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Zoned Heating & Controls

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  • 12-11-2013 1:53am
    #1
    El Nino 9
    Registered Users Posts: 18 ✭


    Hows it goin folks. Im currently converting upstairs & fiiting a new Grant Vortex Condenser boiler. I have 3 zones-upstairs, downstairs & hot water. Ive a fair idea of what way things work with this but just looking to find out if there is any new/more advanced ways of controlling this.

    I was gonna have a motorised valve on both upstairs & downstairs heating lines to rads & also have one at the coil of the tank for the hot water. Ive a triple coil tank & solars so hoping that solars will provide me with hot water in warmer months. Ive a wall stat to control the 2 zones & tank stat for the water all gonna be wired to a 3 channel time clock.

    The existing plumbing system is pressurised & im thinking of adding a stove with back boiler to this eventually. Do i need to install a special unit to run stove through a pressurised system. Should i stick with a pressurised system with new system or whats best?

    Also im gonna fit a pump on both upstairs & downstairs zones but which stat should run the pump. ie.the wall stat for that zone or the stat on the return of the Grant boiler?

    I know i may be mumbling on a bit but im doing the installation part myself & a plumber is going to verify everything for me once complete. Im doin the house in stages so thats why he said to finish it out as much as possible before he comes.

    Open to any suggestions or recommendations.
    Cheers.


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    #2
    freddyuk
    Registered Users Posts: 1,110 ✭✭✭freddyuk


    1. Use 1 pump for the system. Why do you need 2?
    2. Use programmable room stats for each zone. They have up to 6 daily settings for each zone and then any rooms can be fine tuned with TRV's.
    3. Consider zones for bathroom + bedrooms+ living room+kitchen+ maybe conservatory. Only possible when you are installing/building - too late afterwards but maybe you can re plumb downstairs. Only use zone valves with removable actuators.
    4. You need to consider a plan for the cylinder options as you need to have the correct size and position. For solar and a stove you want the biggest cylinder you can get to store the free heat when it is available. Consider a buffer tank feeding you main cylinder. Consider gravity circuit for stove to avoid more pumps (weak spots).
    5. You can get boiler valves for combi boiler/solar integrated systems.

    Others will have other ideas but do lot's of research on solar integration/pressurised systems.


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    #3
    El Nino 9
    Registered Users Posts: 18 ✭El Nino 9


    Cheers for that. In reply to what you said:

    1. Would i not be better using a pump for each zone if it was a case that both zones were active at the same time? I have 12 double rads on the down satirs zone & 9 double rads upstairs. I was thinking of it from the point of view of pumping water to rads as quick as possible when called for?

    2. Would me using a 3 channel time clock not be the same in theory as having programmable zone stats? Im installing TRV's on all rads. Ive bought all new Peglar TRV's & will be fitted in time. 1 channel for each zone & hot water channel.

    3.I take it you mean plumbing each room back to a manifold & have them activated by a room stat as such. I considered this but it would involve alot of work downstairs & dont wana go down that road. The TRV's will be as much heat control per room as ill be getting.

    4. Ive installed a 300 litre triple coil tank & 60 tubes of solars. Some people say say install an even bigger tank but the reason i didnt is cos if its a thing i have to heaten this in the middle of winter for example i dont wana have to heaten a huge volume of water for a quick shower/bath. I know ill be missing out in Summer from "free heat" but 300 litres is loads for what we use. I can always install a buffer at a later date if necessary but hoping that the system i have will not need to be upgraded or added to at any stage. Im not 100% certain whether or not i will install a stove with back boiler or not just yet. Ive been in so many houses that the heat in the room is barely noticeable as they lose it all to their back boiler.

    5. Im fitting a condensing boiler & never looked into or heard of the integrated systems with solar. I will definitely have a look into it though as i havent picked up my boiler yet. I was always told that solars can only heat your domestic hot water through its coil & not provide to the central heating. Maybe im misunderstanding what your saying but if there was a way of gettin my rads to heaten from my solars i would be all for it.

    Thanks again for all your help/advice. Really much appreciated.


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    #4
    MicktheMan
    Registered Users Posts: 2,825 ✭✭✭MicktheMan


    El Nino 9 wrote: »
    Im currently converting upstairs & fiiting a new Grant Vortex Condenser boiler.

    Just to add to what has been said above, make sure you size the boiler right to make sure it is actually condensing the majority of the time.


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    #5
    El Nino 9
    Registered Users Posts: 18 ✭El Nino 9


    MicktheMan wrote: »
    Just to add to what has been said above, make sure you size the boiler right to make sure it is actually condensing the majority of the time.

    Thank you. I stated this to the company that im buying my plumbing supplies & they told me that a 90/120 boiler is whats needed taking into account that i may have to heat the tank & both zones occasionally. I told them i dont wanna oversize the boiler as this may be a complete waste & theyve guaranteed me that the 90/120 is what i need. I dont know how its worked out but i have all the rad sizes if anyone can help out.

    Thanks for your reply.


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    #6
    El Nino 9
    Registered Users Posts: 18 ✭El Nino 9


    I was also advised by someone to look into this Systemlink unit that are now on the market. Some people say that you really only need to install these to tie in syatems together. Im due home in a weeks time & the plumber who is installig/signing off on my heat controls grant is meeting me at the house but i just wanted to ask here on everything mentioned above what the best & most practical system to use is.

    Cheers


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    #7
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    El Nino 9 wrote: »
    Thank you. I stated this to the company that im buying my plumbing supplies & they told me that a 90/120 boiler is whats needed taking into account that i may have to heat the tank & both zones occasionally. I told them i dont wanna oversize the boiler as this may be a complete waste & theyve guaranteed me that the 90/120 is what i need. I dont know how its worked out but i have all the rad sizes if anyone can help out.

    Thanks for your reply.

    Im hoping someone will come along and correct me, but how does the plumbing supplier know what your heat requirement is?
    Im not going to claim I know something I dont, Im not a plumber, and I dont know what a 90/120 boiler is, but I have done some stuff on heat loss calculations.
    Surely the heat loss for each space would have to be added up? to determine what the heating requirement is unless someone else is doing that?


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    #8
    El Nino 9
    Registered Users Posts: 18 ✭El Nino 9


    cerastes wrote: »
    Im hoping someone will come along and correct me, but how does the plumbing supplier know what your heat requirement is?
    Im not going to claim I know something I dont, Im not a plumber, and I dont know what a 90/120 boiler is, but I have done some stuff on heat loss calculations.
    Surely the heat loss for each space would have to be added up? to determine what the heating requirement is unless someone else is doing that?

    They asked me for rad sizes & they worked it out from that. I explained that i was having an upstairs & down stairs zone etc & they advised me on the boiler. They were more for the Firebird than the Grant boiler but i went with grant out of personal favour only.

    Cheers.


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    #9
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    El Nino 9 wrote: »
    They asked me for rad sizes & they worked it out from that. I explained that i was having an upstairs & down stairs zone etc & they advised me on the boiler. They were more for the Firebird than the Grant boiler but i went with grant out of personal favour only.

    Cheers.

    The rad size doesnt give you the heat requirement of your building though, the rad sizes should be determined from the heating requirement surely?
    Im not sure how plumbers work it out myself, but the heat loss of the walls,floor and ceiling some of which may be little or nothing if they are backed onto a room that is also heated will determine the heat required to maintain a desired temperature, then you'd know how many kW's required to maintain that temperature, do that for each room space and then adding the hot water requirement would equal the boiler output, Id have thought. I cant see how a final figure would have been come to otherwise, but Id certainly be interested to hear if someone knows how its done.
    Given each building is different, I can see a rule of thumb being off regarding correctly sizing a boiler, especially for a non usual space or design.


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    #10
    JohnnieK
    Registered Users Posts: 2,526 ✭✭✭JohnnieK


    A heat loss calculation needs to be done to determine the correct output. If it is a semi-d you have I have found most would be a 70/90 or occasionally a 50/70.


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    #11
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    JohnnieK wrote: »
    A heat loss calculation needs to be done to determine the correct output. If it is a semi-d you have I have found most would be a 70/90 or occasionally a 50/70.

    I live in a (original) 3 bed room semi, cavity BLOCK house with a 16 ft X 12 ft extension and an attic conversion, house built in 1970. I have no really special insulation apart from double glazed windows and the roof is well insulated. I have TRVs fitted in all rooms bar 1 but no zoning apart from a motorised valve on the cylinder coil.
    I have a 70/90 (20.5 KW/26.4 KW) Firebird Oil (non condensing) Fired Boiler, I dont know what size burner nozzle is fitted but I'd say its safe enough to assume that the output is around 23.5 KW.
    The boiler takes 25 to 30 minutes of continuous firing to get up to temperature in the morning from the shut down at midnight the previous night even when the ambient temperature is as low as minus 4 in the morning. I have often monitored its running time during the evening and the maximum continuous firing even when the ambient was minus 6 was for 34% of the cycle, ie it was inputting approx 8 KW (per hour) to the building. The normal running time is 22% to 28% of the cycle. Based on those conditions the Boiler is grossly oversized and a 50/70 (14.7 Kw/ 20.5 KW) would be a far better fit for me and I would say this would fit the bill in most 3 bed semis.
    A lot more involved calculations must be taken into account when sizing both the rads and the Boiler operating in the so called condensing mode. If the Boiler is to run in the condensing mode then the return water temperature probably has to be as low as 50C to 55C, this in turn means that the mean radiator temperatures will be much lower than in the non condensing mode so they will have to be sized accordingly, if retrofitting a condensing boiler then its more than likely but not certain that the rads are oversized anyway.
    Its also vital that the Boiler Burner is adjusted to give as low excess air required for combustion as possible as the greater the excess air the lower the dew (condensing level) temperature point of the flue gases, I cant comment on domestic boilers but on the fairly large industrial Steam Boilers (55 MW to 100 MW) units, the excess air is maintained automatically at 5% to 10% or 1% to 2% Oxygen.
    A condensing boiler will still be more economical to run because it will run with lower flue gas temperatures even in the non condensing mode. Happy system sizing....John.


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    #12
    JohnnieK
    Registered Users Posts: 2,526 ✭✭✭JohnnieK


    Are you trying to dangle a carrot there Mr Carroll?


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    #13
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    JohnnieK wrote: »
    Are you trying to dangle a carrot there Mr Carroll?
    I would certainly hope not JohnnieK and apoligies if I gave that impression.

    I


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    #14
    JohnnieK
    Registered Users Posts: 2,526 ✭✭✭JohnnieK


    John T Carroll wrote: »
    I would certainly hope not JohnnieK and apoligies if I gave that impression.

    I

    No problem. My apologies to you too for jumping at you. I totally miss read the tone of the text.


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    #15
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    Im interested to know what the 50/70, 70/90 definitions are related to,
    I see a poster has mentioned certain kW values, not sure why there are two kW values mentioned?

    Im also unsure how in a domestic scenario, how it is possible to allow the boiler to condense (edit; all the time)when it could be under a varied load ie heating under variable conditions and heating under any conditions with or without hot water requirements, other than a modulating boiler, I cant see how this can be accounted for? I think someone mentioned here on boards that all A rated boilers are now modulating, but are there condensing boilers that dont modulate?
    It seems to me, (just a curious and interested person) that it would be a requirement for a boiler to be able to meet the minimum heating load (maybe even as important as meeting its max load?) where thespace heating system is in use for a limited demand or when its likely only hot water say during the summer period is needed, when the max capacity of the boiler isnt required.


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    #16
    John T Carroll
    Closed Accounts Posts: 757 ✭✭✭John T Carroll


    The numbers 50,70 and 90 refer to boiler outputs of 50,000, 70,000 and 90,000 BTU.s per hour. (British Thermal Units per hour). It is now far more common to rate energy in KWH (kilowatt hours) and Power output in KW (kilowatts). 1 Kw equals 3412 BTU,s. So the figures above become (50000/3412) or 14.65 KW... (70000/3412) or 20.5 KW......(90000/3412) or 26.38 KW. As far as I know, by fitting a different sized jet in the fuel nozzle, a 50/70 Boiler can have a maximum output of 14.65 KW or by fitting a bigger jet it can have a maximum output of 20.5 KW. Similarly, a 70/90 boiler can have a max output of either 20.5 KW or 26.4 KW. There is often confusion over KW and KWH, A boiler could be said to have a power output of 26.4 KW, if its ran for 1 hour then the energy output is (26.4X1) or 26.4 KWH and so on, if its run for say 2.5 hours, the energy output is (26.4X2.5) or 66 KWH.
    Gas Fired modulating Boilers have a turn down ratio of something of the order of 5:1 (someone out there can easily tell you) A 5:1 turndown means that the Boiler can modulate its Power output between 20% and 100%. Modulating Oil Fired Boilers are now available, if you write "modulating condensing oil boilers in household use" into the boards.ie search then you will find quite alot of info.
    Hope the above is of some help to you.
    I should maybe add that an Oil Fired Boiler probably does the "modulating" in a number of steps, these might only be either 50% output or 100% but again make sure you ask the manufacturer or seller what is meant exactly by their version of modulating.


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    #17
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    John T Carroll wrote: »
    The numbers 50,70 and 90 refer to boiler outputs of 50,000, 70,000 and 90,000 BTU.s per hour. (British Thermal Units per hour). It is now far more common to rate energy in KWH (kilowatt hours) and Power output in KW (kilowatts). 1 Kw equals 3412 BTU,s. So the figures above become (50000/3412) or 14.65 KW... (70000/3412) or 20.5 KW......(90000/3412) or 26.38 KW. As far as I know, by fitting a different sized jet in the fuel nozzle, a 50/70 Boiler can have a maximum output of 14.65 KW or by fitting a bigger jet it can have a maximum output of 20.5 KW. Similarly, a 70/90 boiler can have a max output of either 20.5 KW or 26.4 KW. There is often confusion over KW and KWH, A boiler could be said to have a power output of 26.4 KW, if its ran for 1 hour then the energy output is (26.4X1) or 26.4 KWH and so on, if its run for say 2.5 hours, the energy output is (26.4X2.5) or 66 KWH.
    Gas Fired modulating Boilers have a turn down ratio of something of the order of 5:1 (someone out there can easily tell you) A 5:1 turndown means that the Boiler can modulate its Power output between 20% and 100%. Modulating Oil Fired Boilers are now available, if you write "modulating condensing oil boilers in household use" into the boards.ie search then you will find quite alot of info.
    Hope the above is of some help to you.
    I should maybe add that an Oil Fired Boiler probably does the "modulating" in a number of steps, these might only be either 50% output or 100% but again make sure you ask the manufacturer or seller what is meant exactly by their version of modulating.


    Thanks for that, when Im getting a replacement boiler, it will be a gas boiler as thats what I have now, as long as the existing boiler holds out. I plan to do up my own calculations just to get an idea what I might need. The above information is interesting and useful, the 5:1 ratio is something thats good to know about asking when the time comes.


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