Hi all, I've just drained my central heating system and moved some pipes.
I've now filled the hot water tank in the loft but nothing is in the pipes.
I assumed that there must be an air lock so I've connected a hose to the bleed valve on the bottom radiator and pushed water up into the rad system but still no joy.
All valves etc are open the water just won't budge.
I assume that there must be an air lock somewhere can anyone help??
Chris
In message , cj wrote
Including the 3 port valve that selects just the hot water loop, just the heating loop or both?
The valve defaults to hot water only and may not let water circulate around your heating system if is in that position. If you have one of these valves you will need to manually move the lever that is fitted to it to open up the central heating circuit
See
for a picture of what you may need to look for.
or it could be muck in the system - if there was crud in the header thank that could have got drawn into the pipework. blow out with mains pressure. that may also help clear any airlock and fill the system again
"cj" wrote in news: snipped-for-privacy@h48g2000cwc.googlegroups.com:
I have to clear airlocks eevery time on my topdwn system.
The radiators are on branches, maybe more than one rad per branch, maybe only one.
After filling, close what radiator valves you need to to leave only one branch open.
Then turn the pump up to high, run it by turning the thermostat way up and blast out the airlock. Don't leave it on for long, unless you tweak the wiring, the boiler is firing. When the gurgling dies down turn it off by winding down the thermostat. and bleed the radiators in that branch - hopefully allthe air is in the radiator and not in the pipe.
Next close down that branch and open another; repeat the process till all branches are fixed, you should now be able to finish the job by conventional bleeding.
As I have to do this every time, it doesn't take me long at all!
mike
Alan, I really apreciate your reply, I think you may have hit the nail on the head! There are however, a few problems....
1). I Can't find this valve; where are they usually installed? Near the boiler, near the water tank?2). Our system has one of these....
I am obvuously most confused!
My gut instinct tells me to turn on the boiler which will pump the water around the system but acording to other web sites turning your boiler on when there is no water in can damage it.
Any ideas or info would be gratefully recieved!!!
Chris
In message , cj wrote
The suggestion was only based a guess about you system about which you gave very few details.. Not all systems will have a 3 port valve. If installed it should be somewhere relatively easily accessible as its not unknown for them to go faulty. Do you have a hot water cylinder or an airing cupboard? Try looking there.
What kind of boiler/central heating system do you have?
It could/would be also be wired in with a room thermostat. Just turning the heating on may not switch the valve. If your room is up to temperature the room thermostat could/would stop the valve from providing hot water to the radiators. The room thermostat will need to be adjusted for perhaps 30+ degrees C - especially for this time of year
- to call for heat and switch the valve over.
Not recommended.
_IF_ you have a 3 port valve find it and move the (small) manual lever you will find on it. If you don't have such a device then consider some of the other suggestions in this thread.
Ok Chris you drained the heating system. What was your problem before you started to do this? Are we to understand you didnt change any piping in the loft or at the boiler? To help you one would need to know what pipes exactly you moved and were they shortened or tidyied up but no extra rads installed?
obviously if you just changed the length or layout of a pipe run that would only indicate an air lock or dirt in the system but any other changes may c*ck it up especially when you dont even know that a tank of cold water supplies the system and the hot water is in a copper cylinder on a lower level.
Anyway despite the advice dont fire the boiler until you are sure you have water in the system and beware of all the would be plumbers on this site.
You can run into two issues doing this:
- The pump can run dry. If that happens for any length of time (which can be short), the bearings will become aufgeficht and you will need a new pump.
- If the gas is on and the boiler fires up without water in the heat exchanger, you may have issues with that as well.
The best and safe solution is to force water into the system through a drain c*ck using a hose and mains pressure. If the water fills the tank in the roof, open all the radiator valves fully and arrange for an assistant to undo the vents one at a time while you block the feed/expansion pipe (at the bottom of the tank) with your thumb. This should force water into the CH circuit. Then you have something to work with.
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