Let me say something about the heating system mods i made.
First of all it was a big pain in the ass and a lot of measurements all over the place.Then it took me few good weeks of intensive thinking and trying on different theories in practice.
I gathered a lot of data and it wasn't always easy to interpret it in a right way.But to the point.
My heating system is a normal natural gas burner with a pilot flame,pipes and radiators.System is closed with a balloon expansion chamber(constantly under pressure of 1.5 atm).Only controll on heater is the adjustable thermostat taking the measurement on exiting water temperature and cutting the gas supply when it reaches set temperature.It also has overheatting protection(that i learned later on, with one of my experiments).Next to the heater i have a water pump with 3 stands 30,55 and 80 W it makes the circulation of water faster or slower according to the speed selected.
Hot exhaust gases are premixed with the cold air before they reach the chimney entrance.
Water pipes have a master valves on them.
Radiators are of type 22 and old 20.They are connected ina way that the warm water enters them from under and leaves from the opposite side top(so on the diagonal).
Described above was the situation before modifications.
now some discussion on my ideas/implementations and their results:
1)by observing the heater i noticed that the time before it starts releasing the gas and the flame starts was an interval of 8-9 s followed by small explosion in the heating chamber.The total time the burner was on was around 92 s +-1s.This time was counted from the beginig of the gas release until the burner stopped.
it was thus around 9% of the total time that gas was released let us say for nothing(it was not burned).Exposion that followed was noticeable in the exhaust chimney so i concluded this energy wasn't used to heat the water!
It took me quite a few try outs to reduce the start up delay of the burner to 2 s,all i did it was to notice that there are rust chips covering the burner holes.
Who would expect that!
I cleaned up the burner top.This rust comes from water that condensates inside of the burner chamber when it stops to operate.Chamber walls are made of the steel so it corrodes and pieces of the corrosion fall down on the burner.
To prevent future condensation i insulated the chamber walls with 6cm of rockwool.In this way it wasn't cooled down to the condensation point.
IMPORTANT: any insulation and material used around the heater should be of A1 fireproof class!!!it comes down to rockwool mineral insulation made of vulcanic stone (NOT GLASS WOOL or STYROFOAMS!!)As a result the time the burner delivers the work reduced by 4 sec!
before it was in worst case 90s-8s=82 s of burning time it got reduced to 78 sec for the worst case scenario.So it means that the explosion in the chamber was a lot of wasted gas. A direct improvement of more than
4% just by cleaning ur burner...
2s delay still worked on my nerves so i didn't gave up until i came with the nice solution to that either
Burner is in fact 5 parallel pipes with gaps in it,through this pipes the gas is exiting and burned.Above the pipes is the heat exchanger.What i noticed it that the pipes close to the pilot flame caught fire almost instantly after the gas started to be released.Pipes further from it followed in a chain reaction with some delay.
My solution to this problem( took some hours of experimentation) was an U shaped piece of aluminium profile(6X6 mm inner depth).I placed it on the burner pipes perpendicular to them.Profile is facing down so it is reversed U shape.Why?
As i imagined it will help the gas that started to flow through the gaps to meet with the neighbouring burner pipes.The gas will fill the u profile very fast because of its small volume,this will lead to fast propagation of the flame from neighbouring pipe into the u profile.
My idea seems to work just as i predicted
the flame spreads across all the pipes almost instantly with just under the 0.6 s delay measured from first to last pipe.
In total it caused the starting delay of whole burner close to 1s.I believe no further improvement can come here,because in the 1 s the pipes get filled up with the gas and this doesn't count as the wast in my opinion.
it wasn't so easy
after 2 weeks the aluminium profile was bent by flame and not working anymore :| i replaced it with stainless steel one and it seems to work just fine until now.
One thing more.Insulating of the chamber raised the temperature in the exhaust chimney.Why was it important comes later on.
2) pilot flame is a nightmare!
seriously if u measure just how much u spend during the heating season on the pilot flame u will be surprised!
Mine was using around 0.067 m3 per hour it is good for 1.6 m3 of gas per day.Roughly speaking in my region 1m3 of gas is equivalent to 10 kwh and it cost around 1 €!
It means i spend during my 160 days of heating season 160*1.6= 250€ just for pilot flame ...nice isn't it?The problem is that installer of the heater doesn't care about how much it will use,he is not paying for ur bill....So in order to have it done right do it by yourself.
Pilot flame adjustment screw is easily found if u follow the pipe from the pilot flame to the gas distributor in the heater.I screwed it in to the minimal position so it still could start up the burner.By doing so i reduced gas use to 0.045 m3 per hour,good for 172 € per year.Or to say it in savings around 80€!
Here still i am disappointed.I would truly prefer electronic ignite and i am sure it will cost much less to buy one than to have a pilot flame
I face a problem here as i have also a thermocouple next to the pilot flame that controlls if its is burning,or it cuts down the heater gas supply.So i can't easily replace pilot flame without safety distortion.
IMPORTANT:Thermocouple must be in the flame even when the burner operates.It is not always so straight forward,one thing to notice is that when main burner burns there is a pressure drop across pilot flame and it can easily stop heating the thermocouple.
In this design i have here i moved thermocouple a bit closer to the pilot flame,that solved the problem when i wanted to screw the pilot screw all the way in to get the smallest flame possible.It works fine for me for 2 heating seasons already.
3)heating cycle.
Heating cycle is more or less like this.Water in the radiators looses its heat and comes back to the heater.Heater thermometer notices the temperature drop and the thermostat starts the burner.After some time the water on the outlet of the heater reaches the set temperature and gas it cut out.
Noticeable r periods of burning and not burning of the burner.The more the power the heater has the less time it needs to warm up the water.The more radiators are open the more power is needed from the heater.
So simple isn't it? yes,but there is one drawback.In older heaters (as mine) the power it delivers is not depending on the radiators opening(inahbitant needs).
There is a serious mismatch of the required power(home heating needs) vs supplied power(heater power).
To put it in light let us see my home.it takes around 78 s to warm up the water in heating system to the desired temperature (86 kW heater).But it takes almost 3 minutes to cool down the water on average(typical day in December).Obviously the burner is much to strong for the needs.At the same time the exhaust gases temperature after mixing with cold air reaches 82 degC.
Before the heater,on ht emain gas pipe stands the master valve.I turned it a bit to a more closed position,just to see what happens.Time burner operation increased to 115 s due to lowered power of the heater.Temperature in the rooms after 2h of operation didn't changed(measured by digital temp meter between around 13.00 and 15.00).I measured the temperatures for few days in a row and saw no noticeable differences.
What i noticed is the exhaust gases temperature drop to 63 degC.
To put the accent here...all the temp in the exhaust is lost temperature,that is given out to the outside of the house and u pay for it!
Obviously lowered flame didn't affected the radiators power to give out the heat.What dropped is gas usage and this by not less than 12%
I tried further and manager to reduce the exhaust temp to 57dgC before i noticed that heater was switching off itself during the morning start up.It normally took around 18-20 min to warm up the system in the morning(before gas restriction).After mod it was taking around 30 min and then heater would fall off.This was due to the overheating sensor i haven't noticed before and i insulated together with the electronic board of the heater.This protection sensor was to ensure that in case of management system overheating(here it happened because of the insulation of it) the heater will be switched off.I took insulation hereoff and it worked just fine
So my advice is not to insulate any electronics or sensors...
Here i come back to the insulation of the burning chamber.it lead to higher exhaust gases temperature indicating the higher temperature of the chamber walls.This by itself should rise the heat exchange efficiency by additional heat radiation of the chamber walls onto the heat exchanging element.I can not measure it directly now because i haven't made this mode apart from others,so it has combined influence.
huh..still lot of things to write
hope u r not getting too bored
one of the next days i will write about the pipes insulation influence,radiators reconnecting and efficiency boosting,heater controls upgrade,circulation speed and inhabitants behavioural changes.
cy
