RMweb Premium Physicsman Posted February 18, 2015 Author RMweb Premium Share Posted February 18, 2015 Hi Jeff SORRY for hitting the LIKE button, I know how much you hate them. That flooring frame looks the dogs mate, Just a bit worried about the amount of weight your putting on the North of England, I think the South may be lifted out of the Solent at your rate. hahahaha You certainly made me laugh, Andy. With the number of screws and nails in the bunker I think the north magnetic pole has shifted position. And as for the weight - have you heard about the tsunami in the Channel tonight caused by my construction!? Jeff Link to post Share on other sites More sharing options...
RMweb Premium Physicsman Posted February 18, 2015 Author RMweb Premium Share Posted February 18, 2015 Hi Jeff hope all is well. The bunker is comming along at a fast rate lol. next there will be trains running Keep up the good work. Mark (grabbing a rest day again) Mark, you must be mistaking me for Andy. He has trains running BEFORE he's even started the layout!! Jeff Link to post Share on other sites More sharing options...
Andrew P Posted February 18, 2015 Share Posted February 18, 2015 Mark, you must be mistaking me for Andy. He has trains running BEFORE he's even started the layout!! Jeff That's EXLAX for you, ahhahah 1 Link to post Share on other sites More sharing options...
RMweb Premium Physicsman Posted February 19, 2015 Author RMweb Premium Share Posted February 19, 2015 Update: 3 floor frames now complete, just starting the fourth. I'm hoping to get the insulation in and the ply top down by noon tomorrow. That will be nearly half of the floor done - the rest can be looked at after the electrics are fitted on Saturday. Good fun! Jeff 4 Link to post Share on other sites More sharing options...
RMweb Premium Jason T Posted February 19, 2015 RMweb Premium Share Posted February 19, 2015 What are you like? I thought it was going to be a couple of weeks before you even started the floor and you're already a big chunk of the way through it. Jeff could build Rome in a day. Bodgit would like to but Dee would clip him round the ear for doing too much 1 Link to post Share on other sites More sharing options...
RMweb Premium Physicsman Posted February 19, 2015 Author RMweb Premium Share Posted February 19, 2015 What are you like? I thought it was going to be a couple of weeks before you even started the floor and you're already a big chunk of the way through it. Jeff could build Rome in a day. Bodgit would like to but Dee would clip him round the ear for doing too much Yep, what am I like? I've just knocked off for the day - I've met today's targets. Half the garage floor frames now in place and insulated. Ply top onto that half tomorrow morning. Then - shock horror - nothing more, floor-wise until Monday! Time for a shower - some pics later. Jeff 4 Link to post Share on other sites More sharing options...
runs as required Posted February 19, 2015 Share Posted February 19, 2015 I've just dipped in and enjoyed skimming through the last few pages about all the industry in your garage over the past few pages. Can I ask about the flooring? Is there a reason for the substantial framed up timber panels laid over the slab that are to bear the ply flooring? Do I assume there are going to be complex wiring looms running through the floor that will require the floor to be lifted from time to time for revisions? I was comparing it the relatively straightforward replacement of a beaten earth floor to the kitchen in our old house a few years back. Our spec was polythene dpc,then 100mm thick insulation, 150mm poured conc slab - then after a 30 day curing/drying period, an underlay and a floated hardwood floor over the top. This has proved a lot warmer than the old beaten earth, looked good and has worn well over the nearly 10 years it has been down. But the drawback is that you can only run wiring and other services around the perimeter. [An early job of mine was a university library - returning to it a few years back, the young librarian bullocked me for failing, in the early 1960s, to specify a computer wiring sub floor!] best wishes dh 4 Link to post Share on other sites More sharing options...
RMweb Premium Physicsman Posted February 19, 2015 Author RMweb Premium Share Posted February 19, 2015 Just re-sized a few pics from earlier today. I'll do a few more later. Frame 3 under construction / frame 3 fixed in place / frame 4 fixed in place... Jeff 7 Link to post Share on other sites More sharing options...
RMweb Premium Physicsman Posted February 19, 2015 Author RMweb Premium Share Posted February 19, 2015 I've just dipped in and enjoyed skimming through the last few pages about all the industry in your garage over the past few pages. Can I ask about the flooring? Is there a reason for the substantial framed up timber panels laid over the slab that are to bear the ply flooring? Do I assume there are going to be complex wiring looms running through the floor that will require the floor to be lifted from time to time for revisions? I was comparing it the relatively straightforward replacement of a beaten earth floor to the kitchen in our old house a few years back. Our spec was polythene dpc,then 100mm thick insulation, 150mm poured conc slab - then after a 30 day curing/drying period, an underlay and a floated hardwood floor over the top. This has proved a lot warmer than the old beaten earth, looked good and has worn well over the nearly 10 years it has been down. But the drawback is that you can only run wiring and other services around the perimeter. [An early job of mine was a university library - returning to it a few years back, the young librarian bullocked me for failing, in the early 1960s, to specify a computer wiring sub floor!] best wishes dh Not sure if that's a tongue-in-cheek question, rhetorical statement or a straight question! The simple answer is, no, no lifting of floors for wiring looms. I'm acutely aware of the tendency of plywood to sag if not given adequate support. So I'm taking no chances here, as once it's down it's down! And given my liking for playing with wood, what else could I do? Thanks Mike (and others) for suggesting I insulate the floor! Jeff 3 Link to post Share on other sites More sharing options...
Andrew P Posted February 19, 2015 Share Posted February 19, 2015 Flooring's looking good Jeff, not to long now, I think your ahead of your schedule mate. Link to post Share on other sites More sharing options...
RMweb Premium Physicsman Posted February 19, 2015 Author RMweb Premium Share Posted February 19, 2015 (edited) Flooring's looking good Jeff, not to long now, I think your ahead of your schedule mate. Thanks, Andy. I think you're correct about the schedule, though that may go by the wayside once the garden work starts - probably in a week or two. Here is another batch of today's pics, showing the state of the insulation - nearly all done for these frames. Jeff Edited February 19, 2015 by Physicsman 10 Link to post Share on other sites More sharing options...
emt_911 Posted February 19, 2015 Share Posted February 19, 2015 Progressing well, although I have to agree with Jason. At this rate the bunker will be bullet proof, bomb proof and temperature proof in the next couple of weeks. 1 Link to post Share on other sites More sharing options...
RMweb Gold Anotheran Posted February 20, 2015 RMweb Gold Share Posted February 20, 2015 If the thermal conductivity of PIR is approx 0.023 W / m.K and that of wood approx 0.14 W / m.K what percentage of heat loss through the floor is via the frame? For a bonus mark... if the thermal conductivity of air at sea level is 0.024 W / m.K what difference will the air gap between the PIR and the plywood make to the tractive effort of a 4mm scale 4F? 1 Link to post Share on other sites More sharing options...
Killybegs Posted February 20, 2015 Share Posted February 20, 2015 It's looking so cosy out in the garage that I can see you moving in there and putting the railway in the house! Link to post Share on other sites More sharing options...
RMweb Premium Physicsman Posted February 20, 2015 Author RMweb Premium Share Posted February 20, 2015 If the thermal conductivity of PIR is approx 0.023 W / m.K and that of wood approx 0.14 W / m.K what percentage of heat loss through the floor is via the frame? For a bonus mark... if the thermal conductivity of air at sea level is 0.024 W / m.K what difference will the air gap between the PIR and the plywood make to the tractive effort of a 4mm scale 4F? Neil, you really shouldn't pose such questions as I can't leave them alone! Given the thermal conductivity values (in Wm-1K-1) of air/PIR and wood (pine) of: 0.024 / 0.022 / 0.12, respectively.... I estimate the area of heat flow to be in the ratio Air 0.73: PIR 0.73: Wood 0.27 (area of trapped air is same as PIR as it sits on top of it). Thickness in the frames: Air 2cm, PIR 7.5cm, Wood 10cm Assuming the Temperature differential is the same across the wood as for the (PIR + trapped air combination)... Giving a heat flow ratio through the Wood and (PIR + Air) combination of nearly 2:1 So, I estimate about 67% of heat is transferred through the frames. All my estimates were done on a bit of paper without a calculator, so apologies if there's a factor of ten - or more! - error in there, somewhere!! Jeff Link to post Share on other sites More sharing options...
RMweb Premium Physicsman Posted February 20, 2015 Author RMweb Premium Share Posted February 20, 2015 It's looking so cosy out in the garage that I can see you moving in there and putting the railway in the house! John, I'm hoping it'll look cosy once it's finished and the "rubbish" in the bunker is rearranged. It's noticeably warmer in there!! The house "takeover" comes later! Jeff 3 Link to post Share on other sites More sharing options...
RMweb Gold Anotheran Posted February 20, 2015 RMweb Gold Share Posted February 20, 2015 (edited) Neil, you really shouldn't pose such questions as I can't leave them alone! Given the thermal conductivity values (in Wm-1K-1) of air/PIR and wood (pine) of: 0.024 / 0.022 / 0.12, respectively.... I estimate the area of heat flow to be in the ratio Air 0.73: PIR 0.73: Wood 0.27 (area of trapped air is same as PIR as it sits on top of it). Thickness in the frames: Air 2cm, PIR 7.5cm, Wood 10cm Assuming the Temperature differential is the same across the wood as for the (PIR + trapped air combination)... Giving a heat flow ratio through the Wood and (PIR + Air) combination of nearly 2:1 So, I estimate about 67% of heat is transferred through the frames. All my estimates were done on a bit of paper without a calculator, so apologies if there's a factor of ten - or more! - error in there, somewhere!! I knew you'd bite That sounds close enough for a physicist... when I studied it I always worked on the basis that physics is correct if it's within a factor of 10! Engineers can keep their super accuracy... of course now that we're model engineers that physics mindset may explain why my OO gauge loco won't run well on my O gauge tracks I have to admit my workings were even more back of an envelope. In fact I deliberately rounded my ratios to figures that meant I could do them in my head: PIR and air have about the same value for thermal conductivity, which is almost exactly five times that of the wood. I assumed that the concrete and ply top were level so that the PIR/air layer would be the same depth as the wood layer, so 1:1 there. Not being able to measure I made a guess that the wood was about one fifth of the floor area (as a fifth made the maths easy!) I multiplied my fifth by my five and got 1. So I ended up with 50%! I suspect that your knowledge of the ratio of areas of the wood to PIR make your 67% more accurate! Nothing better that a bit of back of the envelope physics in the morning Neil Edited to add that I have made no allowance for heat transfer between the PIR/air and the wood. ie all heat transfer is perpendiclar to the floor. And I don't intend to make any such allowance! Edited February 20, 2015 by Anotheran 7 Link to post Share on other sites More sharing options...
RMweb Gold ChrisN Posted February 20, 2015 RMweb Gold Share Posted February 20, 2015 It is interesting as a physicist I tend to do things more accurately than my wife who trained as a chemical engineer. 3 Link to post Share on other sites More sharing options...
RMweb Gold Anotheran Posted February 20, 2015 RMweb Gold Share Posted February 20, 2015 It is interesting as a physicist I tend to do things more accurately than my wife who trained as a chemical engineer. Maybe it's the fact that my degree was astrophysics then... a few light years here and there don't make much of a difference to most distances, and a few million years here and there make little difference to most time scales. As long as we can pick it all up at 21cm wavelength of course! Sorry Jeff, I've taken your thread right off topic again. 4 Link to post Share on other sites More sharing options...
RMweb Premium Physicsman Posted February 20, 2015 Author RMweb Premium Share Posted February 20, 2015 Maybe it's the fact that my degree was astrophysics then... a few light years here and there don't make much of a difference to most distances, and a few million years here and there make little difference to most time scales. As long as we can pick it all up at 21cm wavelength of course! Sorry Jeff, I've taken your thread right off topic again. Neil, you've gone up even further in my estimation! My degree was Physics, but my obsession was astronomy. So I took as many of the optional Astrophysics courses as I could manage. I was offered an astrophysics-related PhD in cosmic rays, but turned it down for a nuclear physics based one - though still close enough to astrophysics as I could make it! We have Chris as a nuclear physicist and Jock has a keen interest in Thermodynamics - as do I. Your comments aren't at all off topic. I couldn't resist a quick scribble estimate and, like you, I played off the area and thermal conductivity factors. Good fun! Back to reality, I type this with a couple of embedded splinters in my thumb. I'm laying the ply tops. Now I wonder what effect the number of screws I fix the ply down with has on the heat transfer? Jeff 5 Link to post Share on other sites More sharing options...
RMweb Gold Anotheran Posted February 20, 2015 RMweb Gold Share Posted February 20, 2015 (edited) Neil, you've gone up even further in my estimation! My degree was Physics, but my obsession was astronomy. So I took as many of the optional Astrophysics courses as I could manage. I was offered an astrophysics-related PhD in cosmic rays, but turned it down for a nuclear physics based one - though still close enough to astrophysics as I could make it! We have Chris as a nuclear physicist and Jock has a keen interest in Thermodynamics - as do I. Your comments aren't at all off topic. I couldn't resist a quick scribble estimate and, like you, I played off the area and thermal conductivity factors. Good fun! Back to reality, I type this with a couple of embedded splinters in my thumb. I'm laying the ply tops. Now I wonder what effect the number of screws I fix the ply down with has on the heat transfer? Jeff I'm not sure I should go up in your estimation for that, especially in the company of nuclear and thermodynamics. That's the sort of physics I always struggled with, the small stuff (not that thermodynamics can be really called small, but it's the effects of the small on the large). So I went for the other end. As I said, millions of years, thousands of light years, you can't go far wrong with those! Sorry to hear about your thumb... but as flesh has a thermal conductivity of about three times that of wood the splinters should help you not loose too much body heat from your fingers As for the screws. Well if you're using 20 per sheet of 8 x 4 your ratio of screws to floor area is still about 25000 to 1. So even with steel conducting heat at 300 times the rate of wood I think your screws are only going to conduct just over 1% of your total heat loss... and that was if they went right through the wood, which as you explained, they wont' because of the DPC In all seriousness though. I am really liking the progress of the bunker. I still have a full garage and modelling is done in the office/train room. But I do want to get the extra space that the garage will give me. So this summer is a mass clear-out of boxes and I think I'll follow suit with your insulation methods. Edited February 20, 2015 by Anotheran 5 Link to post Share on other sites More sharing options...
RMweb Gold Anotheran Posted February 20, 2015 RMweb Gold Share Posted February 20, 2015 My degree was Physics, but my obsession was astronomy. So I took as many of the optional Astrophysics courses as I could manage. I was really lucky on two counts. I went to Queen Mary College in London. We had a modular degree that enabled me to take pretty much one third physics, one third astronomy and one third astrophysics. So at the end, as a result of doing the compulsory ones for all three and having enough total modules for all three I was allowed to select my degree title from Physics and Astronomy, Physics and Astrophysics or Astronomy and Astrophysics! The biggest stroke of luck (which I wasn't aware of until I got there) was the fact that my Planetary Astronomy module was taught by a guest lecturer who travelled up from Selsey to do the lectures 4 Link to post Share on other sites More sharing options...
Jock67B Posted February 20, 2015 Share Posted February 20, 2015 Afternoon all, I have to confess that I'm a bit concerned about the lack of an allowance for the thermal conductivity of the floor covering material as the properties of that could have a profound effect on the final total, and then there is the difference in ambient temperature of the ground below as the seasons change, as well as the air-space above - at this rate we could end up with an equation that looks as complex as Bernoulli's theorem!! Hope the splinters come out clean Jeff, don't forget the antiseptic! Kind regards, Jock. 3 Link to post Share on other sites More sharing options...
RMweb Gold ChrisN Posted February 20, 2015 RMweb Gold Share Posted February 20, 2015 Neil, My nuclear physics is the macro stuff, i.e. what is its half life and what does it emit, so you need not worry. The most complicated equation I use is the decay equation, although I did do a simultaneous equation for three isotopes. Not difficult? Three isotopes, three half lives, three different currents. No not conceptually difficult just that you could not afford to make a mistake as the algebra was long and complicated. Back to the floor. Will not the air come up to room temperature given the insulating material under it, where the wooden frame will always have a temperature gradient over it? Will you be able to feel the temperature difference through the ply? Splinters. Make sure it all comes out as ply splinters are not nice. 2 Link to post Share on other sites More sharing options...
RMweb Gold Anotheran Posted February 20, 2015 RMweb Gold Share Posted February 20, 2015 (edited) I have to confess that I'm a bit concerned about the lack of an allowance for the thermal conductivity of the floor covering material as the properties of that could have a profound effect on the final total, and then there is the difference in ambient temperature of the ground below as the seasons change, as well as the air-space above - at this rate we could end up with an equation that looks as complex as Bernoulli's theorem!! You see what I mean! Detail, detail, detail The floor covering is the same under wood and PIR... so I ignored it (though admit that it may interact with the PIR or wood in a way to make it more complex, but if it's more complex, I ignored it!) The ambient temperatures of ground and air space... I phrased the question as ratios and percentages to avoid such details as absolutes, so I ignored them! Why can't everyone just take the view that a factor of ten is fine and ignore the complicated bits? Having said that, I do like the idea of "the Bunker Equation of thermal transmission in KL style flooring" Edited February 20, 2015 by Anotheran 3 Link to post Share on other sites More sharing options...
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