Sunday, November 28, 2021

Radiators in the UK

This is only meant for the UK and my recommendation is, upfront, get a boiler engineer if you can afford it, £££ wise and can wait for weeks, also as part of an overall boiler check.

Before going any further, I'd not, personally, have anything to do with these climate change heat pumps.  You might love em, good luck. I see them as far worse than boilers, and boilers are bad.

My own amateur notes

1.  Your prob is lower pressure redline more than high redline - high redline generally means overflow kicks in, low redline is trickier.

2.  Never work on bleeding unless low pressure is up on the boiler dial past the redline.  This involves finding that water inlet valve.  Mine is away from the boiler, under the sink inside the cupboard.

3.  Also never work on the radiator in any way unless the boiler is switched off and you've given it a fair time to cool.

4.  Assess your level of ability, dispassionately, even using a rad key, switching things back on in reverse later etc.  If ye do doubt you can cope with a boiler bashing itself to death after you've been mooking about, just don't even start.

5.  Make sure yours has the bits either side of the rad, also the dial and water inlet, as in the video.  Also, I've done this at the start of the winter one year long ago, not every year.

6.  Then follow his advice, providing you have the key, I'd say never use the screwdriver or wrench yourself.  Chances of damage are high, esp. on old boilers and rads.  If you know yours back to front and have talked with your local boiler man before, then Ok.


  1. One important caveat - that only refers to pressurised systems, traditional gravity-fed systems require none of that, you just bleed away happily until the water spurts out, then close the bleed-valve again.

    You will also find that air build-up concentrates in the radiator which is highest in your system, this can often be at a ladder-style towel-rail in an upstairs bathroom, so that's always a good place to start.

    If you're getting a cold patch towards the centre-bottom of the radiator, that usually indicates a build-up of sludge and will require flushing out - bleeding will not have any effect on that.

  2. Ta for that, MP. Yes, pressurised systems. I also have an oil rad, electric, portable.

  3. Shvatio

    That air in the radiator can be hydrogen. Please don't smoke at the same time.

  4. The engineer mentions it at the end but a cold area at the top, usually the furthest away from the boiler, is that the system is not balanced.
    It depends on your skill level but I had a plumber who inserted some liquid into the system by simply removing the thermostat without even draining down the rad. No fuss not a drop of mess done in seconds.

    1. Chances are the magic 'liquid' was Fernox, an inhibitor, a bottle of which should be added occasionally to the header-tank, it helps reduce the build-up of sludge in the system, in addition to suppressing air pockets. Other brands are available from your local plumbers' merchant.

    2. I couldn't recall but now you mention it I think it was.

  5. " upfront, get a boiler engineer if you can afford it, £££ wise and can wait for weeks, also as part of an overall boiler check."

    Your best bet is to religiously have the boiler inspected annually, and any upcoming problems can be sorted before they happen. I used to have a yearly contract with British Gas, but they let me down last year - they wouldn't do the servicing because of the lurgi. To me this was a breach of contract so I ended it there and then, and BG had to refund me. I now have an independent engineer to service the boiler once a year on demand. He is cheaper, calls whatever the situation and frankly does a better quality job.

    If you can afford it, get a magnetic filter fitted. This will keep your radiators clear of sludge. The filter is emptied and cleaned during the yearly boiler service. Also get some anti corrosion into the system (can be put in through the filter), like Fernox.

    Get the radiators balanced - the one nearest to the boiler will get the hottest, leaving the one furthest away cold. Radiators have an inlet valve for this purpose.

    Boilers losing pressure

    Adding Fernox through a radiator

    Flushing a radiator

    When I moved into this house in 2017 it was a wreck (it still is, but greatly improving), the boiler had been leaking for years and caused a huge mess in the boiler cupboard. There was only me to fix it, so I had to learn fast. Possibly the only thing that Youtube is useful for.

    One problem I overlooked was that, if you have a condensing combi boiler like me, and the condenser waste runs outside into a grid, it will freeze over winter and flood back into the boiler. The fix for this is to fit a trap to the boiler (air break) and redirect the waste pipe to a point inside the house, such as a sink or shower drain, or straight out through the wall into the soil stack.

    Also, some tips on staying warm and reducing energy bills.

  6. Thanks for the tips guys. I don't like messing with things outside my competence level, which is just about everything.

    When I was in my first house I had a BG three star service contract. Every year the service engineer warned me that there are engineers who will condemn my boiler. Engineers were encouraged to do this for all old boilers, whether or not in good condition. The encouragement was in the form of bonuses which could amount to hundreds if a new boiler was fitted. Sure enough an engineer condemned my boiler, placing official looking Do Not Use stickers on it. I contacted a independent Corgi engineer who inspected, passed as perfect and removed the stickers. I got another three or four years out of it. BG quoted over four thousand for a new one, the independent guy quoted eighteen hundred.

    1. Great tip. In the days when I rented properties I took great care to cultivate an independent Corgi registered heating engineer. Always paid promptly and remembered him at Christmas. Learnt a lot from him but the downside was that he was openly scathing about my occasional water pipe plumbing efforts.

  7. Without giving too much personal history away, the allegedly 'necessary annual service' is simply a make-work device to create employment for service engineers during the quieter summer months, always has been. Statistics (unpublished, obviously) prove that the greatest frequency of boiler breakdowns is closely related to a recent 'service' visit, i.e. within 28 days.

    Best advice with any boiler is: if it's working, leave well alone - if it's not, get a competent engineer to fix it, nowadays that's rarely one from British Gas.

    1. "the allegedly 'necessary annual service' is simply a make-work device to create employment for service engineers during the quieter summer months"

      Depends how you look at it and how you use it. In my case, the annual servicing was my decision alone, I wasn't talked into it and didn't consult anyone about it. I use the annual service for, among other things:

      To keep the system cleaned out and working optimally. I can smell it a mile off if an engineer gives me bullshit and he will never darken my doorstep again.

      An opportunity to fix anything I have spotted, which, though giving no problem at the time, may well give up the ghost during winter when I need the boiler most. I already have two examples of this, the diverter valve and condenser pipe. The pipe had been leaking for years when I moved here and didn't know anything about boilers. It had been placed next to a hot internal pipe, which in time had melted a hole in it - by a council gas engineer. No heating for a while that first winter.

      I don't want to wait until the system breaks down when most needed, I want my heating to work flawlessly when I need to use it.

      Part of the service is a drop test on the gas meter and flue check for carbon monoxide. To my mind these things are essential.

      To me, its just like having the car serviced. The 4 things I keep an eye on are the basics - lights, tyres, brakes and steering. At the moment I have a front tyre worn on the inside and a scored brake disc, but these will keep until the next service. The car is within legal limits.