Re: Re: Zoned Heating Control

[Chris Hunter <cjhunter@xxxxxxxxxxxx>]

'think we're saying the same thing in different ways ... increasing
the UFH water temp' will increase the 'gradient between 'pipe & air
in the room ... ... given that the distance between the two is a
constant, as it were ... !

linoleum ... 'not heard that ... 'quick Google suggests it depends on
type ... maybe it's the  cushion-floor types that are no-go ?

Chris



On 29 Apr 2007, at 23:58, rb_ziggy wrote:

> Chris
>
> Not sure I quite follow your reasoning on the first paragraph.  I'm
> pretty sure it's the temperature gradient (for a constant resistance)
> that is the absolute determinant for the rate of heat transfer.  The
> "rate of heat supply" has nothing to do with it.  (Consider
the case
> when there is no gradient, it doesn't matter how much energy is pushed
> through the slab in terms of volume of water, no heat will be
> transferred).  As the gradient tends to zero, so does the rate of
> transfer.
>
> When there is more resistance, the rate of transfer is, of course,
> reduced and it slows the warming of the cold side (i.e. it takes
> longer for the gradient to reduce).
>
> Essentially, all that means is that the more insulation you have, the
> longer it takes to warm up (you experience greater thermal lag), so no
> great surprise there then, ;-)  Raising the supply side water temp can
> compensate for this but in the real world the problem is first, more
> overrun (room heats up more than you wanted it to due to the residual
> energy in the slab) and, second,  you go outside the sensible
> boundaries of the materials.
>
> In reality, for normal floor coverings, these things seem to make
> little difference, underfloor heating is just very subtle. You barely
> notice it as the house tends temperatures are constant (no hot spots
> near rads or cold ones in the corners).
>
> I hope that makes some kind of sense.  In reality it just works in my
> experience.
>
> On the other points:
>
> - Loose floating does need an expansion area - usually under the
> skirting.  I can see it being problematic if you don't want
> skirting!!! I did see other systems where wooden battens are laid into
> the screed and well seasoned t&g planks are nailed down onto that.
 I
> took one look at that and thought no-way was I going to find someone
> who could lay battens into wet screed and get it flat.  A more
> realistic system is to stick the engineered boards to the screed.
> There is a special adhesive (sikabond???) that is designed for exactly
> this over UF.  I looked at this closely and it's certainly possible
> but it was a lot more expensive (just for the glue) and might be more
> of a pro job.  IIRC this system still needs some expansion gaps at the
> edges - at the end of the day, wood moves.  I'd love to find out how
> those no-skirting floors are done - they do look great.
>
> - A friend had an old parquet floor glued down.  Flooded and the floor
> rose up in a dome about 12-18 inches high - didn't go back down
> either.  But that was the least of his worries!
>
> - polished screed - interesting. Add an interesting aggregate
> perhaps...
>
> - Epoxy paint - interesting - garage floor???
>
> - Lino - I fancied this but, guess what, its a great insulator and one
> of the few finishes that the UF guys didn't recommend (really).  (I
> wondered if it might get soft if it was warmed???)
>
> Please do that the last few with a pinch of salt. Good luck.
>
> --- In ukha_d@xxxxxxx, Chris Hunter <cjhunter@...> wrote:
>>
>> Richard -
>>
>> thanks ... interesting ...
>>
>> rather than temperature gradient, I guess it'll be rate of heat
>> supply, that would be the constant, for a given room, with a
higher
>> temperature gradient between UFH pipe & air in the room being
needed
>> to drive the heat through if there's more resistance, because of
>> carpet or underlay, say ... and the higher temperature in the
pipes
>> that that would need would lead to some loss of efficiency, thanks
to
>> greater heat losses upstream from the UFH and basic thermodynamics
>> (small temperature differences being more efficient in any
>> thermodynamic / heat-cycle, IIRC) ...
>>
>> 'must say, I'm edgy about loose-floating the wooden covering &
>> leaving a gap at the edge .... noise issues & what happens if
there's
>> a flood !   Plus, we intend not having skirting boards !
>>
>> when we started our build, we had floor-grade hardboard on our
list
>> of options ... didn't sound a good idea, until I got a sample of
the
>> material ... it's still an option (suitably sealed) !
>>
>> 'wonder if it would be possible to leave the screed (anhydrous)
>> uncovered ('might have to be sealed, I guess) ... or if an epoxy
>> paint could be good ??
>>
>> if it was up to me, I think I'd go for welded linoleum, but 'wife
>> wants wood !
>>
>> Chris
>>
>>
>>
>> On 29 Apr 2007, at 09:13, rb_ziggy wrote:
>>
>>> Bit of a gap - been away since your post!
>>>
>>> I wouldn't worry about the underlay. All these 'engineered'
wooden
>>> floors work this way.  The planks are glued/locked together
and the
>>> whole floor 'floats' loose on the screed.  This is what allows
it to
>>> expand and contract without self destructing.  As long as the
whole
>>> floor is subject to the same conditions (and it will be with
UF)
>>> then
>>> there are no problems with differential expansion (i.e caused
by
>>> damp
>>> one side and dry the other).
>>>
>>> I think the underlay does two things, it reduces noise (as
stated
>>> before) and it can (if you use the thick stuff) give a bit
more
>>> insulation to the slab.  You don't need the latter in a
under-slab
>>> insulated house so just go for the 2-3mm underlay.
>>>
>>> It doesn't need any additional calculations / pipe as such.
(Adding
>>> more pipe running at a lower temperature is actually a waste
of
>>> money
>>> as it's the temperature gradient that is the determining
factor.)
>>> From what I remember, the wood + underlay creates no more of a
>>> thermal
>>> barrier than carpet. The company supplying can easily take
these
>>> factors into account when they design the pipe layout.  Most
supply
>>> you with a specific piping layout on your plans.
>>>
>>> With underlay, it doesnt feel markedly 'softer' - just like a
>>> 'normal'
>>> (slightly 'sprung'???) wood floor.  But it's a lot less hard
than
>>> ceramic tiles.
>>>
>>> We something like 120m2 of engineered wood flooring over uf
and it
>>> works flawlessly for over 5 years.
>>>
>>> Richard
>>>
>>> --- In ukha_d@xxxxxxx, Chris Hunter <cjhunter@> wrote:
>>>>
>>>> Underlay ???   'hadn't thought of that !
>>>>
>>>> I imagined it would be glued to the screed, rather than
laid
>>>> loose ... interlocked, presumably, but loose ... ?
>>>>
>>>> which seems odd, because ceramic tiles wouldn't be laid
loose,
>>>> surely, so glues must be available ... ?
>>>>
>>>> 'wonder how much hotter must the water be to cope with
this ...
>>>> maybe
>>>> it's a specially conductive underlay ... maybe doubling
the pipe
>>>> would compensate (IIRC Ian's used more pipe, to run
cooler, so
>>>> might
>>>> work) ... ?
>>>>
>>>> being softer underfoot might be good, of course, but it
rather puts
>>>> me off the idea !
>>>>
>>>> Chris
>>>>
>>>>
>>>>
>>>>
>>>> On 19 Apr 2007, at 01:10, rb_ziggy wrote:
>>>>
>>>>> We have a Kahrs 'engineered' (i.e. laminated not
laminate) wood
>>>>> floor
>>>>> throughout the ground floor.  Absolutely no probs with
UF in
>>>>> over 5
>>>>> years.  Works fine.
>>>>>
>>>>> But as Nigel says, don't go for the thick (i.e.
insulating)
>>>>> underlay,
>>>>> that is rather counter-productive.  (N.B. do use
underlay
>>>>> though, a
>>>>> friend laid the same floating flooring without and it
sounded
>>>>> like a
>>>>> drum when the kids ran around).
>>>>
>>>>
>>>>
>>>> [Non-text portions of this message have been removed]
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
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