ᐅ Installing a Mechanical Ventilation System with Heat Recovery Yourself: Timeline and Costs?

Hi everyone,

We will be building in a few months. The building permit / planning permission was submitted last year to take advantage of the previous energy-saving regulations. So far, so good.

Originally, we planned to build without a mechanical ventilation system with heat recovery. Based on our experience in our current house, we considered such a system unnecessary.

However, for various reasons, we are now reconsidering. A mechanical ventilation system with heat recovery will never really pay for itself, but as a comfort upgrade and to improve marketability in case of a future sale, it might be worthwhile after all.

We are talking about a central system with heat recovery for nearly 180 sqm (approximately 1,940 sq ft) of living space over two floors plus basement.

The general contractor is quoting completely insane prices. I’m still waiting for the detailed offer, but initial estimates were between 15,000 and 18,000 Euros (around 10,000 to 12,000 USD, depending on exchange rate) for a system from Helios, and even more with the basement. So, a classic deterrent offer...

In a thread here, I came across a supplier who designs, plans, and assembles the materials for these systems, delivering everything ready for installation. The installation itself would then be done by us. According to the advisor, it’s truly no rocket science and for a house of this size, two people could easily do it in 4-5 working days (which equals 8-10 man-days).

It would also be a Helios system (specific model to be confirmed) with about 6-7 supply air and 6-7 exhaust air ducts. Installation is done within the impact sound insulation layer, that is, on top of the finished concrete ceiling. The supplier also provides plans for the necessary ceiling penetrations etc., so these can be incorporated directly during the concrete pour.

What caught my attention was his initial rough price estimate for the materials, which was about one-third of the general contractor’s price. So for around 10,000 Euros (about 11,000 USD), I might just take a week off work...!

But is it really that simple? This is a trade that happens right in the middle of construction, so our own work must be absolutely punctual, otherwise the overall schedule collapses...

My question is: How realistic is it to install such a system yourself within one week?

Has anyone done this before and could share some of their experiences?

Best regards,

Andreas

You need to know the original construction setup from the top of the structural floor (OKRD) to the top of the finished floor. The ventilation ducts on the raw ceiling require about 60mm (2.4 inches) of additional build-up height. If the impact sound insulation is no longer present in those areas and the staple plate for the underfloor heating or the screed lies directly on the ducts, you create a sound bridge that could cause disturbance for years.

Regarding your estimate of working time: realistically, it is about 2.5 times the assumed duration for all manual tasks you are performing for the first time. This is based on my experience from many years in construction.

I’ll reply to you here.

Our controlled residential ventilation system, for a similar house size, cost just under 7,000 (also Helios), but with an enthalpy exchanger.

We have 10 exhaust vents and 7 supply vents.

Installation is relatively straightforward, but the blue ducts can be quite frustrating. However, you don’t have those since you have flat ducts (we have them in the structural concrete ceiling) — good luck with the screed insulation then, I’m currently annoyed by every single pipe lying on the floor.

8 to 10 person-days are a realistic estimate — easily, if you really want to do it thoroughly.

Greetings to Mr. Schliebe

Thanks for the answers.
Joints in the impact sound insulation do worry me a bit, as I don’t want to risk any sound bridges forming.

I only thought about using flat ducts on the structural slab because they wouldn’t interfere with pouring the precast concrete slabs.

What are the advantages and disadvantages of the two construction methods:

Flat ducts within the screed insulation or round ducts in the structural concrete slab?

Best regards,

Andreas

If you search online, you will find some expert opinions expressing concerns about the structural integrity being compromised by the pipes in the raw concrete ceiling.

We had the plans approved by a structural engineer – and let me tell you one thing: steel reinforcement is never in short supply in a single-family house. The safety factors are ensured numerous times over – at least, that's what practically everyone tells you. Whether it’s true? No idea...

The pipes are gone once the concrete is poured – but you have to take action before the concreting process. I had one day, or a weekend, to install everything – it was easily manageable on my own.

The advantage of laying pipes on the rough floor is that you don’t damage the structural integrity, and in case something needs to be accessed later, it’s a bit easier (though I personally never had to do that again). However, you need to cut a lot and pay attention to the heights with the screed insulation. My hot water pipes were about 60mm (2.4 inches) high, so that wasn’t an issue if properly planned.

We have 12 cm (5 inches) insulation on the upper floor, and the last board fit perfectly over the ventilation ducts (round, 85 mm (3.3 inches)).

Of course, it was a lot of work to cut all the boards.

But no one does it more precisely than the homeowner...