Ufh and rad circuit

Discussion in 'Plumbers' Talk' started by Jonny999999, Nov 18, 2016.

  1. Jonny999999

    Jonny999999 Member

    IMG_8120.JPG I have just installed a ufh circuit from my combi boiler(pic attached)
    I will be installing a 2 port valve on the flow below the ufh to control the rad circuit.

    Do I need a bypass on aswell?

    If so where would the bypass go and do I need an auto bypass valve?

  2. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member


    Not too bad

    You need a room stat for the rad circuit, in that room you fit just a pair of wheel head & lock shield valves to the radiator, so no TRV.

    If your boiler has an integral bypass you don't need to add one.
    If it doesn't just add one below the boiler from the flow to return and yes auto, set on 2-3.

    Take the ballofix off of the pressure relief?

    And I'd remove those ballofixs off the pipes where they enter the screed or change them to full bore lever valves as they are quite restrictive to the flow.

    Also you shouldn't be touching gas, but anyway it needs to be 22mm unless you have a very low KW combi
  3. Jonny999999

    Jonny999999 Member

    Thanks for your reply.

    I have an rf thermostat in the house, the boiler is situated in a utility room outside with ufh, no rads, the other ufh zone is an outside office space. These 2 rooms will have their own programmable stats which the wiring centre will take care of.

    The ballofix on the broken pressure release is only temp until I fit a new valve.

    Also the ballofix on the return are there because I did have a 2 port valve in there that accepted the same 2 wire actuator as the ufh manifold, but this was restricting the flow too much so was removed and purchased a 5 wire 2 port which will wire to the boiler. I will remove these for straights. I also intend to change the valves at the screed.

    The gas comes in 22mm and is only reduced to 15mm (left of boiler from above) for the 15mm connection on the boiler, which has been tested and certified by a gas safe plumber.

    The boiler is a ravenheat csi low nox 120, not sure if it has an integral bypass or not?

  4. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    Yes well if the working inlet pressure loss is more than 1mbar at the appliance from the meter than its a fail, also gas rate only has to be out by 5% to be classed as at risk.

    Boilers that are 24KW+ should be 22mm all the way.

    What we normally do is have a zone valve for the UF and actuators on the UF manifold loops going to their corrisponding room stats.
    Then a single channel programmer for the radiator circuit room stat.
    All that gets wired through the wiring centre.

    And that pressure relief is a little naughty
  5. Jonny999999

    Jonny999999 Member

    I can assure you the gas has passed. It's 6 metres of 22mm from the meter and only the last 500mm is in 15mm. The boiler is actually running just not the ufh yet.

    And the ballofix will be removed tomorrow when I go get a new prv.

    My thinking is the actuators on the manifold will take care of the 2 ufh zones so why have a zone valve on the ufh?

    I only want a zone valve on the house heating as the ufh will need to run independently.
  6. Jonny999999

    Jonny999999 Member

    Correction: The gas is 4 metres of 28mm track pipe, 6 metres 22mm then 500mm of 15mm.
  7. Jonny999999

    Jonny999999 Member

    Also, from my original question. Does it matter if the bypass is above or below the branches to the ufh?
  8. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    Like I said, under boiler? You need to provide a loop within the primary circuit before any zone valves.

    Also why do you have a washing machine valve on your heating?

    The UF zone valve is so you don't get circulation so perfectly illustrated when the actuator heads are disconnected,
    Also you have separate switch live through the wiring centre for multiple zones with only one single terminal on the boiler.

    Why did you use tracpipe? Why not go all the way to the boiler if so?

    Why did you put copper pipe in screed?

    Is your exp vessel big enough?

    You have 3 x 15 ball o fixes on the hot before it even gets 2 mtrs?
  9. Jonny999999

    Jonny999999 Member

    Because the pressure gauge isn't working so I attached a temp one to that washing machine valve until I get a new one.

    There is hep in the screed it only comes out in copper.

    The trac pipe is buried the 22mm is obviously not.

    There is only 2 ballofix on the hot, they are all temp, which I've already stated.

    any more questions that don't have anything to do with my original post?

    You won't get any circulation through the manifold mixer/pump, so I'm not gonna bother with a zone valve on there.

    Thanks for your input though.

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