One pipe system air locks

[TFGplumbing]

I took this job on to replace TRV's & lock shields on a one pipe system, its donkeys years old, I thought it would be an arsehole job and it has not disappointed me, customer told me all the other plumbers never got back to her haha

Its got some air locks in it and they are proving a ***t to get out. 5 out of 8 rads are getting hot. Anyone got any Ideas for shifting air locks on a one-pipe system, i've tried all the usual stuff to no avail.

Cheers

 

[SimonG]

Boil it.

Dont want to teach granny etc, but you did use non restrictive trv's?

 

[Leo21]

Boil it.

Dont want to teach granny etc, but you did use non restrictive trv's?

That'll be it, remove the trv,s.

 

[TFGplumbing]

Boil it.

Dont want to teach granny etc, but you did use non restrictive trv's?

I used honeywell valencia's, the system had some old honeywell flange fitting TRV valves which seemed more restrictive

 

[SimonG]

Boil it then. Balls of steel required and watch that overflow

 

[SimonG]

Had one just before christmas. One piper on a y plan. A good boil and chasing round. Perserverence is the key.

 

[TFGplumbing]

Boil it then. Balls of steel required and watch that overflow

Why balls of steel? I've seen it done once when i was an apprentice but never attempted it

 

[SimonG]

I know somebody who brought a ceiling down.

 

[SimonG]

Wasnt me either

 

[REDSAW]

heres me thinking 3 days was embaracing shifting an air lock :0

 

[tamz]

It won't be air. Probably too much restriction through the trvs.
Rads on a one pipe system work on gravity.

 

[tamz]

Pulling the stat is easy enough. It just rattles bangs and clicks a bit but down in Englandshire you guys use 3/4" overflows so the f&e could run over if you let it boil for more than a few seconds.
We use 1 1/4 and 1/ 1/2"

 

[SimonG]

Have you varied the pump speed?

 

[TFGplumbing]

Have you varied the pump speed?

Yes, I've been at it for about 6 hours, a strange thing i have noticed is that; it is returning at the boiler, but not all the of the ''flow pipe'' is hot' around the house

 

[TFGplumbing]

Also if I drain water out the cold rads, the flow pipe will come hot

 

[tamz]

Yes, I've been at it for about 6 hours, a strange thing i have noticed is that; it is returning at the boiler, but not all the of the ''flow pipe'' is hot' around the house

See post 11

 

[TFGplumbing]

See post 11

There were already TV's on it though tamz, I am not saying its not that however

 

[tamz]

Not all trv's are alike. Some have higher resistance than others.
Did you push the tails down any when you fitted them? If there isn't a rise or very little rise from the main circuit to the rad it won't work.
Try pulling the tails up a bit if there is any play.
One pipe rad valves are expensive at around 50 quid for the valve body and sensor.
As a compromise they will have a better chance of working if you piped them tboe as the pressure differential is proportional to the rise.

 

[TFGplumbing]

Cracked it got them all heating up