One radiator collecting air

Discussion in 'Plumbers' Talk' started by Daniel Channon, Jan 21, 2020.

  1. Daniel Channon

    Daniel Channon New Member

    Hi all,

    This is my first post in a desperate effort to resolve an issue we are having with a single radiator having to be bled every couple of days.
    The radiator in question is a tall vertical radiator in the bathroom which is closest to the boiler.
    We have had a new central heating system fitted before christmas. All pipework replaced with a new Ideal LOGIC MAX 24 combi boiler installed on the first floor.
    Its only a small system - 6 radiators with all brand new piperwork fitter throughout.
    Only on friday we had the TRV replaced and thought this was the solution as it was getting hotter than ever. But as per 2 days later the radiator is slowly cooling (left to right). The pipework seems sound as both pipes are hot. All vavles are fully open.
    The radiator in question was fitted AFTER the other were fitted as it was fitted when the bathroom was done (if that makes a difference).
    The plumber has suggested it will be the radiator, and as we supplied the radiators and valves we will have to foot the bill (and we could really do without the cost!)

    Any suggestions would be great - ive done some reading but im no expert so suggestions will be very helpful.

    I should add the pressure on the boiler is good and always has been.
     
  2. Hans_25

    Hans_25 Screwfix Select

    Odd. Its not unusual to have some air in the system that takes a while to work its way out to a radiator, but once rads have been bled a few times, there should be no more air. Only place I can think air can get into the system is via the pump.
     
  3. Daniel Channon

    Daniel Channon New Member

    Thanks for a quick reply. We have the had the plumber come round previously and bleed all radiators and suggest that would have sorted it. I have also gone round and bled them myself, but then 2 days later starts going cold. As the TRV has been changed friday and the system was drained is it a case of bleeding a few times to clear any trapped air?
    Thanks again.
     
  4. Hans_25

    Hans_25 Screwfix Select

    It can take a few bleeding times (haha) before all the air is out, so give it a wee while. As I left the house this morning, Ms Hans mentioned the hall rad was only warm and I've had air in that a bit over the past few weeks. Will check it again tonight, it might be that due to the pipe layout, any air will always work itself to a particular rad.
     
  5. Daniel Channon

    Daniel Channon New Member

    This radiator is the highest point so my understanding was that the air would get trapped there. We have another tall vertical rad downstairs and that gets boiling hot with no issues at all. I will try bleeding a few more times to be sure.
    We just want this sorted before carpet gets laid!!!
    Thanks, Dan.
     
  6. The Teach

    The Teach Screwfix Select

    if the tall heat emitters (commonly called radiators for advertising sake+sales) are the same items. There maybe be some settling down with regard to air elimination,hopefully they are fitted correctly.

    Could be something more detrimental but see how if goes.

    depending on the pipe layout from the boiler to the so called tall radiators,tall towel rails,tall lumps of Chinese metal will act as an air separator and collect air etc.

    The logic boiler has auto air-venting facility which would have been left ready to vent out passing air,What can go wrong ?
     
  7. DIY0001

    DIY0001 Active Member

    Are you sure its air in the radiator, which would normally result in the radiator being cold at the top and hot at the bottom, rather than the left/right cooling you describe.

    Are you getting the air out of the radiator when you bleed it? Does the radiator get reasonably evenly warm after it has been bled, or are you left with this left/right hot/cold issue right away?

    Remember, a vertical radiator will always have one side a bit warmer than the other as one side is connected to the inlet, getting fresh hot water, while the other is connected to the outlet, only getting hot water after it has passed through the other side.

    Suggest turning the TRVs off on the other 5 rads for a bit, to force any air in the system into the problem rad. Bleed it to get the air out and then open the TRVs on the other rads to the required settings.

    If you continue to get air build up in the rad then it must be being generated in the system. One cause of air/gas generation is corrosion. Did the plumber refill the system with inhibitor after replacing the TRV on Friday?
     
  8. kiaora

    kiaora Guest

    Hi
    It’s a puzzle eh ?
    Lots of helpful advice ,
    If all fails, one outside chance, ... if the rad is first on the circuit, it could be some cavitation in the pump, that is causing the air, and the tall radiator is acting as an air separator.

    it’s worth actually closing the lock shield valve completely, then opening just a quarter turn, then leave it to warm up, it will warm up, but take longer, if too long , open valve a bit more.
    This will help the cavitation to stop by effectively removing a bit of the negative pressure on the pump inlet.

    good luck
    Peter
     
  9. Jimbo

    Jimbo Screwfix Select

    Do you have inhibitor in the system, and is the pressure dropping?

    You can fit an Alladin auto vent on the top of the towel rail to do the job for you. Just turn off both supply pipes fully, remove the blank and screw in the autovent.
     
  10. Daniel Channon

    Daniel Channon New Member

    Hi all,
    As suggested i turned off all other radiators at the TRV and left it a while to force the air to the problematic rad. I left it for about a hour and by then its had gone almost completely cold, apart from the bottom which was hot. I then bled the radiator, a small amout of air came out but not loads.
    Once it has been bled the radiator again gets hot all over. All other TRV adjusted back to required and still ok. Im only expecting this to last a couple days but lets hope!

    In regards to the auto vent is this not just going to mask the problem and potentially cause a more serious issue down the line?

    Thanks again, Dan.
     
  11. Hans_25

    Hans_25 Screwfix Select

    It doesn't take much air in the rad to cause the top to go cool. I've bled my hall rad a few times recently as it seems to trap air - all other rads are fine. Hopefully the air will stop collecting soon.
     
  12. Daniel Channon

    Daniel Channon New Member

    Thats what im hoping!
    I should note that they can become fairly loud, is this just a by product of the air in the system? The loud ones are downstairs vertical and master bed. The master bed only seems to get hot when the TRV is set to 5 (that was also changed last friday).
    Sorry to bombard with info - im trying to get one thing done at a time not to over complicate matters.
    Ive tried to upload a picture of the rad but the file is too large. Here is a link to the verticals https://www.stylishradiators.com/designer-radiators/malmesbury-vertical/890146/

    Thanks again for your replies, nice to have a few more ears to chew!
     
  13. Hans_25

    Hans_25 Screwfix Select

    You say loud, what kind of sound is it?
     
  14. terrymac

    terrymac Screwfix Select

    As you have a new combi boiler ,sealed system , new pipework ,and air is persistently accumulating and being bled ,then presumably you are regularly topping up pressure by adding water into the system.
    That's not good ,as fresh water continually being added will add to premature corrosion.
    It sounds like you have a weeping joint and Air is being sucked into the system.
     
  15. Daniel Channon

    Daniel Channon New Member



    Ive had to upload my first youtube video to send that! that was this morning at the downstairs vertical, TRV set to 3 and still very hot.
     
  16. Hans_25

    Hans_25 Screwfix Select

    Sounds a bit like my rads, its the water going through the rad. Could be a combination of (a) pump set too high so lots of pressure and hence lots of flow (b) TRV/lockshield closed off so water is pushing against a small opening.

    This also happens if you only have a small number of rads on, as the pump is then pushing against a higher pressure.

    Can you turn the pump down? Another workaround is to have the hot water heating too so water is being pushed around that circuit.
     
  17. terrymac

    terrymac Screwfix Select

    It's a combi boiler Hans .
     
  18. Daniel Channon

    Daniel Channon New Member

    Hi all, hope you've all had a decent weekend. No post in a few days been a bit busy but still the same problems.

    Ive had to bleed the rads twice since the last post, as per the bathroom one still getting cold after 2 days. Bleed the thing and boiling hot again. I must say that ive noticed a smell to the air coming out, almost like a plastic smell .... could this be hydrogen sulphide? If this is the case am I right in thinking it cant be the rad itself as its aluminium (as are they all)?

    I confirmed that an inhibitor was added after the last time the rads were drained. The plumber said it shouldn't be too much of a problem yet anyway as most the pipework is plastic.

    Ive attached a photo of the rad and highlighted the problem that occurs after a couple of day (if that is any help to anyone).

    Thanks, Dan.
     

    Attached Files:

  19. terrymac

    terrymac Screwfix Select

    Are you continually topping up the system pressure ? Those vertical "designer radiators" are notorious for collecting air ,and not heating uniformly.
     
  20. Daniel Channon

    Daniel Channon New Member

    The thing is no im not having to top up the pressure. Today will be the 4th time of bleeding since posting this and ive made note of the pressure. Its sitting at a steady 2.1 bar when heating and drops to 1.4 bar when its not.

    The plumber said that about the 'designer rads'. Seems a bit strange its good for 2 days then having to bleed it. I would understand if it was just taking a bit of time or a just warm one side but its always the same the way its loosing heat.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice