>> Doesn't seem to work with my Renault Megan III.
> 
> That would be the first car I've ever seen (and I've seen lots way older 
> and smaller than yours!) that didn't have such a feature.  You really 
> mean that once you un-latch the door it is free to swing out to 100% 
> open?  Yes, I can imagine that would be really annoying in car parks and 
> garages.

As far as I can tell...

(The other fun thing is that if you swing it open, it hits the end and 
immediately bounces back in your face.)

>> My house doesn't have and has never had a hot water tank. As you say, 
>> water is heated on-demand.
> 
> Was it like that when the house was built?

I can't say for certain. It's been that way ever since I lived here. 
Then again, my dad's house is on the same estate and that does have a 
hot tank, so...

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> As far as I can tell...
>
> (The other fun thing is that if you swing it open, it hits the end and 
> immediately bounces back in your face.)

Sounds broken to me, does the passenger door behave the same way?

> I can't say for certain. It's been that way ever since I lived here. Then 
> again, my dad's house is on the same estate and that does have a hot tank, 
> so...

I suspect it originally had hot and cold tanks, then they changed it to an 
on-demand boiler (common when a boiler gets replaced) but left the cold tank 
(probably didn't want to re-plumb all the upstairs taps).

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Am 07.07.2010 17:59, schrieb Invisible:
> Why has nobody yet invented a car door which can be opened half way?
>
> Every car I've ever seen has hinges which try to force the door fully
> open or fully closed. Now you can see why fully closed would be a good
> idea. But if you're parked in a tight space, it's really irritating that
> you can't let go of the door because you'll either get a door in your
> face, or the door will spring open and scratch up the car next to you.
>
> Such a simple problem, yet nobody has solved it. WHY?!! >_<

Because you're once again wrong?

I recall indeed having operated car doors that had two distinctive 
"open" positions. Never paid much attention to this though, so I can't 
tell what percentage of cars seem to have such a feature.

> Why are the downstairs taps connected to the mains, but the upstairs
> ones connected to a tank? Why do we even *have* a tank??

Maybe because upstairs the water mains pressure drops below atmospheric 
pressure (or at least too low to provide any significant throughput) at 
peak load times?

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On 7/8/2010 1:54 AM, scott wrote:

>
> It's different in the UK, the mains pressure usually equates to about
> 10-50 metres plus of head. Any water from a tank in the roof is usually
> *way* lower pressure than mains. For example you can easily block off a
> fully open hot tap with your thumb with very little force, but it is
> tricky, if not impossible to do the same on a mains pressure cold tap.
>

Is this everywhere, though? I imagine in Andrew's Building's case that 
it could be that his building was on a hill, while the building gets 
reasonable pressure on the lower floor, the upper floor might not get 
enough. Where I live, there's plenty of water pressure. But, if your 
building is taller than the water tower, it'll need a tank to get 
pressure to the upper floors.

-- 
~Mike

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On 7/8/2010 1:50 AM, scott wrote:
>> Every car I've ever seen has hinges which try to force the door fully
>> open or fully closed. Now you can see why fully closed would be a good
>> idea. But if you're parked in a tight space, it's really irritating
>> that you can't let go of the door because you'll either get a door in
>> your face, or the door will spring open and scratch up the car next to
>> you.
>>
>> Such a simple problem, yet nobody has solved it. WHY?!! >_<
>
> Huh? Every car I've had for decades has a soft "stop" half way where the
> door is quite stable. You can then push it a bit harder and it locks all
> the way out. Try it!
>

Yep, mine has a detent about half way, which is usually just a bit too 
much for a cramped parking lot. This makes the task of wrangling a 
squirming toddler into the car ever so enjoyable while you 
simultaneously are trying to keep the door from contacting the car next 
to you, which seems to have been parked by someone who insists on 
parking with their tire touching the line. :)

>> Why are the downstairs taps connected to the mains, but the upstairs
>> ones connected to a tank?
>
> To stop you having mains pressure cold (~1-5 bar) next to tank pressure
> hot (~0.2 bar) in the bath. Imagine what happens when you connect one of
> those old-fashioned shower adapters to the bath taps, turn hot and cold
> to full and then turn *off* the shower head. Fortunately now we have
> taps with back-flow prevention valves and fancy mixer taps to avoid this
> problem. Many houses don't have a cold tank, and some won't have a hot
> tank either (the hot is heated on-demand by the boiler).
>

Hmm, that makes sense... Though a thermostatic valve eliminates that 
need entirely.

-- 
~Mike

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Mike Raiford wrote:

> Is this everywhere, though? I imagine in Andrew's Building's case that 
> it could be that his building was on a hill, while the building gets 
> reasonable pressure on the lower floor, the upper floor might not get 
> enough. Where I live, there's plenty of water pressure. But, if your 
> building is taller than the water tower, it'll need a tank to get 
> pressure to the upper floors.

Is water actually that damned heavy?

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>> It's different in the UK, the mains pressure usually equates to about
>> 10-50 metres plus of head. Any water from a tank in the roof is usually
>> *way* lower pressure than mains. For example you can easily block off a
>> fully open hot tap with your thumb with very little force, but it is
>> tricky, if not impossible to do the same on a mains pressure cold tap.
>
> Is this everywhere, though?

Pretty much, water companies are required to supply at a minimum of 1 bar, 
which means upstairs you'd get a guaranteed ~0.7 bar.  Unless you are able 
to put a tank 7 metres higher than upstairs it's not going to give any 
improvement over the worst mains pressure.

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On 7/8/2010 7:18 AM, Invisible wrote:

> Is water actually that damned heavy?

It's heavier than air, isn't it? ;)

Pick up a 5 gallon bucket of water. it gets pretty heavy pretty quick. 
The towers are there to create pressure to service an area. It's a 
rather efficient system, so long as the demand doesn't drain the tower 
you get very good pressure.

-- 
~Mike

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On 7/8/2010 7:20 AM, scott wrote:
>>> It's different in the UK, the mains pressure usually equates to about
>>> 10-50 metres plus of head. Any water from a tank in the roof is usually
>>> *way* lower pressure than mains. For example you can easily block off a
>>> fully open hot tap with your thumb with very little force, but it is
>>> tricky, if not impossible to do the same on a mains pressure cold tap.
>>
>> Is this everywhere, though?
>
> Pretty much, water companies are required to supply at a minimum of 1
> bar, which means upstairs you'd get a guaranteed ~0.7 bar. Unless you
> are able to put a tank 7 metres higher than upstairs it's not going to
> give any improvement over the worst mains pressure.
>

I figured in some rural areas this may not be the case, though. If, for 
instance, the water were coming from a well...

... But by virtue of what you said the tank seems completely 
unnecessary. I'm going to go out on a limb and say it was a vestige of 
an earlier time back when the house was built. Probably to equalize the 
pressure of cold and hot, as you said.

How do the on-demand hot water systems work, btw? It seems like here in 
the States tanks are by far the norm. It seems like it would be a heck 
of a lot more efficient to have the on-demand heating system, and a tad 
less annoying... .I really, really despise it when the hot water runs out.
-- 
~Mike

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> I figured in some rural areas this may not be the case, though. If, for 
> instance, the water were coming from a well...

In rural areas there will usually be a water reservoir on or inside a hill 
somewhere nearby.  If you water pressure is really so low that adding a tank 
in the roof helps, then you are going to have other problems with washing 
machines and boilers, I've seen some of them that demand a minimum water 
pressure of 1 bar.

> How do the on-demand hot water systems work, btw?

A pipe off from the mains cold supply goes into the boiler, gets heated, and 
then goes to all the hot taps.  A flow-rate sensor detects when a hot tap is 
turned on and fires up the boiler.  It is the same boiler that does the 
central heating, usually a smallish wall mounted unit like this:

http://www.petesheating.co.uk/images/examples/boiler_in_cupboard_2.jpg

(You can see in that photo there probably used to be a hot water tank there)

Advantages are higher efficiency, more space (no hot or cold tanks needed) 
and unlimited hot water.  The disadvantage is that unless you have a really 
beefy boiler and gas supply, the hot water isn't going to come out as fast 
as if you had a tank.  For a shower this is usually not noticed because the 
pressure is much higher, but you'll notice when it takes 2x longer to fill 
the bath!

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