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
neo-sciliar schrieb:
I will agree with the general contractor to commit to:
- The house will be warm
- Maximum 4-5 cycles per day in winter
- Annual performance factor > 4.5 (calculated is 4.9) And that’s exactly why you get a buffer, because you expect everything that everyone wants. The difference is that you already know beforehand that the setup is not ideal. With this knowledge, you won’t even have to show up in another forum in 1-2 years asking if the consumption can be reduced by adjusting settings.
However, I argue that the cycling frequency will not be achieved with the buffer in the supply line. The question is whether this is really a problem. An expert I heard at the shopping center nearby says that modern heat pumps can handle somewhat more frequent cycling without any issues.
I also have a Vitocal. It uses ground source heat, not air source, but that shouldn’t matter for the question of whether to use a buffer or not. As far as I know, Viessmann only recommends having a small buffer tank on the return line. They even offer specific Viessmann units for this purpose. The 200-liter (53 gallons) tank on the supply line most likely does not come from Viessmann. You can try looking up planning diagrams online or ask Viessmann directly and discuss it with your heating engineer.
Everything you criticize in the opening post is completely justified. The loops are too far apart in length, distances are too large. Insist on a room-by-room heating load calculation using the guidelines you know. The buffer tank must be removed. If necessary, use ones that are passively open (without electricity). Then simply disconnect them yourself at the end.
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Daniel-Sp16 Jul 2021 22:41Is there a room-by-room demand calculation?
If necessary, you can also have a "bypass" installed with manual 3-way valves for the buffer. This way, after handover, you can easily remove the ERR and take the buffer out of operation. This will save you a lot, and the general contractor’s heating engineer still gets their buffer. The heating engineer should be able to install this for a small cost.
If necessary, you can also have a "bypass" installed with manual 3-way valves for the buffer. This way, after handover, you can easily remove the ERR and take the buffer out of operation. This will save you a lot, and the general contractor’s heating engineer still gets their buffer. The heating engineer should be able to install this for a small cost.
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