|
[email protected] wrote:
|>
|> | I thought that the biggest problem was the conditioning system working
|> | less efficiently if they have to draw heat from a room which is already
|> | cold to bring it to a place which is already hot.
|> | Is this factor irrelevant?
|>
|> It's what A/C systems are designed to do. They "compress" heat so it is
|> actually coming out of the precipitator at a higher temperature than it
|> entered the evaporator. Stick your hand in the air flow out from the A/C
|> outside and you will see it is hot.
|
| I understand that it's what they are supposed to do, and approximately
| how they work, but are you sure that the efficiency of the AC is not
| influenced by the temperature difference between the room and the outside?
That depends on what kind of efficiency you mean. Sure, if the outside is
hotter on one day than another, the A/C has to work harder on that hot day.
This is due both to the greater heat flow coming in, as well as the lesser
temperature difference at the precipitator. But this is a working condition
and not a part of the equipment efficiency. But maybe what you are wanting
is a working efficiency level.
| I kinda understand the steps involved in determining the heat flow
| through the walls due to the temp difference, what I don't know how to
| keep into account is the decrease in efficiency in the AC system if the
| room where to draw heat from is 8 celsius below the outside temp
If the inside room temperature equals the outside, there is no heat to move.
Heat the room up and it flows outside. The flow will be in proportion to
the temperature difference. The details of the building insulation itself
would give you some absolute figures (if you want to spend all the time to
model every aspects of the building construction). Normally one would want
a computer room to be at some specific temperature, such as 18C. Then you
have to consider the extra heat coming in, and opposing the precipitator,
at the highest outside temperature you need to handle. The heat released
by the computers usually well exceeds the heat ingress through the building
in a typical computer room installation. You need enough A/C to keep the
room cold if it didn't have computers, plus enough A/C to remove the heat
released by the computers, plus a level of redundancy to handle taking a
unit or two offline for maintenance or failure.
What is your highest outside temperature? Are you in Troms? Norway?