Replacing radiator - Advice

Discussion in 'Plumbers' Talk' started by pledgeX, Mar 14, 2019.

  1. pledgeX

    pledgeX New Member


    I’d like to replace the standard radiator and the TRV in my bathroom with a towel radiator. I’d like to have a go at doing this myself as a bit of a learning exercise and was wondering if anyone had any tips?

    I’ve read through this guide (the “Changing an Old for a New TRV” section half way down the page).

    This guide is only for switching a TRV, but I assume the process is the same if I’m switching the radiator at the same time? Re-pressurising the system is the bit that is a bit daunting (boilers are expensive and I don’t want to break anything!), but looking at this guide it looks fairly simple.

    Couple of questions:

    1) In the guide it only mentions draining the nearest radiator. Do I not need to do all the radiators? The radiator is upstairs and the combi boiler is downstairs, so I guess if I drain one radiator upstairs it should drain all water from upstairs hence only needing to do the one? In case it matters, the heating is connected by flexi-pipes that run through the ground floor roof and either drop down to the ground floor rads, or go up to the 1st floor rads.

    2) The last step mentions adding inhibitor to the system. We had some radiators moved this time last year and he added some inhibitor at the time. Would I still need to add a fresh round of inhibitor this time? I’m guessing so as it would come out when the system is drained?

    3) If the answer to 2 is yes, I was planning to put it in via the top of either the new or another existing towel radiators as I’ve read they’re easiest to access. How much are you supposed to put in?

    Thanks for any help.
  2. fostyrob

    fostyrob Active Member

    If all pipes are in the upstairs flooring and no radiators above that level then yes you would only need to drain that one radiator down. Crack the radiator unions and drain into a tub/bucket.
    Once you have fitted the new radiator, trv and lockshield (after tightening) I would put the inhibitor into the top of the new radiator and then refill/re-pressurise. I would just put a bottle (500mls) in. You can't have too much inhibitor.
    Baxi Boy likes this.
  3. DIYDave.

    DIYDave. Well-Known Member

    Buy two 9” paint roller trays (or you may have) and use these under each rad valve when you drain down

    Place old towel underneath tray, push tray tight up to wall/skirting and go ahead and crack your nuts ;)
    - After isolating water and slacken off bleed screw

    Depending on size of rad, trays may take all water from rad but have bucket handy to drain trays into

    If you buy £ shop roller trays they are bendy when full of water so easier to drain into bucket next to rad :)
    Baxi Boy likes this.

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