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Control for HW in the Cylinder - Gravity Fed System. I need

Discussion in 'Plumbing and Central Heating' started by galegp, 26 Feb 2015.

  1. galegp

    galegp

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    Hi,
    I need a bit of advice. Two question basically.

    I have a gravity fed heating system that when the heat is on, heats radiator and hot water cylinder. I don’t seem to have any sort of control in the HW cylinder. So my two questions are:

    1- Is it worth for me to spend money and fit some sort of control in the HW cylinder?
    2- I heard of two option. A motorized value + thermostat around cylinder or a thermostatic valve (one of those which look like a radiator TRV). Which one would you go for and why? (if any)


    Thanks and look forward to some advise.


    Edit: heat source is an outdoors oil boiler.
     
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  3. stem

    stem

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    Ideally, you should have separate control of your heating and hot water. This normally involves adding a 3 port motorised valve that diverts water from the boiler to the hot water cylinder and / or radiators as required. This valve is linked to a room thermostat to control the radiators and a cylinder thermostat to control the hot water temperature. Both thermostats are wired to a programmer for time control. This type of system is often referred to as a 'Y Plan'

    How big a job it is to convert your existing system depends upon its configuration and interconnecting pipework. If you have a fully pumped system, it can be fairly straight forward. However, if you have a gravity hot water system with pumped central heating it will be slightly more difficult, and if you have a 'Primatic' cylinder with only a single feed and expansion tank, that makes things even more complicated.

    In order to advise further, you will need to provide details of your existing installation and how the various parts are interconnected.
     
  4. galegp

    galegp

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    I have a very “primatic” system! I got a new boiler fitted a year and half ago and the plumber thought it was a pain to separate the hot water therefore he fitted it with two pipes (the return cold water and the hot water). He also fitted a motorized valve to be able to just run hot water in the summer (without heating the radiator). Then I fitted a programmable thermostat in the hall and that is as much control as I have over my heating system.

    I was under the impression that the water in the cylinder gets heated by the boiler as long as the heat is on and regardless what temperature it is inside. So I thought that installing a thermostatic valve or a motorized valve + a cylinder thermostat, I could improve the efficiency in the system. So the boiler could divert the effort of heating the cylinder to the radiator and heat these quicker. Is that correct?
    But I seem to hear from some people that, 1- it is not worth the expense, 2- it wont really improve efficiency.

    What do you think?

    Is the above clear enough?
     
  5. stem

    stem

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    It's still not that clear, so I'll try some specific questions.

    1. Is the hot water supply from the boiler transferred to the cylinder via the pump. If not how does it get there?

    2. How many cold water feed and expansion tanks do you have?
     
  6. galegp

    galegp

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    1. Is the hot water supply from the boiler transferred to the cylinder via the pump. If not how does it get there?

    Yes via a pump which is located in the outdoors boiler case.
    http://www.warmflow.co.uk/products/boilers/k-series_he/kabin_pak_he_pre-pumped

    2. How many cold water feed and expansion tanks do you have?
    Only one cold water feed. Only one expansion tank (located in the attic)

    Are things starting to make sense to you?

    Sorry I am not the best explaining things.

    Many thanks for taking your time to advise me.
     
  7. stem

    stem

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    No sorry, it still doesn't make sense to me.

    If you only have one header tank that indicates you have a primatic cylinder. But then you say the hot water is pumped from the boiler to the hot water cylinder which won't be a primatic cylinder.

    Maybe someone else will be along that can make sense out of it :confused:
     
  8. galegp

    galegp

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    I will take some photos and post them here.
     
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