PELLAQUA solar heating 12 m2 struggles to provide DHW in summer

[Christophe]

Sylvain did not answer my question on the pressures of the solar circuit.

If you have the possibility (it looks like there is a valve, without lever on the solar circuit), close the solar circuit to 80-90% and see what it gives ... if that does not change anything it is internal fouling (and good luck with purging and cleaning ...) solar side so ...

[sylvain52220]

The pressure in the solar circuit is 3 bar, you can see it in the photo.
We put the pump on its maximum speed, we'll see what happens tomorrow.
For the time being, the probable explanation remains that there is a problem with the solar exchanger / tank, it remains to be seen if it is accessible.
There are two heating circuits because a ground floor (living rooms) and a floor (bedrooms) each with a heated floor.
Thanks for your help and good night!

[sylvain52220]

Sylvain did not answer my question on the pressures of the solar circuit.

If you have the possibility (it looks like there is a valve, without lever on the solar circuit), close the solar circuit to 80-90% and see what it gives ... if that does not change anything it is internal fouling (and good luck with purging and cleaning ...) solar side so ...

Hearing the pump working, you don't have the impression that the fluid is flowing badly, the flow measurement also shows that it is going well (I will have my father read the flowmeter tomorrow, but going from speed 2 at the 4, I think we will not be far from 20l / min). I'm a little afraid of making the pump suffer by closing the valve so much (it is indeed a quarter-turn valve)

[sicetaitsimple]

Well, above all, not to do both at the same time, that would be completely silly!
Leave the pump at maximum speed, note the flow when it will run, the temperature evolution, and tell us what will have happened during the day tomorrow evening (if there was a significant sun).

[Christophe]

The pressure in the solar circuit is 3 bar, you can see it in the photo.
We put the pump on its maximum speed, we'll see what happens tomorrow.
For the time being, the probable explanation remains that there is a problem with the solar exchanger / tank, it remains to be seen if it is accessible.

It was the dynamic pressure that I was asking ... but if you have a flowmeter then the question no longer arises!

There is no problem running a circulator when a valve is 100% closed ... as long as it doesn't last for months!

20 L / min is not a very high flow rate for a circulator in max position.

[Christophe]

20 L / min is not a very high flow rate for a circulator in max position.

After checking, the flow recommended by the manufacturers of solar thermal panels is 20 to 30 L / h.m²

If you have 12 m², you therefore need 25 * 12 L / h = 300 L / h or 5 L / min.

At 20 L / min, i.e. 4 times more, the hot water will probably not have time to heat up in the solar panels ... But if the solar exchanger in the tank is almost inefficient, it necessarily goes up anyway since the calories are not dissipated!

How much does the flow vary depending on the power settings of the circulator ???

This will tell you if it is blocked on the inside (cap) or the outside (limestone) ... but a priori if you already go up to 20 L / min it is not blocked.

Can you take a picture of the flowmeter?

[sylvain52220]

Can you take a picture of the flowmeter?

Hello,

At speed 4 (max): ~ 15 l / min (we read below the cursor, right?)

image000001.jpg (22.55 KIO) Viewed 2137 times

At speed 2: 8-9 l / min (can we read above the cursor?)

20200816_122644.jpg (90.05 KB) Viewed times 2137

At maximum speed, the temperature difference between the start and the arrival of the fluid was always 4 ° C. The system stopped at 11:30 am because the fluid had reached 120 ° C, the lower part of the balloon was at 40 °.

[sicetaitsimple]

At maximum speed, the temperature difference between the start and the arrival of the fluid was always 4 ° C. The system stopped at 11:30 am because the fluid had reached 120 ° C, the lower part of the balloon was at 40 °.

Good ... Disappointing, especially since if, as I said at the beginning, the measurements are representative of reality (which is not always the case), a flow X1,5 with the same deltaT would mean that the power traded was multiplied by 1,5.

And do you have any other temperature measurements of the water in the tank, apart from the lower part which was at 40 ° at the time of triggering?

Another question: with 12m2 in the Drôme in the middle of summer, with consumption only linked to DHW at this period, at least that's what I understand, you are necessarily surplus in terms of energy if there is several consecutive days of good weather once the storage is thermally "full", except for annex use such as pool heating or other. Has never been a problem before?

[sylvain52220]

There was 48 ° in the middle and at the top of the ball.

In the past, the tank actually remained hot (I believe that the max set is 82 °), I do not remember any lack of DHW, so the operation of the system had not been monitored as it is now. ..

I am almost convinced that the secondary of the solar exchanger is "dirty". I'm going to get closer to Okofen to see what we can do. On closer inspection, our Pellaqua model would not have an inspection hatch for the solar exchanger so it is not easy ...

[Christophe]

we read below the cursor, right?
do we read above the cursor?

A no it's either one or the other but not both at the same time!

At a time (bygone) on the internet we said RTFM ... In polite mode and in French it meant "Please look at the notice"

Otherwise it's a beautiful installation, having a flowmeter is rather rare!