Downstairs Radiators Cold

Discussion in 'Plumbers' Talk' started by Shanks1986, Aug 30, 2021.

  1. Shanks1986

    Shanks1986 New Member

    Hi All,
    I live in a 2 storey house with 5 radiators upstairs and 6 downstairs. The boiler is downstairs in the utility room next to the kitchen and hot water tank and central heating pump are upstairs in the airing cupboard.

    The problem is that when I keep all the radiators on, only the upstairs rads get hot and downstairs are cold. When I close all the upstairs rada, the downstairs rada get warm. A plumber has done a power flush, added a central heating system cleaner and bled the rads. His suggestion is to add another pump downstairs to help the hot water reach all rads. Does that sound it will help by adding secondary pump downstairs?

    Thank you
     
  2. pppmacca43

    pppmacca43 Super Member

    Shouldn’t need two pumps for only 11 radiators in my opinion. Sounds like the radiators need balancing.
     
  3. Shanks1986

    Shanks1986 New Member

    thanks @pppmacca43 for the suggestion. The plumber has tried to balance the radiators but still the same issue. Also the existing pump when started seems to run only for few minutes and makes the upstairs radiatord hot but after some time it stops vibrating and even the upstairs rads become cold. Does it sound like an issue with the existing pump?

    Thanks
     
  4. pppmacca43

    pppmacca43 Super Member

    I would guess you need a new pump rather than two pumps, maybe it isn’t running at its full capacity
     
    exbg likes this.
  5. exbg

    exbg Active Member

    Why did he decide a PR was needed?
    Assuming that the system worked okay previously: the essential problem is either a partial restriction (increased resistance) or a defective pump.Os the system fully pumped? If so, a defective motorised valve can cause circulatory problems.
    Another favourite is sludge on the junction of the cold feed and system.
    Had anyone worked on the system and left a valve partially closed?
    Does the system make any odd noises?
    If it is an old gravity system, suspect the anti gravity valve. I have also found these left on a system after a conversion to fully pumped, thereafter clogging and resisting.

    My point is that there are a lot of things that could cause the issue, and PF would be last on the list.
    The system almost certainly does not need a second pump - it needs someone who knows what he is doing, in my opinion

    When he did the PF, how pong did he take?
    Did you observe ugly black sludge being discharged (when I did a lot of PF'ing, while converting from gravity to FP, I always tried to engineer the client to see the garbage being removed - it helped them feel a bit better about the cost )

    Finally, would you mind disclosing the cost of the Flush?

    BTW, if I had to bet on the actual cause, without visiting, my cash would be on the pump.
     
    pppmacca43 likes this.
  6. exbg

    exbg Active Member

    Also, where would he fit this second pump?
    May sound a daft question but the properly initiated would understand that the question (with most pipe work configurations ) has more merit than the suggestion
     
  7. pppmacca43

    pppmacca43 Super Member

    Very good post @exbg lots of possible causes, very difficult to diagnose without being there but I’m the same as u, I would put my money on the pump not performing as it should
     
    exbg likes this.
  8. Shanks1986

    Shanks1986 New Member

    Hi @exbg
    Thanks for taking time to respond.
    I was wrong in saying we did a power flush. My plumber charged me 120£ for adding a system cleaner, draining down the system, bleeding and balancing the radiators.
    I took a second opinion as and that person also tried to balance the radiators. The upstairs got hot, then tried to push the heat downstairs so those got hot but upstairs got cold. And then when he opened the valves on the upstairs rads they did not get back hot. He also said that it looks like the pump is not working as expected.

    So previously I had the Grundfos 15-50 pump and now it has been replaced by Grundfos UPS3 15-50/65. But the issue still remains.

    Today the plumber while the heating was working, opened the bleeding valves of 2 radiators and got the water flowing through to get rid of any airlock. But still the same issue.
     
  9. Shanks1986

    Shanks1986 New Member

    Just to add he said it might be because the heating system is on 15mm pipes all over and that is why it’s losing the heat when reaching to more radiators.
     
  10. pppmacca43

    pppmacca43 Super Member

    15mm can only do so many radiators, normally u would say a max of three rads on 15mm but depends on there size
     
  11. Mike83

    Mike83 Screwfix Select

    Could be a restriction in the pipework.
    Are there any bypass valves on the system?
    Some pictures may help.
     
    exbg likes this.
  12. exbg

    exbg Active Member

    But, presumably, all was working okay previously?
     
  13. exbg

    exbg Active Member

    You are correct, but I have seen many smaller terraced 2/3 bed houses ran completely on 15mm.
     
    pppmacca43 likes this.
  14. Shanks1986

    Shanks1986 New Member

    @exbg Thanks for your response. We bought the house last year March and the boiler was replaced just a month before that. I have asked the previous owners if all the radiators ever worked in the house. They lived in the house for more than 10 years I hope they had all the radiators working.
    The only thing I can think of is that since they changed the boiler the radiators have not worked propery so maybe the person who replaced the boiler did something.
     
  15. Shanks1986

    Shanks1986 New Member

  16. Shanks1986

    Shanks1986 New Member

    I have checked with the previous owner as well and they said that all the radiators worked fine previously. I don’t have a reason to not believe them really.
    The only thing that changed between them moving out and we moving in was the new boiler installation.
     
  17. exbg

    exbg Active Member

    New boiler? Is that new info, or did I miss it?

    So the system was apparently fine, a new boiler was fitted and now the INSTALLER is saying you need a 2nd pump?
     
  18. exbg

    exbg Active Member

    Is there a bypass fitted?

    can you show the pipes from boiler to cylinder
     
  19. Shanks1986

    Shanks1986 New Member

    I may have missed to present the sequence of events:

    February 2020 - New boiler installed
    March 2020 - We bought the house
    August 2020 - moved into the house
    Winter 2020 - Radiator issue discovered but due to Covid could not get anyone to take a look at
    August 2021 - Got plumber in as mentioned in the above posts

    The previous homeowner has said that when they lived in the house all radiators worked fine. Probably when the new boiler was added they did not check the radiators and the first time they were used after that was when we did in Winter 2020.
     
  20. Shanks1986

    Shanks1986 New Member

    And I have just found the installer plumber so I am going to call them next , for now other plumbers have checked.
     

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