Our planning is becoming more concrete now, and the architect is obtaining initial quotes for the trades. This includes a quote for the heating system, and I’m unsure how to evaluate it. I have no idea whether the offered system is correctly sized, whether the price is justified, or if there might be a much better alternative.
We definitely want to install an air-to-water heat pump with an outdoor unit. If the budget allows, we would also like to install a photovoltaic system with battery storage right away; if not, this will definitely happen later. I assume this needs to be taken into account when planning the heating system. The house will have a living area of about 155 sqm (1,670 sqft) over two full floors, all underfloor heating, and will be occupied by four people. What else should be considered regarding the heating system?
The first quote is as follows:
Buderus air-to-water heat pump package WLW196i.2-6 AR with heat pump manager for outdoor installation, heating capacity 7.3 kW, immersion heater, 190-liter hot water storage tank, connection accessories, circulation pump, pump group for heating and domestic hot water operation, heating circuit connection set, boiler safety set, cap valve, 120-liter buffer tank, diaphragm expansion vessel, circulation pump, shut-off valve and piping, including 8m (26 ft) of supply line between outdoor and indoor units through builder-installed conduit, heat pump prepared for cooling with humidity sensor and dew point sensor, supply and installation: €19,468.30.
Additionally, of course, all preparations for the underfloor heating, insulation, controls, etc.
This raises a lot of questions for me. Is this a good system? Is the heating capacity properly sized? Is the hot water storage tank correctly sized? Is the buffer tank appropriate? Is the price reasonable? When I search for the same system on Google, I find offers under €12,000, but of course, I don’t know if these include everything listed above and whether such offers are truly comparable.
I would like to better understand what to watch out for and how to proceed. This trade is one of the bigger and more important items, where it’s easy to spend too much or choose the wrong option.
We definitely want to install an air-to-water heat pump with an outdoor unit. If the budget allows, we would also like to install a photovoltaic system with battery storage right away; if not, this will definitely happen later. I assume this needs to be taken into account when planning the heating system. The house will have a living area of about 155 sqm (1,670 sqft) over two full floors, all underfloor heating, and will be occupied by four people. What else should be considered regarding the heating system?
The first quote is as follows:
Buderus air-to-water heat pump package WLW196i.2-6 AR with heat pump manager for outdoor installation, heating capacity 7.3 kW, immersion heater, 190-liter hot water storage tank, connection accessories, circulation pump, pump group for heating and domestic hot water operation, heating circuit connection set, boiler safety set, cap valve, 120-liter buffer tank, diaphragm expansion vessel, circulation pump, shut-off valve and piping, including 8m (26 ft) of supply line between outdoor and indoor units through builder-installed conduit, heat pump prepared for cooling with humidity sensor and dew point sensor, supply and installation: €19,468.30.
Additionally, of course, all preparations for the underfloor heating, insulation, controls, etc.
This raises a lot of questions for me. Is this a good system? Is the heating capacity properly sized? Is the hot water storage tank correctly sized? Is the buffer tank appropriate? Is the price reasonable? When I search for the same system on Google, I find offers under €12,000, but of course, I don’t know if these include everything listed above and whether such offers are truly comparable.
I would like to better understand what to watch out for and how to proceed. This trade is one of the bigger and more important items, where it’s easy to spend too much or choose the wrong option.
W
WilderSueden30 Sep 2023 20:00xMisterDx schrieb:
The claim that electricity won’t get cheaper is a bold statement that is heard more and more often, but is not supported by any evidence. Well, the plan is to electrify everything currently running on fossil fuels within the next 1–2 decades. At the same time, the existing fossil fuel power supply is intended to be almost completely replaced. While sun and wind don’t issue bills, the installations themselves do cost money. You often tell us how photovoltaic systems can’t be profitable at 4% interest. On top of that, grid-scale storage (which is significantly more expensive than a pile of coal sitting next to a power plant) and lots of new high- and extra-high-voltage lines need to be financed at the same 4% interest rate. By the way, the equity used for this can be charged at 7% interest to your network fees.
So… nothing is actually proven, and soon we’ll all be getting electricity in the green wonderland at 10c/kWh.
B
Benutzer 100130 Sep 2023 20:38xMisterDx schrieb:
The claim that electricity will not get cheaper is a bold statement that is being heard more and more often but is not supported by any evidence.
When the heating system becomes 10, 15, or 20 thousand euros more expensive due to partly absurd requirements like a maximum supply temperature of 25°C (77°F), when will you recover those costs? You have to advance the money first... And once again, you prove that you should sometimes just not comment on certain topics.
Every modern heat pump can reach a supply temperature of 25°C (77°F). The additional costs involved are for roughly 200 meters (650 feet) more piping and the technician installing it, so approximately 2 to maybe 3 hours of work.
That’s nowhere near 10,000 euros.
By the way, the increase in electricity prices is simply due to the fact that the currently burned resources are limited and we also have to import them from abroad. The only positive aspect is that it forces us to think hard and maybe, in a few years, come up with a groundbreaking invention.
Offtopic schrieb:
The spacing of the pipes must nowhere exceed 10cm (4 inches) in the bathroom; the walls are mandatory, and the maximum pipe length is 80m (260 feet)A smaller pipe spacing is necessary for the heating system to operate at a lower flow temperature. Is that correct?
Hello,
(Almost) correct. With a smaller pipe spacing, your heating system CAN run at a lower supply temperature. Essentially, with closer spacing, you have more pipe length (= “radiators”). This means you can manage with a smaller temperature difference.
Where the optimum lies is highly debated. In this forum, the mantra used to be a maximum 30°C (86°F) supply temperature, but now I see that 25°C (77°F) has become the new trend.
Basically, it is true that a lower supply temperature results in higher efficiency for the heat pump. However, this comes with significantly more pipe length and therefore flow resistance, which your pump must overcome. On top of that, you may face considerably higher investment costs due to more heating circuits, and so on.
Best regards,
Andreas
Karlsson schrieb:
A smaller pipe spacing is necessary for the heating system to operate at a lower supply temperature. Did I understand that correctly?
(Almost) correct. With a smaller pipe spacing, your heating system CAN run at a lower supply temperature. Essentially, with closer spacing, you have more pipe length (= “radiators”). This means you can manage with a smaller temperature difference.
Where the optimum lies is highly debated. In this forum, the mantra used to be a maximum 30°C (86°F) supply temperature, but now I see that 25°C (77°F) has become the new trend.
Basically, it is true that a lower supply temperature results in higher efficiency for the heat pump. However, this comes with significantly more pipe length and therefore flow resistance, which your pump must overcome. On top of that, you may face considerably higher investment costs due to more heating circuits, and so on.
Best regards,
Andreas
In the past, a buffer tank was necessary with non-modulating heat pumps to prevent constant cycling. The heat pump would raise the water temperature higher than actually needed, and only enough water was drawn from the buffer to reach the target supply temperature.
If the heat pump can modulate, this is generally no longer necessary for underfloor heating. However, since the building energy regulation unfortunately requires individual room controllers (ERR) for heating in every room, many manufacturers recommend a small buffer tank. This prevents the heat pump from running without load when there is a general heating demand (e.g., actual temperature drops below target temperature) but the ERRs are all fully closed throughout the house, which would cause the compressor to cycle rapidly and not be properly lubricated (minimum runtime of 5 minutes is required or specified).
Solution: Simply keep the ERRs always open, or better yet, omit them altogether (exemption required).
If the heat pump can modulate, this is generally no longer necessary for underfloor heating. However, since the building energy regulation unfortunately requires individual room controllers (ERR) for heating in every room, many manufacturers recommend a small buffer tank. This prevents the heat pump from running without load when there is a general heating demand (e.g., actual temperature drops below target temperature) but the ERRs are all fully closed throughout the house, which would cause the compressor to cycle rapidly and not be properly lubricated (minimum runtime of 5 minutes is required or specified).
Solution: Simply keep the ERRs always open, or better yet, omit them altogether (exemption required).
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