Gurgling and air in central heating

[SJB060685]

Suction side is the inlet to pump. The discharge side (after the pump) should be under positive pressure, relative to pump ∆P (delta P).

If during summer use you accumulated no air then that would suggest as you say something somewhere is weak. You could go around tightening all connections above the floors, if the problem lies beneath floors that's a bit more of a problem.

 

[jim843]

Suction side is the inlet to pump. The discharge side (after the pump) should be under positive pressure, relative to pump ∆P (delta P).

If during summer use you accumulated no air then that would suggest as you say something somewhere is weak. You could go around tightening all connections above the floors, if the problem lies beneath floors that's a bit more of a problem.

Really hard to say, there was a tiny bit of air over the summer (a tiny spurt and then water) but not this much. I’m bleeding every day for between 3 and 10 secs.

I did notice this on one of the rads:


This rad is very rarely on as the room gets warm during the day and is cool at night.

Could this be a cause?

 

[John.g]

Would definitely prefer to see the EV installed on the pump suction side like this Vokera Combi but there must be thousands of Baxis with them on the discharge side.

 

[SJB060685]

That rad lockshield looks like it's been bombarded with PTFE on the return, possibly because of a leak on the old system under positive pressure and could quite well be the culprit. I would consider remaking that joint. Where is that rad in relation to the towl rail?

 

[SJB060685]

Would definitely prefer to see the EV installed on the pump suction side like this Vokera Combi but there must be thousands of Baxis with them on the discharge side.

View attachment 65231

Many systems would work like that if air tight but not if there's a weak point.

 

[jim843]

That rad lockshield looks like it's been bombarded with PTFE on the return, possibly because of a leak on the old system under positive pressure and could quite well be the culprit. I would consider remaking that joint. Where is that rad in relation to the towl rail?

This is on the same floor, about 8m away.

What would you recommend when redoing the joint? How many winds of PTFE?

As this rad is almost always off I could always just cap off the pipe work for a few days and see if that resolves?

I’m not adverse to doing this myself but I must admit I don’t like it. I fit an 8000 BTU rad in the kitchen and hated every minute of it!

 

[SJB060685]

Ok. Close both valves for a day or two and see if it draws in air. I'm willing to bet based on the state of that lockshield and the crude attempts to fix an obvious problem that no air will be drawn in to the towel rail. If this proves correct you would need to remake that joint. You shouldn't need any PTFE or jointing compound on a valve if holding true.

 

[John.g]

With EV on the pump discharge, the way I see it is that the pressure at any point in the system will be reduced by the pump head so presumably a severe restriction can allow air ingress at a weak point(s).

 

[jim843]

Ok. Close both valves for a day or two and see if it draws in air. I'm willing to bet based on the state of that lockshield and the crude attempts to fix an obvious problem that no air will be drawn in to the towel rail. If this proves correct you would need to remake that joint. You shouldn't need any PTFE or jointing compound on a valve if holding true.

ok, will try.

here is my attempt at fitting the rad in the kitchen.


there is some blue staining underneath the TRV bit and also on the pipe coming out the wall. The thing is, when the floor is mopped this pipe can get wet. That would cause the blue staining?

I put loads of PTFE on this rad because the lad that fit two other rads in the house for about £300 said you need 25 turns of PTFE on these acova rads?

 

[SJB060685]

The rads closest to the boiler and at lower points in the system should be under positive pressure and a weak point would be recognised as a drip. Any points higher in the system and weak could well be under negative pressure.