On 23/12/2012 13:36, ss wrote:
I am trying to get the best economies with an acceptable level of
comfort, so a bit of a balancing act. Using a Baxi combi boiler with 14
radiators. (some rads turned off) (house occupied 24/7)
In general terms I can take lower temps during the day but raise them at
night which I have done via the time control/stat.
Now as I can see there are 3 elements.

1. The temp controls at the boiler (low/med/high)for controlling the
water and another for the rads.
2. The thermostat on the time control box.
3. TVR valves

Is there a `best way` to adjust anything eg is it better to have a lower
temp setting at the boiler or a higher one and let the stat control the
heat.
As far as the TVR valves are concerned I have them mid point in bedrooms
etc but full on in the main lounge (where the stat is)
Short of getting uncomfortable is there a `best` set up for economy use
in general terms accepting we all have different comfort levels.


As far as hot water is concerned, if you have the hot water too hot, the
DHW HE in the boiler will scale up and so will your hot water pipes.

If you have the hot water temperature too low, you can be at risk of
catching legionnaires disease. So most hot water is set at 55°C to 60°C
to avoid either scaling or legionnaires.

With regards to the radiator water temperature, what you need to ensure
is that the returning water temperature is less than 60°C for the
condensing to take place and hence improve efficiency.

so the flow radiator water temperature should be adjusted such that
after allowing the temperature drop across the rads the returning
temperature is at say 55 °C or less.

This is where balancing the rads is very important in a condensing
boiler system.

I have all my rads adjusted to a temperature drop of 15° which means i
can have a flow output temperature of 65° and the returning temperature
is 50°C

My rads are deliberately oversized for the rooms so I can have lower
flow temperatures as that also reduces risk of burns to kids and elderly
as well as ensuring condensing as much as possible.

Radiator Balancing is easily done, there are guides in how to do it.

Regards

Stephen.