ᐅ Which type of heat pump is suitable for an existing building?

nordanney schrieb:

Insulating the top floor ceiling as a DIY project to reach new-build standards requires about an afternoon of work and costs less than €1,000 (approx. $1,100). This is one of the most effective measures you can take.

So, here is the conclusion: an older building with practically no insulation is not energetically renovated and only the windows are replaced.

That’s true, I could also do that myself. That would be an option as well.

If you look at it from an energy renovation perspective, then the windows, front door, and new underfloor heating will be installed, with the floor being milled, and the new heating system (heat pump).

asaid10 schrieb:

energetische Sanierung betrifft, wird dann Fenster, Haustür

Only that changes the energy consumption of the house.

asaid10 schrieb:

und neue Fußbodenheizung wird gefräst und die neue Heizung (Wärmepumpe).

The house doesn't care whether you supply the heating load with a heat pump and underfloor heating or build a campfire in every room. In the end, the house will always consume the same amount of energy. Therefore, the first step is to reduce the house’s energy consumption.

If you like, grab two friends, three heavy sledgehammers, and just remove the old screed. Then add as much insulation as possible on the concrete slab (this doesn’t matter in the upper floor) and install new screed. This has several advantages:
- probably cheaper than milling
- improved insulation = lower heating costs
- underfloor heating can be laid individually. If nothing else is being done, I would almost recommend spacing the pipes 5cm (2 inches) apart everywhere (which massively increases the heating surface so the supply temperature can be kept as low as possible) – this is not possible with milling.

nordanney schrieb:

Go ahead, grab two buddies, three heavy demolition hammers, and just remove the old screed. Then put as much insulation as possible on the floor slab (in the upper floor it doesn’t matter) and lay a new screed. There are several advantages:
- probably cheaper than milling

So, only completely remove the screed on the ground floor and mill the screed on the first and attic floors?

Then apply new insulation on the ground floor slab and probably edge insulation as well if the new screed is going to be installed.
New insulation and new screed, plus removing the old screed with disposal—wouldn’t that be more expensive overall than just milling?

If installing new insulation makes a significant difference, then sure, I have to consider it if it’s only slightly more expensive.

asaid10 schrieb:

So, only completely remove the screed on the ground floor and mill it on the upper floors and attic?

Then apply new insulation on the ground floor slab and probably also perimeter insulation if the new screed is going to be installed.
New insulation and new screed, plus removing and disposing of the old screed – wouldn’t that be more expensive overall than just milling?

If adding new insulation makes a significant difference, then sure, I need to consider it, but if it’s only a bit more expensive, I’m not sure.

You also need to consider the available build-up heights.
I’ve been through this on a 120 sqm (1,292 sq ft) area – disposal cost was zero since I took the material to the recycling center myself with my own trailer. You’ll need to check container costs. New screed will probably cost around 2,500–3,000 (currency not specified), plus new insulation.
You can calculate it for yourself – including the upper floors.

Now the question remains whether it should be a 7.5 kW (10,060 BTU/h) heat pump or a 10.5 kW (35,860 BTU/h) one, both offered by Vaillant.

asaid10 schrieb:

Now the question remains whether it should be a 7.5 kW (10,600 BTU) heat pump or a 10.5 kW (35,800 BTU) one, both offered by Vaillant.

A heat pump should always be sized precisely or slightly smaller than necessary. Please avoid choosing a model that is too large. The 10.5 kW (35,800 BTU) option would be out of consideration for me.