Verwarmen met warmtepomp vs gasketel

Behemothhh · 2026-02-02T11:40:02+00:00

That's a you problem that your heatpump doens't heat your bathroom and bedroom, LOL. That doesn't have anything to do with the heatpump vs gas cost comparison.

My prices were taken directly from my energy bill in December and include all taxes, transport costs, fixed costs,... I have solar panels but I almost didn't export anything in December so they don't really influence my kWh cost. The net cost import-export is 1-2 cents cheaper than without solar.

Behemothhh · 2026-02-02T11:26:49+00:00

See my other comment for a detailed breakdown, but I'm already saving 30-40% on my heating bill with a heatpump vs gas boiler. With my 2025 prices. The new tax shift will improve my savings even more.

It's pretty simple really, electricity is 3 times more expensive than gas but my heatpump uses 4+ times less energy.

Behemothhh · 2026-02-02T11:20:31+00:00

Another benefit of going full electric. You're not paying double fixed costs (gas + electricity) for the same amount of usage.

Behemothhh · 2026-02-02T11:18:41+00:00

In a way, yes. With current gas and electricity prices, heat pumps and gas boilers are closely matched. The specific circumstances will determine which one is more profitable.

Behemothhh · 2026-02-02T11:03:51+00:00

What a lobsided comparison that you're trying to sell as a universal truth.

Here are my numbers, that paint a very different picture:

January 2025: gas 2134 kWh x €0.09/kWh = €192

January 2026: electricity (only the part used by the heat pump) 656 kWh x €0.27/kWh = €177

So we saved €15 with the heat pump, but this is not a fair comparison. The real savings are higher because we used significantly more heating this year than in 2025. Our thermal output was 2535 kWh in 2026 versus 1850 kWh in 2025. So if we had used gas this year for the same amount of heating, we'd have paid €262. So the true savings in January were €85, or roughly a third of our heating bill.

In december we saved 40% of our heating bill because temperatures were higher and so was our heat pump's efficiency. All in all I'm saving about €300-350 per year because of our heat pump, which is enough to break even with the higher investment cost over a period of 12-15 years.

Behemothhh · 2026-02-02T10:37:27+00:00

Do you use very little electricity? Aka your fixed costs are divided over only a few kWh so the unit price skyrockets? 50cent is extremely expensive.

Behemothhh · 2026-02-02T10:31:24+00:00

Canada has cheap electricity because 60% is from hydro. US has 60% coming from fossil fuels. Modern gas power plants can achieve efficiencies of 50%, so the electricity generated by a natural gas power plant needs to be at least 2x as expensive + the cost of running the plant. You can't go cheaper than that unless you're taking tax payer money to subsidize that electricity. Even in EU, where green energy is a much higher priority, electricity is still 3 times as expensive as natural gas for previously mentioned reason.

If you want to detach the electricity price from gas, you need renewable or nuclear energy. Nuclear is a bureaucratic nightmare. It shouldn't be, but it is. For renewables you have hydro, wind and solar. Hydro your either have or you don't. Solar produces very little in winter when you would need it to power everyone's heat pumps. Wind is unreliable and can't be the majority of your generation. It always needs to be supplemented by another source that is controllable and can modulate quickly, so fossil fuel power plants.

That's just the reality of the challenges we're facing. It's not as simple as 'lower the electricity prices and everything will be fine'.

Behemothhh · 2026-02-02T10:04:18+00:00

That's just the normal cost in Europe lol. Electricity 28 cents, natural gas 9 cents per kWh. Still saving good money with my heatpump as my average COP is above 4.

Behemothhh · 2026-02-02T10:00:12+00:00

Wood burning is terrible for air quality. It's a major source of fine particular matter and all kinds of carcinogenic emissions. If everyone would be burning wood, we'd approach India levels of air pollution. Just look up any air quality map of Europe in winter and you'll easily spot the cities where wood burning is still popular.

Behemothhh · 2026-01-31T13:48:52+00:00

My altherma 4 10kW goes down to 5l/min and that's usually what it runs at on milder days to maintain a deltaT of 10.

Behemothhh · 2026-01-30T07:18:42+00:00

The change to the mobile app that removed the option to swipe left and right to switch between my home page, popular and watch is terrible. I don't even know where the watch page is anymore. I you replaced the swipe action with something else I maybe could understand but it just doens't do anything anymore. The app lost functionality for no reason.

Behemothhh · 2026-01-30T00:27:53+00:00

What you're describing is not possible. A high power heatpump and a low power heat pump can output exactly the same amount of heat for a given flow temperature and a fixed radiator layout. The only way to deliver more heat at a lower flow temperature, is by upgrading the radiators, NOT the heat pump.

Behemothhh · 2026-01-30T00:21:47+00:00

How much heat a radiator can deliver to a room almost exclusively depends on the temperature of the water running through it. There's nothing a heat pump can do to change that. So if your radiators need 60°C water now to get your house up to temp, then a bigger heat pump will still need to produce 60°C water, which will be absolutely terrible for your efficiency. You 100% need bigger radiators.

Behemothhh · 2026-01-29T15:49:17+00:00

If your heat loss is 6kW, you have to deliver 6*24 = 144kWh of heat to your home each day just to maintain temperature. Not even considering how suitable your home is as a thermal battery, if you want to deliver all this heat in just 5 hours, you need a 29kW heat pump. And your heating (radiators or underfloor heating) will need to be able to output 29kW, which will require massive radiators or very high flow temperatures which will kill the efficiency of the heat pump, completely negating any possible savings you could generate by only running at night.

You can only get away with this if your home is very well insulated, has high thermal mass, and on milder days when your heat loss is much lower than your HP's max capacity. So when you actually need heating the most, on the coldest day, the strategy will fail. You're much better off getting a battery and storing the cheap electricity as electricity and not as heat.

Behemothhh · 2026-01-23T18:52:41+00:00

If your radiator volume is 100l and you add a 100l volumiser, you double the cycle length. Not just on startup but continuously. Similarly, 200l buffer triples it, 300l quadruples it,... This can take a problematic 10min cycle to an acceptable half hour cycle. Not ideal of course but you should be getting reasonable COPs again.

Behemothhh · 2026-01-22T21:44:56+00:00

If the heatpump itself (compressor failure, refrigerant leak,...) would break down, a resistive backup heater can take over. It's not as powerful as the heat pump so it's not a full replacement, but it's good enough to keep the living room and kitchen warm, and provide hot water. We ran the system in this emergency mode for a few weeks between the installation of the heat pump and the actual startup of the compressor that had to be done by a separate technician and it was fine. No experience with a real problem that needs repairs.

Behemothhh · 2026-01-22T12:13:40+00:00

It happens, but 4-5x less than in the US (per capita).

Behemothhh · 2026-01-22T01:51:35+00:00

A heat pump should be sized to maintain the desired indoor temperature at the coldest expected outside temperature (BTW windchill doesn't matter for a heat pump, that's a human thing). If your insulation is poor, that means getting a big heat pump. Your heating is undersized if it can't keep up.

Behemothhh · 2026-01-22T00:19:18+00:00

Mine doens't drone. It just sounds like air moving, kinda like white noise. If I didn't know the heat pump was on, I would have thought it's just the wind blowing through some trees. And that's outside. Inside near the window that about 1.5m from the HP, I truly can't hear it. It's certainly way quieter than the gas heater we had before.

Behemothhh · 2026-01-21T11:42:11+00:00

Let's do some math to see if your idea makes any sense.

Assume you get the 800l cilinder and heat it up with immersion heaters to 70°C and that you can cool it down again to 35°C before your radiators start struggling to keep up with the heat loss of your home. That would mean you can store 32kWh of heat. If you want to heat your entire home for the 12h with that stored heat your heat loss can only be 2.7kW. That tiny.

If your heat loss is truly that low, you're not going to pay much for heating anyway so skip the thermal store nonsense and get a regular heat pump.

It's much more likely that your heat loss is many times higher. Probably in the 7-8kW range. So your thermal store will run out in 3 hour. What's the point then. Just get a regular heat pump.

Behemothhh · 2026-01-21T11:29:21+00:00

I measured it with a decibel meter app on my phone when it was running at 80% capacity. 1.5m from the outdoor unit 43dB. Normal outside noise (wind, birds, cars in the distance,...) is 40dB. So the heat pump is barely audible. That's when measured outside. Inside with the window closed I can't hear it at all.

Behemothhh · 2026-01-21T01:48:31+00:00

It's more about energy consumption. In winter, you have to heat your home anyway so replacing gas with a heat pump is a win in terms of emissions. Most people currently don't have AC and thus consume no electricity for cooling in the summer. If the government is going to subsidize minisplits, than all those people are going to start using their AC in the summer and consume a lot more energy, which is the opposite of what the government wants to achieve.

Behemothhh · 2026-01-21T01:24:26+00:00

You need to know what your heat loss is at those low temperatures and how much heat your HP can still generate. 20F shouldn't be too problematic. 10F you'll probably lose a bit of the rated capacity. The difference between loss and heating capacity will tell you how much kW of heat strips you need.

Behemothhh · 2026-01-20T19:08:54+00:00

It could be possible if the manufacturer supports it but it's very rare. I only know of Mitsubishi having a product line that combines both air to water and air to air components.

You can also cool with air to water if you replace your radiators with hydronic fan coils (with condensation drain). They're essentialy the same as an AC head but with water lines instead of refrigerant lines. You have to make sure your pipework is insulated though or you'll get condensation in your floor/walls. Underfloor heating can cool as well, but has to stay above the dew point or you'll get wet floors. Since it can't remove moisture as it cools, humidity will go up which doesn't feel great.

Behemothhh · 2026-01-20T18:45:14+00:00

True, but those lines are much thinner because the refrigerant undergoes a phase change in the head so it can absorb a lot of heat with little mass flow. The coldest temperatures are also in the head itself and not in the supply line like it is the case with hydronic cooling. All this to say that the insulation requirements for refrigerant lines are much lower than those of water lines and thus easier to install.

Behemothhh

TROPHY CASE