Reduced usage of natural gas – Electric supplementary heating or a heat pump installation?

In this post we’ll describe our solution to reduce our domestic natural gas consumption by at least 50% in the coming winter ’22-’23.

The original plan:

  • stop heating part of the house;
  • per room where necessary additional heating with electric ceramic 500 watt wall plug heaters with thermostat;
  • Downstairs in the living / cooking room primarily with an LPG-fired potbellied stove to heat the room, possibly supplemented by 2 pieces of ceramic heaters, with thermostat.
LPG gestookte potkachel met katalysator, zuurstofsensor enz.
thermostatisch geregelde elektrische mini bijzetverwarming 500 Watt

Second thoughts..

When you start calculating with energy values and electricity prices you quickly find out that a solution with electric supplementary heating is not very feasible.

Electric heating is just not very economical because -despite the high energy prices- it is still twice as expensive to heat with electricity compared to heating with natural gas (in a nutshell: 1 m3 of natural gas at Eur 4 per m3 provides as much energetic energy as 8 kWh of electricity at Eur 1 per kWh. And 4 Euro is half of 8 Euro).

The heat pump installation instead of the ‘old’ natural gas powered central heating system

If energy prices remain as high as in August 2022, we will as soon as possible install a complete electric heat pump system with split units.

We will then also completely abandon the natural gas-powered central heating system, because we already have a low-temperature central heating system with underfloor heating.

And that’s extra handy when using a heat pump system:

Split outdoor unit (left) and the indoor unit (right) with 12.6 kW heating capacity for an all-electric heat pump system without gas-fired C.H. support.It’s not going to be a hybrid system, with the gas-fired central heating system staying put when it gets colder than about -5 degrees.

You’ll never get rid of the gas, because you’ll just have a heat pump system that’s too small to continue without the central heating support if the gas is ever turned off, or you just want to get rid of it.

With a hybrid heat pump system, the gas-fired central heating boiler has to intervene when it gets too cold (outside below -5 degrees) or if you haven’t heated up for too long and it therefore takes too long without the intervention of the gas-fired central heating boiler before it gets a little warm.

Up to 6-8 kW there are hybrid systems that work together with the existing central heating boiler.  If you want a system that can replace the gas-fired central heating boiler, we need to calculate exactly what heat output we need.

The existing gas fired HR boiler is a Nefit smartline HRC24 CW4.  It has a maximum output of 24kW.

According to the experts, our heat pump must have a SCOP value of at least a factor of 5.

This means that the electrical energy that you put into the heat pump system for the transport of energy ensures that five times more energy is delivered to (hot central heating) water at a maximum temperature of 55 degrees Celsius.

This is due to the operating principle of the heat pump, just like condenser (washing) dryers and air conditioners with heat pump principle.

When it gets colder outside, the efficiency of the heat pump in terms of heating does decrease.

So, for a heat output of 24 kW, you need a heat pump system that can deliver 24 kW of energetic water heat.   And that system uses 24/5 = about 5 kW of electricity at a SCOP value of 5.

Because such heat pump systems are based on standard connections to the 230Volt mains supply with a 16 Ampere connection rating, the common heat pump systems are usually somewhat smaller than 24kW.  The value we selected for the split system is 12.6 kW.  This keeps the electrical power consumption well within the 16 amp standard of the connection value of the electrical groups in our house.

It could be that in case of severe frost we have a problem to really heat up the house, we take that for granted.  When we talk to the installer/supplier about the heat pump system we’ll also have them calculate whether a 12.6 kW system will do. And if necessary, we will opt for a slightly larger system.

The split outdoor unit will be placed on the flat roof, somewhere between the solar panels, or on the sloping roof, just below the skylight with special sloping roof brackets.  It has to be a quiet model anyway, which may be difficult because these outdoor units are never quiet.  So it also needs a night mode with low-speed pump and fan operation.

We might also install an intermediate boiler next to the indoor unit, so there will always be a supply of hot water.  If we can take a shower with that, we can turn off the instantaneous water heater and only use the instantaneous water heater when it gets too cold outside.

The cost is about 7500 Euro for this installation and we are willing to pay that.  You will also receive a 2500 Euro subsidy in retrospect.

The insulation of our terraced house is also excellent, and we will be satisfied if the heat pump works in such a way that the first floor can be heated to 20 degrees. We want to keep the bedrooms at an average of 15 degrees.  The second floor goes on the anti-frost mode…

And I’m not even thinking about the payback.

We have to get rid of the gas in any case, and our C.V. boiler is now 20 years old, all kinds of things have been replaced and it works fine again every time after the repair.

But replacement is coming.

And whether that is useful, given the desire to get rid of gas?

Better to do it right the first time.

Cooling with the central heating system and the heat pump is also possible.

Incidentally, I want a heat pump system that can actively cool in summer.

In principle, this is quite possible with an all-electric heat pump system.

The radiators will then become cold.

That seems like a very useful option, I’m curious how my thermostatic valves would cope with that!

Our household’s heating situation

Our house still has, among other things, a floor heating system directly fired by the central heating system on the first floor and insulated glass on all floors. The cavity walls are still without insulation (we should do something about that but the wall surface is so small compared to the windows that the effect of wall insulation is probably not very big, according to the experts…) and we have an attic that is not used as a bedroom.

So we are not going to heat the attic in any case, and that makes a difference.

And we already cook electrically, the oven is also electric.  The kitchen tap is electric, and the shower water (and sink) are also heated electrically via an 11kW instantaneous water heater.

Heat pump or air conditioning system?

An air conditioning system would also be an option, of course, as this also works on the heat pump principle. At the moment, the only air conditioning system that is quite OK in terms of efficiency and affordable in terms of installation is a multiple air conditioning system with one unit outside and several inside.

You must have an installation with a COP value above 5 because then you also have a bit of efficiency when it gets cold if you also want to heat with it.

Such a multi-airco system with 4 indoor units and 1 outdoor unit with a COP value of 5.5 can be installed in your home from about 5 to 7 thousand euros.  Whether it’s beautiful, in each room such an air conditioner on the wall and outside a large unit on the give or on the sloping roof, I do not think, but at least all ugly CV pipes and radiators can be removed.  Maybe the holes in the mezzanine floors can be reused for the air conditioning pipes…. Advantage of such an 80’s house: there are no central heating pipes in the floors, everything is in sight.

The price for such an airco installation seems a lot of money and it is.

A central heating system is just as expensive to install. From scratch, that is.

Not to mention the installation of heat pump systems in existing houses, because that easily exceeds 7500 Euros.  But then you can leave the radiators in place and just use the underfloor heating system.

Not to mention the subsequent installation of heat pump systems in existing houses, because that easily exceeds 7500 Euros.  But then you can leave the radiators in place and just keep using the underfloor heating. That seems to me the best solution in the end.

But I will quickly check the prices and options of complete air-to-heat split units heat pump systems.

We’ll try to prepare as best as possible and choose upon all available data.

11-9-2022: To be continued!




Web hosting at home with a DS718+ Synology Web server

The performance of my larger sites left a lot to be desired, and the costs are running up considerably.  I had over 10 sites running, all with the same provider and the costs per site vary between 185 Euros per year and 65 Euros per year.  For the large sites I have 5GB storage and the smallest is 200MB.

HOMESERVER: Previously I hosted a few websites from home, on a Zyxel NAS with a cheap domain provider.  That all worked fine then.  Based on my previous experience I have bought a Synology DS718+ web server, a few fast SSDs with mirroring in it and up to RAM.  The cost is about 800 Euro.  As a backup I have a DS218 play with a couple of big harddisks in it and extra RAM as a normal local NAS with an extra mirrored wordpress server for emergencies and maintenance on the main server.

So now you see this post from my home server.

My experience is that it is always better to be the only one on your own web server than to rent shared hosting, regardless of the so-called SSD hosting et cetera.  That’s what larger companies do as well: Just a fat server on a fast internet connection.

Just to be sure, I do have a backup (UPS) with battery for the 230 Volt power to the internet modem/router and web servers, and a data connection backup via a mobile connection, in case the internet connection goes down. The autonomy of the UPS is about 6 hours.


And… whether I like it?  Actually, I’m mostly very happy with the merging of my various sites into 1 overall site because of its clarity.  Because of my diversity of interests I had just too many sites running which resulted in insufficient attention on the sites.  Now that I only have one for my hobbies and one for my business everything has become much simpler.

And how to proceed? I will cancel my webhosting and I have to see which domains I want to keep.  That also depends a bit on the costs.  If only the costs of the domains are not too high, I can keep 6 or so. Which I then redirect (fixed, 302) to my home server.  Eventually only 1 domain will remain, but which one should that be…?  And then I can make my URL unambiguous again!

That’s it!

Dometic tropicool TC21FL silenced

Recently I bought us a portable dual power cooler from Tropicool, 21 liters content.  BUT- as I started it up, the noise was a bit more than I expected.

I already own a larger ‘VRIJBUITER’ 38 liters portable freezer/cooler with a  compressor that I silenced last year.

DC mini fridge/cooler - DC-40Y (China Manufacturer) - Refrigerator - Consumer Electronics & Lighting Products - DIYTrade China manufacturers

This 40 liter machine had a 50mm (2 inch) fan to cool the condensor and I completely repositioned some movable parts to get a 120mm (4.8 inch) fan in the machine instead.  The 120 mm fan is a silent fan and this resulted in an almost silent and  better operating freezer/cooler.  But- this machine does not run on the car battery, only on A/C  230 Volts.

So- back to the Dometic machine:  This is the machine

At the front lower  part a large area shows a fan behind the plastic front.  A 12 Volts DC fan is positioned behind this front . The fan is managed by the electronics and only switches on and off. No PWM or similar technique is used.  This cooler is not working with a compressor but with a/some Peltier element(s) and cooling/heating radiators, so a big aluminium block needs to be cooled by the fan to get the machine to work (and cool or warm the inside).  This machine can either cool -25Deg C or warm +25Deg C the inside.  A failsafe mechanism prevents freezing and temperatures above 65 DegC.

The picture below shows the original fan below and the replacement fan above.

The original fan was IMHO rather loud at 53 dBm (at 50cm distance), I presume mainly due to its design.

On the net, I read that most users of this machine are pleased with it and don’t think it makes much noise.

But- I need to operate this in our rented place which can either be an apartment, B&B or hotel room during our visits so I want it to make as little noise as possible. The replacement fan is a ball-bearing super-silent PC fan and runs at 12 Volts. 

The replacement was quite easy: Open the lower front by removing all crews around and bottom.  Disconnect the fan-connector from the electronics board.  Unscrew the old fan.  Screw the new fan in place.  Connect the new fan to the electronics board, replace the housing part and screw it back in place.

So- the result is that this cooler now actually works a lot more silent, AND a lot better.

I could not get a fixed dBm reading with my portable dB-meter due to the low noise level.

Cooling goes faster than before at about 30% as I measured it in difference in the before- and after situation in cooling to 5 degrees C from room temp of 25 deg C.  Another succesfull project!

We’ll see how we like this cooler during our short stay in France this summer, in Granville!  C) JG 2021-06-30.

Afterthoughts:  To be sure that the cooler is indeed super silent at night, I also put in a DC voltage regulator that can regulate the voltage for the fan between 5 V DC and V max (about 12Volt).

During oiur holiday in France, the machine worked awesome.

In the hotel, we experienced no disturbances from the cooler at all, nore in the car.

And it kept everyrhing cool without too much noise.


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