ᐅ Insufficient solar output; how to set up three flat-plate collectors
Created on: 28 Oct 2012 14:25
C
Capone2000
Hello everyone,
We have been living in our beautiful house for several months now, which came with quite a few construction issues. We have managed to resolve most of them, but we are unsure whether our solar system is working correctly.
Here are the key details of our system:
We have a Vaillant solar system with three horizontal flat-plate collectors connected in series, one above the other. Total net surface area: 7.05m² (76 ft²)
Flow rate of the solar fluid: 2 l/min (0.53 gal/min) (the operating manual requires at least 3 l/min (0.79 gal/min), with a recommended flow of 4.6 l/min (1.22 gal/min))
Flow velocity in the circuit: 0.13 m/s (0.43 ft/s) (the manual requires a minimum of 0.4 m/s (1.31 ft/s); otherwise, the Vaillant venting system will not function properly)
Circulation pump type: Wilo RS25/7-3P; power consumption Stage 1: 62 W; Stage 2: 92 W; Stage 3: 132 W; set to Stage 2 as Stage 3 did not noticeably increase the volume flow.
According to Vaillant, this is a low-flow system and everything is fine.
But is that really the case?
We received a tip from a heating technician to check whether the system is set up for three flat-plate collectors, since factory settings often only cater to two collectors. We have searched through the manuals but could not find any setting options.
The controller is the Vaillant auroMATIC 620 model.
Despite repeated follow-ups with the plumbing company that installed the system and Vaillant, we have received no response or feedback for months.
We would greatly appreciate any insights or advice based on experience.
Good luck,
Thomas
We have been living in our beautiful house for several months now, which came with quite a few construction issues. We have managed to resolve most of them, but we are unsure whether our solar system is working correctly.
Here are the key details of our system:
We have a Vaillant solar system with three horizontal flat-plate collectors connected in series, one above the other. Total net surface area: 7.05m² (76 ft²)
Flow rate of the solar fluid: 2 l/min (0.53 gal/min) (the operating manual requires at least 3 l/min (0.79 gal/min), with a recommended flow of 4.6 l/min (1.22 gal/min))
Flow velocity in the circuit: 0.13 m/s (0.43 ft/s) (the manual requires a minimum of 0.4 m/s (1.31 ft/s); otherwise, the Vaillant venting system will not function properly)
Circulation pump type: Wilo RS25/7-3P; power consumption Stage 1: 62 W; Stage 2: 92 W; Stage 3: 132 W; set to Stage 2 as Stage 3 did not noticeably increase the volume flow.
According to Vaillant, this is a low-flow system and everything is fine.
But is that really the case?
We received a tip from a heating technician to check whether the system is set up for three flat-plate collectors, since factory settings often only cater to two collectors. We have searched through the manuals but could not find any setting options.
The controller is the Vaillant auroMATIC 620 model.
Despite repeated follow-ups with the plumbing company that installed the system and Vaillant, we have received no response or feedback for months.
We would greatly appreciate any insights or advice based on experience.
Good luck,
Thomas
B
Bauexperte30 Oct 2012 19:11Hello €uro,
This is not about reviewing what has already happened (which was bad enough) or what might have gone wrong beforehand... I myself have asked the user to share their experience here in the forum. Hopefully (perhaps naively or unfortunately without results—if it goes really badly) to get a response from the very well-known heat generator manufacturer who invests heavily in advertising.
Some criticized suppliers respond here; they also take action—and often a mutually satisfactory solution is found.
I’m not making any progress—do you have similar cases from the past or any ideas? Possibly a starting point...?
Best regards
€uro schrieb:
Usually ....
This is not about reviewing what has already happened (which was bad enough) or what might have gone wrong beforehand... I myself have asked the user to share their experience here in the forum. Hopefully (perhaps naively or unfortunately without results—if it goes really badly) to get a response from the very well-known heat generator manufacturer who invests heavily in advertising.
Some criticized suppliers respond here; they also take action—and often a mutually satisfactory solution is found.
I’m not making any progress—do you have similar cases from the past or any ideas? Possibly a starting point...?
Best regards
Hello construction expert,
However, it is important to clearly differentiate! Manufacturers are often quickly and usually hastily blamed when something "doesn’t work." Often wrongly, but in some cases justified. A manufacturer is neither a system planner nor an installer!!!! Most faults or deficiencies are rooted here!
As a rule, the manufacturer is not the contracting party, but a general contractor (GC)/main contractor or a heating or system builder. If something essential (planning/dimensioning/execution) was neglected there, it is not the manufacturer’s fault. It would be a courtesy for the manufacturer to respond, for which there is likely little time available! The contracting party is responsible for guarantee and warranty of the "complete installation," while the manufacturer only comes into play afterward together with the installer when it is about actual device defects.
Anyone who cannot handle manufacturer specifications should reconsider! GCs/main contractors are not blameless here. They order x devices from manufacturer y because they are cheap, then push them on the naïve building owners without considering whether this is truly economically sensible for them or not! This is possible, as energy efficiency or consumption costs are not part of the contract.
Anyone needing information on what to include in a GC/main contractor contract regarding this can get in touch.
If in this case the manufacturer requires an optimal flow of xy, the planner or installer must ensure this, otherwise it is a defect!!!
Even the original poster’s description already shows deficiencies here!
I only specify devices from manufacturers who provide me with all necessary data, such as performance curves and technical specifications. Those who rely solely on marketing gimmicks are usually found at the GC/main contractor level.
Best regards
NB: The best advice to give to building owners is to take the system technology out of the GC/main contractor contract and assign it externally after prior planning/dimensioning by an external expert! Alternatively, the GC/main contractor contract should be “upgraded” to prevent any problems!
Bauexpert schrieb:At least it’s an attempt!
... I personally asked the user to speak up here in the forum, hoping (perhaps naively or unfortunately without result – in the worst case) to get a response from the very well-known heat generator manufacturer who invests heavily in advertising.
However, it is important to clearly differentiate! Manufacturers are often quickly and usually hastily blamed when something "doesn’t work." Often wrongly, but in some cases justified. A manufacturer is neither a system planner nor an installer!!!! Most faults or deficiencies are rooted here!
As a rule, the manufacturer is not the contracting party, but a general contractor (GC)/main contractor or a heating or system builder. If something essential (planning/dimensioning/execution) was neglected there, it is not the manufacturer’s fault. It would be a courtesy for the manufacturer to respond, for which there is likely little time available! The contracting party is responsible for guarantee and warranty of the "complete installation," while the manufacturer only comes into play afterward together with the installer when it is about actual device defects.
Anyone who cannot handle manufacturer specifications should reconsider! GCs/main contractors are not blameless here. They order x devices from manufacturer y because they are cheap, then push them on the naïve building owners without considering whether this is truly economically sensible for them or not! This is possible, as energy efficiency or consumption costs are not part of the contract.
Anyone needing information on what to include in a GC/main contractor contract regarding this can get in touch.
If in this case the manufacturer requires an optimal flow of xy, the planner or installer must ensure this, otherwise it is a defect!!!
Even the original poster’s description already shows deficiencies here!
I only specify devices from manufacturers who provide me with all necessary data, such as performance curves and technical specifications. Those who rely solely on marketing gimmicks are usually found at the GC/main contractor level.
Bauexpert schrieb:See above!
... - Do you have similar cases from the past - any ideas? Possibly a starting point ... ?
Best regards
NB: The best advice to give to building owners is to take the system technology out of the GC/main contractor contract and assign it externally after prior planning/dimensioning by an external expert! Alternatively, the GC/main contractor contract should be “upgraded” to prevent any problems!
B
Bauexperte31 Oct 2012 12:15Hello €uro,
I completely agree with you! It was never my intention to blame the manufacturer – what I aim for is that all parties involved, whether plumbing experts or manufacturer representatives, come together to find a solution in the best interest of the homeowners.
Currently, it is obvious that the “fault” has not been identified. According to the plumbing company, the measured values correspond to the installed system – yet the system does not operate smoothly. Both the master plumber and a technician from the manufacturer’s side have been on site several times and searched for possible sources of error. Always without success, and unfortunately, to this day, the homeowners are left alone with their faulty system. In my opinion, this cannot be the answer!
Therefore, the attempt is being made to raise public awareness and initiate a change of mindset through this approach. Who takes action and why, or whether additional costs arise, is initially secondary – after all, warranty applies on the one hand, and liability applies in the case of faulty calculations on the other. What matters most is that the homeowners ultimately have a functioning system.
Against this background, it seems only logical to me that finding a solution is also in the manufacturer’s interest and that they will leverage their market presence to do so.
Best regards
€uro schrieb:
However, one should clearly differentiate! Very quickly, often hastily because it seems so simple, manufacturers are blamed when something does not “work.” Often completely unjustified, but in some cases quite justified. ....
I completely agree with you! It was never my intention to blame the manufacturer – what I aim for is that all parties involved, whether plumbing experts or manufacturer representatives, come together to find a solution in the best interest of the homeowners.
Currently, it is obvious that the “fault” has not been identified. According to the plumbing company, the measured values correspond to the installed system – yet the system does not operate smoothly. Both the master plumber and a technician from the manufacturer’s side have been on site several times and searched for possible sources of error. Always without success, and unfortunately, to this day, the homeowners are left alone with their faulty system. In my opinion, this cannot be the answer!
Therefore, the attempt is being made to raise public awareness and initiate a change of mindset through this approach. Who takes action and why, or whether additional costs arise, is initially secondary – after all, warranty applies on the one hand, and liability applies in the case of faulty calculations on the other. What matters most is that the homeowners ultimately have a functioning system.
Against this background, it seems only logical to me that finding a solution is also in the manufacturer’s interest and that they will leverage their market presence to do so.
Best regards
Hello construction expert,
Falsely optimistic calculations of solar thermal systems affect not only an efficiency rating defined on paper but also consistently and permanently the homeowner’s wallet. Anyone who feels compelled to hold back here does not know what they are giving away, but have paid dearly for it.
Best regards
Bauexpert schrieb:The contractor assigned to the homeowner should primarily take responsibility here!
- come together at the table and work out a solution in the interest of the homeowners.
Bauexpert schrieb:What exactly is the fault? What does it mean that the system is not operating “smoothly”? Which parameters is this based on? The fact is that the optimal mass flow rate required by the manufacturer is not being reached. Period! If the installer cannot guarantee this, it is their problem and liability. The client should not be burdened by this. On the contrary, they can claim financial losses from the contractor!
...Currently, the “fault” cannot be found. According to the plumbing company, the measured values correspond to the installed system – yet the system is still not operating “smoothly.”
Bauexpert schrieb:How blind can all of them be? The contractor has not even disputed the economic outcome but only the compliance with the manufacturer’s specifications!!!!
...Both the plumbing company foreman and a technician from the manufacturer’s side have been on site several times searching for potential causes of error.
Bauexpert schrieb:Then they should stick to their contract partner and put sustained pressure on them!
...Always without results and unfortunately, to this day, the homeowners are left alone with their faulty system.
Falsely optimistic calculations of solar thermal systems affect not only an efficiency rating defined on paper but also consistently and permanently the homeowner’s wallet. Anyone who feels compelled to hold back here does not know what they are giving away, but have paid dearly for it.
Bauexpert schrieb:Whoever turns out to be a novice must eventually pay the price for it!
...In my opinion, this must not be the solution to the mystery!
Bauexpert schrieb:What exactly is a properly functioning system?
...– after all, warranty applies on the one hand and on the other hand liability in the case of faulty calculations; the main priority is that the homeowners ultimately have a properly functioning system.
Best regards
M
Micha&Dany1 Nov 2012 07:18Hello building expert,
I can’t really judge the situation from a distance and I’m not very familiar with solar thermal systems, but I did have one idea (though it’s probably already been checked):
Is the pump operating single-phase at 230V, or is it a three-phase 400V pump?
I once had a similar issue with a much too low flow rate in my system, and increasing the speed didn’t help. Eventually, I realized that although the pump was connected correctly, the lab had a left-handed rotation of the phase sequence. After switching the rotation to right-handed - miraculously - I got the expected flow rate.
@Euro: You are absolutely right with your points - but “would have,” “should,” and “must” don’t really help the homeowner! The homeowner may (from your perspective) have made a mistake (I myself sometimes do when I’m not familiar with a topic), and I believe they have understood that now - but what matters now is solving the situation as effectively as possible. So either you have a *helpful* idea based on your experience, then please share it with us poor, uninformed people, or just say that you don’t have any suggestions either...
Regards,
Micha
I can’t really judge the situation from a distance and I’m not very familiar with solar thermal systems, but I did have one idea (though it’s probably already been checked):
Is the pump operating single-phase at 230V, or is it a three-phase 400V pump?
I once had a similar issue with a much too low flow rate in my system, and increasing the speed didn’t help. Eventually, I realized that although the pump was connected correctly, the lab had a left-handed rotation of the phase sequence. After switching the rotation to right-handed - miraculously - I got the expected flow rate.
@Euro: You are absolutely right with your points - but “would have,” “should,” and “must” don’t really help the homeowner! The homeowner may (from your perspective) have made a mistake (I myself sometimes do when I’m not familiar with a topic), and I believe they have understood that now - but what matters now is solving the situation as effectively as possible. So either you have a *helpful* idea based on your experience, then please share it with us poor, uninformed people, or just say that you don’t have any suggestions either...
Regards,
Micha
Micha&Dany schrieb:
....@Euro: You are absolutely right in your statements — but “would have,” “should,” and “could” don’t help the homeowner! The homeowner may have made a mistake (from your perspective) .... However, the system was not installed or designed by the homeowner; someone else was paid for this and therefore is obligated to deliver a defect-free product! Micha&Dany schrieb:
....So either you have a *helpful* idea based on your experience, .... Or is the homeowner now supposed to try fixing it themselves through remote forum diagnosis? Best regards
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