ᐅ Heat pump LWZ 403 Sol: high supply and return temperatures with solar thermal system. Underfloor heating system is not working...
Created on: 10 Apr 2023 21:23
P
Phansol
Hello dear forum,
When our LWZ 403 Sol solar thermal system is active, the underfloor heating does not seem to work properly – at least the heating circuit pump does not appear to run.
(Room temperature 18.6°C (65.5°F))
Flow temperature: 58.7°C (137.7°F) (normally, of course, much lower, but this fits since the hot water is being heated intensely)
Return temperature: 54.6°C (130.3°F)
Setpoint HK1: 25.2°C (77.4°F)
Actual value HK1: 59°C (138.2°F)
Setpoint HK2: 25.3°C (77.5°F)
Actual value HK2: 59.2°C (138.6°F)
The heating circuit pump does not run at all during the day as long as the sun is shining and the temperatures are high enough to charge the domestic hot water (max. 65°C (149°F)).
Since the actual temperatures of the heating circuits are so high, the pump probably does not start either?! What could be the problem here?
When our LWZ 403 Sol solar thermal system is active, the underfloor heating does not seem to work properly – at least the heating circuit pump does not appear to run.
(Room temperature 18.6°C (65.5°F))
Flow temperature: 58.7°C (137.7°F) (normally, of course, much lower, but this fits since the hot water is being heated intensely)
Return temperature: 54.6°C (130.3°F)
Setpoint HK1: 25.2°C (77.4°F)
Actual value HK1: 59°C (138.2°F)
Setpoint HK2: 25.3°C (77.5°F)
Actual value HK2: 59.2°C (138.6°F)
The heating circuit pump does not run at all during the day as long as the sun is shining and the temperatures are high enough to charge the domestic hot water (max. 65°C (149°F)).
Since the actual temperatures of the heating circuits are so high, the pump probably does not start either?! What could be the problem here?
Thank you for your reply!
I appreciate any help or ideas 🙂
Actually, I started getting into FHEM after I noticed these short compressor starts and wanted to understand what the heat pump is doing... So yes, I’ve witnessed it several times live 🙁
The compressor briefly jerks (turns on, starts, and honestly switches off after about a second or less, then stays off for a while until the same thing happens again).
How can I best exclude a hydraulic short circuit? ERR is deactivated in almost all rooms (except one), and the flow seems to be there at least according to the underfloor heating manifolds, as the floors warm up measurably. Even if I close all the rooms with ERR (which was the case with the previous owners), the hallways and bathrooms are always heated – that alone should allow some flow.
However, I’ve also considered that something might not be 100% right with the heating pump; it makes a noticeable whining noise and maybe the water sometimes doesn’t move away quickly enough? (Could this be a short circuit?!)
What can I check or do with the non-return valve (ÜSV)?
I think the compressor run time was actually more coincidence (maybe it was colder outside temperature, not enough heat from the collector, so the compressor kicked in).
What do you mean by I and P values?
Currently set at the default 30/70 setting.
Thanks for the pointer to the forum, I’ll definitely check it out!
I appreciate any help or ideas 🙂
KingJulien schrieb:
What do you mean by the compressor running for 1 second? Do you mean each time the integral resets, it jumps? Seen live?
Actually, I started getting into FHEM after I noticed these short compressor starts and wanted to understand what the heat pump is doing... So yes, I’ve witnessed it several times live 🙁
The compressor briefly jerks (turns on, starts, and honestly switches off after about a second or less, then stays off for a while until the same thing happens again).
KingJulien schrieb:
Can you rule out a hydraulic short circuit? What about ERR and the non-return valve (ÜSV)?
How can I best exclude a hydraulic short circuit? ERR is deactivated in almost all rooms (except one), and the flow seems to be there at least according to the underfloor heating manifolds, as the floors warm up measurably. Even if I close all the rooms with ERR (which was the case with the previous owners), the hallways and bathrooms are always heated – that alone should allow some flow.
However, I’ve also considered that something might not be 100% right with the heating pump; it makes a noticeable whining noise and maybe the water sometimes doesn’t move away quickly enough? (Could this be a short circuit?!)
What can I check or do with the non-return valve (ÜSV)?
KingJulien schrieb:
Does the compressor always run only as long as the solar pump? Or is that just coincidence?
What are your I and P values set to?
I think the compressor run time was actually more coincidence (maybe it was colder outside temperature, not enough heat from the collector, so the compressor kicked in).
What do you mean by I and P values?
KingJulien schrieb:
Are you running 100% return flow control?
Currently set at the default 30/70 setting.
Thanks for the pointer to the forum, I’ll definitely check it out!
KingJulien25 Apr 2023 08:22Okay, I just saw that you joined the HTD forum, very nice.
And Bignose, who owns an older air-to-water heat pump (forget my question about the P component – you have an ON/OFF compressor), also chimed in right away. He has thoroughly dealt with his heating system, has the basic knowledge, and explains things well, perfect! 🙂
To me, this sounds like some kind of error; you usually can’t generate a half-second Vd cycle just by adjusting settings, I would say.
If it were due to any safety shutdowns, there should be an error message every time.
Somehow, it seems like a release parameter for the Vd suddenly disappears or is only checked at startup. But that’s just speculation.
If I had to guess, I would say that some sensor measurement is faulty or unstable and sometimes works properly.
Well, since you’re now in much more competent hands, I’ll just follow along with interest “over there” and look forward to the solution.
And I hope you don’t need a Stiebel Eltron KD – they supposedly have, at least here, absolutely ridiculous waiting times.
And Bignose, who owns an older air-to-water heat pump (forget my question about the P component – you have an ON/OFF compressor), also chimed in right away. He has thoroughly dealt with his heating system, has the basic knowledge, and explains things well, perfect! 🙂
To me, this sounds like some kind of error; you usually can’t generate a half-second Vd cycle just by adjusting settings, I would say.
If it were due to any safety shutdowns, there should be an error message every time.
Somehow, it seems like a release parameter for the Vd suddenly disappears or is only checked at startup. But that’s just speculation.
If I had to guess, I would say that some sensor measurement is faulty or unstable and sometimes works properly.
Well, since you’re now in much more competent hands, I’ll just follow along with interest “over there” and look forward to the solution.
And I hope you don’t need a Stiebel Eltron KD – they supposedly have, at least here, absolutely ridiculous waiting times.
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