New Radiators Not Working

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Gidders

Gidders

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In May I had my garage converted into a room & the builders plumber A, fitted a new radiator in there & moved the one in the hall

In June my plumber B, fitted a new gas boiler.

Now I've had the central heating on I've found the 2 new radiators don't heat up - all the other radiators in the house get red hot.

A is saying that B has left an airlock in the system - B is saying that A hasn't fitted the new rads correctly.
  • I have bled the new rads & there is no air in them
  • The pipe to the inlet valve of the hall rad gets hot but the rad doesn't
  • If I shut down all the old rads, the new rads get hot, although not as hot as the old ones
  • I've left the system running for 2 hours
  • After getting the new rads hot, if I open the old rads, the new ones go cold
  • The new rads are plumbed in 10mm pipe, all the old system is 15mm
Any suggestions what the problem is please
 
Last edited:
For a start guy who fitted boiler should have made sure all radiators worked before leaving job. As many pictures of install boiler ect as you've got please.
 
Open up the lockshield valves on the opposite end of each rad, maybe they haven't been balanced properly, open them right up and see if the rads get hot. If that works you'll need to balance them, I think there's a radiator balancing thread on here somewhere.
 
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Balancing Radiators Thread.

How To Balance Radiators Tool List: Radiator-bleeding key Lockshield valve adjuster or adjustable spanner Screwdriver Digital thermometer or multimeter with thermometer function 1. Make sure all the radiators have been bled. Turn off the central heating and allow the radiators...
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Sounds like not balanced correctly also how many rads do you have in the house ?
 
There are 9 rads inc the new one & replaced one.

I suspected a balancing issue - would the fact that the newly fitted rads being on 10mm pipework vs old rads on 15mm pipework cause that sort of problem?
 
Yep as 15mm will flow easier than 10 mm close all the lockshields shut and open the 15mm ones 1/4-1/2 of a turn the 10mm ones 1/2-3/4 of a turn if you get some that are slow / not heating up open it a bit more
 
Gidders said:
In May I had my garage converted into a room & the builders plumber A, fitted a new radiator in there & moved the one in the hall

In June my plumber B, fitted a new gas boiler.

Now I've had the central heating on I've found the 2 new radiators don't heat up - all the other radiators in the house get red hot.

A is saying that B has left an airlock in the system - B is saying that A hasn't fitted the new rads correctly.
  • I have bled the new rads & there is no air in them
  • The pipe to the inlet valve of the hall rad gets hot but the rad doesn't
  • If I shut down all the old rads, the new rads get hot, although not as hot as the old ones
  • I've left the system running for 2 hours
  • After getting the new rads hot, if I open the old rads, the new ones go cold
  • The new rads are plumbed in 10mm pipe, all the old system is 15mm
Any suggestions what the problem is please
Click to expand...
NO air in rads is not the same as air in the main circuit. New boilers have low pressure pumps so often between 1-1.5bar. Any air in the system is always going to be at atmospheric pressure i.e. 1 bar. So fighting 1bar with a system that is 1.5bar before losses is never going to happen. You only have 2 options (forget this whole balancing thing, that was in the old days before variable speed pumps) You have to remove air by hiking up the pressure (to the point before the relief valve kicks in) to 2.75 bar so you can fight the air lock or you need to do a full re-circulation i.e. push water through until it has been round ever rad and pipe bend/high point. And before I hear the siren call of "the joints will burst" consider this. If your pipework cannot handle 3 bar then the problem you have is minor compared to the cost of what you have to do to fix the underlying pipe problem.
 
hometech said:
NO air in rads is not the same as air in the main circuit. New boilers have low pressure pumps so often between 1-1.5bar. Any air in the system is always going to be at atmospheric pressure i.e. 1 bar. So fighting 1bar with a system that is 1.5bar before losses is never going to happen. You only have 2 options (forget this whole balancing thing, that was in the old days before variable speed pumps) You have to remove air by hiking up the pressure (to the point before the relief valve kicks in) to 2.75 bar so you can fight the air lock or you need to do a full re-circulation i.e. push water through until it has been round ever rad and pipe bend/high point. And before I hear the siren call of "the joints will burst" consider this. If your pipework cannot handle 3 bar then the problem you have is minor compared to the cost of what you have to do to fix the underlying pipe problem.
Click to expand...
The new rads get hot when all, the other rads are closed off. Could there still be air in the main circuit in this instance?
 
No as they wouldn’t get hot try balancing them takes 10 minutes to do
 
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