ᐅ Underfloor Heating and Air-to-Water Heat Pump in New Construction: Am I Inviting Problems?
Created on: 16 Jul 2021 18:03
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neo-sciliar
Hello everyone,
I have posted here several times before and have received a lot of really helpful advice. I have learned a lot. But reality is catching up with me: we are currently building a new house, and because of the builder, we are tied to a specific heating installer (alternatively, we could choose our own, but then we would have to find all the other tradespeople ourselves, including electrical, plumbing, and everything that follows). Since this is already contractually agreed, the matter is settled.
In my opinion, based on what I have learned here, he is doing everything "wrong":
1.) Viessmann air-to-water heat pump Vitocal 222-S with 7.2 kW, although the calculation shows only 5.5 kW needed
2.) Buffer tank to enable flow rate and prevent short cycling
3.) ERRs (electronic room regulators) in the main rooms (he wanted ERRs in all rooms, I limited it to the important ones)
4.) I saw on site today: heating circuits of varying lengths—from 30 m (98 feet) up to 120 m (394 feet). At least the spacing of the underfloor heating pipes is adjusted according to the room requirements, from 5 cm (2 inches) in the bathroom to 30 cm (12 inches) in the bedroom
Now my questions: Am I setting myself up for real problems, or is all this actually irrelevant (as he claims) and the system will still run properly? By properly I mean that a) it heats well and b) electricity consumption stays within reasonable limits (seasonal performance factor > 4.5, calculated at 4.9).
Best regards, Andreas
I have posted here several times before and have received a lot of really helpful advice. I have learned a lot. But reality is catching up with me: we are currently building a new house, and because of the builder, we are tied to a specific heating installer (alternatively, we could choose our own, but then we would have to find all the other tradespeople ourselves, including electrical, plumbing, and everything that follows). Since this is already contractually agreed, the matter is settled.
In my opinion, based on what I have learned here, he is doing everything "wrong":
1.) Viessmann air-to-water heat pump Vitocal 222-S with 7.2 kW, although the calculation shows only 5.5 kW needed
2.) Buffer tank to enable flow rate and prevent short cycling
3.) ERRs (electronic room regulators) in the main rooms (he wanted ERRs in all rooms, I limited it to the important ones)
4.) I saw on site today: heating circuits of varying lengths—from 30 m (98 feet) up to 120 m (394 feet). At least the spacing of the underfloor heating pipes is adjusted according to the room requirements, from 5 cm (2 inches) in the bathroom to 30 cm (12 inches) in the bedroom
Now my questions: Am I setting myself up for real problems, or is all this actually irrelevant (as he claims) and the system will still run properly? By properly I mean that a) it heats well and b) electricity consumption stays within reasonable limits (seasonal performance factor > 4.5, calculated at 4.9).
Best regards, Andreas
Tolentino schrieb:
What’s important is the return flow—that the buffer tank doesn’t heat the underfloor heating first and then something else afterward, and that it’s not oversized. Thanks for putting my thoughts into words. Yes, that’s exactly what I meant. However, I don’t think the heating engineer will do it that way, since he would have reasoned through the other points better if he had. Ideally, no buffer tank would be used, despite the ERRs.
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neo-sciliar16 Jul 2021 20:08Tolentino schrieb:
I wouldn’t generalize that so broadly. What’s important is the return flow—meaning the buffer tank shouldn’t be heated first, followed by the underfloor heating from the buffer, and it also shouldn’t be oversized.
If the buffer tank is several hundred liters large and placed on the supply side, that’s really problematic.
Regarding not being able to change it: If the buffer is on the supply side and you can’t convince the heating engineer to do it differently, you could try what I accidentally managed: ask so many questions and keep insisting until the heating engineer gives up in frustration. Then it’s not your fault, you can find your own specialist (or the general contractor must find an alternative), but basically the general contractor can’t require you to organize all the following trades on your own.
But be cautious, this can cause significant cost increases and delays. So this is only a suggestion as a last resort... Besides, I would also need an external energy consultant to get the confirmation for the KfW. With the extra costs, I might as well replace the whole heating system and install a new one...
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neo-sciliar16 Jul 2021 20:11The buffer tank should be connected to the supply line with 200 liters (53 gallons). This is the specification from Viessmann.
I will agree with the general contractor to fix the following:
- The house will be warmed up
- Maximum 4-5 cycles per day in winter
- Annual performance factor (seasonal efficiency) > 4.5 (calculated as 4.9)
I will agree with the general contractor to fix the following:
- The house will be warmed up
- Maximum 4-5 cycles per day in winter
- Annual performance factor (seasonal efficiency) > 4.5 (calculated as 4.9)
neo-sciliar schrieb:
The buffer tank is supposed to have 200 liters (53 gallons) on the supply side. That’s the specification from Viessmann.Terrible 😡 You can understand the installers if manufacturers give instructions like that.neo-sciliar schrieb:
I will agree with the general contractor to hold him to these points:
- The house gets warm
- Maximum 4-5 cycles per day in winter
- Annual performance factor > 4.5 (calculated is 4.9)Sounds like a clause he probably won’t accept, but good luck and please keep us updated!N
neo-sciliar16 Jul 2021 20:23Tolentino schrieb:
Terrible 😡 You can understand the installers when manufacturers set such requirements.
Sounds like a clause he probably won’t accept, but good luck and please keep us updated!The question is, what exactly is the general contractor committing to when selling a house with a heating system, providing an energy demand calculation, and stating an annual performance factor of 4.9 in order to qualify for BAFA funding.The annual performance factor is just a rough estimate and doesn’t really say much. The energy demand calculation is the same.
Has he contractually committed to you that certain consumption values will be met? I doubt it, because ultimately it depends on your heating habits.
If I were you, I would try to switch to a manufacturer that includes a buffer in the return flow (Vaillant, for example, does this with the Arotherm plus 75/6). Maybe your heating engineer can still implement that.
Otherwise, maybe consider my emergency fallback option...
Has he contractually committed to you that certain consumption values will be met? I doubt it, because ultimately it depends on your heating habits.
If I were you, I would try to switch to a manufacturer that includes a buffer in the return flow (Vaillant, for example, does this with the Arotherm plus 75/6). Maybe your heating engineer can still implement that.
Otherwise, maybe consider my emergency fallback option...
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