ᐅ Cost-Benefit Comparison of Controlled Residential Ventilation With and Without Earth-to-Air Heat Exchanger (EWT)

Hello,

We are still in the planning phase for our property. Now the question has come up about using a ground heat exchanger with the mechanical ventilation system. The model has been decided: it will be a Zehnder ComfoAIR 350 with enthalpy recovery. The heating installer mentioned that a ground heat exchanger would be cost-effective for the ventilation system because it would eliminate the need for heating elements during the frost period.

However, I am wondering when such an investment pays off. Just for the ground heat exchanger, I’m looking at around 1,600 euros plus VAT, excluding installation costs. The ventilation system was already a concession for my partner, but an additional ~2,000 euros for a ground heat exchanger on top of that?

What are your experiences? How often does the heating element actually turn on, and what does that cost annually, assuming a region like HRO?

I would really appreciate it if some of you could share your experiences with this...

Best regards
mirage

Hello,

mirage schrieb:
... with enthalpy.

I would have skipped that.

mirage schrieb:
... The heating engineer also mentioned that an earth heat exchanger for the controlled ventilation system would be cost-effective, as it would eliminate the heating elements needed during frost periods.

Does he only say this and list it as a point open to dispute in the contract?

mirage schrieb:
... What are the experiences? When and how often does the heating element activate, and what are the additional annual costs, assuming the HRO region?

Ask your HVAC planner.

Best regards

Hi,

okay. Are there any experiences with a mechanical ventilation system with heat recovery and what the unit typically consumes in kW per year without a ground heat exchanger? That would provide a rough overview and estimate, as the entire heating season is covered there, including frost days with the heating element for air warming.

Regards
mirage

A ground heat exchanger is beneficial for plate heat exchangers when outdoor temperatures drop below -2°C (28°F)! It is never worthwhile for rotary heat exchangers! I’m not exactly sure about enthalpy exchangers. For that, I would recommend asking Zehnder about frost protection, since enthalpy exchangers handle moisture transfer similarly to rotary heat exchangers, which may mean that a ground heat exchanger is no longer cost-effective.

However, a ground heat exchanger is also advantageous because it pre-cools the air in summer!

How much you save depends on your air exchange rate!