Is weather dependent really worth turning on on a worchester bosch greenstar 4000?

[Odds]

We were looking at a new boiler and the saving is small if you turn on but it is a saving
3-5% in running cost.
Up to you if you use it.
Add a few other saving strategies and maybe you could save 10% a year.
That's £200.
Bit difficult in our house as it's whacked on high 24/7, even the lemons plants are wilting!
Ha

You could try adding humidity to help them out, along with a slow soak to fill the pot with water from the base rather than top-down watering.

 

[fitzykev]

That's what the weather dependant setting does, saves having to do it manually.

I know but i am not sure it needs to come on as early as that as the house was at temp around 630am and i have it set to be at that temp for 730am. With weather dependent off as long as timing is set it will come on still. And if i set the temp directly on boiler to 56 degrees it will still modulate right?

 

[endecotp]

i just feel at a hotter temp for less time still might save money.

Your boiler manual may say something about how its efficiency varies with the flow temperature. Look for a graph.

 

[ericmark]

Do you imagine that they would include the feature if it did not work?

Good point.

With a condensing boiler, the whole idea is to have the return cool enough to allow it to do its job, but if it doesn't the boiler will still work, so it is near impossible to work out if the system is doing it job, and it is all down to how the whole system is set up, not just the weather dependent function.

EvoHome came out many years ago, followed by a whole host of systems to do the same thing, which is to set up analogue control as much as possible, often there has to be a digital on/off part, but we should aim for as much analogue as we can.

But the government did not help, the building regulations, told us we needed to have more control, but this resulted in on/off valves being added, and the house being split in a way which was rather inflexible, and resulted in the reverse to what was intended.

Basic point is the TRV is king, all the house is controlled by TRVs, but although there has been some attempts to improve them, we ended up in the main, with two controls, neither with a simple setting method, which are installed on the same radiator and need to be set to work together, the TRV and lock shield valve, the books tell us to set the lock shield with a temperature drop of say 15°C but with no way for the user to set them, the installer may have a differential thermometer, but the user does not, so the user looks at the wall thermostat marked in °C and they can understand that, so all this clever control goes out of the window.

It is not helped by where the radiators are placed, we have furniture in most rooms, but it is not placed under the windows, so placing a radiator under the window means it often has unrestricted air flow, but it is also against a cold wall, so a TRV is colder than the room.

So we look are work around methods, the electronic TRV linked to a wall thermostat or sensor, so it is controlling the room from an inside wall, and also it can be programmed, but some method is needed to tell the boiler when to run.

One room is not really enough load for the whole boiler, so although at first glance, it would seem a linked TRV in every room is the way to go, this often does not quite work out, having key rooms linked with other rooms dependent on the boiler being triggered by another room, often works out better. It means the minium output of the boiler can be transferred to rooms.

Autumn and Spring are the problem seasons, Winter the boiler can run for hours on end, and modulate as designed, but Autumn and Spring often simple not enough load to run the boiler in an efficient way.

We look at the control reports really will the boiler heat up much in 15 minutes, most boiler need to run for a couple of hours to modulate and run in an efficient mode, but if we don't need that much energy, then not much we can do.

Every home is different, I on moving in here, tried to set the wall thermostat to keep the rooms warm all day, it was located in the hall, there was not really the option to re-wire, and to use wireless, one is relying on batteries, and I have had cold days in the past where the batteries have become discharged, so I tried a sequence the idea was to try and stop a hysteresis, to be frank it did not work, it was an improvement, moving ½ºC at a time, the boiler would fire each time there was a change, but the problem was, the hall cooled to slowly, so living room was cold, even with TRV heads set to 22ºC, so today I have three main house thermostats which can fire the boiler, living room, hall, and coldest bedroom, in the main the other rooms can draw heat when required as one of the three has fired the boiler.

But to begin with, I got it wrong, and I had to add Drayton Wiser to the original Google Nest to get the control I want, so the Wiser does use batteries, but I have a back-up with my Nest, so one set of discharged batteries does not mean no heating, just the heating is not working as well as it could.

So the whole system is near enough engineering, it is not perfect, and you have to decide how far to go. Yesterday and today the central heating has been running, but up to yesterday, I have been using an oil filled radiator, as not really economical to run central heating to just heat one room. My system has 14 radiators, and 13 areas heated, now last house, completely different, as open plan, so main wall thermostat turned on 3 large radiators, one was 3 kW fan assisted, so in that house the TRVs were to stop bedrooms overheating, rather than controlling room by room. There were no TRVs down stairs, not needed in an open plan house.

Here I use oil, which is likely more expensive to gas, so I use an oil filled radiator electric powered for the small amount of heating required as Autumn approaches, last house I had a gas fire and a flue brick, so I could have used the gas fire all winter if I had wanted, the house was designed without central heating in the late 70s, idea was one gas fire was enough, the problem was it was not thermostatically controlled, or programmable, so central heating was added.

So what I am saying is there is no right or wrong, it is down to what suits you and your house, and only you can decide that.

Odd, this house a lot bigger to last one, and heating bill has gone down, as to why I don't know, moved from gas to oil, and knowing I need oil delivered likely I am more aware of what I am using, I want the tank to last the whole winter.

The back kitchen is heated in the main with the losses from the solar inverter, the front kitchen is often on the cold side, my utility room is unheated, except for heat from washer and tumble drier, seven of our rooms are rarely used, so only have back ground heating, just six rooms and hall heated in the main. Upper bathroom there is not TRV on radiator/towel rail, four radiators have mechanical TRV heads, and ten have programmable heads, and we can isolate the four mechanical TRV controlled radiators with a motorised valve.

Clearly larger systems will need more control, and smaller systems less control, so size does matter.