In this central heating system, the water is heated using steam from a boiler and the secondary water temperature is kept constant at 80 deg C by a valve. the water is pumped by two pumps whicha are in a closed loop system to different rooms while the individual temperature is controlled by a thermostatic valve which close the water to the room radiators when the selected temperature is reached.

suddenly the heating output capacity of th room radiators has dropped drastically. the return line pressure in secondray circuit has also dropped.

first i thought that there was an increase in a damaned but this fault had occured suddenly so i dont think that this is the fault. can someone help me with this problem and tell me what is the possible faults ??
And what is the best diagnostic technique to find this fault?? i am considering using the functional chart is it right ??

and the last question is what are the primary and secondry performance in the centarl heating system ??

if someone can help me with this i appreciate it and if there is any links which can help me with this problle list them please.

thanks
J.Borg

dOES SOMEONE CAN HELP ME WITH THIS ??? PLEASE

J. Borg,

Is the drop in heat output from the radiators an individual problem or a common one? If it is common, has a check for a piping leak been done. I am sure you have done this but this would be my first suspect. If there is no leak then I would suspect blockage in the supply piping. Is the water treated? What kind of pipes are in use? Common steel pipes can build up corrosion that if it comes off the walls can clog valves. The decrease in heat coupled with the low return pressure would make me start investigating the valving in the supply system.

Ken Culverson

and what about the pressure dropp ??

Mazda
Sounds like there is air in the system this is a common cause of your symptoms is there any cavitation in the pumps or surging? Can the radiators be bled or is it possible to bleed the pumps?

Chemic.

Mazda can you post a simple sketch of the system, indicating where are the block valves, sensors and other instruments?

Did you check if somebody accidentally throttled a valve because it was too hot or too cold in the room?