Glow-worm Climapro Weather Compensation

[sjr56]

This summer I installed a Glow-worm Flexicom 18hx, with Climapro and Smart Wiring Centre. I initially had some problems with bugs in the Climapro software, which were fixed when Glow-worm replaced it free-of-charge with an updated version.

One of the things that impressed me with the operation of my system was the way in which the Climapro modulated the boiler water temperature downwards as the temperature in the room approached the set room temperature. This resulted in no overshoot, and a very closely controlled comfort temperature in the room.

I was recommended to add an outside temperature sensor so that the system could move to an even better level of control and efficiency. This I did, but am rather disappointed in the result.

I understand that the idea behind weather compensation is that the controller will use a lower boiler water flow temperature if the outside temperature is reasonably mild, and will only use the maximum boiler temperature (say 82 degrees) if the outside temperature is very low (say –5 degrees). You set this by selecting a heating curve or gradient at the Climapro. This should improve the efficiency of the boiler operation by only using the highest flow temperatures when really needed.

So far so good, and yes it is clear that the boiler is not using the highest flow temperatures – the outside temperature has yet to drop low enough.

However the system seems to have become a lot more dumb with respect to the set room temperature. As far as I can tell there is now no modulation downwards as the room set temperature is approached, with the result that I now get overshoot. Also the Climapro doesn’t seem to fire up the boiler until the room temperature has dropped significantly. It now seems to be behaving like a simple on-off thermostat.

It seems to me that the addition of the outside sensor, whilst adding some intelligence regarding the maximum flow temperature, has removed the previous intelligent modulation with respect to the set room temperature. These two features ought to be working together to maximise efficiency, but the one seems to have just overridden the other. Does anybody out there know whether this is supposed to happen, or whether this is a fault, and if there is a fix?

 

[glasgowgas]

remove weather comp

or overide weather comp, run through the climapro, and when and if it really gets cold, revert back to w.c

a real thorough knowledge of the heating curve is vital.

ie if outside weather temp is 14 deg C (as it is now, in Glasgow) what flow temp is your htg curve looking for. it could be somewhere as low as 38-40deg C

 

[sjr56]

Removing/disabling the weather compensation would be admitting defeat!

I am happy with the heating curve. Currently the outside temperature here is 11deg and the boiler is giving 50deg, which is fine whilst there is a significant room temperature demand. But as it get close to satisfying the room temperature demand it should modulate the temperature down further (as it used to before I fitted the outside sensor).

Perhaps I will hack into the e-bus and write my own control software!

 

[glasgowgas]

Removing/disabling the weather compensation would be admitting defeat!

I am happy with the heating curve. Currently the outside temperature here is 11deg and the boiler is giving 50deg, which is fine whilst there is a significant room temperature demand. But as it get close to satisfying the room temperature demand it should modulate the temperature down further (as it used to before I fitted the outside sensor).

Perhaps I will hack into the e-bus and write my own control software!

How does it work?
A small temperature sensor is located on
the outside of the building, normally on a
north facing wall. This is wired to the internal
controls of the boiler and information about
the outside temperature is sent to the boiler
every few seconds.
When the temperature changes outside
the boiler responds and starts to increase
or decrease the radiator temperature to
compensate. This pro-active mechanism
means that people inside the building won’t
even notice that the temperature has
changed outside.
For example, when the outside temperature
drops in the evening, more heat is lost
through the walls of the building. Because
the outdoor sensor detects the fall as soon
as it happens, the boiler is able to start
working a little harder to increase the
radiator temperature and keep the inside
temperature stable. With a conventional
system, the temperature is dependent on
a room thermostat, which will can only take
effect after the inside of the building has
become too hot or too cold.
In summary, weather compensation
controls enable the boiler to respond to
outside temperatures changes and quickly
adjust the radiator output, to maintain a
constant temperature indoors.
The above diagram helps to demonstrate
how this compares to a heating system
without weather compensation – where
the boiler runs very hot then very cold as it
constantly ‘plays catch up’ to achieve the
desired room temperature.

 

[sjr56]

I am not sure where you got that wording from, but it is a very simple-minded and incomplete description of weather compensation.
It ignores the role of the room temperature sensor (not a thermostat!), and how both the outside temperature AND the inside temperature are used to control the boiler.

 

[glasgowgas]

Advanced Weather Compensation Controls
This type of boiler control is very sophisticated in that the
slope of the heating curve can be adjusted to suit not only
the householder, but also the type of building construction.
For example a very well insulated house will lose far less heat
than an older house and will not require the boiler to work so
hard when the outside temperature drops - so a flatter heating
curve will achieve the desired room temperature for such a
building. A badly insulated house will experience high heat
loss in the winter and require a steeper heating curve to
compensate.
Once again the position of the heating curve is set according
to the householder’s heat requirement in terms of personal
comfort. Vitotronic controls also feature a night set-back
function to maximise comfort and savings.
Setting the heating curve
When the advanced controls are fitted, the heating curve
setting should be selected according to the type of house.
For a well insulated new house, the curve will need to be
set at around 1.3 to 1.4. An older house, with less insulation
and single glazing, would need a curve of around 2.2 to 2.3.
This setting can be adjusted and ‘fine tuned’ by the
householder. If the temperature proves to be too high, then
the value of the curve should be lowered. If the house is
too cold in the winter months, more heat is being lost than
expected and a steeper curve (higher value) should be
selected.


For more information please visit
www.viessmann.co.uk



yeah yer probably right, what do these dingbats know about weather compensation

i`m out

 

[ob1knbxtrail]

Got aUltracom 30 hxi +Climpro RF + Weather sensor installed 1 week ago but have a problem in that the boiler does not modulate on HW only demand. Works fine on CH only. double checked wiring and can find no fault so am wondering if I have old S/W?

Thanks

 

[D_Hailsham]

have a problem in that the boiler does not modulate on HW only demand.

Why should it need to modulate when on HW only? You want the HW brought up to temp as quickly as possible, don't you? So the boiler runs at max to achieve this.

 

[ob1knbxtrail]

I think the burner should modulate to maintain the max temp of 80C on HW only. What happens is boiler does go up to max 80C as on max power with HW demand but then shuts down completely till water flow cools to around 40. Then it tries to fire on max again, then shuts down as it hits 80C within seconds. Surely it should modulate burn as it does on CH

 

[snb]

glowworm system is only designed for weather comp on heating. it purely modulateson HW.

as for the curves that need to be set for outside sensor.

change via D35
you will need to look at htg curve and choose the curve which will give about 75 flow at zero outside. but then modify the offset in either d45/46/47 (not sure which one)so that you get 50 flow at 15 degrees outside. normally i use curve 6 and then alter the offset.

 

[bw65587]

I initially had some problems with bugs in the Climapro software, which were fixed when Glow-worm replaced it free-of-charge with an updated version.

Can I ask what the Climapro problem was which the software bugs caused? Also is it the wired or wireless model?