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Central Heating controls

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  • 20-06-2014 10:43am
    #1
    n0brain3r
    Registered Users Posts: 919 ✭✭✭


    Hi all,

    I've a Siemens RWB 29 timer on my boiler. It has separate programs for both heating and hot water. At the moment I've everything wired to the CH terminal so boiler, circulating pump and motorized zone valves all operate on the CH program.

    I've switched lives at the timer the boiler, circulating pump and motorized valves.

    I'd like to have the following setup CH powers all 3 circuits so providing heating and hot water but that the HW powers only 2 the boiler and circulating pump.

    I've been able to get it to function as above but the motorized valves are always powered and are only turned off when the HW program runs and I'd like to avoid this if possible.

    The wiring diagrams and manual for the timer are here http://www.leeds.gov.uk/docs/Boiler%20and%20Heating%20information%20-%20siemens%20rwb%2029.pdf

    Can anyone suggest a better way to wire it to achieve what I'm after?


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    #2
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    n0brain3r wrote: »

    I've been able to get it to function as above but the motorized valves are always powered and are only turned off when the HW program runs and I'd like to avoid this if possible.

    This is confusing, can you put up a drawing of your installation?


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    #3
    n0brain3r
    Registered Users Posts: 919 ✭✭✭n0brain3r


    I'll try get a pic up tomorrow but here the txt of what I did.

    I powered the thermostats/zone valves from the HW off terminal and the boiler and circulating pump from the CH on terminal. I then looped the HW on terminal to th CH on terminal. When the cH program runs all 3 are powered but when the HW program runs only the boiler and pump are powered but when CH and HW are off the thermostat/ zone valves s are powered which I wanted to avoid. There's a switch/terminal diagram in the pdf linked above if it helps too


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    #4
    n0brain3r
    Registered Users Posts: 919 ✭✭✭n0brain3r


    Ok heres the graphic I hope it makes sense!

    311643.jpg


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    #5
    frankmul
    Registered Users Posts: 375 ✭✭frankmul


    I think that we need to know how you have the stats and the valves wired. The switch on the valve should bring on your boiler.


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    #6
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,565 Mod ✭✭✭✭2011


    frankmul wrote: »
    The switch on the valve should bring on your boiler.


    +1
    This is a good way of bringing the boiler on.


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    #7
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,565 Mod ✭✭✭✭2011


    n0brain3r wrote: »
    Ok heres the graphic I hope it makes sense!

    311643.jpg

    By connecting the stat & zone valves to terminal #1 these devices will only be powered when the HW channel is off. This is not what you want.


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    #8
    n0brain3r
    Registered Users Posts: 919 ✭✭✭n0brain3r


    frankmul wrote: »
    I think that we need to know how you have the stats and the valves wired. The switch on the valve should bring on your boiler.

    For the stats and valves I only have a single wire back at the boiler. I'm guessing this splits and runs via the 2 stats and on to the valves. I've 5 wires at the boiler neutral, live and a switched live to the boiler, pump and stats.
    2011 wrote: »
    By connecting the stat & zone valves to terminal #1 these devices will only be powered when the HW channel is off. This is not what you want.

    I know but it works crudely when the CH program runs the boiler, pump and stats are powered (HW is off) so I have CH and HW and when the HW program runs only the boiler and pump run as the stats are switched off so I have just HW. I just don't like having the stats powered all the time and wasn't sure how electrically safe this was either.


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    #9
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    n0brain3r wrote: »
    I just don't like having the stats powered all the time and wasn't sure how electrically safe this was either.

    As in room stat and hw stat on cylinder?


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    #10
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,565 Mod ✭✭✭✭2011


    How many stats?
    What does each stat serve?
    How many zone valves?
    What does each zone valve serve?

    Answer the above and a diagram will be posted by myself or someone else.


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    #11
    n0brain3r
    Registered Users Posts: 919 ✭✭✭n0brain3r


    What does each stat serve?
    2 stats one for upstairs and one downstairs

    How many zone valves?
    3, 2 on the room stats and one TRV type on the cylinder

    What does each zone valve serve?
    1 upstairs
    1 downstairs
    1 hot water cylinder(TRV type)

    thanks!


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    #12
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    You are not taking advantage of your seperate heating zones with your current clock, why not get a 3 channel one?


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    #13
    n0brain3r
    Registered Users Posts: 919 ✭✭✭n0brain3r


    Sir Arthur Daley wrote: »
    You are not taking advantage of your seperate heating zones with your current clock, why not get a 3 channel one?

    I only have a single live for both zone valves at the clock and wanted to do the best with what I have thanks for the suggestions though!


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    #14
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    Have the motorised valves got an auxillary contact?


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    #15
    n0brain3r
    Registered Users Posts: 919 ✭✭✭n0brain3r


    Sir Arthur Daley wrote: »
    Have the motorised valves got an auxillary contact?

    I don't know they're Danfoss ill try attach a pic too


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    #16
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    How many wires are in the flex?


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    #17
    n0brain3r
    Registered Users Posts: 919 ✭✭✭n0brain3r


    There's 4 in the flex label on the side says type HPA2 p/n 5927


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    #18
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,565 Mod ✭✭✭✭2011


    This will do it for you.
    However it requires a 3 channel time clock as Sir Arthur Daley suggested.


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    #19
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    He could use the single CH output on his clock to supply the two stats.


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    #20
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,565 Mod ✭✭✭✭2011


    Sir Arthur Daley wrote: »
    He could use the single CH output on his clock to supply the two stats.

    True.
    Personally I would prefer the 3 channel.


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    #21
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    2011 wrote: »
    True.
    Personally I would prefer the 3 channel.

    I would too as you are utilising your zones.

    He could use the HW to bring on one CH zone and HW and use the CH from clock to bring on the other CH zone. Just turn down the stat then whenever you dont want heating on the zone the HW is coming from.


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    #22
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    2011 wrote: »
    This will do it for you.
    However it requires a 3 channel time clock as Sir Arthur Daley suggested.

    In my opinion the valve contacts should be connected to the boiler control loop, where there is one, rather than be fed directly from the circuit live. In most cases its probably simply taking a link from the boiler permenant live terminal anyway. But it's better practice to use the terminals in the boiler control board.

    Obviously if the boiler has switched live and permanent live terminals, then the diagram is perfect. Any I seen have a set of control loop terminals.


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    #23
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    Do you mean take the live on the boiler side of the isolater for the auxiliary contacts?


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    #24
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Sir Arthur Daley wrote: »
    Do you mean take the live on the boiler side of the isolater for the auxiliary contacts?

    Gas boilers usually have L N E terminals. They are supplied by the fused spur.

    There is a link to be removed at the terminal block. And the 3 zone motor valve switches all wired in parallel, are connected into where the link was.

    It might be an oil boiler in this case.


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    #25
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    The drawing is for an oil boiler set up i imagine, im with you on the gas boiler that volt free link.


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    #26
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    I get the impression from op that his boiler is oil.


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    #27
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    If I'm reading correctly what the op is trying to do, then the HW channel can bring on the pump and boiler.

    The CH channel can bring on a DP relay.

    Connect zone valves to one pole. And other pole can switch in parallel with HW channel.

    So HW switches only pump and boiler. CH brings all on. I think that's what OP was asking for.

    But if there are 3 motorised valves, the one for HW has to come on with HW channel once it's stat is closed.

    Anyway, relays can be used to keep different items isolated from each other with reference to exactly what's needed.


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    #28
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Sir Arthur Daley wrote: »
    I get the impression from op that his boiler is oil.

    Yea I have that in last post myself.


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    #29
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    Bruthal wrote: »
    If I'm reading correctly what the op is trying to do, then the HW channel can bring on the pump and boiler.

    The CH channel can bring on a DP relay.

    Is there need of the relay, just let the ch output of clock power the stats, cant he have the hw time period come on the same as the ch?


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    #30
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Sir Arthur Daley wrote: »
    Is there need of the relay, just let the ch output of clock power the stats, cant he have the hw time period come on the same as the ch?

    He could. I actually drew it out just like that. But a relay is how I'd do it. Keeps it simpler to operate.

    But I'm not completely clear on the setup. Are the valves simply being used as valves?

    Are their contacts being used?

    A pipe stat giving pump over run might be good as well. Might be OK without it on oil boiler though.


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    #31
    Sir Arthur Daley
    Closed Accounts Posts: 6,720 ✭✭✭Sir Arthur Daley


    Bruthal wrote: »

    Are their contacts being used?

    I dont think he knows about that, i asked that earlier.


    Are the valves simply being used as valves

    I believe so, this is his only way to achieve zoning.

    A pipe stat giving pump over run might be good as well. Might be OK without it on oil boiler though.

    Good idea, oil boilers can trip out the high limit especially if the thermostat is turned up high.


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