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New Build, 7 months in with a Danfoss heatpump

  • 08-01-2017 2:32pm
    #1
    Registered Users Posts: 152 ✭✭ matrat


    Hi all,

    I used this forum alot during my self build so wanted to share my experiences now having being in the house 7 months.

    General Spec;
    - House was built to square in 2009, 100mm cavity, already had 60mm foil back board in place.
    - 3000sq ft
    - Munster Joinery triple glaze windows and doors.
    - Pumped the remainder of the 40mm on ground floor and full 100mm cavity from floor slab up with Icynene Technitherm Closed Cell Cavity Wall Insulation.
    - Pumped roof with Icynene LD-C 50 Spray Foam Insulation.
    - Had air test done at this stage and decided to tape windows internally with pro clima Contega Solido SL.
    - 130mm insulation ground floor, 60mm insulation on first floor slab.
    - Self designed and installed 2 NUAIRE - MRXBOX95-AB-WH1 units, one for upstairs, one for down.
    - Local installer for Danfoss DHP-H Opti 8 SP

    I appreciate that this is not everyones idea of a great spec, but naturally i was budget restricted and as this was a self build with no contractor or architect, all decisions where made by myself based on my own personal research. Multiple quotes where sought for every item and i did a substantial amount of the work myself. I have no trade or massive experience, but given some of the cowboys that were recommended to us, i genuinely feel myself and youtube have done a better job.

    Naturally i have my opinions on all of the above products/companies but i wont go into them here. Feel free to message me if you have any questions on any of them.

    House is set up that bedrooms have stats, all set to 21.5, all other areas are about 23 (wife loves heat).

    This is the first house i have ever spent much time in which was built to this kind of spec and honestly i could never go back. No draughts, no smells and lovely uniform heat. We have no other heat source than HP. What has surprised me the most is how quickly the house heats you when you come in from the cold. No need to stand next to the fire, a few minutes and you are warm. Biggest downfall is constantly leaving the house and having no coat or jumper on! :rolleyes:

    Regarding the HP, i am overall extremely satisfied, i am keeping an excel file tracking the running times and costs associated (happy to share) and here is the headlines;
    - The unit had cost 334.27 by the time we moved in. This is hot water used cleaning, and bringing whole house up to around 24c from cold and wet.
    - Average WEEKLY cost for ALL domestic hot water, that is all showers and washing etc.(we have used dishwasher twice as the hot water is so readily available) is 4.23e.
    - Average cost for heat is a bit trickier as there is much more variation naturally. I will list the average WEEKLY cost per month;
    June = 1.81e
    July = 2.16e
    August =1.06e
    September = 3.80e
    October = 11.21e
    November = 22.52e
    December = 22.17e

    Again, these are WEEKLY costs!!! All costs taken at either the exact rate charged per unit by my provider, or 19c for the last few weeks in December for which i dont have a bill for.
    I contacted Danfoss direct, they advised the following;
    For the heating function, the machine uses 2kw/h
    For domestic hot water, the machine uses 2.7kw/h

    I record the times the unit has being on every Saturday, as of yesterday, 224 days in total, thats 32 weeks;
    Total cost for heating has being 321.87e
    Total cost for DHW has being 139.55e

    That is total house cost of 461.42e which i am very pleased with.

    As maybe you can tell, overall i am delighted we chose to go down the HP route, we very nearly had it wrote off assuming it would be too expensive but it just isnt when you do the maths for a few years.

    Hope this helps making someones decision easier and any questions please let me know!!


«1345

Comments

  • Registered Users Posts: 1,005 ✭✭✭ Ray Donovan


    Praise the Lord.

    At last a positive news story from a new build and a heat pump. My own house is currently being built with the following specs:
    2650 sq ft
    Triple Glazed windows (Taped obviously) with U-Value of window (not just glass) not to exceed 0.85.
    External Walls - 150mm pumped graphite bead to cavity which achieves a U-Value of 0.2
    Ground Floor Slab - 150mm of Xtratherm insulation which achieves a U-Value of 0.13
    Roof Insulation - where horizontal 300mm of rockwool achieving a U-Value of 0.15
    -where ceiling follows slopes of rafters 125mm of Kingspan Kooltherm K7
    -between rafters with 47.5mm of Kooltherm K18 insulated plasterboard to achieve a U-Value of 0.16
    Provisional BER of A2

    I did some outrageous tossing and turning on how to heat it but eventually settled on A2W pump and HRV system. Engineer did up all sorts of costs analysis for me and it seemed the way to go. I also have 2 external air supply stoves going in but hopefully they'll be more for aesthetics!! The pump
    will be installed in the next month.

    Great to hear someone with a good news story about it.


  • Registered Users Posts: 95 ✭✭ Robert Allen


    Hi Ray donovan & matrat.

    Thanks for posting the info here - im in the middle of a self build at the moment with loads to try sort out so your posts are after solving a few problems for me and im pointed in the right direction now.

    Many thanks again & glad it all worked out & you are happy with your progress!


  • Registered Users Posts: 1,005 ✭✭✭ Ray Donovan


    Hi Ray donovan & matrat.

    Thanks for posting the info here - im in the middle of a self build at the moment with loads to try sort out so your posts are after solving a few problems for me and im pointed in the right direction now.

    Many thanks again & glad it all worked out & you are happy with your progress!

    Best of luck with it. Some undertaking!!!


  • Registered Users Posts: 95 ✭✭ Robert Allen


    Its crazy but worth it in the end! I would recommend a builder/project manager if anyone was to ask me again!

    P.s. - if anyone wanted to send on contact info for tried and trusted heat recovery and Air to water heat pumps it would seriously help me out.

    Thanks again guys and best of luck.


  • Registered Users Posts: 42 ✭✭✭ sparks3000


    Great information matrat.
    I built a new house in 2015 . I put in oil solar and a boiler stove .
    I ran ducting for a future hrv system not installed yet. I installed a hybrid dcv system using hole in wall ventilation for now.
    I also installed the pipework for underfloor heating in the future. I am currently heating using radiators and not the underfloor.

    I will put up running costs and amount of oil used at the weekend. I will put up my homes insulation spec and total electricity costs.

    If you would not mind could you post what your total electricity bill has been for each two month period.


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  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    @matrat
    Thanks for info.

    Is that ground pump OR air_to_water !?
    If you have had access to gas, will you still have gone with the heat pump !?

    Rgds


  • Registered Users Posts: 152 ✭✭ matrat


    @Ray Donovan
    Good to hear you didnt let old fashioned ne sayers put you off either.
    One thing i would advise, like yours my house was designed with two chimneys. When we purchased, and had decided on heating source, i took the chimney down in a room with it on an external wall. We left one in the living room, it was an internal wall and left an air supply, and with the idea being we would like the look and feel of a fire of winter. Was one of the first things we picked aswel was a wood burning stove but as we moved in May, we decided it could hold off until end of summer to go in. One thing led to another and none was ever installed. We are thinking now of going down the route of maybe an electric stove just for the look as we struggle to see when we would ever light it with the heat we have. Both chimney are air intake are sealed up and is looking like they might stay that way.

    @Robert Allen
    Best of luck with your build and try and enjoy! If you are like me you will be secretly loving the whole process and be quite disappointed when it is all done!
    I am happy to send on the contact info for the Heat pump guy i used and the supplier of the mhrv system bits who gave me a great deal as i picked up equipment from his warehouse myself!! Where are you based?
    Pretty sure i contacted most of the heat pump installers in Ireland, several in NI and even a few in UK during my search and have all the quotes about the office somewhere. To give you an idea of what you have to look forward too, my calculations pointed to an 8KW heat pump. I have quotes there stating i need to use a 16KW heat pump. I have quotes from 16k to 37k. Price was not ever the deciding factor but im sure you will find it heart warming to know that the guy i used was second cheapest!! And the only guy who didnt fall under my questioning!!
    Regarding the mhrv, again i contacted as many as i could find. I found one guy down the country, cant remember his name, only one who could stand to any questions but his price was about 3 times what i could buy materials for. Everyone else who i spoke to and quoted where a shambles. Ask about flow rates, cfm, cross talk etc and none had an idea. The material supplier i used was very good and answered loads of my questions and i did all the spec and installing myself. Is good documentation out there about best practices, and i used the uk building regs as the base for all my calculations. I still have to get a vaneometer and balance each room but that is just fine tuning.

    @sparks3000
    No problem, i work at home average 4 days a week, misses works here 3 days a week and we aint the most efficient with alot of gadgets, media server etc running ha.
    Period Cost Units
    10-Mar-13-Apr €103.65 295
    13-Apr-14-Jun €179.26 961
    14-Jun-17-Aug €162.18 839
    17-Aug-12-Oct €168.12 884
    12-Oct-09-Dec €191.07 1031

    We moved in at end of May, so all before that was drying out, work being done etc.

    @rolion
    We went with geothermal and borehole. Personally i felt for the slight extra premium i was getting a more tested technology, was slightly more efficient, more proven over a lifetime and easier to manage.
    We have no access to natural gas and consumer gas would not have a patch on geo. Even if i did have access to natural gas, i would have serious reservations and i would guess that heat pump would still prove to be more cost effective over its lifetime.
    A big attraction to the heat pump is also the idea of being totally energy dependent at some stage. I researched PV panels etc but i just couldnt make the numbers work. I am hoping that more items like tesla powerwall come where i would shift to night rate and use the powerwall be my source for daytime power. I have no doubt that PV will come down in price and within the next 5 years or so it may be an investment i will be making.


  • Registered Users Posts: 3,903 ✭✭✭ zulutango


    hi Matrat,

    This is great info, thanks for posting. A few questions ...

    1. Can you give any insight into the capital costs of the heat pump versus a standard oil boiler installation?

    2. Presumably you have underfloor heating through the house?

    3. What air tightness did the house achieve when you had it tested?

    Thanks!


  • Registered Users Posts: 152 ✭✭ matrat


    Hi zulutango,

    1:My site is covered in old trees so the idea of having to dig that up to lay pipework was never that appealing. Given that vertical borehole are proven to be more efficient and the cost to dig around trees etc, we went with borehole. Was 3850e. The supply, fitting and commission of heatpump and underfloor was 16.5k.
    The quotes i got for an oil boiler, oil tank, boiler stove, stove box, all associated rads, pumps, valves etc. all supplied and fitted with first fill of oil was around 15k.

    2: Yes, underfloor to whole house. It is essential for this type of system. I labored to the installer for two days to do the whole house. A simple process. I would imagine for the small amount of euros people save by using alu rads upstairs only for example, would be offset by the higher running costs or more unstable temps.

    3: No problem. As i was the first new house the insulation installer completed with the cavity insulation, part of the deal was that the house would be air pressure tested (at his expense) before final payment to confirm its results. The magic number agreed upon was 3m3/hm2 which i thought was ambitious ha. The test was done with no internal plaster or floor, no tape on windows, a big sponge up the chimney, and a few crudely placed pieces of plastic under external doors. The result came in at 5.1 which i was quietly impressed with given the level of "sealing" at the above areas. We shook hands on me buying the materials to tape all windows and doors out of final payment and i did the work myself. As to what it is at now after tape, plaster, floors etc. i would guess maybe 3 but really have no idea. I am happy enough it is to the level that i am getting good use and need for the mhrv so i am happy enough. And given the fact we see literally no bugs in the house i am assuming it is fairly well sealed.


  • Registered Users Posts: 3,903 ✭✭✭ zulutango


    Excellent, thanks!

    A few more questions ..

    4. Was there any issue with having underfloor heating upstairs, i.e. structural floors were necessary? What depth of screed?

    5. Do you have an idea of the u-values for walls and windows?

    You seem to have done it all very well. Well done!


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  • Registered Users Posts: 152 ✭✭ matrat


    Hi zulutango,

    4: We have used concrete slabs at first floor level so we had no issues with anything structural. I went with 130mm insulation on ground (made up of a 70mm + 60mm) and a 70mm screed. Upstairs was 60mm insulation with 70mm screed. I was 50/50 about using insulation upstairs but we used a solid slab which would soak up plenty of heat and kept the "insulation will pay for itself" moto in my head! I have read of people who have used a thin screed or "in-joist" system on timber constructed first floors but we wanted to go slab for noise etc. so i didn't look much into it.

    5: My downstairs wall uvalue would be made of skim, scratch, 100mm block, 60mm foil back board, 40mm icynene, blcok, plaster. Upstairs be same except no foil back and 100mm icynene. Im sure somebody smarter than me could figure that out. Woindows are munster joinery passive, somewhere around 0.6/0.7.

    As far as doing it well, i set out to achieve as good of results for what my budget allowed. My budget by no means was big either, and my current unfinished house reflects that but to me it is more important to do things right and let the rest come as it does. The way i seen it my time was free so i did as much research as i could. My personal experience is that the vast majority of tradesmen in this country have no interest in evolving, make things as easy as they can for themselves and take no pride that they are involved in building somebody's home. As such i used as little tradesmen as i physically could, and the ones i picked met my specific needs. As far as shops and retailers, building, plumbing, electrical merchants etc., very early on in the project i realized that if didnt undertake all research and find what was best for myself, then i would be subject to their advice, which 99% of the time is rubbish. I live in a town with 2 large builders merchants. I ended up only working with one man out of around 30 staff between the two places. I have since found out he self built, so no surprise there. Also, the prices can be crazy. I priced a local glass company to make a shower panel, i got a custom made panel, a toilet and a set of taps from a supplier in another country for the price they quoted me for the panel alone!


  • Registered Users Posts: 19,025 ✭✭✭✭ Water John


    Matrat, I'll go back and read this thread a second time, it's very good.
    I agree with the borehole. I would prefer to ground collector which can be variable with our type of subsoil.
    Many do use Alu rads upstairs. The bedrooms in these good new builds need little heat. Even though I sold UFH, my boss nor I ever pushed people to use it upstairs.
    Using spreader metal panels on timber joists to conduct the heat can be expensive.


  • Registered Users Posts: 152 ✭✭ matrat


    Hi Water John,

    Yeah i agree the smaller heat demand of highly insulated houses means there is less difference. However i still find the ufh to be the most efficient and the alu rads are purely a cost saving exercise. It was worth more to me to sacrifice other areas of the build.
    And yes i would imagine that using ufh on joist construction could be costly but it is an option. We were sold on slabs for several reasons, noise, having block walls upstairs, walk in showers etc. and the fact we could use ufh, was a no brainer for our needs.


  • Registered Users Posts: 1,504 BarneyMc


    Can I ask what temperature is your UFH water (leaving the HP) set to?


  • Registered Users Posts: 152 ✭✭ matrat


    BarneyMc wrote: »
    Can I ask what temperature is your UFH water (leaving the HP) set to?

    Hi Barney,

    That is actually something i have being meaning to do now for some time is plot the heat curve to determine that. I haven't played much with any of the settings as it has worked so well out of the box. But i do want to get a better understanding of the process so as i say it is something i intend to start recording.

    Just checked the machine and is reading the following setings for the curve;
    Heat Curve = 29 deg
    Min = 15 deg
    Max = 55 deg

    I don't have any of the adjustments set and heat stop is 17 deg.

    Temperatures read;
    Outdoor = 5 deg
    Supply line = 27(30) deg
    Return line = 26(55) deg
    Hot water = 51 deg
    Integral = -6
    Brine In = 6 deg
    Brine Out = 6 deg

    With the supply and return so close, naturally the machine is not on at present. I don't know what the numbers in the brackets represent so if anyone could shed any light on that, would be much appreciated.

    Kind regards
    Shaun


  • Registered Users Posts: 1,504 BarneyMc


    So it looks like your water is supplied at 27C? Mine has just been commissioned and is set to 37C. I have an almost passive house and quite a lot of thermal mass and think it's set too high. My thinking is that it should run at a low temp and for longer periods rather than short periods of relatively high temps?


  • Registered Users Posts: 19,025 ✭✭✭✭ Water John


    Congrats to the new build Barney. Someone supplying and fitting HP may answer you better.
    With mixer systems for high heat sources eg oil, we used set the mixer manifold to 40 C. At that floor temp could be about 28 C.
    The lower the output heat from the HP, the more efficient it will be in COP.

    Before people used 75mm screed for UFH. Others now, use 150mm. If that is the mass, you could certainly use night rate mostly on it. that would be your best saving.


  • Registered Users Posts: 520 ✭✭✭ Shaunoc


    My danfoss A2W HP reads at
    Outdoor = 5 deg
    Supply line = 24(26) deg
    Return line = 24(55) deg
    Hot water = 51 deg
    Integral = +2


  • Registered Users Posts: 1,504 BarneyMc


    Water John wrote: »
    Congrats to the new build Barney. Someone supplying and fitting HP may answer you better.
    With mixer systems for high heat sources eg oil, we used set the mixer manifold to 40 C. At that floor temp could be about 28 C.
    The lower the output heat from the HP, the more efficient it will be in COP.

    Before people used 75mm screed for UFH. Others now, use 150mm. If that is the mass, you could certainly use night rate mostly on it. that would be your best saving.

    Thanks John. I have an A2W HP and 55mm liquid screed floors but solid 6 inch block walls. The house retains the heat really well albeit not in the floor. Does the 37C water temp seem a bit high? I would like a slow gradual heat up of the house during the night and a low water temp is my guess to a longer compressor life and better running costs.


  • Registered Users Posts: 152 ✭✭ matrat


    BarneyMc wrote: »
    So it looks like your water is supplied at 27C? Mine has just been commissioned and is set to 37C. I have an almost passive house and quite a lot of thermal mass and think it's set too high. My thinking is that it should run at a low temp and for longer periods rather than short periods of relatively high temps?

    Hi Barney,

    This does not match my understanding. My system is geothermal and the Danfoss book stated that you should start the heat curve at 40 deg and adjust over time from there. My installer set my heat curve to 27 deg when we moved in but as with most men, i was quickly advised (by the wife) that wasn't warm enough so it was dutifully turned up. When turned on first the machine was set at 20 deg i think and i turned it up by 1 deg a week to dry the place out. I think the highest it ever got was 34 and it only lasted there for a few days as my dad came down to help paint one evening and had to be taken outside to cool off after a half hour painting.

    My understanding in basic turns about the heat curve is that mine is set to 29 deg. What this means is that at 0 deg outside, that is the floor temperature the machine has being told is required. The curve is a line plotted for outside temperature against the floor temperature supplied by the machine. Every degree below 0 deg is plotted to a higher temperature than 29 deg, every degree above 0 deg is plotted to a lower temperature than 29 deg. That is why when outside temperature is 5 deg, the machine is happy with the water temp returning to the machine being 26 deg and not coming on to increase this. The curves are i assume designed fir each machine and u can adjust them at + & - 5 deg from zero, but i have never needed too.

    All of this is separate to the domestic water on my machine. The machine heats the volume of water, i think its 180l, in its internal tank to a set temperature, i think it might be set at 54 deg. Then when it reaches its lower setting, i think its 44 deg, the machine comes in to bring it back up to temp again. I don't know the mechanics of how this all works but i know from Danfoss that time spent heating the domestic water uses more kw/h then for floor heating and thats why they are recorded separate.

    I am not sure if this is even relevant to your machine but this is the explanation i got from my installer but i would agree, it would be best to get your own installers input or contact the manufacturer direct for their input also. I dont believe too much information ever killed anyone!!


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  • Registered Users Posts: 152 ✭✭ matrat


    BarneyMc wrote: »
    Thanks John. I have an A2W HP and 55mm liquid screed floors but solid 6 inch block walls. The house retains the heat really well albeit not in the floor. Does the 37C water temp seem a bit high? I would like a slow gradual heat up of the house during the night and a low water temp is my guess to a longer compressor life and better running costs.

    Hi again Barney,

    Do you mind if i ask what way you are running your machine? I assume when you say "a slow gradual heat up of the house during the night" that you are running a on-off approach? How do you find it?

    I was tempted by this but couldn't find any documentation of someone who had tried both ways to see how much, if anything, could be saved. And with being at home during the day i didn't want to be in a position of a possible temp drop and having to wait until evening/night to bring it back up. Be very interested to hear others experience with it though.


  • Registered Users Posts: 19,025 ✭✭✭✭ Water John


    55mm is pretty near a low one would go with screed.That means you haven't a great mass for heating.
    The solid blocks walls are secondary and I presume the floor is isolated from them with no heat bridge between the two. The walls will help the rooms to not drop temp quickly.
    You really cannot use night rate as a main source of heat in this case without having a large insulated storage tank.

    I think usually their is a secondary scroll to take the temp higher for the hot water. Any extracting of higher temp by heat pump it becomes much less efficient.
    The only major use of hot water are showers. Would an electric shower be more economical?

    Your looking to have rooms and open areas at 18 C air temp, with 21 C preferred for living area. Id assess the system in reverse from these targets.


  • Registered Users Posts: 1,504 BarneyMc


    matrat wrote: »
    Hi again Barney,

    Do you mind if i ask what way you are running your machine? I assume when you say "a slow gradual heat up of the house during the night" that you are running a on-off approach? How do you find it?

    I was tempted by this but couldn't find any documentation of someone who had tried both ways to see how much, if anything, could be saved. And with being at home during the day i didn't want to be in a position of a possible temp drop and having to wait until evening/night to bring it back up. Be very interested to hear others experience with it though.

    Just started playing with it but my installer just said to let it regulate itself - i.e. let the stats work away. I suppose I ought to go with this for a while and see how it goes. If I run it at night the heat drop during the day is next to nothing so it is tempting also.


  • Registered Users Posts: 19,025 ✭✭✭✭ Water John


    Many just leave them on, especially if you have programmable thermostats, so you can set a lower temp during the day.
    At 55mm, the pick up for the evening would take relatively little time.
    Worth trying for a month and seeing running cost.


  • Registered Users Posts: 18,884 ✭✭✭✭ murphaph


    BarneyMc wrote: »
    So it looks like your water is supplied at 27C? Mine has just been commissioned and is set to 37C. I have an almost passive house and quite a lot of thermal mass and think it's set too high. My thinking is that it should run at a low temp and for longer periods rather than short periods of relatively high temps?
    Barney, the supply line temp is not set to anything. It's a function of the outside temp and heat curve. The colder it is outside, the higher the flow temp should be.

    However, 37 is pretty high unless it was very cold when you checked that as IIRC you had very good airtightness and I assume U-values.

    Right now (I have the online module installed so can check from work lol) our outside temp is 3°C and the flow temp is 23 with room temps of an average 20.5°C.

    For info: I do NOT use the room stats at all. They are all "wide open" (and I will decommission them in time but they were required for the "BER" here) and I regulate house temp entirely via the heat curve on the heat pump and 2 auxilliary towel heaters/rads in bathrooms where you are wet/naked and need the extra 3 degrees to make it comfortable but I don't want to jack up the flow temp in the whole system for a few mins a day in one/two rooms where you're bathing/showering. It's more efficient to have a towel rack come on in the mornings on a timer for that little boost.

    I leave the HP on permanently during the heating season. This topic gets debated to death on German forums and there is never a clear winner where the house is "well insulated with UFH", so I just go for the most comfortable option which is (for us) constant temps throughout the house.


  • Registered Users Posts: 19,025 ✭✭✭✭ Water John


    The stats in rooms are as much about them getting too warm as anything.
    Open areas of the house 18 C. Depending on personal pref bedroom can have set back to about 16 C. Living area 21 C. And agree with you bathroom needs to be about 23 C.
    Since the stats are there, I would set back all the house at night eg from 10 pm until 6 am a few degrees.


  • Registered Users Posts: 18,884 ✭✭✭✭ murphaph


    Personally I think room stats with UFH are largely a complete waste as the reaction time is so slow. You turn the stat down and it closes the valve to that room but the result is felt hours later as the slab has so much latent energy. Worse in the morning when you get up and turn the stat up you'll be out and gone to work and having your lunch before the room is up to the temp you wanted. You could factor in an offset I suppose once you figure out the reaction time but this is not the path I've chosen to go down. Each to his own however.

    I honestly think you need to set the temps you are happy with (preferably hydraulically by balancing the system rather than closing off the flow to a room periodically as happens with room stats) and then control the entire house with the heat curve.

    At the end of the day the slow response time of UFH is the main (only?) disadvantage of the system compared to high flow temp boilers and rads which respond very quickly to demand. I would still choose UFH over boiler + rads any day though. The even heat it delivers is phenomenal. I'm constantly amazed that when I come into the house it feels toasty warm but I cannot tell where the heat is coming from. The floor is not even luke warm to the touch.

    We achieved a "natural set back" in the bedrooms by installing carpet there. It obviously acts against the UFH and insulates it more than the rest of the house (tiles) so I didn't need to do anything there.


  • Registered Users Posts: 152 ✭✭ matrat


    murphaph wrote: »
    Barney, the supply line temp is not set to anything. It's a function of the outside temp and heat curve. The colder it is outside, the higher the flow temp should be.

    However, 37 is pretty high unless it was very cold when you checked that as IIRC you had very good airtightness and I assume U-values.

    Right now (I have the online module installed so can check from work lol) our outside temp is 3°C and the flow temp is 23 with room temps of an average 20.5°C.

    For info: I do NOT use the room stats at all. They are all "wide open" (and I will decommission them in time but they were required for the "BER" here) and I regulate house temp entirely via the heat curve on the heat pump and 2 auxilliary towel heaters/rads in bathrooms where you are wet/naked and need the extra 3 degrees to make it comfortable but I don't want to jack up the flow temp in the whole system for a few mins a day in one/two rooms where you're bathing/showering. It's more efficient to have a towel rack come on in the mornings on a timer for that little boost.

    I leave the HP on permanently during the heating season. This topic gets debated to death on German forums and there is never a clear winner where the house is "well insulated with UFH", so I just go for the most comfortable option which is (for us) constant temps throughout the house.

    This is my understanding too and based on my setup, 37 deg would be very high for me too.

    I have a slightly different setup, i have stats placed in each bedroom. Each of these are set to 21 deg. and work off the manifold and do not in any way communicate with the machine. All other areas, kitchen, living, bathrooms, halls etc. are on an uncontrolled loop. This way they can be slightly higher than the rooms, and the stats stop the rooms over heating as much as possible. I also leave the system on full time to regulate itself. I find this the most convenient setup and is very comfortable to live with.

    I was suspicious of my setup at the start as i felt with the open loops adjoined to the controlled loops, the heat in the open loop would just soak into the closed loop even if it was closed and render the stat essentially useless but in reality i dont find that to be the case. My bedroom is upstairs and in the early hours of the morning at this time of year i do find it ever so slightly cooler than the open loop downstairs. And by cooler i mean that it isnt uncomfortable to wear a jumper. The opposite may be true during the day but i dont be in bed to notice :p

    I am also always surprised to hear people turn off their machines in the summer. I do not know of any way to heat all domestic water cheaper than the unit does when you include total cost.


  • Registered Users Posts: 152 ✭✭ matrat


    murphaph wrote: »
    Personally I think room stats with UFH are largely a complete waste as the reaction time is so slow. You turn the stat down and it closes the valve to that room but the result is felt hours later as the slab has so much latent energy. Worse in the morning when you get up and turn the stat up you'll be out and gone to work and having your lunch before the room is up to the temp you wanted. You could factor in an offset I suppose once you figure out the reaction time but this is not the path I've chosen to go down. Each to his own however.

    I honestly think you need to set the temps you are happy with (preferably hydraulically by balancing the system rather than closing off the flow to a room periodically as happens with room stats) and then control the entire house with the heat curve.

    At the end of the day the slow response time of UFH is the main (only?) disadvantage of the system compared to high flow temp boilers and rads which respond very quickly to demand. I would still choose UFH over boiler + rads any day though. The even heat it delivers is phenomenal. I'm constantly amazed that when I come into the house it feels toasty warm but I cannot tell where the heat is coming from. The floor is not even luke warm to the touch.

    We achieved a "natural set back" in the bedrooms by installing carpet there. It obviously acts against the UFH and insulates it more than the rest of the house (tiles) so I didn't need to do anything there.

    I agreed with you originally but i am glad that i didnt go that route. The stats just give enough control to have the bedrooms slightly cooler than the main areas. And it is very possible that this just happens to be during the night and by the time i get up in the morning, the whole house has become balanced and the stats are redundant. But to have it cooler just when going to bed and getting to sleep then it is worth it for me. Given how warm my wife likes the main areas of the house, i am glad we have this control. If i built the house as a single man, would have being one zone and no stats. O what a life i could have had!!!!

    Great to hear also you have used carpet and dont find any real notice other than slower reaction. Did you got for one with a low TOG or was that a factor? We have went with laminate floors over tiles in most areas as was a bit scared of carpet having an impact but the stairs are to be carpeted and i always hated the idea of carpet stairs meeting laminate on the landing so maybe it may be a solution to carpet the landing also. As you say, the carpet slows the heat but to my understanding it doesnt use the heat if that makes sense, so yes you need to generate more heat to come through the carpet but it will eventually all end up coming through the carpet or back into the floor so isnt like its wasted as such!


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  • Registered Users Posts: 19,025 ✭✭✭✭ Water John


    Murph, you need programmable stats. Come on higher, 1/2 hours before you get up.
    Matrat, your very comfy at 21 C in bedrooms. I would find that uncomfortable.


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