ᐅ Extending a Ground Source Heat Pump System to Heat a Small Indoor Pool
Created on: 19 Mar 2023 21:24
J
jx7
Hello everyone,
Would it be feasible to connect an additional heating circuit for a small indoor pool (9 sqm (97 sq ft) surface area) to a geothermal heat pump (Ecoforest C3 3-12 kW HTR EH with 2x 99 m (325 ft) boreholes)?
The capacity of the heat pump should actually be sufficient, both considering the ground loop (2x 99 m (325 ft)) and the heat pump itself (12 kW):
- It is not an outdoor pool that cools down significantly at night.
- The initial heating of the pool could take place during the summer.
- The pool’s heat is not lost but remains inside the house.
- If the capacity is not enough during the coldest winter months to heat both the house and the pool simultaneously, it would not be a problem; the pool simply would not be heated during that time.
- In an emergency, the pool’s internal heater (4 kW electric heater) could also be used.
Here are all the relevant details:
Currently, 190 sqm (2045 sq ft) of underfloor heating and the domestic hot water for 5 people run through the geothermal heat pump.
The house has nearly KfW-55-standard:
Final energy demand: 21.4 kWh/(m²·a)
Primary energy demand: 51.4 kWh/(m²·a)
Thermal performance of the building envelope: 0.25 W/(m²·K)
Room dimensions:
5.08 m x 4.65 m x 2.31 m (16.7 ft x 15.3 ft x 7.6 ft)
Pool size:
246 cm (width) x 460 cm (length) – external (8.1 ft x 15.1 ft)
213 cm (width) x 427 cm (length) – internal (7.0 ft x 14.0 ft)
Desired water temperature: 28°C (82°F)
The basement is a waterproof concrete shell with excellent insulation. The house was built in 2016 and nearly meets KfW-55-standard.
I would appreciate knowledgeable answers and/or experiences from homeowners!
Would it be feasible to connect an additional heating circuit for a small indoor pool (9 sqm (97 sq ft) surface area) to a geothermal heat pump (Ecoforest C3 3-12 kW HTR EH with 2x 99 m (325 ft) boreholes)?
The capacity of the heat pump should actually be sufficient, both considering the ground loop (2x 99 m (325 ft)) and the heat pump itself (12 kW):
- It is not an outdoor pool that cools down significantly at night.
- The initial heating of the pool could take place during the summer.
- The pool’s heat is not lost but remains inside the house.
- If the capacity is not enough during the coldest winter months to heat both the house and the pool simultaneously, it would not be a problem; the pool simply would not be heated during that time.
- In an emergency, the pool’s internal heater (4 kW electric heater) could also be used.
Here are all the relevant details:
Currently, 190 sqm (2045 sq ft) of underfloor heating and the domestic hot water for 5 people run through the geothermal heat pump.
The house has nearly KfW-55-standard:
Final energy demand: 21.4 kWh/(m²·a)
Primary energy demand: 51.4 kWh/(m²·a)
Thermal performance of the building envelope: 0.25 W/(m²·K)
Room dimensions:
5.08 m x 4.65 m x 2.31 m (16.7 ft x 15.3 ft x 7.6 ft)
Pool size:
246 cm (width) x 460 cm (length) – external (8.1 ft x 15.1 ft)
213 cm (width) x 427 cm (length) – internal (7.0 ft x 14.0 ft)
Desired water temperature: 28°C (82°F)
The basement is a waterproof concrete shell with excellent insulation. The house was built in 2016 and nearly meets KfW-55-standard.
I would appreciate knowledgeable answers and/or experiences from homeowners!
T
taschenonkel22 Mar 2023 14:28If I were you, I wouldn’t touch the heating circuit and instead make a borehole outside for the pool and install a proper inverter heat pump for the pool there. So, the heat pump outside with piping going inside. This way, you remain independent and will most likely save money as well.
taschenonkel schrieb:
If I were you, I wouldn’t modify the heating circuit. Instead, I would drill a hole to the outside for the pool and install a proper inverter heat pump for the pool there. So, the heat pump outside with piping going inside.
This way, you’ll be independent and (very likely) even cheaper. Thanks for the reply.
Disadvantages:
- Additional cost for a second heat pump (4 kW like the supplied electric heater? 400–600 €)
- Additional cost for drilling through the wall
- Lower efficiency of the pool heat pump (air-to-water) compared to the house heat pump (brine-to-water/geothermal)
Advantages:
- No intervention in the configured heating circuit
Am I missing something?
Do you mean the advantages outweigh not only in terms of the cleanliness of the solution (independent heating systems) but also economically?
T
taschenonkel22 Mar 2023 15:10jx7 schrieb:
Thanks for the response.
Disadvantages:
- Additional cost for a second heat pump (4 kW like the supplied electric heater? 400-600 €)
- Additional cost for drilling through the wall
- Lower efficiency of the pool heat pump (air-to-water) compared to the house heat pump (brine-to-water/geothermal)
Advantages:
- No modification to the configured heating circuit
Am I missing something?
Do you mean that the advantages outweigh the disadvantages not only because of the cleaner solution (independent heating systems), but also economically? Have you already requested a quote from a heating engineer to connect the geothermal heat pump circuit to the pool system? Normally, a heat pump is sized based on a heating load calculation to supply the house as efficiently as possible.
Your indoor pool represents a significant additional load that your heating system is probably not designed to handle. Or did you plan from the beginning to include the pool and size the system accordingly?
taschenonkel schrieb:
Have you already obtained a quote from the heating engineer to connect the geothermal heat pump circuit to the pool system? Normally, a heat pump is designed according to the heating load calculation to provide maximum efficiency for the house.
Your indoor pool represents a significant additional load, for which your heating system is probably not designed. Or did you originally plan to connect a pool and size the system accordingly? The pool was not planned from the beginning.
My considerations were – as mentioned –:
- It is not an outdoor pool that cools down significantly at night.
- Initial heating of the pool could take place during the summer.
- The pool’s heat is not lost but stays within the house.
- If the capacity in the coldest winter is not sufficient to heat both the house and the pool at the same time, that would not be a problem; the pool simply would not be heated during that period.
My energy consultant contacted her building services engineer, who writes:
“It is technically possible, in principle, to connect the pool to the heat pump. How exactly it works with the Ecoforest unit would need to be assessed by an installer, as he is not familiar with this specific system. He recommends installing a priority switch so that only surplus energy is directed to the pool, with the building’s heat demand met first. That should work.”
If the heating capacity is insufficient, an additional heat pump can always be considered.
T
taschenonkel22 Mar 2023 15:24jx7 schrieb:
The pool was not part of the original plan.
My considerations were—as I already mentioned—:
- It’s not an outdoor pool that cools down significantly overnight.
- The initial heating of the pool could take place in summer.
- The pool’s heat is not lost but stays inside the house.
- If during the coldest winter the capacity is not enough to heat both the house and the pool at the same time, it wouldn’t be a problem; the pool simply wouldn’t be heated for a while.
My energy consultant contacted her HVAC planner, who wrote:
“It is generally technically possible to connect the pool to the heat pump. How exactly this works with the Ecoforest would need to be assessed by an installer, since he is not fully familiar with this device. He recommends installing a priority circuit so that only surplus energy is directed to the pool, and the building’s heating demand is covered first. This should work.”
If the heating capacity is insufficient, one can still consider an additional heat pump. I’m quite sure that you would be better and cheaper off with a separate inverter heat pump costing around 1000 EUR (about 1100 USD) and a small outdoor borehole, rather than having an installer modify your existing house heating system. I don’t know what a priority circuit costs, but it sounds expensive :-)
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