Which heating system to choose when replacing heating after 30 years?

Our newly acquired property currently has an oil heating system installed. This must be replaced by the end of 2017, as it will then be 30 years old. The tanks are in impeccable condition, so "only" the heating system needs to be replaced. We have 2 floors + basement + insulated attic. The ground floor has underfloor heating + convectors, the basement (basement bar + bathroom) has convectors as does the upper floor. The ground floor is designed very openly, so a lot of heat is distributed throughout the house (and thus also the upper floor). The living area is 220m².

The first idea (and still the most favored) is the installation of a new oil heating system. Gas would theoretically be interesting, but unfortunately is not available. Heat pumps are out because the insulation would certainly not be sufficient for them. Since we have a well-oriented roof surface, I thought about solar thermal with heating support, but that also depends on the costs, as it usually just barely pays off.

I wonder whether I should/need to seriously consider a pellet heating system. The high investment costs naturally scare me off (25,000€ compared to 8,000€ for oil, or 14-15,000€ for oil/solar), and I wonder whether they will actually pay off at some point.

The previous owners' energy consumption was not good (final energy consumption 143kWh/m²), but a lot of wood was also heated with, and from my observation with low calorific value wood. Therefore, I think that if one would heat with pure oil, the energy demand would be somewhat lower. I suspect that with a pure new oil heating system without "wood support" I will come to 110-120kWh/m², with solar thermal maybe approach 100kWh/m². Does a conversion to pellet heating even make sense?

Hi,

if the tanks are really still in good condition, and you don't need the space they take up: simply replacing the oil burner with an oil condensing boiler will certainly be the cheapest and most economical solution.

Everything else will – as you already wrote – be much more expensive. For the pellet solution, you need to create storage space. Whether the costs will ultimately pay off and by when – hard to say from here. It would be worth considering if your oil tanks were no longer in order.

An ST system (surely with heating support?) for a 220 sqm house, you will need a good 7-8 sqm of collector area. For the system to work sensibly, please choose one with flat tube vacuum collectors (but that drives up the costs!). In our latitudes here, I see one thing with such a system: enormously long payback periods. You can safely leave it out; you won’t save that much with it. Rather consider installing a photovoltaic system, possibly with a smaller storage (5kWh), from which you will benefit much faster.

I would choose the cheaper solution and simply live well. By the way, the energy value of your house is not that bad at all. There are much, much worse houses.

Best regards
Thorsten

PS: With your calculation assumption above, you save about 400 liters of oil/year with ST. Very roughly estimated at a very high efficiency. I would rather say it’s 270-300 liters. And that brings you to the end of the life with the payback period. Especially with today's oil prices.

I believe old oil tanks could also be converted into pellet storage, I once read something about that when we were discussing whether we could set up a pellet storage or not (we couldn't). Pellet boilers are available starting from 2500 euros (Atmos D15p, it can also use firewood), plus there is a 3000 euro BAFA subsidy or 3500 with a buffer tank. You only add a few euros for installation. Of course, you can also buy a pellet boiler for 25,000 euros if you want to spend that much money. Or if you get wood cheaply, you can take a look at the firewood boilers, which are also eligible for BAFA subsidies. In the end, we chose a pellet boiler for the living area; the boiler alone cost 3500 euros, everything together with installation, new pipes, expansion vessel, and buffer tank came to 6000 euros.

The oil tanks could theoretically disappear and the space be used for pellets, but is the space of the 6000l tanks sufficient? Is a pellet heating system including automatic feeding feasible for €15,000?

Hello,

in the context of our renovation, we face a similar question.
Basically conceivable would be (Gas would also have been interesting, unfortunately there is no connection in the street)
- new oil condensing boiler
- new oil condensing boiler including solar with heating support
- pellet heating system

Price-wise, the picture would be roughly as follows (only approximate figures):
- oil condensing boiler: €8,000
- solar system (heating support): €10,000 (including buffer storage)
- pellet system 20kW: €20,000 (including silo storage, condensing technology, buffer storage)

The tendency is currently clearly towards pellets for the following reasons:
- I somehow find oil not "cool" anymore nowadays
- Regarding solar thermal energy, I am no longer really convinced (also thanks to the forum here) concerning its usefulness / economic viability. For a long time, we also favored the combo oil + solar (but the roof orientation is not quite optimal for us, though it would work)
- Our oil tanks would also have to be renewed / replaced. Therefore, an additional €2,000 - 3,000 applies to the oil option
- Subsidies for pellet heating systems are currently quite attractive (precisely because the pellet market has collapsed quite a bit due to the oil price). The Bafa currently offers a good €6,900 back here (pellet heating including buffer storage, including condensing technology, plus incentive program Energy Efficient APEE). In addition, there are further funding opportunities in Bavaria (which of course do not apply with 86bibo). Moreover, with a pellet system, more favorable constellations arise for possible further KFW renovation measures (which are also on our agenda)
- Some acquaintances have had a pellet heating system installed and are consistently very satisfied (so far )

In our case, pellets vs. oil+solar ultimately hardly differ (pellet is maybe around €1,000 more expensive). Only oil without solar would then again cause problems regarding KfW. I personally (!) tend rather towards pellets overall.

For the OP, the overall situation is somewhat different (price difference between pellets and oil larger, oil tank system still intact, ...). Therefore, I would probably also lean towards the "bare" replacement of the oil heating here, see Thorsten's contribution.

If not done already:
Take a look here at the measure packages from the KfW Program 151 (Energy Efficient Renovation) (keyword: heating package). If you want to finance the new oil heating through this, you could still get a grant of 12.5%.

The oil tanks could theoretically disappear and the space be used for pellets, but is the space of the 6000l tanks enough? Is it possible to realize a pellet heating system including automatic feeding for 15,000€?

For that price, definitely twice or three times over. For example, you can also buy the Atmos with the appropriate accessories, i.e., a 1000 l storage tank and up to 2.5m feed screw. That would be 4000 euros or 1000 euros minus the Bafa subsidy. Plus installation. Since I once requested a quote for that, the final price (including subsidy) should be around 2500 euros. That is very, very far from 15,000. Of course, there are more expensive pellet boilers that can certainly do one or two more things, lambda probe etc... Those then cost ten times as much. And then there is also a wide range of models priced in between. A little research does no harm. What I liked about the Atmos was the lively online community with immediate assistance in its own forum. Ultimately, however, due to lack of installation space, it became a boiler for the living area from another company.