and work back to the boiler.

Answer 5

Sounds like your radiators need "balancing".

There are two valves on modern radiators, one with the thermostat and one on the other end which is "Shielded". Take off this shield and you will find a screw or nut which controls the flow of water through the radiators. Try opening this valve a bit. You really need special thermometers to take temperature readings of the in and out pipes to do this properly but try without a thermometer first yourself to see if you can get the radiator hotter.

Without any more info that is the best I can offer other than get a specialist central heating engineer in to do the balancing. Also I agree with another person you may need a power flush.

Answer 6

As Jimmy mentioned - your thermostat, have you checked it?

Also each radiator generally has its own valve 0-6, so you can have each radiator in your property set to how much heat it gives out.

Firstly, your thermostat will cut out when the temperature you have set it to reaches that degree. Secondly, check all individual rads for the temp gauge.

If that fails to correct the problem, then probably like the majority of answers you need to bleed your rads - but much longer than just letting out the air. Turn the key - making sure you have a bowl and cloth underneath the outlet - until water flows out, this can take a while to rectify.

Answer 7

I am assuming you don't have a Combi.
The water is flowing but not quick enough are you sure the pump is running ? put a screwdriver largish one on the pump and listen at the handle bit like a stethoscope one can hear if its ruining (pump will be very hot ) If its ruining then the impeller could have come loose or try and increase the speed (switch on the side marked 1,2,3. 3 is the fastest. ) If its not ruining test for electrical supply to pump if OK then it might just be stuck. In most cases remove large screw and spin the shaft with a small screwdriver ( a small amount of water will leak) If it wont start replace. Next look at the diverter valve if you have one, manually open it. you may have to remove the head.

Answer 8

There maybe a bypass valve in your system. This means that you can regulate the water that goes through your heating system or it bypasses the heater. If all water bypasses the heater your radiators stay cold. The bypass valve can be set say between 0 to 10. In case you set the valve at "5'
then halve of the circulating water goes through the heater the other part bypasses the heater. Your radiators will be warm. The higher the number the warmer your radiators.

Answer 9

if the rads are cooler at the bottom and warmer at the top then it's a build up of sludge. if this is the case,
1. turn off the valves that lead into the rads
2. gently crack the nut at the rad side of the valves
3.drain the water from the rad also open the vent at the top of the rad to allow air in and water out.
4. flip the rad upside down to prevent the sludge dripping on the carpet, remember to re -tighten the vent.
5. take the rad outside put a hose pipe in one side and flush it through,
this should sort the problem if not call a plumber. good luck.

Answer 10

main clue here is all the radiators are not hot...not just one...
check aquastat setting inside main control...it has a dial with numbers and is set up at whatever temp you want the radiators water to heat up to...should be set around 150 -170 degrees for most. also check pressure at boiler... should be prior to start 15 pounds of water...pressure...if not add water...another thing is check if circulator pump is actually working..turn on furnace and check... it might possibly run but not turn inside that could be it also