Monthly Archives: October 2013

Reverse engineering my central heating

I am trying to figure out how my oil-based central heating works, as I want to adjust it properly for the winter season and possibly replace the old, energy-wasting water pumps. Unfortunately, all the components are tightly fitted in a cabinet, which means that I cannot see the connections (piping) between them. The first two pictures provide an overview of the cabinet:

20131023-centralvarme-med-oliefyr-01-overblik   20131023-centralvarme-med-oliefyr-02-overblik

Click on the pictures 😉

It is my current understanding that the cabinet contains at least the following:

  • Oil burner/boiler (grey metal at the bottom).
  • Hot water storage tank (green, huge, in the middle).
  • Expansion tank (red, at the top).
  • Manual, two- or three-way shunt valve (to the left of the bottom of the hot water storage tank).
  • Pump for hot water for radiators and underfloor heating (at the bottom).
  • Pump for hot tap water (at the top).
  • Control unit for the temperature in the hot water tank (next to the upper pump).
  • Thermometer on the supply pipe for radiators and underfloor heating.
  • Thermometer and manometer on the hot water storage tank.

Close-ups of the components:

20131023-centralvarme-med-oliefyr-03-shunt-og-pumpe   20131023-centralvarme-med-oliefyr-04-oliebraender-og-afloeb   20131023-centralvarme-med-oliefyr-05-pumpe-til-brugsvand   20131023-centralvarme-med-oliefyr-06-ekspansions-og-varmtvandsbeholder   20131023-centralvarme-med-oliefyr-07-fremloebstemperatur-til-opvarmning   20131023-centralvarme-med-oliefyr-08-temperatur-i-varmtvandsbeholder   20131023-centralvarme-med-oliefyr-09-shunt   20131023-centralvarme-med-oliefyr-10-regulering-af-varmtvandsbeholder

Rotated close-ups of the pumps, showing their specifications:

20131023-centralvarme-med-oliefyr-11-pumpe-til-varmt-brugsvand   20131023-centralvarme-med-oliefyr-12-pumpe-til-radiatorer-og-gulvvarme

The pump to the left, which I suspect is pumping hot tap water, is a Grundfos UPS 20-45. It is class F and supposedly consumes 44 W when pumping. I am not sure that it is pumping continously – it might be regulated by something. If it is only pumping once in a while, it might not be profitable to replace it. According to online material from Grundfos, the current pump has to be 180 mm and a suitable replacement is their Alpha2 25-60 180 mm. The replacement, in a tap water edition, seems to cost a lot, which puzzles me a bit.

The pump to the right, which is certainly for supplying radiators and underfloor heating, is a Grundfos UPS 25-40 180 mm. It is class F and pumps continously. Currently, I have it set at position 2 out of the 3. This means that it continously consumes 55 W. If it is set at 2 for the five coldest months and at 1 for the seven other months, it consumes approx 354 kWh/year, which is approx 800 DKK/year. I have no doubt that it should be replaced. The constant, high-pressure pumping makes my radiators a bit noisy, thus replacing the pump will also increase comfort. Supposedly, a suitable replacement is an Alpha2 25-40 180 mm, which is relatively cheap in a heating edition (not for tap water). The investment will probably be recouped in two years and a few months.

I want to end up with a schematic for my central heating, however, it will require some assistance from family, friends and people in DIY forums. My quite optimistic plan is to replace the latter pump myself. It is not a simple task, as the pump is inaccessible and there are no valves next to it. I might have to drain the system for water and fill it afterwards.

Before I forget: The low temperature (approx 30ºC) of the supplied water to radiators and underfloor heating is probably due to the latter type of heating – the underfloor heating. Floors will be damaged if they are exposed to water with the same temperature as the water in the hot water storage tank, i.e. approx 60ºC. The setting of 5 out of 10 on the shunt valve possibly halves the 60ºC to 30ºC.

Netic’s 11th birthday


Today, most of my colleagues, their “better halves” and I celebrated the 11th birthday of our workplace, Netic A/S. The event took place at Køreteknisk Anlæg Aalborg ApS in Støvring, next to E45. All times being approximate, we ate breakfast from 7:30 to 8:00, were taught a bit about the forces involved in driving from 8:00 to 8:30, drove in our own cars with professional instruction on dry and wet track from 8:30 to 12:30, had a nicely roasted pig and a giant ice cake for dinner, and were given very fast laps in an Audi S5 by the race car driver Marco Sørensen. A truly awesome day! The ice cake, which is shown above, was from Ryå Is (Aabybro Mejeri) and it was as delicious as it looks (which is very, if you’re in doubt 🙂 ).

Considering a stove

By the way, this is post no. 100 on my blog 😀

Many things have happened since the previous post, but I will only mention that I had a very nice vacation in Lloret de Mar, Spain, and that I have begun playing badminton regularly.

I’m considering installing a stove in my living room, as it is a cozy and economical heat source. I have inquired with the chimney cleaner, and he approves. Installing the stove in my living room yields a furniture puzzle, which I am trying to solve. One possible solution is the following:




The modelling is carried out in Sweet Home 3D, which is, ehh, okay – maybe a bit better than average. It worked using Java in Firefox on my Ubuntu laptop, and it was rather easy to get started.

The particular stove, I’m considering, is an Aduro Asgård 4. I have borrowed a picture from the manufacturer’s homepage (I hope they don’t get mad…):


It’s a nice looking, simple stove with fine specifications. Eco-labelled (Svanemærket), 79% efficiency, 6 kW (3 – 9 possible), 80 kg. Also, it’s on sale in one of the Danish DIY stores this week. According to the chimney cleaner, my oil burner and the stove should be able to share the chimney.

Today I have begun my “heating season”, as I – for the first time this fall – have turned on my radiators and increased the speed of the circulation pump in the central heating (back to normal). Let’s burn some oil! I have only used approx 22 liters in September for the hot water supply.