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Lockshield valves, wheelheads - balancing

Discussion in 'Plumbing and Central Heating' started by a4007035, 4 Dec 2020.

  1. a4007035

    a4007035

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    Hi,

    I tried to balance the raditators in the house that we're renting. The system is an old hot water tank system heated by an oil boiler. The valves are lockshield valves and wheelheads at either end.
    The upstairs radiators are closest to the hot water tank. Essentially I want the downstairs radiators in particular the living room radiator to be the hottest and the upstairs radiators to be warm.

    I started by turning everything open - lockshield valves and wheelheads. Bathroom radiator which is closest to the tank got hot first followed by the bedroom radiators. Downstairs radiators got lukewarm at best.

    I then started to close the lockshield valves of the upstairs radiators with half and quarter turns. The downstairs radiators got very warm at best but I wouldnt say hot i.e. I could easily place my hand on all of them without getting burnt.
    So I continued closing the upstairs valves - however, it then seemed to have the reverse effect on the downstairs radiators i.e. the downstairs radiators were getting cooler.
    I have left the wheelheads open throughout the experiment and these have not been touched.

    We're essentially finding that the bedroom gets to 20C which is too hot to go to bed but downstairs only gets to about 17-18C.

    Any ideas anyone? Does closing the lockshield valves limit the supply to the downstairs rads?
     
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  3. Elkato531

    Elkato531

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    Have a look at the FAQ section of this forum on balancing rads. If you haven't got trvs in the bedrooms at least, then hassle your landlord to have them fitted. In my house I don't think any bedroom radiator has been above the frost setting for years but we don't tend to do much in the bedroom that can't be done under a duvet. ;)
     
  4. oldbuffer

    oldbuffer

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    1. It is possible that you have a one pipe system. This essentially place radiators in series, so that, starting from the first one on the flow from the boiler, they get progressively cooler. Balancing such a system is extremely difficult as so much depends on the size of each radiator and the number / size of those before it.
    2. On a "normal" two pipe system, the radiators are in parallel across the flow and return "spine". Each radiator is broadly independent of the others, although if some are allowing water to flow through in too great a quantity, there will be less heat for the others.
    3. As you have done, leaving the wheel head valves open is correct.
    4. As a rough guide, you should be able to almost close the lock shields on the radiators nearest the boiler (nearest hydraulically, not necessarily physically) and that on the furthest radiator should well open.
    5. The distance between a radiator and the hot water cylinder has no bearing on balancing. The hot water is entirely separate from the heating, except that if you have both on together, you need to limit the flow into the hot water cylinder's heating coil, or it may rob the heat from the rest of the system.
     
  5. a4007035

    a4007035

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    Thanks for this - really good advice.

    (1) - I think you may be right that it is a one pipe system. Do you think I should attempt through trial and error to get the radiators that are nearest hydraulically - which I think are the upstairs ones as they get heated first) to a lukewarm temperature? So, maybe just do one at a time but always come back to re-check all of them if one changes.

    (5) When we turn the heating on the hot water comes on. Like there were times in the summer (when we didnt use the heating) where we'd have no hot water for example. What I would say is that the hot water is scalding - it must be about 75-85C. How would you limit flow? The stop tap?
     
  6. oldbuffer

    oldbuffer

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    1. If the hot water is on at the same time as the heating, then a proportion of the hot water flowing from the boiler will be going through the coil in the hot water cylinder (HWC). The cylinder needs to be treated as an additional radiator, and the flow through it reduced if it is robbing heat from the rest of the system.
    2. The rate of flow through the HWC does not affect the eventual temperature of the hot water, just how long it takes to go hot. So slowing the flow will make no difference to the temperature. There are only two ways of reducing the hot water temperature:
    2a. Reducing the temperature of water from the boiler by turning it down. This will also slow down the heating of the radiators, and they may not reach a high enough temperature to warm the rooms.
    2b. Fitting a motorised valve to the hot water primary circuit (the coil) and a thermostat to the HWC about 1/3rd the way up (and in contact with the copper). When the thermostat detects the water has reached a pre-determined temperature (usually around 60 degrees), it shuts off the motorised valve. Shutting the valve would normally turn off the boiler, but that gets into boiler control systems, which is a complicated topic in its own right.
    3. I'm afraid you are going to need to know a good deal more about the system before it can be made more effective. If you want to post some photographs of the boiler, airing cupboard (showing pump and motorised valves), programmer and thermostat(s), and a couple of radiators (particularly any that appear to have a pipe underneath joining the two valves) you may be able to get more specific advice.
    4. You landlord's obligations are to provide space heating and hot water. It is not his / her obligation to bring the system up to the latest standards. You may have to work with what is there.
     
  7. a4007035

    a4007035

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  8. a4007035

    a4007035

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    Pics attached
    1. Boiler
    2. Boiler controls
    3. Radiator with underneath pipe
    4. and 5. Hot water cylinder in airing cupboard
    6. and 7. Thermostat controls
    8. and 9. Tank in loft
     
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