Heat produced by boiler Polling CESI

[max 01]

Hello
I installed a little over a year ago a wood pellet boiler and a CESI.
The boiler heats 2 apartments and the CESI is only used by 1 apartment.
We distribute the heating costs when we fill up with pellets by rule of 3 using calorie counters installed on each heating circuit.
There is also an electric sub-meter for the sole consumption of the boiler.

On the other hand, we do not have a calorie counter for the CESI reading which works only on circuit 1 from 7h to 8h and from 17h to 19h.

I have heard that DHW represents on average 20% of the total consumption of a boiler in winter.

Given that the DHW is produced through a CESI, that we operate the shift by the boiler only 3 hours a day and that we are only 2 people in this apartment, so we have estimated the calories needed for reading by applying only 9% in addition to the calories counted by the counter of circuit 1.

Of course this% is arbitrary but does it seem "correct" (we only take showers)?

We are not considering placing a calorie counter only
for the relief by the boiler because the cost is too important.

I would like to take a more detailed approach to calculating the calories necessary for this production of DHW in boiler backup.

Does anyone have the capacity and the time to make this estimate?

Summary:
CESI of 300 liters.

the solar EC of 150 liters is approximately at 20 ° at the start of the relief.

the EC of the 150-liter relief is approximately 30 ° when the relief is started, the maximum ° is limited to 58 °.

The shift is between 7 a.m. and 8 a.m. and then between 17 p.m. and 19 p.m.

Of course the calculation can only be done with an estimate of the quantity of hot water produced .... which we do not know but which can be estimated on the basis of 3 showers / day + sink / sink.

I think that this estimate should be made by considering the balloon of the relief only as a cumulus which should produce hot water at 58 ° with a starting temperature at 30 °.

Thank you in advance to whoever sticks to it.

[Did67]

How is the energy meter installed on circuit 1?

Or, in other words, why not have installed the energy meter on a branch common to heating circuit 1 + DHW complement circuit ???

In other words again, is there not a way, by a T placed after the energy meter, to postpone the tapping of the departure of the CESI complement so that its energy consumption is counted ???

Otherwise, the approximate calculation is simple if we have the volume of water. Attention, from experience, to the sum of small draws of hot water (if you draw a glass of hot water, it is not the volume of the glass that must be counted, but all the water flowed up to at the end of the glass; the rest will cool in the pipe).

[max 01]

Hello again Did67

Following your relevant remark concerning the positioning of the energy meter I looked more precisely at the installation.

The flow counter of the counter for circuit 1 is positioned after the 3-way valve and the circulator.
The start of the boiler reading is located upstream of the supply of circuit 2.
This whole installation is confined in a small space and it is unfortunately not a simple T which would be to be put, it would be necessary to take over the entire network ..... it was originally feasible.

This provision which would have the merit of having precise consumption per user in order to then distribute the costs is no longer feasible now because it would now require far too much work.

So I come back to estimate the calories needed to heat this hot water produced by the boiler.
You say that the approximate calculation is quite simple if we have the volume of water.

It has been estimated that we consume 250 liters of DHW at 38° / day to 2 people.

Little reminder :

CESI 300 liters
Solar hot water 150 liters
hot water by reliever 150 liters

At the start of the changeover, the water temperature is around 30 ° in the tank at the top of the CESI.

The maximum T ° is limited to 58 °.

There are 2 shift time slots (7 a.m. to 8 a.m. and 17 p.m. to 19 p.m.) so there are 2 temperature rises from 30 °.

I do not know if it is necessary to integrate into these parameters values ​​concerning the T ° of the solar hot water which fluctuates ... this is why I think that it is perhaps necessary to reason by considering the only heating by the boiler .

Can you enlighten me on this estimate of the calories needed to heat this water by the boiler?

Thank you

[dirk pitt]

personally, I will take another approach:
you want to quantify the contribution of the boiler in the production of DHW. so do not take into account the hot water consumed since a non-quantifiable part comes from the sun.
in general, the "tap" of the DHW tank reheater is taken from the primary boiler outlet circuit, ie upstream of the mixing valves.
during the hours when the changeover is triggered, I imagine that this changeover stops if the CESI setpoint temperature is reached.
therefore by multiplying the flow rate of the circulator by the input-output temperature delta of the CESI we have the power injected. (P = QxDeltaTxCm). by multiplying this power by the operating time, we have the energy.
delta T must be approximately constant once the regime is established. easy to measure by measuring the temperature of the inlet and outlet pipe (do some tests to validate that this delta is about the same)
the flow rate of the circulator can be estimated according to its characteristic curve which must be found with its reference (taking into account the speed set if it is a 3 speed)
it therefore suffices in the end to count the actual operating time of the circulator to have an approximate idea of ​​the energy injected into the CESI as part of the solar. a time meter in // on food should do the trick.

[max 01]

Your dirk pitt approach is certainly more technical than mine!

I have room to install an hour meter, I found the flow rate of the circulator set to its speed, I saw where I could put a thermometer for the T ° arrival .......

On the other hand, the pipe leaving the water heater is connected to a pipe located between the pipe leaving the heating and the expansion tank, therefore although currently reading from the boiler does not work the pipe leaving from the reading of the heater water that measures only 50cm is hot.
A thermometer will therefore not indicate the correct outlet temperature of the water heater when it is operating.

Regardless of the fact that I cannot place a thermometer on the pipe leaving the water heater, I think that the Delta T must vary according to the progress of the heating cycle (it must be more important at the beginning of the cycle-since the water is around 30 ° - only at the end of the cycle where there should be less calories needed).
What value should we take?

As I can not measure the right output temperature and therefore do the proposed calculation that I understand, I come back to ask a competent person who could take the time to try to estimate at best the amount of calories produced by the boiler
to take over from the elements I indicated in the previous message.

So I come back to estimate the calories needed to heat this hot water produced by the boiler.

Recall previous message

You say that the approximate calculation is quite simple if we have the volume of water.

It has been estimated that we consume 250 liters of DHW at 38° / day to 2 people.

Little reminder :

CESI 300 liters
Solar hot water 150 liters
hot water by reliever 150 liters

At the start of the changeover, the water temperature is around 30 ° in the tank at the top of the CESI.

The maximum T ° is limited to 58 °.

There are 2 shift time slots (7 a.m. to 8 a.m. and 17 p.m. to 19 p.m.) so there are 2 temperature rises from 30 °.

I do not know if it is necessary to integrate into these parameters values ​​concerning the T ° of the solar hot water which fluctuates ... this is why I think that it is perhaps necessary to reason by considering the only heating by the boiler .

Although this is not your approach can you "study" it?

Thank you

[dirk pitt]

in my approach, we consider that the reading, if it is done, is that the water in the balloon is below a certain value. I imagine indeed that there is a threshold to trigger this relief.
so it suffices to carry out a single experiment with temperature measurement at the inlet and outlet of the exchanger on the complete temperature rise cycle. for the experiment, you cut the heating before so as not to be influenced by the temperature coming from the tee of the heating.
actually, the exit temp will vary a little (not much in my opinion)
in short, you make a complete temperature rise cycle. you calculate the energy with the delta T (quite to average them over time) and then for the rest, we only base ourselves on the hour meter.

the method that you suggest or you consider only the total calories to produce hot water will not take into account the solar contribution or the boiler is only an additional contribution.
that would amount to considering that solar does nothing. I think that is far from the truth.
but you can calculate it easily if you want. to heat 1000 liters of water by 1 ° you need 4.18 / 3.6 = 1.16kwh. so to raise the same 1000L of 23 ° (38-15) it would take 23x1.16 = 27kwh. for only 250L, it is 4 times less or about 7kwh

[Did67]

1) With the characteristic curve of the circulator, it is still necessary to have the pressure drops in the circuit, in HMT, to deduce the flow ... According to diameter and length of the coil and baffles on the circuit ...

2) As the "hot front" rises in the CESI tank (I also have this configuration: CESI + additional boiler, with two thermometers, one at the start and the other at the return), the delta decreases ... So 5 minutes of circulation at the start of warming "deliver" a lot of calories, while 5 minutes at the end do not bring so much ...

I don't think it's linear, but I don't have a recording. I can simply testify to having seen very variable deltas ...

PS: I am taken there, but during the weekend, I will calculate the energy that represents the volume indicated, with the temperature of arrival of cold water indicated ...

[Philippe Schutt]

even simpler:
each time the boiler heats 150L from 30 ° to 58 °, or 28 °.

150x28x4186/3600 = 4884wh

then we count the number of relays

What do you think ?

[dirk pitt]

even simpler:
each time the boiler heats 150L from 30 ° to 58 °, or 28 °.

150x28x4186/3600 = 4884wh

then we count the number of relays

What do you think ?

except that it is a CESI. if the sun has heated enough, the relief does not raise anything at all, or a little or a little more, etc.

[Did67]

Let's be clear: if we want precise data, apart from moving the energy meter, no salvation.

And without intervention on the system, only the estimates with a big ladle. The "method" does not matter, whether by "evaluating the quantity of DHW consumed" or "the number of relays" ...

We could refine a little with a beast recording thermometer placed on the return of the DHW heating circuit. It would "log" the readings provided by the boiler, and if applicable, the duration of these readings ...

By multiplying by the energy consumed by a succession, we would have a less misleading approximation.

Otherwise, it's like: a succession = so many kwh; 50% or 60% is provided by solar energy, therefore 40% provided by the boiler ... therefore so and so many days of presence X so and so many kwh x 50% or 40% ...

Hard to beat...