Gas heating and Thermostat setting?

[hitman32]

Hello, everyone, I have a small question, which I ask you the problem:

I bought this summer a house with a gas heating (radiator type convector)

I immediately installed a room thermostat to limit the bill. I set 20 ° during the day and 15 ° at night

However, I ask myself a question:

Is it better after the night that I put 15 ° knowing that in the morning, the boiler will work a lot to go back to 20 °, or is it better that I put 17 ° at night so that she works less in the morning, but will work a little more at night. What do you think is the most economical solution?
thank you in advance for your answers

cordially

[Did67]

The question is simple but the answer is complicated: it depends!

It depends on the inertia of your house: that is to say, the rate at which it cools and also to which it warms itself.

The more you lower, the less calories your house will lose at night. There at least it is clear and mathematical. And contrary to a widely held and unfounded "belief", "warming up" the house in the morning will not consume more calories than if you had kept it warm without letting it cool the night before. It will consume less. We forget that at the moment of lowering, the control will stop for a while. So these calories there, obviously, it will be necessary to inject them at the time of the restart. And so there, your heating will "panic" a little ... But do not forget the gains of the night before ...

But for it to be "livable", the house must be reheated at the desired time.

And that's where inertia comes in. If your house has a lot of inertia, you can switch to "comfort" mode at 6 am and still be cold at 9 am!

The risk is then to "push" the thermostat and forget it. There, and only there, you then risk consuming more than you saved (you easily get used to one or two degrees more!).

Also know that "comfort" does not result from the only "thermal" temperature (that of the thermometer). It also depends on the temperature of the walls (walls, floors, ceilings) ...

So lowering too much, you can be "up" to 20 ° "thermal" but be cold ...

In short, lower and let the programmer: in this case, in any case you win.

But to be done in moderation by pushing jsqu'à to the limit "so that comfort does not suffer" or "not too much ...": find the minimum "acceptable" and play on the advance (to "cancel" the inertia if there is any: cut comfort mode a little early - 21 p.m. to 22:30 p.m. for example; put comfort mode back in advance (6 a.m. for 8 a.m. for example) ...

At home, with a strong inertia, I switch to night mode from 18 h and comfort mode from 4 am!

So finally, all that also refers a little to the tolerance of the occupants (put on a sweater or not?), Their age, their occupation (TV or gymtonic?), Their sex (women are more cold at the ends of the hands and feet - and it's objective: for the same reason, they have much less infarction!) ... lots of things not mathematics at all!

[hitman32]

Hello, thank you for your answer.

I ordered a usb temperature recorder and would do 2 test:

15 ° - 20 °

17 ° - 20 °

(and more test can be)

in order to see already the number of hours of operation of the boiler in the 2 cases.

in a second time I would do another test:

20 ° and 19.5 ° (the day) because I saw that my convectors have a big enough inertia. And after the boiler has been shut off by the thermostat (at 20 °) these continue to heat up to 20.5 ° the house.

So if I set it to 19.5 I should arrive safely at 20 °

[dedeleco]

When I sleep, I need to be hot, my metabolism is reduced and so I can not stand to be cold at night, while the day, increased metabolism, out at work or in the garden, the house has less need to be hot, since there is less and so I do not understand at all not to heat the night, absurd for me, because in the opposite direction of my metabolism !!!

When we sleep, the metabolism is reduced and so when I wake up I need to be very hot !!

Finally without recorder, just look how long the house is cooling down by cutting the heating, and if you need a recorder, it is likely that its thermal inertia is of the day (typical concrete).

[hitman32]

Ben in fact my house and a house on crawl space above ground (75cm)
the tower of the house consists of concrete posts. The interior is made of glass wool + honeycombed plasterboard, the internal partitions are honeycombed only

glass wool 15 cm ceiling

here is

[hitman32]

I ordered a temperature recorder and I did several experiments, here are the results:

Hello, here I am again with first results.

First of all, I explain how my mood works: It has a sensitivity of 0.5
that is, if the temperature displayed on the th is 19.5 it will heat the house until 20 ° will then stop to restart at 19

I have two experiences:

1 Experience: 19.5 daytime and 15.5 nighttime temperature (+ 0.5 for sensitivity)
Starting values:
- Temperature ext 1.4 degrees to 21h
- Temperature ext -1 degrees to 10h the next day
- Outside temperature of 8.2 degrees to 11h59

Here is the curve:



We see here that there is 6 in total at night for a total of 3h32 (not obvious on the graph but I did all my calculations with excel)
Then to reset the temperature to 20 ° C the day we set 2h47
which makes a total of heating for the night + warming up in the morning of 6h19

2 Experience: 19.5 daytime and 17.5 nighttime temperature (+ 0.5 for sensitivity)
Starting values:
- Temperature ext 3 degrees to 21h
- Temperature ext 3.4 degrees at 10h the next day
- Outside temperature of 8 degrees to 11h59

Here is the curve:



We see here that there is 7 in total at night for a total of 3h46 (against 3h32)

Then to reset the temperature to 20 ° C the day we put 1h41 (against 2h47)

which makes a total of heating for the night + warming up in the morning of 5h27 (against 6h19). We have a gain of 52min.

However the outside weather conditions were slightly more favorable for the 2 number experience than 1 number. That is why if the same climatic conditions are represented at night I will do the experiment again number1

However, it is nevertheless obvious that too much lowering the temperature at night cancels all the energy saving effects of the installation of a room thermostat.

See you soon (ptete tomorrow) for new results.

[hitman32]

and maybe I would do a 19.5 night test and 19.5 to compare (trying to get the same outdoor temperature conditions)

[dedeleco]

Some thoughts:
With this nice recording we see the cooling time constant from about 3 to 4hours to finish at 13 ° at 14 ° C in a plateau of time constant much longer than one to two days, buffer of the concrete of the house around 13 ° C, unmeasured ??? !! T hysteresis 1,5 ° C, the heating rate of the boiler much faster (2 3 times approximately) which therefore often starts the night!
You have an 1 / 2h heating and 1 cooling time !!
Less than 1 / 2h heating at the beginning of the night we go to significantly more this 1 / 2h heating at the end of the night, slow cooling of the buffer during the night from 1 to 2 ° C !!
The boiler must have a non-constant power regulated in a complex way because its speed is not exponential at all and therefore the real economy is not measurable in heating time, but only in recording gas consumption !!! (by filming the counter one image per minute !!)
The gain is not zero but seen thee buffer around 13 ° C to 14 ° C long inertia (over night) of house with outside 1 ° C about the gain is reduced in the factor in the factor (20-1) / (20-13) = 2,7 compared to that of a time constant of the whole building of 3 hours (cooling to 1 ° C exponentially d a factor e = 2,7 in 3 hours).
On the other hand, your boiler has a slightly strong power that reduces oddly above 16 ° C.
Your boiler has a complex regulation probably !!!

The house has a complex thermal structure with a large T-buffer at 1-1 / 2,7 times the difference of T with the outside (probably not very strong interior insulation with a thick tile or wall with a big heat capacity with T mean around 13 ° C ??????

To measure the gain it is necessary to record the consumption of gas (image one per minute with camera) and to see the gain by decreasing the power of the boiler ??
Finally if you start with a cold house around 1 5 ° C heating time is over the day and not 3 hours!

In fact it is possible to modulate the power of the boiler according to the strong use at cold start of the house but half in usual operation (for a better performance of the boiler)

[hitman32]

indeed the ideal would be to film the counter 1 image per second at night, but this solution is in practice quite impossible to achieve (gas meter outside in a closed box.

But thank you for your answer anyway. To evaluate my savings I can not only rely on what I presented here.

[dedeleco]

to shoot the counter 1 image per second at night

No one per minute or 5 minutes !!
Possible if camera with slow pictures.
At the limit by hand once every 10m !!