ᐅ Heating System for New Build (Heat Pump + Stove + Solar)

Created on: 24 Dec 2017 08:58
B
bau_name
Hello everyone,

I would like to introduce myself briefly. We started building a new single-family house five years ago. We moved in about 2.5 years ago.

Unfortunately, after the first few weeks, we had to part ways with the architect and construction management, as their services (planning, etc.) were a disaster, and some of the craftsmen were far from professional (just my personal opinion).

But this is not meant to be a story about our struggles; by now, we are living very satisfactorily in our home.

However, we plan to build again in the near future. To avoid going through the same issues, we want to form our own opinion as thoroughly as possible beforehand.

Now, onto the topic:

Heat pump
Water-circulating stove (to provide support during cold temperatures)
No solar panels (energy saving regulations are met)
Heating load approximately 7000 kWh per year excluding hot water
Flow temperature 26-32°C (79-90°F), temperature spread is 5°C (9°F)
Room volume approximately 600 m³ (21,200 ft³)

These values are based on our current house; the new house will be built almost the same but possibly with better insulation. So I think it can be used as a reference.

Example: At 0°C (32°F) outside and 23°C (73°F) inside, we have a flow temperature of 30°C (86°F) and a return temperature of 25°C (77°F), which equals a 5°C (9°F) spread.

In summary:

- The heat pump should be able to heat and cool the house independently.
- The concrete ceiling should be actively cooled (down to the dew point), possibly also the floor heating.
- The water-circulating stove is intended to provide supplementary heating and create a cozy atmosphere.
- Solar panels are not to be installed (optional).

I have drawn a simple schematic with two storage tanks (1000-liter buffer / 300-liter domestic hot water tank).

How it works:

- Normally / summer, the heat pump heats the domestic hot water tank to 50°C (122°F), starting at a certain time (yellow).
- When the stove is turned on, it first heats the domestic hot water tank via the lower heat exchanger and then cools down the buffer tank (red).
- When the stove is off, water from the buffer tank is circulated until the domestic hot water tank reaches 60°C (140°F) or the same temperature as the buffer (blue).
- Solar panels could possibly be connected to the upper heat exchanger of the domestic hot water tank (brown). Additionally, the buffer tank might also be heated via the lower heat exchanger.
- If the domestic hot water tank is cold, the stove is off, and hot water is needed quickly, the heat pump switches on and an electric heating element in the domestic hot water tank supports heating. Otherwise, heating is controlled normally by the heat pump according to the schedule.
- The underfloor heating and ceiling heating are supplied by the heat pump or via the buffer tank.

The control system is very simple and would be managed by a programmable controller. Also, there are few components, which reduces potential failures or troubleshooting complexities.

I do not want a combined unit / combined storage tank, as I consider them relatively expensive, and they always require a service technician if something goes wrong.
If problems do occur, the valves can be switched manually, and the heat pump will operate independently.

This is very important to me.

The domestic (fresh) water is not connected to the heating circuit.

Please do not discuss the type of heat source (heat pump, solar, etc.) at this time. I would like to do that later, unless it’s related to the system’s function. Thank you.

The control system for underfloor and ceiling heating needs to be discussed in a second step, but that can only happen after the system is installed.

Thank you very much for the support.

Schematic building services diagram with heating, pipes, and radiators
J
Joedreck
29 Dec 2017 20:32
Personally, I don’t believe there will be an energy exodus.
That said, I agree with you on one point: the best energy is the energy you don’t use.
In terms of pure kWh comparison, you can make a good comparison.

Electricity for me costs 21.5 cents/kWh (÷5 for heat pump)

Gas costs me 4.58 cents/kWh

According to online sources, oil is about €61.8 per 100 liters (approximately 6.2 cents/kWh)

However, this is only a direct comparison of energy prices. A full cost calculation over 15–20 years would make more sense.
J
Joedreck
29 Dec 2017 20:34
Oh, and with gas/oil systems, solar thermal is often added because otherwise it can be difficult to meet the energy saving regulations.
B
bau_name
29 Dec 2017 20:36
Ok, we didn’t need that; we increased the insulation accordingly. Ok, should that then be added to the heating system? For me, energy efficiency was important.
A
Alex85
29 Dec 2017 20:47
That is no longer possible today. A share of renewable energy is required. Unprofitable solar thermal systems are the usual solution; those who can invest more and want greater comfort choose a ventilation system with heat recovery. Biogas is also an option, but not many people have access to it.
J
Joedreck
29 Dec 2017 20:49
Efficiency is essential for me. However, general contractors often add significant markups here as well. Not everyone can or wants to pay that.
The energy saving regulation was tightened in 2017.
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bau_name
30 Dec 2017 07:59
We also have a mechanical ventilation system with heat recovery installed, which is, in my opinion, essential.
I fully agree with you about solar energy.
General contractors not only add extra costs but often also do poor workmanship.

Regarding the energy-saving regulations, many say that building has become expensive, but that’s not entirely true. I also get a lot more (whether you want that is another matter). However, the claim that everything costs twice as much as before is not accurate. I can’t buy a Polo for 5000 euros anymore either, but nobody cares about that.