Central Heating Problems - sorry!

[planenut]

Hi gang, got a house in which a chap CORGI) installed a new pump in the system at Christmas. The system's not worked properly since.
I noticed a locking valve slightly leaking (first floor), touched it and found, terrific, it was now flowing out (eventually found the thread had sheared); drained the system below the first floor, replaced that valve and two others that were leaking slightly, refilled the system, still the same problems, in that water on led to some of the upstairs rads. heating up, turned heating on, most upstairs rads. cold, some warm.
Tried again today, drained the system down to the ground floor, refilled using one valve, then the last. Same problem, so thought it's got to be an airlock, so drained it again, using the other valve open first, both times allowed the water to fill up very slowly. Hey Presto...........
no darn difference.
Is it possible that there is an airlock in a pipe somewhere that will never move, only by opening the pipe?i.e. cutting, drastic but they are all hidden.

Makes a change for me to ask a serious question I know, but I would appreciate suggestions.

(I have not included the details of the lumps in the system as I don't think that will make any difference.)

 

[doitall]

Perhaps you should drain it all out.

 

[MANDATE]

If you have a large air lock, bleeding a radiator is not going to move it. The bleed hole is too small and you would have to run off loads of water.
When fitting valves etc, it's better to fill the system before putting the radiator back. You can then run off a bucketful of water from each radiator valve (you may have to fit a hose ) before replacing the radiator. By using the valve and hose there is hardly any resistance and the air will pass with the water easily. after that the only air will be that in the radiator. If you have a 3 port valve remember to put the lever to mid position while filling, also bleed the pump. also helps turn off all the radiators except the one giving problems and open them one at a time bleeding each one before dealing with the next one.

 

[kevplumb]

could try taking the top rad off and as mandate suggests fit a hose and move it quick

 

[planenut]

Thank you so far, here we go again.

 

[doitall]

Perhaps you should drain it all out.

Air will stick between the two floors, one should also check the pumps now going the right direction

 

[planenut]

Thank you doitall, I have wondered about that aspect of things. I am certain that it was fitted with the arrow pointing in the same direction, and I checked the wiring, (well I thought that might make it go the other way). I will have another two goes at draining completely, then return to the drawing board.

Sorry folks, what is the best way to refill, trickle or full pressure?

 

[doitall]

sealed system get somene to hold the pressure at 2bar tops.

open vented system let the water flow as normal, and fill from the bottom furthest rad

 

[dmikem]

you dont say whether there is air in some radiators. vent them all again starting with the ones on the ground floor then do upstairs. if you have a 3 port valve, turn the boiler stat off, turn the cylinder stat off, turn the room stat up, then the pump is only pumping round the heating pipework and may manage to displace the air. if this doesnt work, and there are isolating valves each side of the pump, it would be worth turning it so it is pumping in the other direction, -- this will only take half an hour, and is certainly worth trying before you do anything as drastic as cutting pipework etc. by the way if you do have a 3 port valve the pump should (in 99% of cases) be pumping towards the valve

 

[kevplumb]

it in 100% of cases should be

 

[dmikem]

it in 100% of cases should be

try fitting a 3 port valve to a primatic cylinder and see what happens!

 

[doitall]

try fitting a pump to the primaries of a primatic cylinder and see what happens

 

[kevplumb]

done that the water went a funny colour

 

[dmikem]

so obviously you now know that pumps and 3 port valves are not always fitted in the flow.

 

[doitall]

so obviously you now know that pumps and 3 port valves are not always fitted in the flow.

pump can be on the return I think we knew that before.

3 port valve is fitted depending on use, heating or cooling, diverting or sharing, or controlled temperature circuits