sometimewoodworker
-
Posts
9775 -
Joined
-
Last visited
Content Type
Profiles
Forums
Downloads
Posts posted by sometimewoodworker
-
-
12 hours ago, bluejets said:
AVR won't fix a voltage drop problem.
That is precisely one of the fundamental functions of an AVR/AVS, it regulates over and under voltage to maintain the optimum (220v, other voltages are available, ) output. There are certainly some extremes that it can’t fix but then usually has a Hi/Low voltage cut contactor for the extremes, if not they are simple enough to fit.
-
45 minutes ago, 4MyEgo said:
You say, the metal roof doesn't heat up as fast as the concrete tiles,
Again you are misquoting I said Exactly the opposite
45 minutes ago, 4MyEgo said:orand doesn't hold the heat for as long as the concrete tile doesCorrected wording
45 minutes ago, 4MyEgo said:when I tested all 3, the concrete tiles took the longest
That is absolutely true but irrelevant
45 minutes ago, 4MyEgo said:I was looking for something to take longer for the heat to penetrate
Again it is true but it fails to address the point
45 minutes ago, 4MyEgo said:I didn't test if it would hold the heat for longer
It not only holds the heat for very significantly longer but because of that it gives a greater total heat load into the roof space.
If your insulation, ventilation etc doesn’t allow your ceiling to heat up at all the fact that you get a greater heat load above the ceiling means that any roof material is perfectly OK. That however would be a very unusual situation as usually nobody bothers with that level of insulation
-
22 hours ago, NorthernRyland said:
well if you can prevent the house from heating during the day using insulation on the ceiling than it's a win. I'm very skeptical you can insulate the ceiling well enough to cope with a metal roof but in theory it's possible.
Of course it’s rather expensive to insulate any Thai roof so that you get no daytime heat gain.
However it’s not at all difficult to insulate any roof be it metal or concrete to reduce the heat gain to a manageable level. The problem with concrete is that you get the heat gain during a rather unfavourable period.
My roofing is all metal and I can assure you that it is not only a theoretical possibility to insulate to a good level but I have done so and my roofing is an example of how easy it is to do it.
FWIW Without AC the interior of the house is on average 10C lower than the daytime high, and with an AC unit that most would consider to be significantly undersized (316 BTU sqm) it’s not difficult, given enough time, to drop the temperature by 20C, I don’t drop the temperature to be polar bear or penguin friendly but could if I wanted to.
-
1
-
-
1 hour ago, NorthernRyland said:
OK so the roof reaches equilibrium faster and at that point the heat is being transferred in to your house. That's the trade off.
You miss understand the meaning of equilibrium.
A roof has in essence 2 sides the top receives heat, the bottom (if you are sensible has insulation so radiates little heat.
Once equilibrium is reached the top side will be loosing heat by radiation and convection at almost the same rate as the sun is radiating heat to it, not quite the same as some is being lost into the roof.The quality and thickness of the insulation on the underside some heat will be transferred to the house though the percentage will be much smaller than the heat lost from the top.
The heat transfer from the metal roof stops very shortly after it stops being heated by the sun._—————-_
with a concrete roof the amount of heat being transferred into the house is smaller at the beginning of the day while the roof is heating up. However the heat transfer to the house extends hours into the night while the thermal mass of the roof cools down
-
- Popular Post
- Popular Post
9 hours ago, NorthernRyland said:So basically the trade off with the metal roof is you're taking on more heat during the day but releases faster at night. This all relies on the ceiling insulation being of the highest quality also.
No that is not correct. The insulated metal roof doesn’t magically take on more heat than the insulated concrete roof
The heat received by both is equal, the metal roof will reach equilibrium faster than the concrete roof (equilibrium being the point at which heat leaving the roof is equal to that arriving at the roof) take away the heat source (sun down) and the temperature will drop immediately.
The concrete roof will reach equilibrium much slower that the steel one due to the much greater thermal mass of the roof, this however is a problem in countries like Thailand where the thermal mass, that is a great benefit in cold climates, stores and releases the daytime heat long into the night.
10 hours ago, NorthernRyland said:What do you think about the metal roof panels with foam inserted in the middle? I guess that has the same problem of trapping heat though if it does pass through.
We have just recently roofed the outside kitchen and dog house with these. They trap heat generated from under the allow little to be transmitted from above. The significant advantage is that the insulation doesn’t deteriorate as it is enclosed. Our previous roof had the insulation drop off after a few years while the roof rusted through.
-
1
-
2
-
1 hour ago, 4MyEgo said:
So what you are saying is that a metal roof with insulation will not heat up the interior at any greater speed than that of a concrete tiled roof. If it has a gable roof I will agree as it will have enough clearance in the attic for the hot air to be circulated, that said, I would assume that the noise from the rain would be noticeable at times, vs nil from the concrete tile on a gable roof.
You did rather ignore the fact that a concrete roof will continue to radiate heat for a much longer period than metal one. And while insulation will reduce the amount radiated into the roof spaces it doesn’t eliminate it.
The rain noise will be greater on metal than concrete but you will still get some.
-
1
-
-
2 hours ago, 4MyEgo said:
It helps when you lived in a similar climate, and have an understanding of buildings, construction materials and designs, like I said, having I studying roofing before I went down the path I did and if anyone has a different way to reduce the heat in their roof space, then hats off to them, but I doubt it, and your statement that metal roofs are better than cement roofs just goes to show you have no idea what you are talking about IMO.
It actually shows that while you may have studied roofing you neglected, forgot, or never learned basic physics and are attributing statements to me that I never made.
QuoteConcrete has a high thermal mass with properties similar to brick and stone. It is possible to absorb heat from the atmosphere in warm weather
Also from the sun in the usual Thai weather.
Metal roofs do not store heat (or at least the thermal mass is so small the heat storage is minimal)
Metal roofs will quickly transmit heat.
in direct sun A metal roof with sufficient insulation will not heat up the interior at any greater speed than than a properly insulated concrete (cement tile) roof
With no sun and a low air temperature (Thailand after sunset)
The metal roof will almost instantly (in a few minutes) be at ambient air temperature.
Conversely it will take hours for the concrete (cement tile) roof to loose the heat it has gained
I will use the option that is suitable for myself.
you are welcome to continue the your your night storage heater roof
-
1
-
1
-
-
1 hour ago, NorthernRyland said:
Summarize this for me, so the debate with ceramic tiles is that while they block heat penetration they retain heat and will radiate heat during the night after the sun is down, therefore ventilation is extra important as compared to some lighter material. Is this correct?
my post got eatenQuote
Ideally modern buildings should be constructed in such a manner as to minimise temperature build up in the room space during warm weather and yet prevent the loss of this excess heat in cold periods. To achieve this, a combination of insulation to exterior walls is required for colder weather and a high thermal mass to act as a heat sink for hot weather. Concrete has a high thermal mass with properties similar to brick and stone. It is possible to absorb heat from the atmosphere in warm weather and release it during cooler periods, e.g. overnight. This is known as the ‘thermal flywheel’ effect. In a passive concrete design the cooling capacity of concrete can be up to 25W/m2 and with an active system, e.g. by ducting of air through a concrete slab, up to 40W/m2 can be absorbed.-
1
-
-
8 minutes ago, NorthernRyland said:
In fact I have a roll of single sided foil foam insulation I bought from HomePro. It says to point the reflective side UP towards the sun too.
That goes to show that the information printed on it is not enough as you must have an air gap between the silver side and the roof, it could be completely correct if it is designed to lay on a ceiling.
-
1
-
-
1 hour ago, NorthernRyland said:
this goes over my head I guess. The reflective part is facing DOWN? I thought it was supposed to face up towards the sun?
You are getting confused by the difference between a reflective barrier, where the reflective side goes up
And a radiant barrier where the non radiant (shiny side) goes down.
There are 2 different laws of physics involved radiation (shiny side down) and reflection (shiny side up)
The silver film sold in Thailand is either shiny on one side (cheapest) where it is important to have it shiny side down on the underside of a roof as it is a good radiant barrier. Or shiny on both sides where it can act as a reflective barrier on one surface and a radiant barrier on the other surface
The problem with reflective surfaces is they quite quickly get dirty/dusty so loosing effectiveness
The benefit of non radiant surfaces is they face down so dirt and dust has little effect so maintaining effectiveness
-
1
-
-
FWIW There is a very simple experiment you can do to demonstrate the effectiveness of a radiant barrier.
materials required; black surfaced frying pan, a spatula and aluminium cooking foil. NB insulation foil will not work
method
- heat the frying pan to just under the smoke point of peanut oil
- hold your hand a close to the surface of the pan as you can for at least a minute (without burning yourself) this will be several to many cm above the pan surface (is it isn’t the pan is not hot enough or you have no nerves)
- take a piece of aluminium foil that is at least 5cm large on all sides than the pan, place it dull side down, using the spatula (don’t use a plastic one) press the foil down to the surface of the pan
- hold your hand a close to the surface of the pan as you can for at least a minute (without burning yourself) this will be Very much closer than in number 2.
You can avoid the use of the spatula by forming a bowl shape to fit into the frying pan before heating the pan.
The foil can be touching the frying pan’s surface so at or close to the same temperature as the pan. This demonstrates that a polished aluminium surface is a poor radiator of heat, while a black surfaced frying pan is not.
A demonstration of a reflective barrier is a rather more complex process.
-
1
-
- Popular Post
- Popular Post
On 4/16/2024 at 11:47 AM, 4MyEgo said:I studied roofing for years and the only way your going to reduce heat penetrating below your roof is to:
2. Put cement tiles on
It seems that your studies did not include anything to do with night storage heaters! If it did you would know that cement is a good storage medium for heat. The mass of the cement tiles will nicely absorb the heat from the solar furnace AKA the sun, and then radiate that through the night keeping you nice and toasty warm.
So in fact metal roofs are far better than cement, as they don’t store anything like the amount that cement does.
-
1
-
4
-
1
-
13 hours ago, Muhendis said:
I'm going to backtrack on this a bit.
The plywood is still a reasonable idea but, having gained some more knowledge I would supplement that with aluminium foil arranged to have free air on both sides.
I changed my idea because I read this:-
Regrettably that post very much glosses over the difference between using aluminium foils as a reflective barrier and using them as a radiant barrier.
Given that in Thailand the heat is virtually always from the roof, a radiant barrier with the high gloss surface facing down in contact with the underside of the roof is extremely effective, there is a need for the underside to face an air space, the topside doesn’t need an air space.
-
1
-
1
-
-
15 hours ago, Luuk Chaai said:
Most common insulation materials work by slowing conductive heat flow and -- to a lesser extent -- convective heat flow.
I agree
15 hours ago, Luuk Chaai said:Radiant barriers and reflective insulation systems work by reducing radiant heat gain.
No they don’t. You missed the full information in your physics classes, or you’re really confused in your wording.
Radiant barriers function by NOT radiating heat, they can be hot (very hot) but they don’t radiate heat well.
Reflective barriers function by being good reflectors of heat so don’t get hot.
15 hours ago, Luuk Chaai said:Dust accumulation on the reflective surface will reduce its reflective capability.
Correct
15 hours ago, Luuk Chaai said:The radiant barrier should be installed in a manner to minimize dust accumulation on the reflective surface.
You are confusing the 2 different functions (this is not helped by the double sided silver film sold in Thailand)
a radiant barrier needs a relatively clean surface the reverse side has no effect on the functioning of the radiant barrier.
15 hours ago, Luuk Chaai said:When installing a foil-type barrier, it's important to allow the material to "droop" between the attachment points to make at least a 1.0 inch (2.5 cm) air space between it and the bottom of the roof.
This is only if you have double sided film and want to allow reflection back to the roof surface.
You can use single sided silver faced plywood boards with the silver face down and they will be as effective.
I used single sided foil in my install as it was half the cost, as effective and I did remember my physics lessons 😉
-
1
-
-
- Popular Post
- Popular Post
4 hours ago, tomster said:Hi,
I need to insulate a roof on a bar as cheaply as possible.
I'm not sure what the roof type is called, but it's very common here, this is what it looks like underneath:
When the sun is on it it's literally too hot to touch the underside and this heat is radiating down into the area below, making it crazy hot in the space.
I would rather deal with this with something from underneath as it would save the headache of working on it from above, weight issues etc.
Is there something I can stick or paint on the underside that would block a decent amount of the heat out, it doesn't need to be 100% effective, 80--90% would be good enough.
Thanks in advance.
Yes there is though you don’t stick it onto the roof. It is the radiant barrier film
i went from a roof that was over 60C
to one that was ambient temperature 37C
full story, including some who disagree vehemently that it could work. It does
-
3
-
1
-
1
-
7 hours ago, Liverpool Lou said:
With Kasikorn? Doubt it. How can you do that with a service that is not available to, or required for, foreigners with Kasikorn? Krungsri and BBL, yes, bit not Kasikorn.
I don’t accurately recall , quite likely K Bank does not need it however the account I have with them seldom has over 20k in it so I wouldn’t have hit the 50 general limit for unverified transactions. So since I’ve been in to several banks I assumed that all of them had implemented stronger controls.
-
19 hours ago, GammaGlobulin said:
But, I am living in Thailand.
So...OBVIOUSLY...My ACs run 24/7/365.
Well! I also live in Thailand, and have lived in various areas, and have never needed to run the ACs 24/7/365, even at the moment when the temperature got to over 40C so it is far from OBVIOUS to me. However I do have rooms with doors that can be closed so don’t have a desire to condition the full 200sqm + at the same time.
-
1
-
1
-
-
11 hours ago, NoshowJones said:
Thanks George but I can assure you it only accepts Visa.
I only have U.K. master cards, I use Agoda. My cards are accepted.
-
On 4/9/2024 at 5:17 PM, Kenny202 said:
What is the current status of this? Have people successfully done the scan thing and can now transfer higher amounts?
FWIW I have authorised SCB to not require face scan I have scanned my face with Bangkok Bank, Kasikornbank & Bank of Ayudhaya (KMA Krungsri). The face scan is not always successful first time.
-
1
-
-
17 hours ago, richard_smith237 said:
The Bangkok Bank WebPage is clearly wrong.... NDID can be set up to work for foreigners - enough of us have already done so.
Those who have done so have self evidently done so against the regulations for the NDID system
It is likely that those who did so slipped through the cracks
The Bangkok Bank web page is not wrong and is mirroring the NDID information, from the faq page of the NDID site
What qualifications must I have to use the NDID service?
Must be of Thai nationality
17 hours ago, richard_smith237 said:Rules ???... its something written on a website which is most likely a mistake... (clearly it is a mistake)...
The mistake made by Bangkok Bank was that any non Thai national was allowed to register for a NDID not that the current website is wrong. Do note that the service provider (in your case Bangkok Bank) has the responsibility of identification and verification of identity.
The only exceptions to the registration could be those who have permanent residence or have gained nationality.If you are so confident that the websites are wrong then you will be able to go to any other bank and register with them using your current registration.
It maybe that you can since you have erroneously have been allowed to register or you could loose the registration you have now
However and much more importantly every other foreigner will be able to register!
Do you care to roll the dice? Do you know anyone (non Thai ) who has recently got an NDID?
I know that I was not able to register, I don’t remember who I asked as I have 4 banks that I use.
-
7 hours ago, GammaGlobulin said:
On the Samsung; the AC indoor unit seems to have a function for drying the inside of case, and internal parts, which can become corroded when moisture invades certain components, or the casing, it seems.
The only thing that I would question is:
If you are running your AC 24/7/365, as do I, then would there be any down-time when this cleaning function might be able to work?
My guess is NO.
When the AC is running 24/7 there is always air being blown through the indoor evaporator unit, and this should be sufficient to keep it dry enough to prevent much condensation.
Just my guess.
I think that you may not understand the function of the self clean function of the majority (not just Samsung) AC units.
The majority of AC units do not run 24/7 nor 365 if your units do you have no use, or need, for the self clean function. However you postulate that with the fan running 24/7/365 there will be little condensation, this would be true only if the humidity in the house was always very low but that is never true in Thailand, so you have conditions that will permit slime mould growth so regular cleaning of the water drain system is a very good, if not essential, idea.
However the majority of AC users switch them off for periods of time, usually several hours long, when switched off the internals of the unit has both condensate water and is cold enough that more condensation occurs within the indoor unit. The way to avoid mould and corrosion is to run the fan for long enough, in some cases up to 30 minutes possibly more, this will dry the both the condensation water remaining and the internals of the unit so reducing or eliminating the slime mould build up and water remaining on the inside of the unit.
the self clean option does nothing for the filter units of the AC these need regular cleaning, the more dust or hair (we have 3 cats) in the house, the longer the run time, the more frequently the need cleaning, anywhere from monthly to quarterly will usually be required.
-
1
-
-
14 hours ago, richard_smith237 said:
I'm lying then ?????
Is Bangkok bank lying on its own website then ?????
14 hours ago, richard_smith237 said:Nan Leaw is lying then ????
Is Bangkok bank lying on its own website then ?????
14 hours ago, richard_smith237 said:Everyman is lying then ????
Is Bangkok bank lying on its own website then ?????
14 hours ago, richard_smith237 said:Doesn't matter what links you drag up from the internet
Is Bangkok bank lying on its own website then ?????
14 hours ago, richard_smith237 said:it doesn't beat first hand experience
TIT you can bend and break rules with sufficient pieces of pretty pieces of paper.
Does the fact that you were able to do something that is against the rules specifically posted by Bangkok bank make the rules invalid or that they are lying on the website?
-
- Popular Post
- Popular Post
14 hours ago, Thaipwriter said:I saw on another thread you mentioned you used Wago 773 push wire connectors in your house build. I'd like to know if it ok to use three of those in a junction box in the ceiling space above each drop down to each socket on a radial circuit. The Wagos would connect the incoming 3 x2.5mm2 wires to three 2.5mm2 wires that drop down to the socket and also to the three wires that run onwards in the circuit to the next socket outlet, and so on up to a total of 8 double sockets per circuit? Would that be up to an acceptable standard?
NB there are Wago, copies of Wago, copies of copies of Wago all the way down to items that are not very safe.
The major differentiation is that Wago plastics are heat resistant and self extinguishing as you go down the scale the plastics become less heat resistant and more inflammable.
The majority of the copies along with the genuine Wagos will actually stay connected at significant multiples of the 35A ish current that a 20A breaker will disconnect at, so much so that the insulation will melt off and the connector stays connected, John Ward an English electrician has posted a few interesting videos, as I recall the current he got up to was over 150A and the 2.5mm wire was at least very hot.
this is one of the tests
-
2
-
1
-
11 hours ago, Joinaman said:
so where is the load bearing on a small 4x4 extension ?
If you have the standard posts, often at 4 meter centres and those have a ring beam it the top and if required part way down. The that structure is bearing the weight of the roof so is load bearing, for example like this
if you add fill in walls etc you have a small house, the roof is supported by the posts and tied down to them, FWIW the tie downs on a roof like this must be stronger than an enclosed structure
If you don’t have posts supporting the roof then the walls are load bearing QED. Don’t forget that Thailand like other countries does have wind! Wind even if not a typhoon exerts force on roofs and walls these forces come in all directions from pushing down on the roof to lifting it up and of course pushing it sideways, post and beams are designed for these forces, Thai AAC over 200mm are also capable of withstanding these forces. Thai AAC at half the load bearing thickness however interlocked the corners are not rated for this use. Can you use them? Of course you can. Is it a good idea? Absolutely not. The cost difference in material between 100mm and 200mm blocks is an insignificant amount when compared to the overall cost of building.
all the talk of comparing Thai AAC 100mm (an unusual size) to UK 100mm blocks is totally irrelevant. The U.K. doesn’t use the same specifications of AAC blocks that are standard in Thailand. Thai AAC blocks are predominantly used in 75mm thickness and always as a fill in wall never as load bearing walls. It is foolish to think that a U.K. building practice can be transplanted to Thailand without all the other design elements surrounding it.
-
1
-
1
-
AVR and a/c
in The Electrical Forum
Posted
The assumption of an inexperienced poster can often be made when not every scenario has been explained in the detail and manor that someone who has seemingly only ever been exposed to a subset of situations is expecting.
From experience as well as the knowledge of the basic physics that @JBChiangRai has well explained, the cure suggested of larger cabling could be a part of the problem that @zlodnick is experiencing, this is unlikely to be the fix as the PEA has visited on 4 consecutive days, and while there is a significant lack of belief by some in the competence of the training required to become an electrician for the PEA this is a canard, the PEA has excellent well trained employees, though I don’t know if they also have muppets, it is less likely that all of local staff are incompetent.
The statement that the the only other “fix” than larger supply from the meter to the house, would be to move the house closer to the supply is a possible answer but again is fanciful, impractical, likely impossible and does not guarantee a cure.
There are other, more likely, correct answers that have not been thought of but @zlodnick will have difficulty getting implemented.
If the second scenario is correct the only people who can fix the problem are the PEA who likely don’t have the budget (though reducing tea consumption could help).
All in all an AVR is a relatively cheap answer to test and while it will increase the load on the current section of the network it maybe enough for @zlodnick. It may also make the voltage drops for other users annoying enough that they will put more pressure on the PEA and persuade them that your section is higher on the list for upgrading.