HVAC configuration

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  • JonS
    Automated Home Guru
    • Dec 2007
    • 202

    HVAC configuration

    I have my heating controlled by Cortex with an upstairs radiator zone and individual zones down stair heated by UFH. The control is way better than achieved by the standard controls but I was wondering how other people had theirs set-up.
    For the 2 upstairs floors I have a single HVAC zone at the moment with the temperature averaged between the room sensors. Control is "on/off" with a minimum duration of 20 minutes.
    In the UFH zones it’s a 30 minute minimum period (the floors take a long time to react).
    All the HVAC objects are connected to delayed occupancy set at 5 minutes. This is generally fine but as there are no doors between kitchen and family room an active parent in the kitchen can suppress heating demand in the family room if the kids a in front of the TV - I like this feature!
    How water is timed as I do not have a tank thermometer.

    One thing I have observed is that a traditional room-stat setting is really an average with large over and under shoots. The HVAC object's temp is the minimum, but with much less (approx 1C) overshoot.

    I am happy but wondering how to improve further. What is other people's experience and with so many options to tweak what have others found most successful optimisations?

    Thanks
    JonS
    JonS
  • jpdw
    Automated Home Guru
    • Oct 2007
    • 169

    #2
    I've had a setup for a about 4 years which is not dis-similar, though I was fortunate to get the radiators zoned by floor - ie zone 3 zone valve for ground first & second (loft) floor.

    I've mainly concentrated on using the ability to tune the HVAC demand temperatures to the fraction of a degree per hour per day, gradually tweaking demand down when its not needed (so Cortex is helping my energy miser efforts). Only in a couple of rooms did I add presence to switch between occupied/unoccupied.

    We're just nearing the end of an extension/refurb of our kitchen which now has UFH on it's own zone separated from the rest of the ground floor. My intention is to use a couple of temp sensors around the room but not presence sensors for the UFH as advice on here was that the slow heating time of UFH mean waiting for occupancy doesn't really work. I had thought about using an 'aggregate' of bedroom presence to decide upon target temp for the kitchen UFH in the morning, but not got that far.
    Jon

    Comment

    • chris_j_hunter
      Automated Home Legend
      • Dec 2007
      • 1713

      #3
      we're still installing (most of the plumbing & half the UFH now pressure-tested, half the electrics also, MVHR installed but too much dust about to run it yet, something over half our 'modules installed, Cortex about to be loaded), so our thinking remains theoretical atm, but ...

      with a largely open-plan all-electric layout, we've gone for a fairly liberal spread of peripherally-placed PLH modules augmented by some centrally-placed black-bulb sensors (working into QAIs) & several clip-on pipe temperature sensors (also working into QAIs) that we'll use to modulate the speed of the UFH pumps (one per floor), to switch ventilation & secondary HW flows according to presence & calendar / diary, and move heat between thermal stores (solar / HW & heat-pump accumulators) ...

      we've also included some pulse flow-meters, working into DIs, to ensure we can measure heat, not just temperature ...

      initially, the plan is to have the pumps & fans on automatic & use just time & the black-bulb sensor readings to simply switch them on & off, keep an eye on the data-logs for all sensors, look for clues, and move to variable speed & sophistication as seems sensible !

      Chris
      Last edited by chris_j_hunter; 30 November 2011, 09:00 AM.
      Our self-build - going further with HA...

      Comment

      • Paul_B
        Automated Home Legend
        • Jul 2006
        • 608

        #4
        Hi Chris,

        Any chance you could list and link the products you purchased from the above e.g. black bulb, thermistors, pulse flow sensors?

        Many thanks

        Paul

        Comment

        • chris_j_hunter
          Automated Home Legend
          • Dec 2007
          • 1713

          #5
          Hi Paul -

          yep ... hopefully later / late today ...

          Chris
          Our self-build - going further with HA...

          Comment

          • chris_j_hunter
            Automated Home Legend
            • Dec 2007
            • 1713

            #6
            Hi Paul -

            OK, as promised :

            A. temperature & humidity sensors ...

            - generally PLHs - by windows (light-level sensor determines location), and by mirrors & elsewhere (motion sensor determines location) ...

            some MFPs ...

            and an LTH-X01 (outside) ...

            all work well ...

            plus individual temperature sensors wired into QAIs ...

            - these clipped onto pipes :



            - these inserted into pockets & laid in tile-adhesive & tied to ducts :



            - and these for room comfort sensing :



            QAI resolution is a bit coarse, but it's OK ...

            B. rate meters ...

            - water-flow meters :



            ours are ten-litres per pulse - we wanted one-litre per pulse, but they weren't to be had ...

            these weren't available when we bought, but look interesting :

            Bio-Tech - Vision 2000 - Bio-Tech Vision 2000 B.I.O-TECH e.K. NPN Non Aggressive Axial Turbine Flowmeter - The only 59 x 17 x 31 mm wide measuring turbine


            but they look to generate too many pulses (our circuits have flow-rates in the range one to ten litres per minutes)

            - power meters :





            C: water-level sensors :



            use more than one for more detail of level & rate-of-change ...



            the Titan has a rain-sensor option, but we'd already used one of these :

            Irrigating a landscape during a rainstorm not only results in oversaturated plants and turf, it also wastes water. Hunter's Mini Clik rain sensor provides the simplest, most effective way to prevent sprinklers from running during or after any level of rainfall. It easily installs on any automatic irrigation system. The Mini-Clik stops scheduled irrigation when it detects a pre-set level of rain has fallen. This automatic process ensures landscapes aren’t watered during a storm. Once the storm passes, the Mini-Clik allows the controller to resume normal irrigation.


            all connected to digital-inputs ...

            water-valves :

            regular two & three-port by Honeywell :

            Business as usual at BES.co.uk. Next day delivery on more than 15,000 plumbing supplies online in the UK. Contactless delivery to your door. Buy now.


            E: water-pumps :

            The United Kingdom division of Wilo: A world-leading manufacturer of air & water pump systems for commercial, residential and agricultural use.


            we used Wilo-Stratos ECO-Z pumps with BMS option for UFH & heat transfer between 'stores, the 0-10V coming from Cortex via QAOs, and a Wilo-Star-Z NOVA for DHW secondary flow - augmented by solenoids, with both pump & solenoids controlled by Cortex via QRI relays ... with three UFH zones on the top floor (driven by available pipe lengths), and four UFH zones on the middle-floor (two plus two half-lengths, again driven by pipe-length availability), all being cast within anhydrous screed with ceramic tile laid-over ... plus a loop for post-heating of the MVHR airflow ...

            so-far, we're controlling things via simple Cortex Macros, keeping an eye on how things go & experimenting with various strategies ... we've read-through a good many Cortex Help screens, among them those for HVAC objects, but have yet to choose how to do it ...

            lots of sensors are helpful, around the house & on pipes, etc, we found, to be able to understand what's going-on - else it's just guess-work - very precarious !

            NB: we've found Rapid v'good to deal with - very fast & reliable, as also BES for all manner of plumbing bits & pieces, Titan were fine, if a bit slow ... SwissNox was via Amazon, also good, and the rest we sourced via local people, from whom we got reasonable prices, with some waiting ...

            HTH

            Chris
            Our self-build - going further with HA...

            Comment

            • Paul_B
              Automated Home Legend
              • Jul 2006
              • 608

              #7
              Chris,

              Many thanks for putting this post together. I know what I will be doing tonight when I get home after work! Did you install solar thermal, solar PV or both during your build? Is the house now complete and do you have any pics?

              Paul

              Comment

              • chris_j_hunter
                Automated Home Legend
                • Dec 2007
                • 1713

                #8
                Paul -

                solar-PV - too marginal, even with FiTs, for us anyway - as an add-on (rather than being fully integrated) the cost-benefit seemed about quits if nothing went wrong ...

                solar-thermal - yep, vacuum tubes, for which good data here :



                lots to choose from, and quite a lot of variation in design & installation details ...

                quite popular (in the UK) are the Navitrons (SPF-Nrs 781 & 782), but we went for the Riomays (SPF-Nr 939) - about twice as effective in our situation, half from basic design, half from ability to install at optimum angles (Navitrons go down the roof, Riomays go along & can be individually rotated for best elevation) ...

                we aligned ours to maximise Winter gains & ease Summer excesses ... and they feed the solar coil of our DHW thermal store (800 litres, ACV tank-in-tank) ... we find them as effective as expected (SPF data) ...

                big tank was sized for maximum demand, when family descends, but its size is useful at other times, in that lower temperatures mean more opportunity for solar-gain ...

                we bought anti-freeze, but found it a both a nightmare & unnecessary (the tubes being good at capturing heat & not losing it, it takes not a lot of heat on frosty nights to keep them from freezing) ...

                keeping them from overheating is an issue, though - due to temperature sensors lagging water temperature rise ...

                control is by a IntaEco SolarLogic controller, which varies pump speed to maximise ‘gain, with Cortex keeping an eye & able (by thresholds & a DRB relay) to by-pass it when trouble looms - works well !

                we’ve an ASHP as well, and the ‘tubes do a good job at keeping the demand on that down (HW & UFH) - for us, the ASHP offered lower costs than gas (haven’t run it long enough to be sure but, if the Winter just gone is any guide, signs are promising), but it’s sized to match the long-term heat-load rather than short-term fast response (as is usually the case with gas), so things have to be managed carefully (well-insulated house with UFH & plenty of thermal storage - in tanks & structure - is a good match) ...

                house - not quite, it’s probably now over 90% done ... the 10% includes quite a lot of work with Cortex (which is v.capable & quite brilliant), to get everything fully-working ...

                Chris
                Last edited by chris_j_hunter; 14 May 2013, 01:24 AM.
                Our self-build - going further with HA...

                Comment

                • Paul_B
                  Automated Home Legend
                  • Jul 2006
                  • 608

                  #9
                  Originally posted by chris_j_hunter View Post
                  B. rate meters ...

                  - water-flow meters :



                  ours are ten-litres per pulse - we wanted one-litre per pulse, but they weren't to be had ...
                  Chris,

                  I had the same feeling as you that 10L per pulse was possibly a bit coarse for my requirement and after a lot of searching was coming to the same conclusion as you, but then came across the following:



                  I've got a quote from the guys of ~£56 and gone for a hot water unit with pulse output of 1 pulse per litre, it should arrive on Friday so will see if it fits the bill

                  Paul

                  Comment

                  • chris_j_hunter
                    Automated Home Legend
                    • Dec 2007
                    • 1713

                    #10
                    Paul -

                    well done - well worth a try ...

                    our heat transfer circuits run for hours rather than minutes, so 10 per pulse isn't the end of the world, but it does mean we have to manually interpret the graphs Cortex produces - whereas we were hoping to have Cortex present heat transfer data directly ...

                    some of our circuits run at precise speeds (speed control has, say, five settings) - so we might be able to add some logic to home-in on the right figures ...

                    but others are continuously variable, so not so easy - perhaps with some experimentation, we could work-out a calibration ...

                    still, the data they've produced has been invaluable - in assessing how things are actually working, and giving us the ability to optimise ...

                    we couldn't find one to work on the solar circuit - which can sometimes get quite hot - but the pump station came with a simple ring-pull device which we were able to calibrate (SolarLogic will run the pump at ten speeds, and the pump has three ranges, so some simple experiments gave us some graphs we could improve (smoothing-out the errors) and cross-correlate with the SPF data for the vacuum-tubes (with the addition of the clip-on temperature data) ...

                    BTW - temperature sensors ... we find clip-on / strap-on has its limitations - ie: the sensor isn't actually immersed in the fluid, so there are significant lags to be taken into account, when starting & stopping ...

                    BTW, too - your 0.5degC temperature drop for the tank with 100mm insulation might be optimistic - ours is not much bigger & similarly insulated, and losses are more like 5degC per day (without us using water) - the solar loop is partly responsible, but we've yet to fathom it out ...

                    Chris
                    Last edited by chris_j_hunter; 15 May 2013, 06:31 PM.
                    Our self-build - going further with HA...

                    Comment

                    • Paul_B
                      Automated Home Legend
                      • Jul 2006
                      • 608

                      #11
                      Chris,

                      How many water meters from JetRange have you installed? Shame we couldn't find a more basic flow meter with pulse output rather than a full fledged water meter.

                      Have you insulated all the pipework to and from your thermal store? Could this be the cause of the temperature loss or possibly thermosyphoning? When my system is completed I be able to determine just how accurate the manufacturer quotes really are.

                      Paul

                      Comment

                      • chris_j_hunter
                        Automated Home Legend
                        • Dec 2007
                        • 1713

                        #12
                        Hi Paul -

                        we put one in every heat-transfer circuit, so one per pump - bar solar, which could get too-hot - so, one in the loop between ASHP & its thermal store (235 litres), one per UFH circuit (ie: two, one per floor, with the circuits including three & four loops), and one per inter-'store circuit ...

                        we tried to devise a lower-cost way, perhaps sharing them, but extra motor-valves would have been needed ...

                        all pipes, all around the house, are insulated, using standard stuff - but it's surprising how the losses add-up - we lose a bit more than 0.5degC between 'stores, three or four times that between ASHP & 'store, and a touch more even than that between vacuum-tubes & 'store - we should have done the sums, rather than rely on following what we thought was normal practice ('stores & sources are not co-located, the runs between being in the range 10 to 15m long - 'tubes on the roof, tank in basement, ASHP in yard, tank in sub-basement, etc) ...

                        of course, we know this only because we've clipped sensors onto each end of each run (sensor resolution is ±0.5degC, so also need to try to take that into account) ...

                        v.glad you're including at least one flow-meter - so few people do and, without it, there's no way to know (rather than speculate or think wishfully) about heat transfers ! Only exception to that is with heat-exchangers - we've one where we measure flow-rates on one side only, and compare the temperature deltas to deduce the flow-rate on the other ...

                        thermo-syphoning (and other induced flows), yep, did wonder ... we added some solenoids to the DHW secondary-return circuits because we thought losses there were too great (despite being well insulated), to ensure only necessary loops were activated at any time in response to Presence - 'though we've yet to try it / them (needs us to add some logic to our Cortex database - part of the 10%) ...

                        Chris
                        Last edited by chris_j_hunter; 16 May 2013, 10:04 AM.
                        Our self-build - going further with HA...

                        Comment

                        • Paul_B
                          Automated Home Legend
                          • Jul 2006
                          • 608

                          #13
                          Originally posted by Paul_B View Post
                          ...had the same feeling as you that 10L per pulse was possibly a bit coarse for my requirement and after a lot of searching was coming to the same conclusion as you, but then came across the following:



                          I've got a quote from the guys of ~£56 and gone for a hot water unit with pulse output of 1 pulse per litre, it should arrive on Friday so will see if it fits the bill
                          The meter has now arrived and is plumbed in, completed wiring the pulse output into a ODI last night and very happy with the results. Already worked out the little darlings probably didn't wash this morning as no hot water usage between 07:00-09:00 when they got up and allegedly washed!

                          HotWater.jpg

                          Paul

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