JohnW

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About JohnW

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  1. JohnW

    UFH loop design help

    I've been wrestling with Loopcad for sometime now and am loosing the will to live. I take 1 step forward only to follow it with 2 steps back!! Are there any kind souls out there who are proficient in using Loopcad who could help with my loop design for the ground floor and save me from tearing the rest of my hair out? I'm trying to use spiral counter-flow where possible. Here are 2 versions of the GF plan, one with dimensions and one without.
  2. I plan to use electric UFH in my first floor bathrooms. They will have the following buildup; Tile Electric UFH 75mm sand & cement screed 50mm insulation 150mm hollow core slab We also have towel radiators which will provide the majority of heat and we plan to use the UFH to warm the tiles for comfort. Presumably some of the heat generated will head down into the screed rather than up into the tiles above. Should I put anything between the screed and the UFH to force the heat up and if so, what?
  3. @Alphonsox are you happy with your Warmstar electric UFH? Would you recommend it?
  4. JohnW

    Radiator sizing

    Thanks @PeterW are you suggesting I use the spreadsheet to calculate the whole house heat loss and then if a rooms volume is 10% of the whole house volume then the heat loss for that room will be 10% of the total heat loss?
  5. JohnW

    Radiator sizing

    Just trying to resurrect this thread - I can't find an online radiator sizing calculator that accounts for triple glazed windows or really well insulated walls, floors & roof. Does anyone know of a reliable one that does?
  6. Hi We have been asked if we would consider using "Thermal Bead Screed" on the ground floor, it's an Italian product, real name Politerm Blu 110. It appears to be a lightweight screed with insulation beads used as aggregate. My original ground floor build-up gives me a respectable U-Value of 0.14 and is as follows; 100mm Sand & cement screed with UFH pipes embedded 3mm Polythene 125mm Thermafloor TF70 insulation boards with hot & cold water pipes embedded 3mm Raydon barrier 150mm dense concrete sub-floor The key to reaching the U-Value of 0.14 is that the boards are installed correctly without gaps or voids. The "Thermal Bead Screed" approach appears to remove the risk of gaps & voids and the floor build-up is as follows; 50mm Liquid Hemihydrate screed with UFH pipes embedded 3mm Polythene 175mm "Thermal Bead Screed" with hot & cold water pipes embedded 3mm Raydon barrier 150mm dense concrete sub-floor This won't give me as good a U-Value, I've been told 0.16 by the company selling it to me and 0.18 by an independent energy assessor. Have any of you used "Thermal Bead Screed" or know anything about it?
  7. JohnW

    Importing lights from China

    @Dudda Can you tell me where you sourced the replicas from please?
  8. Thanks @JSHarris - I've been playing with your fabulous spreadsheet (never thought I'd ever use those 2 words together) for some time now and it appears that changing the floor U-Value doesn't have a very big impact on the overall results. I tried Floor U-Values of 0.14, 0.18 and a Regs matching 0.25 for comparison and the results are shown below; What surprised me most, apart from the low values, was that the adjusted July & August figures appear to show the house over-heating more with a U-value of 0.25 than at 0.14 or 0.18. Can you confirm that this is what you would expect?
  9. I know the lower U-value I achieve for my ground floor the better but is there a maximum U-value beyond which under floor heating is not advisable?
  10. Thanks all for the explanations. I think I now understand that the P/A ratio has an impact on the overall U-Value and it sounds like potentially a negative impact in many cases. How does the P/A ratio take into consideration the fact that all our external walls have thermal blocks for the first 2 courses and 25mm insulation to mitigate horizontal thermal transfer? In my example, I know the P/A Ratio and the U-Value of the floor build-up but I would really like to know how the P/A Ratio reduced our overall floor U-Value from 0.17 to 0.14. It seems to me that there are many variables at play e.g. soil type, which could allow a more cynical person than me to achieve whatever result they want by simply tweaking those variables.
  11. Hi I think I understand how U-Values are calculated e.g. (Layer thickness) X Lambda = R in m2 K/W Add up all the R-values for each of the layers and 1/(Total R-Value) = U-Value in W/m2 K However if you look at the calculations from my "As-designed" SAP 2009 report below, the calculated Total R-Value = 5.844 m2 K/W and if you take the inverse of that the U-Value is 1/5.844 = 0.171 W/m2 K and not the 0.14 shown on the report below. Can anyone please explain how the 0.14 was achieved...what am I missing??? Thanks
  12. JohnW

    WiFi standards change name.

    Makes it a bit easier for consumers to follow and a bit harder for retailers to get rid of old stock.
  13. JohnW

    UFH upstairs - alternatives?

    Great - Thanks
  14. JohnW

    UFH upstairs - alternatives?

    @Alphonsox can you recommend a make of electric underfloor heating?
  15. Hi, I'm thinking of going with Rehau Total70C triple glazed uPVC windows, with a height of 1500mm. The documentation on the Rehau website suggests a maximum for side hung openings of 900x1500mm (WxH). I would be interested in hearing from anyone who has used these frames with 3G and a height of 1500mm and whether they have functioned properly in day to day use. Thanks