Easiest way to find the radiator flow "order"

Discussion in 'Plumbing and Central Heating' started by biriyaniboy, 28 Jan 2012.

  1. biriyaniboy

    Joined:
    12 Dec 2011
    Messages:
    21
    Thanks Received:
    0
    Country:
    United Kingdom
    Hello all, sorry for the newbie question, but..

    Is there an easy way for a slowpoke like me to find out the order of my radiators? I want to write up which one is first, second, third, etc in the piperun (I'm going to have someone balance them for me, but want to save him some time if possible). I've got so many of them and I don't think running around the house is the best way of doing this as some may heat up at the same time, or one downstairs might heat up first and I miss that one - if you see what I mean.

    Your advice is appreciated as always :)
     
  2. gaswizzard

    Joined:
    8 Oct 2011
    Messages:
    6,277
    Thanks Received:
    989
    Location:
    Hertfordshire
    Country:
    United Kingdom
    Turn all radiator lockshield valves on fully counter clockwise , that should give you a starting point as to what gets hotter first etc.......................& if you have a reverse return system forget the above. :mrgreen:
     
  3. Agile

    Joined:
    26 Jun 2004
    Messages:
    55,396
    Thanks Received:
    3,638
    Location:
    London
    Country:
    United Kingdom
    I just set them to open 1/2 turn for small rads and 1 turn open for large ones.

    In most cases I can just walk away from them with that setting.

    In most cases that provides a higher pump pressure and that together with the higher resistances is somewhat self balancing.

    Its similar to Kirchhoff's Law.

    Tony
     
  4. MJN

    MJN

    Joined:
    30 Apr 2008
    Messages:
    539
    Thanks Received:
    63
    Location:
    Wiltshire
    Country:
    United Kingdom
    And here's me thinking you were one of the good ones Tony. Very disappointing.

    At best you may have crudely accommodated the differing flow requirements between small and large radiators however you have made no consideration whatsoever for their distance from the pump (and/or other causes of pressure/flow variations).

    To the OP, it is not overly critical to determine the exact pre-balanced order of radiators; it just helps you to start from a sensible reference point. Furthermore if you're struggling to keep up and are getting someone else to balance just let them implement their own strategy (and make sure they don't do a 'Tony' as it is now called).

    Mathew
     
  5. bengasman

    Joined:
    28 Jan 2005
    Messages:
    31,104
    Thanks Received:
    2,777
    Location:
    London
    Country:
    United Kingdom
    Why would you want to know which rad is closest to the boiler? It's totally irrelevant.
     
  6. MJN

    MJN

    Joined:
    30 Apr 2008
    Messages:
    539
    Thanks Received:
    63
    Location:
    Wiltshire
    Country:
    United Kingdom
    The OP is referring to the order that the radiators heat up, not their position from the boiler. There is usually however a correlation between distance from the pump and heating order in an unbalanced system by virtue of the diminishing pressure and corresponding reduction in flow. Equalising this is one aspect of balancing.

    Mathew
     
  7. bengasman

    Joined:
    28 Jan 2005
    Messages:
    31,104
    Thanks Received:
    2,777
    Location:
    London
    Country:
    United Kingdom
    There is only one aspect in balancing, and that is getting the required drop; the pipe length to the rad is of no import.
     
  8. Agile

    Joined:
    26 Jun 2004
    Messages:
    55,396
    Thanks Received:
    3,638
    Location:
    London
    Country:
    United Kingdom
    My simple method enables me to achieve a working balance within 10 minutes in over 90% of cases. That gives very good performance at a minimal cost to the owner. I realise others like to take 90 minutes and charge for their time accordingly! That does not make me popular with them!

    I find that over 90% of the properties I visit have had absolutely no balancing at all and have the valves fully open. In fact 70% have hand knobs on both valves. This is in London.

    Without wanting to start a technical discussion which not many will understand, I should say that my method increases the pump pressure which encourages flow to the further radiators.

    Its easiest to use an electrical analogy to understand this but equally few would understand that either.

    Tony
     
  9. MJN

    MJN

    Joined:
    30 Apr 2008
    Messages:
    539
    Thanks Received:
    63
    Location:
    Wiltshire
    Country:
    United Kingdom
    Absolutely. I suspect we are talking at cross purposes here.

    The drop is indeed ultimately what counts and this what you will affect through adjustment. The pipe length is merely an unalterable contributing factor to why, with all else being equal, a radiator at the beginning of a run will have a lower drop (higher flow) than one at the end in an unbalanced system. In such a case this is why you would end up throttling the near radiator more than the far one. Knowing the heating order in advance merely helps you start from a good approximation as to which direction you're going to be heading in.

    Mathew
     
  10. MJN

    MJN

    Joined:
    30 Apr 2008
    Messages:
    539
    Thanks Received:
    63
    Location:
    Wiltshire
    Country:
    United Kingdom
    That's fair enough Tony, and apologies for my somewhat curt initial response. Your strategy is indeed fine in the context of getting the best bang for the buck but I dare say many adopt a rule of thumb in ignorance of the fact that it could be improved upon, and may allow for increased efficiency and performance if, for example, it can lead to lowering the pump speed through less reliance on maintaining a higher-than-needed pump pressure just to ensure each radiator gets sufficient flow.

    Mathew
     
  11. bengasman

    Joined:
    28 Jan 2005
    Messages:
    31,104
    Thanks Received:
    2,777
    Location:
    London
    Country:
    United Kingdom
    All else is never equal; you would need all valves being the same, all opened exactly the same and all rads the same size; bit unlikely.

    It would be one of the smallest of all factors, and as such can be ignored. The influence is so minute that it takes more time to try figuring out what the order is, than to do a quick second run around the rads after the first adjustment; tail wagging the dog.
     
  12. Agile

    Joined:
    26 Jun 2004
    Messages:
    55,396
    Thanks Received:
    3,638
    Location:
    London
    Country:
    United Kingdom
    I find that the probable "heating order" is pretty obvious from the layout of boiler and rads.

    Perhaps I should state that the 1/2 and 1/1 turn was a simplification for the posting.

    In practice I adjust each rad from 1/8 to 1/1 according to my estimation of the required setting.

    Nevertheless the main feature is that I intentionally add resistance to the flow so that the pipework resistance becomes less relevant.

    Tony
     
  13. MJN

    MJN

    Joined:
    30 Apr 2008
    Messages:
    539
    Thanks Received:
    63
    Location:
    Wiltshire
    Country:
    United Kingdom
    Why do I get the feeling you're just after an argument? You've got the wrong department for that... it's just down the hallway... ;)

    My point was to illustrate that the heating order is affected by all those non-equal factor such as pipe length, size, radiator size, valves etc etc. All of these 'fixed variables' (for want of a better phrase!) directly affect the heating order in an unbalanced system.

    Of course, they - and in practical measurable terms their effect on heating order - can be ignored as any iterative balancing process will eventually reduce their significance to zero. However, particularly for difficult-to-balance systems, knowing this first approximation can greatly help the balancing process.

    Horses for courses, and we've all got our preferred strategy to reaching the same end goal and how we get there is down to personal preference - if we can agree on nothing else it is that there is more than one way to skin this cat.

    Mathew
     
  14. bengasman

    Joined:
    28 Jan 2005
    Messages:
    31,104
    Thanks Received:
    2,777
    Location:
    London
    Country:
    United Kingdom
    Altering pump speed AFTER balancing can throw the balance. If you want to use a lower pumpsetting, you should do that BEFORE starting the balance procedure. Proper balancing is entirely empirical and therefore should have all desired elements implemented as early as possible in order not to throw the end result.
     
  15. Agile

    Joined:
    26 Jun 2004
    Messages:
    55,396
    Thanks Received:
    3,638
    Location:
    London
    Country:
    United Kingdom
    I should also add that following one particular trainee who thought that it was both good fun and useful, we learnt to estimate the temperature of rads by hand. Also the same for DHW.

    What we did was to first each feel and estimate and then measure to achieve feedback and see who was closest. We found that we could learn to estimate the temperature of DHW in the useable range of say 35 C to 45 C to within a degree.

    Its slightly more difficult estimating rad temps but we could still do that to within 5 C in most cases.

    Tony
     

Share This Page