Time has changed! Winter is coming… 

… And for me, and for our boiler, it is now the Moment Of Truth.

Remembering the past issues

As you may remember from some previous posts (27.03.2017 – Pressure loss discovery in the heating system; 29.06.2017 – Heating system: technician advice) we have had multiple issues with our boiler: the water pressure was slowly but constantly decreasing, which led to the boiler stopping every now and then, or, the boiler kept running but the water/house wasn’t warm enough. Particularly the decreasing of the water pressure disturbed me as I didn’t have any clue of where the water was going: having a floor heating system, the idea of a water leak was terrifying me.

After multiple interventions of the technicians I finally discovered that the issue was related to a lack of maintenance and to my ignorance. In fact I always thought that the maintenance performed by Elco’s technicians was enough for the boiler to be in a good shape.

It is not.

The boiler has to be cleaned every year by a chimney sweeper, too. From what I understood the chimney sweeper opens the boiler and performs a chemical wash which removes the combustion residuals as well as the limescale which is generated while heating the water: further,  in our specific model of boiler, the heat exchanger features many thin fins which get clogged easily, therefore I believe it is particularly sensitive and should be maintained with extra care. Indeed, after the cleaning, the boiler was working much better. But, my little quest wasn’t finished, as the loosing water pressure issue wasn’t solved yet. After further researches we discovered that, probably due to the accumulation of residuals in the past six years, the heat exchanger wasn’t waterproof anymore: we had to change ours with a new one. And, as often happens, the warranty already had expired!

How does it look like today, then?

As the technician said, after all the interventions, basically we now have a new boiler. Since the substitution I have been checking the water pressure with some apprehension, as I was afraid that it would start dropping again. From the measurements that you will see below you may notice that there is still some pressure loss, still it is slower than before: as you may observe, starting from June 2017 the pressure is decreasing way slower. I hope this is an acceptable level of pressure loss.

Raw data

Here below some of the measurements that I have made during the past months. Please note that the change of the heat exchanger happened on the 29.06.2017. After that date the pressure loss is still there but happens in a time frame of over 2 months.

  1. Date: 27.03.2017 Water Pressure (bar): 2.0
  2. Date: 02.04.2017 Water Pressure (bar): 1.9
  3. Date: 11.04.2017 Water Pressure (bar): 1.85
  4. Date: 18.04.2017 Water Pressure (bar): 1.75
  5. Date: 29.06.2017 Water Pressure (bar): 1.9 – New heat exchanger
  6. Date: 30.06.2017 Water Pressure (bar): 1.9
  7. Date: 17.09.2017 Water Pressure (bar): 1.8
  8. Date: 03.10.2017 Water Pressure (bar): 1.75
  9. Date: 19.10.2017 Water Pressure (bar): 1.75
  10. Date: 28.10.2017 Water Pressure (bar): 1.75

How could you define what pressure loss is acceptable?

I have asked to the technicians what they expect as a normal pressure loss and apparently there is no rule and no answer I have got is the same. Therefore I believe that one way of getting a rough idea is to keep track of the changes, possibly starting immediately since the first installation of the boiler. This is very important because it would give you the starting point, when you know that everything works perfectly (in an ideal world/case, it should be like this, yes! :-))

This is one of the reasons why I’m writing about our boiler, which per se, is not at all an interesting topic: I try to keep track of the changes and of the major events, so that if something should ever happen, I have some sort of diary. And yeah, absolutely, turning on the heating is definitely a major event, or, The Moment Of Truth.

The Moment Of Truth

As the temperatures are slowly decreasing yesterday night I decided of switching on the heating for the whole house. And this is the Moment Of Truth! Will it work? Will the house heat up without too much hassle? And what will happen with the water pressure, will it increase a little, since it is going to be hot water running trough the pipes?

Curious observation

During one of the many diagnostic moment I had the chance to record some strange noises made by the boiler. This was after having opened again the water and I believe the noise we hear is the pump trying to get restore the correct flow. Those are my interpretations only though.

Heating system, boiler and burner maintenance

This year I had a few issues with our heating system at home: I’m going to describe what happened and what I learned from my little incidents.

Description of the heating system

Based on our experience, we decided to install an underfloor heating system when we built the new house, therefore we do not have any radiators to be seen: the heat is carried by a liquid which is constantly pumped through tubes running under our floor. The burner is a gas powered Remeha Calenta 35S+. We bought it and installed it during 2011.

I have understood that the “+” in the model name refers to the fact that this burner is built for the preparation of hot water to be used e.g. in the shower as well as the heating. Other models like the “35” have been developed for the heating system only.


Manuals for the burner (sadly in Italian language only, I wasn’t able to find them in English).


PM 2975 OGZ

The burner has a second computer on board, the so called PM 2975 OGZ, which is dedicated to the control of the temperature of the heating, of the hot water, the scheduling…  Sadly I have lost the manual explaining how this particular computer should be set. In any case I remember it wasn’t that clear. 

One example that explains the role of the PM 2975 OGZ is the following: the PM 2975 OGZ uses a temperature probe installed outside the house to measure the outside temperature and based on this information and on an algorithm it increases or decreases the heating temperature.

Maintenance duties

  • Every year let the company perform the maintenance of  burner
  • Every year have the chimney sweep clean the burner
  • Every three years have the plumber clean the pipes of the underfloor heating
  • Every five years have the boiler cleaned

During the year it is a good idea to check the pressure of the liquid in the circuit. It is known that the pressure may go down so that once or twice a year a refill needs to be made. The refill is usually done with water: you should take care of refilling slowly and avoiding air to get into the tubes. To do that it is recommended to add water into the refilling tube until it is completely full before opening the tap and letting the fresh water into the circuit.

Water pressure gauge
Our water pressure gauge

The recommended pressure is around 2 bars in the winter time, when the heating system is on, while in the summer the pressure may lower to 1.5 bars.

Why is it important to have the chimney sweep clean the burner?

Because of my ignorance I never called the chimney sweeper for 5 years: I was convinced that the regular maintenance performed by Elco was the only one regular maintenance to be made. But I was wrong. This year we realised that the heating system wasn’t capable of reaching the temperature we wanted while outside the temperature was going below zero. Also the water for the shower was hot, but not as usual. Therefore I started to worry and called Elco, announcing that the burner wasn’t working properly. As the technician arrived we checked the methane consumption over a period of time of some seconds and quickly he was able to tell me that the burner was working at a third of its capacity. Then he disassembled the whole burner and he discovered that it was clogged and that needed to be thoroughly cleaned. The Elco technician made what he could in order to start the burner again and on the first days of January I called the chimney sweeper.

As per the moment being everything works fine: the shower is hot enough and the heating works fine. Pressure in the tubes is around two bars.

The one thing I have realised is that the burner needs attentive care and should be checked ever now and then, maybe a quick look every month, in order to see if everything works fine or at least have a date to refer to, in case something suddenly stops working correctly.