How best to use a Worcester Digistat DT10RF Programmer and Greenstar Si Compact.

Linda32

Hello all,

I wonder if you could give me some advice please on how to use the above central heating system from a money saving point of view, or tell me that this is how it works.

We are in a two bedroom mid terraced with 6 radiators.

Currently, we are out at work during the weekday so the heating is on for an hour in the morning then from 17.00 to 22.30 at night.

The morning isn't an issue. Its the evening, the room stat is set at 18 which we find comfortable. We also have radiator valves fitted.

The issue is that the room stat shows the temperature of the house drops to about 14 degrees (when it has been very cold recently) during the day so the boiler fights for about 3 hours to reach 18 degrees before it eventually goes off. So in the mean time the house is cold and the heating is on which to me seems to defeat the object.

Obviously, using the manual overide to turn the stat up makes no difference as it still won't reach the higher temp.

It seems at the moment that having invested in an upto date boiler from our previous very old one that we have not got anywhere as still the heating is either on or off. Rather than keeping the temperature steady as we expected.

The alternative seems to me is to set the temperature on the room stat to say 16 degress and have the heating on low even when we are out.

st999

The alternative seems to me is to set the temperature on the room stat to say 16 degrees and have the heating on low even when we are out.

That is sometimes the best solution.


Also what is the temperature of the water in the radiators.


If it is too low it will take a long time to heat up the rooms

st999

Third link down, at least on my computer.




http://www.bing.com/search?q=How+best+to+use+a+Worcester+Digistat+DT10RF+Programmer+&src=IE-SearchBox&FORM=IESR02

Linda32

The display on the front of the boiler is currently showing 42.0c Eco.

Is this the water temperature? We don't heat up the water for a timed period as such, like we did with the other boiler. If we want hot water, so long as we turn the hot taps on to their fullest then we have hot water.

espresso

Linda32 wrote: »

The display on the front of the boiler is currently showing 42.0c Eco.

Is this the water temperature? We don't heat up the water for a timed period as such, like we did with the other boiler. If we want hot water, so long as we turn the hot taps on to their fullest then we have hot water.

That is the HW temp. What if the heating temp set to? The knob underneath the display:

I_have_spoken

The room with the thermostat should not have TRV on the rads, or set the heads to max.

The CH water coming from the boiler should be 65C to 70C to bring the house up to temp quickly and ensure the boiler is working efficiently

jamesd

If you have a fan, try an experiment of having that blow from the side of the radiator in the living room. This will increase the heat output of the radiator by increasing the air flow rate over it.

If that solves the problem it means that your radiator is under-sized for the heat output needed and a radiator change is one way to go to improve things. If you have a 10 radiator (drawings to illustrate) you could double the heat output by replacing it with a 22 type or more with 33, with more potential by going taller or with more piping work, wider.

Some examples from the same company:

type 10: not normally available these days
type 11 60cm wide 40cm tall: 1355 btu 397W
type 21 60cm wide 40cm tall: 2025 btu 593W
type 22 60cm wide 40cm tall: 2570 btu 753W
type 11 60cm wide 60cm tall: 1900 btu 556W
type 21 60cm wide 60cm tall: 2799 btu 820W
type 22 60cm wide 60cm tall: 3745 btu 1097W
type 22 60cm wide 70cm tall: 3952 btu 1158W
type 33 120cm wide 60cm tall: 10180? btu 2983W (different company)

So even with the same width and height you could go from 397 watts of heat output to 1097 watts by going for a deeper radiator. A type 10 would be even lower output than 397 watts.

The heat output also depends on the central heating water temperature, the hotter it is, the greater the heat output but lower water temperatures increase the chance that a condensing boiler will operate in condensing mode, saving energy and heating cost. If the temperature is set low you could try an experiment of setting it to the maximum to increase radiator heat output as another way to see whether larger radiators would help. The lowest temperature possible is likely to save most energy if you can reach comfortable temperatures.

I'm assuming that the boiler itself is capable of meeting the heat demand from all of the radiators, that is, that it's not under-sized for the heating load. If the flame is on continuously when you have the heating on that can be one indication that it is under-sized for the load. On and off periodically would be normal. But there are some variable output types which vary the amount of gas being burned and those could have the gas burning all the time at lower gas flow rate, so this isn't a perfect way to find out about this.

Linda32

I_have_spoken wrote: »

The room with the thermostat should not have TRV on the rads, or set the heads to max.

The CH water coming from the boiler should be 65C to 70C to bring the house up to temp quickly and ensure the boiler is working efficiently

The room with the thermostat is the hallway, this radiator does not have a TRV the landing radiator above this does have a TRV

It looks as if I need to turn up the CH water then.

Seronera

Linda32 wrote: »

It looks as if I need to turn up the CH water then.

I think you are on the right track. To get heat out you have to put energy in and there will be plenty of power available in the boiler. I don't think you mentioned what setting you have the CH dial on. Turn it up somewhere near Maximum and see how you get on. You can always adjust it down again but it will tell you if you are on the right track. Also suggest you manually turn room stat up to about 19 or 20C just to give the system some 'elbow room' to heat the house. Once you know what it can do you can then start to tune it for better economy, but getting warm quickly is the first target for you, so try and achieve that first.

Edit: If the boiler reads 42C on the CH setting its way too cool. Try 60-65C...