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Heating system queries

Discussion in 'Plumbing and Central Heating' started by tkk, 27 Feb 2008.

  1. tkk

    tkk

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    I have a couple of queries, regarding my current setup and a couple of changes I would like/need to make, on which I'd like some advice please .


    I have a Vokera Mynute 14e gas boiler for hw & ch. The boiler flow goes to the cylinder and has two ch zones (upstairs & downstairs) branching off it in the form of t-joint, each with a Myson motorised valve (each controlled by a dedicated room thermostat), feeding into a manifold and on to the radiators. The return from the cylinder similarly has two t-joints which connect to the return manifolds from the radiators.

    Currently the filler loop for the heating is taken from the pipe coming from the attic tank to the cylinder (incorporating a control valve operated by a screwdriver and a non-return valve).

    This has caused problems for me as yesterday the system stopped working due to low pressure. I checked and figured out the pressure vessel also needed recharging so I drained off some water, leaving the system open and sorted out the pressure vessel. Afterwards I set about refilling the system and struggled to get the pressure high enough.



    1. Should the filler loop be a mains feed rather than coming off the cylinder fill pipe from the attic tank? I suspect so as there doesn't seem to be enough pressure with the current setup to properly pressurise the heating. I temporarily disconnected the feed to the tank in the attic and connected this to the filler loop in order to get the system pressurised for now but I am thinking of taking a branch off the tank feed down into the hotpress to facilitate future heating system top ups. Is this a good idea?

    2. The Vokera's pressure relief valve has the standard preformed pipe section on it and nothing else. I need to run this through the wall to outside in case of any problems as otherwise the place will just flood! Can I join directly onto the standard pipe or should I look at replacing the lot from the valve out?

    3. The time clock on the Vokera is the standard 24hr type and I'm looking to change this for something that will allow 5+2 or 7 day operation. Is it easy to bypass the Vokera timer and use an external one?

    4. I also need to change the thermostats controlling my ch zone valves as recently they've started acting up - one needs to be all the way up to switch the valve on and the other doesn't switch off once the temperature reaches the correct level and has to be manually switched off. Seeing as I'm looking at changing the system timer and thermostats should I consider a different way of managing the heating system? Is there a better way?


    I know there's a lot there but I hope some users will be willing to help me out with some bits.
     
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  3. Bahco

    Bahco

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    Yes :D

    Can't help with other questions sorry. :(
     
  4. gas4you

    gas4you

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    If you have more than 1 ch zone, then you should be looking at a programmer such as the Horstmann 37XL which can control 3 zones seperately and leave your built in timer on constant on.
     
  5. Softus

    Softus

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    How did that come about?! :eek:
     
  6. Nixt

    Nixt

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    You are right Bahco, but in Ireland it was common for system boilers to be tank (not direct mains) filled. This is because poor available pressure led to authorities frowning on anything mains fed apart from the kitchen sink, hence not many combi's sold through 80's & 90's.

    OP- I believe the Mynute has no standing pressure switch so if its full & bled, pump will pull flow switch and fire.

    Vokera did supply a 2 channel ACL branded programmer which may still be available as a spare, otherwise 24hr can be de-mounted and replaced with proprietary external brand. You'll need the manual with schematics.
     
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  8. ChrisR

    ChrisR

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    2 join it
    3 yes
    4 programmable thermostats
     
  9. tkk

    tkk

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    That was the original installation in the house. For whatever reason, best known to themselves, they put the filler loop where there isn't enough pressure to fill the system correctly and also where you can't see the pressure gauge. I'm going to take a branch off the mains feed in the attic and put in a proper filling loop. I may also install a pressure gauge in the hotpress so I can see it when topping the system up.
     
  10. tkk

    tkk

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    Is there not an issue when the ch is not seperate from the hw, i.e. the hw always has to be on in order to have the ch on?
     
  11. tkk

    tkk

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    I'm now thinking of getting a timeswitch linked into the boiler to act as a master controller to determine when the heating system is on. Then I could use two programmable thermostats (or maybe only one for the upstairs zone as it's the one that wouldn't need to be on during the early evening) to further restrict the times that the ch zones are allowed to call for heat during the boiler on time. Any thoughts?
     
  12. beolight

    beolight

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    did you get a third party programmer fitted
     
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