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Thread: Adding Underfloor

  1. #1
    Automated Home Sr Member
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    Jan 2017
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    79

    Default Adding Underfloor

    Hi all,

    We’re in the process of knocking two rooms together, and whilst we dig out the floor to sort out some damp issues, we’re going to take the plunge and add some UFH, to our evohome system.

    The room is pretty large, so we need two loops, but there are no dividers, so I think I just need to control it as one zone.

    The current system has a zone valve on the DHW, but no valves on the heating as it’s controlled by the HR92s on the rads. The boiler is controlled by an opentherm controller.

    So correct me if I’m wrong (and I may well be!), but as I’m not zoning the different loops, I don’t need to run a manifold with actuators? This means can control the pump with a BD91, and wire in a control valve to be actuated with the pump? I have spare BD91s from some thermostats I bought, so I’m hoping this is right!

    Finally with regards to controlling the temp of the UFH, it seems that the JG pump has a knob on the front with blue and red arrows. I’m assuming this controls the temp. Anyone have any experience of this?

    Only other question, is do you think I would actually be better off zoning the system? The room is 10.5m long, with a lounge at one end, dinning area in the middle and kitchen at the other. Although I could get the thermostat in the middle, I wonder if I would be better with the two loops independently controlled.

    Cheers,

    Ian

    Family Room Plan.jpg

    UHF Circuit 1.jpg

    UHF Circuit 2.jpg
    Last edited by kimber.kimber; 14th August 2018 at 03:24 PM. Reason: Images added

  2. #2
    Automated Home Ninja
    Join Date
    Mar 2017
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    Default

    Quote Originally Posted by kimber.kimber View Post
    Hi all,

    We’re in the process of knocking two rooms together, and whilst we dig out the floor to sort out some damp issues, we’re going to take the plunge and add some UFH, to our evohome system.

    The room is pretty large, so we need two loops, but there are no dividers, so I think I just need to control it as one zone.

    The current system has a zone valve on the DHW, but no valves on the heating as it’s controlled by the HR92s on the rads. The boiler is controlled by an opentherm controller.

    So correct me if I’m wrong (and I may well be!), but as I’m not zoning the different loops, I don’t need to run a manifold with actuators? This means can control the pump with a BD91, and wire in a control valve to be actuated with the pump? I have spare BD91s from some thermostats I bought, so I’m hoping this is right!

    Finally with regards to controlling the temp of the UFH, it seems that the JG pump has a knob on the front with blue and red arrows. I’m assuming this controls the temp. Anyone have any experience of this?

    Only other question, is do you think I would actually be better off zoning the system? The room is 10.5m long, with a lounge at one end, dinning area in the middle and kitchen at the other. Although I could get the thermostat in the middle, I wonder if I would be better with the two loops independently controlled.

    Cheers,

    Ian

    Family Room Plan.jpg

    UHF Circuit 1.jpg

    UHF Circuit 2.jpg
    You'll need a BDR91 and a Temp Sensor (A Y87RF or DT92E). Set it up as an additional Zone on the control panel, and pair up the sensor and BDR91. BDR91 controls the zone valve and pump. The temperature mixer on the UFH manifold will control the temperature of the water pumping around the floor.

    Yes if your having it as one zone, actuators aren't required. However if your using Opentherm there is benefits to using actuators rather than a zone valves due to the possibility of them staying open longer. (Opentherm is running at lower temperatures, may run round the UFH longer) Although I can't say i've had any issues in the past with Zone Valves on UFH, i've actually had more actuators fail.

    Can't see any benefit of zoning two ends of the room separately unless you've got a big heat loss at one end.

  3. #3
    Automated Home Sr Member
    Join Date
    Jan 2017
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    Default

    Thanks for the reply. I should have said, I do have a room stat, from when we were originally using the room with a rad, hence the left over BDR91... think I actually have 3 spare!

    So basically there are two set ups...

    Option 1
    Room stat
    BDR91 controlling mechanical (wet) zone valve
    Zone valve controlling pump unit
    No actuators on the manifold (manifold always open)
    Evohome haze station controlling boiler

    Option 2
    Room stat
    HCE80 controlling manifold actuators (one per loop) and pump unit
    No mechanical (wet) zone valve
    Evohome bass unit controlling the boiler

    Out of interest, what make of actuators have you been running? How many failures have you had?

  4. #4
    Automated Home Ninja
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    Mar 2017
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    Default

    Quote Originally Posted by kimber.kimber View Post
    Thanks for the reply. I should have said, I do have a room stat, from when we were originally using the room with a rad, hence the left over BDR91... think I actually have 3 spare!

    So basically there are two set ups...

    Option 1
    Room stat
    BDR91 controlling mechanical (wet) zone valve
    Zone valve controlling pump unit
    No actuators on the manifold (manifold always open)
    Evohome haze station controlling boiler

    Option 2
    Room stat
    HCE80 controlling manifold actuators (one per loop) and pump unit
    No mechanical (wet) zone valve
    Evohome bass unit controlling the boiler

    Out of interest, what make of actuators have you been running? How many failures have you had?
    You wouldnít need a HCE80 when using actuators for one zone, you can still use a BDR91. Even for two you could just use two BDR91s. Your Opentherm relay fires the boiler so you donít need any micro switches for firing the boiler (you can actually get 4 wire actuators with built in switches though).

    I come across a variety, some are polyplumb, others are different brands. I usually find On UFH issues though actuators are things I replace more than Zone valves. Although zone valves donít seem to be last long these days even in standard applications.

  5. #5
    Automated Home Sr Member
    Join Date
    Jan 2017
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    Default

    Oh ok, so the actuators can be wired straight to the BDR91, and leave out the zone valve. TBH, I didn’t know this was an option! I thought the BDR was just on/off though, so won’t actually modulate the zone valves.

  6. #6
    Automated Home Ninja
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    Default

    Quote Originally Posted by kimber.kimber View Post
    Oh ok, so the actuators can be wired straight to the BDR91, and leave out the zone valve. TBH, I didnít know this was an option! I thought the BDR was just on/off though, so wonít actually modulate the zone valves.
    No they wonít modulate, as theyíre just open or closed. The HCC80 only does the same, as in open or closed as far as I am aware. There was a discussion about it on a thread some time ago about this feature could be achieved in Europe but the UK didnít have this certain feature, canít recall the specifics. Iím not 100% on this though.

    I donít really see any advantage anyway, youíre heating up a slab that retains that heat.

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