[TRNSYS-users] error - transfer function stability criteria

[Thomas Minten <t.minten@gmail.com>]

dear TRNSYS-users,

i'm trying to simulate a dwelling with normal wall and floor insulation.
however when i try to lower the Type56's output timestep, i get these 
stability criteria errors.
i can succesfuly set the timestep to 0.25, but i need to set it to 0.1 
in order to get more accurate results from my model.

as i've read most of the previous user-mails related to this error, i 
already replaced all insulating layers by a massless layer with the same 
resistance.
i checked and checked and checked and checked all of my materials 
properties, but can't seem to get any closer to a solution.

from what i understand about the mathematical background behind this 
method, there should only be trouble when setting a timestep which is 
larger then
the timeconstant of any wall. since i want to set such a small timestep 
on quite massive walls, this shouldn't be of any concern.

the walls that cause trouble are the folowing:

outside wall:
14cm brickwork (massive, c=0.84, lambda=3, density=1500)
5cm PUR insulation (massless)
9cm brickwork (massive, c=0.84, lambda=3.024, density=1700)

floor:
20cm concrete (massive, from the library)
10cm insulating screed (screed with lots of air, massive)
5 cm PUR insulation (massless)
3 cm screed (massive)
active layer
5 cm screed (massive)

if anyone has had previous experience regarding this problem, i'm 
looking forward to hearing from them.

kind regard,
Thomas Minten