On Sat, 23 Aug 2003 11:25:52 +0100, "IMM" wrote:
"Peter Parry" wrote in message
.. .
On Thu, 21 Aug 2003 17:03:30 +0100, "IMM" wrote:
Forced air and underfloor can mean the stat can be turned down a few
degrees. Both about the same.
On the contrary, to quote from
http://meanradianttemperature.com/
"Good Thermal Design Tips (extract)
Use hydronic radiant floors
Heat people, not air"
Richard Kadulski wrote the following on MRT in the Renewable Energy
Policy Project :-
"A simple formula has been developed that allows normal comfort level
of a room to be calculated by adding the two primary heating
components: air temperature and mean radiant temperature (average
room surface temperature).
The formula is: air temperature ( F) + mean radiant
temperature ( F) = 140 ( F).
For example, with a conventional forced warm air heating system we
can maintain comfortable conditions at an air temperature of about 72
deg F (22 C) with a mean radiant temperature of 68 F (72 + 68 =
140).
With a radiant heating system, comfort is achieved at 68 F air
temperature if the mean radiant temperature is 72 F (68 + 72 = 140)".
With blown air systems the radiant temperature of all surfaces must
always be equal to or below the air temperature and for equivalent
levels of comfort higher, not lower, temperatures are required.
Ever heard of Mean Radiant Temperature?
I would have thought you would have known that was the subject of the
references I quoted.
Whilst it is possible, given big enough radiators, to achieve
similar boiler efficiencies with radiators it isn't possible to
overcome this basic perception of comfort at a lower temperature.
It is. Install perimeter skirting heating. Room temps can be lowered too.
It still doesn't give you the large radiant surface.
Underfloor heating can be run 2 to 4 degrees lower in room
temperature than any other system to maintain equivalent levels of
comfort. This accounts for the well established lower running costs
of underfloor systems compared with other heating methods.
Only for all day occupation. The erratic lifestyles of modern people means
underfloor is unsuitable for many in running costs and warm up.
I don't know of many people whose "erratic lifestyle" means they have
in advance no idea whatsoever of the time of day they will be in or
out. Equally I don't know of many who have remotely controlled
heating controls or only switch the heating on when they get in.
For those few who don't know whether they will be in or out at any
time at all and who habitually leave the house unheated until they
get in and then want a very rapid response then underfloor heating
has little attraction. The running costs as I am sure you are aware
will still not differ markedly.
In today's instant society, of instant communication and next day
deliveries, underfloor will not suit most people.
I hadn't thought about the influence of next day deliveries on
heating systems I must admit.
I think it is correct to say
you have never lived in a house
with underfloor heating
I have. Electric.
Ah.
and gain most
of your "knowledge" from manufacturers
pamphlets is it not?
No a pro in the game sonny boy.
Plumber?
Listen and learn!
One waits. I have a feeling it will be a long wait however.
The most basic competent design will
give even heat throughout the
floor.
Not so. The reason why Santoprene pipe was invented in Canada was that
running a spiral of plastic pipe caused uneven floor temps. The floor would
be far hotter on the flow side and at time very cool on the return after it
released its heat to the floor.
For some reason that doesn't happen in mine or any other I have seen.
Might possibly have something to do with the way the pipe runs were
planned.
Whilst the controls must be carefully
planned they do not need to be complicated
and certainly not expensive. The thermal lag
of the system cannot be overcome by fancy
controls
It can be greatly minimised.
Could you explain the physics behind this assertion please?
A number of articles in BSEE have covered
this over the years, I assume you subscribe
to that publication and have access to them.
I have access to most HVAC mags and browse them all.
You will be able to read the articles then.
"Build IT". Ever browsed that mag? Full of UFH adds.
Possibly because it is popular with people more concerned about
quality than price?
They are pandering to their advertisers.
Are you suggesting the results were falsified?
You have "never" lived in properly designed and installed up to date forced
air and vent system. Fresh air all the time and silent. Yu experiences are
limited.
Possibly, but certainly greater than yours.
As has been explained to you before I have had some experience of a
very modern system near here with all the bells and whistles. It has
now been removed at considerable expense because the owner found it
to be far too uncomfortable.
A plug-in electric fire or
wheeled Calor Gas heater is certainly more appropriate in that
situation.
Wheeled calor gas. Are you mad? You spend a fortune on a heating system and
you have to wheel in a box to heat the place.
As usual you rather missed the point.
--
Peter Parry.
http://www.wpp.ltd.uk/