Central Heating Temperature differences

Discussion in 'Plumbers' Talk' started by The Enforcer, Apr 29, 2010.

  1. The Enforcer

    The Enforcer New Member

    57degC with one in particular (drop fed) reading in at a rather tepid 43degC at the top and 42degC at the bottom.

    What should I be aiming for once its all done - I appreciate it depends on how well the boiler works etc to give me the hotter temp, but what heat loss should I expect to have in a rad from top to bottom. Should I be looking to get it within a degree for example?

    Thanks in advance!
  2. Dick Puller

    Dick Puller New Member

    You clearly don't have a clue, get a Plumber in......................Jeez, there's one on every forum, how did we manage to get this turkey??!!!
  3. The Enforcer

    The Enforcer New Member

    .... Thanks in advance for any useful comments!
  4. The Enforcer

    The Enforcer New Member

    It appears I managed to delete half the message before I posted it ... which could explain DP's little outburst.

    What I missed out was that Im going to get the system powerflushed and have been round with an IR thermometer to get some "before" readings. Most of the rads come in at around 60degC at the top with a difference of anything up to a loss of 10degC at the bottom of the radiators.

    Once of the rads, which is drop fed from the 1st floor for some reason is the rather tepid one ....

    What I was asking was what is a normal or acceptable heat difference over a radiator. Im assuming that the cold spots at the bottom of the rads are caused by sludge and debris and the drop fed one is most likely coldest as any crud just sits in there as it can flow anywhere without being lifted by the CH pump.
  5. G Brown

    G Brown New Member



    Save your money.

    Run some cleaner thru for a couple of weeks, drain and re-fill with some new inhibitor. Then balance your system properly.

    The only time you need to powerflush is when changing your boiler, anything else is a waste of money.
  6. The Enforcer

    The Enforcer New Member

    Not a fan of powerflushing then Mr Brown?
  7. tomplum

    tomplum Active Member

    niether am i, enforcer, its a gimick, i get get same results with water pressure, a couple of hoses and a bit of know how, the differance is,on a powerflush the water comes round and into a bucket so you can say to the customer " ohh look at the much in here", its salesmanship, and at £400 pound a pop, you need to show um some muck to give the flush credability, i send the muck to the drain and charge a good deal less, but the result is the same, all rads work well,
  8. The Enforcer

    The Enforcer New Member

    thanks chaps,

    cant back out of it now as ive already brought a kamco and she'll murder me if I now say we dont need it.

    Just for the gimmick value Ive gone and gotten a magnaclean twintech too!
  9. mantor10

    mantor10 New Member

    kinnel, you'd have been cheaper buying new rads.
  10. Captain Leaky

    Captain Leaky New Member

    Have fun with the leaks!
  11. imran_

    imran_ New Member

    Putting chemicals in a system is the same as putting some Bold in a bucket with your clothes.

    Powerflushing is like using a washing machine.

    Now I'm no expert, but there is a strong preference for the washing machine.....
  12. Tony Soprano

    Tony Soprano New Member

    the hose pipe crew ,a properly powerflushed system using the correct chemicals and fully heated water will clear the system just the way it should

    I love the way some people here think they can do with cold water what we using a heater a powerful powerlfush pump with reversing and huge magnetic filter as well as proper chemicals designed for the job and achoeve the same results

    Never in month of sundays ,but you carry on,I would love to be there when Tom says to his customer " ah reet dont worry about a flush i can do with hose pipe what them using over 1500 quids worth of gear and chieve same results"

    Kamco,norstrom sentinel and the rest should all stop selling these machines because they waste of time,a piece of FLUSHING HOSEPIPE should be issued to all plumbers!!!!***
  13. tomplum

    tomplum Active Member

    tony you are a salesman, a southern smarmey greasy gelled back, swiss tony, i'll sell my grandma a french knicker set con man , stay down london mate, cos you'd sell nothin in't real world mate,
  14. sam spade

    sam spade Active Member

    It's not the temperature difference between the top and bottom of the radiator which is important, but the difference between the temperature of the water entering and leaving the radiator,as measured on the pipes connected to the radiator. The actual value depends on your boiler.

    The output of older boilers are specified for an 11C drop between flow and return, so you should balance the system based on this. The output of modern condensing boilers is often stated for a drop of 20C. It is rarely possible to achieve exactly 11C or 20C as the drop is determined by pump speed, and most pumps only have three settings. So you aim for the same drop across the boiler and all radiators.

    There are detailed balancing instructions here:


    If you are using an IR thermometer, you should wrap some black insulating tape round all the pipes first and point the gun at the tape. If you don't, you will not get consistent results, as the reading will vary depending on the colour and shininess of the surface.

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