Increase the efficiency of a boiler and decrease its consumption

Heating, insulation, ventilation, VMC, cooling ... short thermal comfort. Insulation, wood energy, heat pumps but also electricity, gas or oil, VMC ... Help in choosing and implementation, problem solving, optimization, tips and tricks ...
gisier
I learn econologic
I learn econologic
posts: 27
Registration: 16/12/08, 22:26

Increase the efficiency of a boiler and decrease its consumption




by gisier » 14/08/10, 20:03

Hello,
I believe that I will not have the means to invest in a heated floor, however I would like to have a return of water in the boiler as low as possible in order to increase all the same the efficiency of the condensing boiler that I plan. I speak of pc because it allows to have an interesting output since it is low temperature.

Increasing the size of the radiators will allow it to have a cooler temperature in return? and will it really affect consumption ???

the house which will soon see the light of day will be a very well insulated mob, with 1 floor, 165m².

Thank you for your wise comments.

ps: the boiler will also produce the DHW.
0 x
bernardd
Econologue expert
Econologue expert
posts: 2278
Registration: 12/12/09, 10:10
x 1




by bernardd » 14/08/10, 22:28

The best way to save on fuel is to use solar thermal collectors as much as possible: all the easier on a new house, you can orient part of the roof at best. Ideally, 20m2 is sufficient, even if you do not immediately cover this surface.
0 x
See you soon !
Christophe
Moderator
Moderator
posts: 79138
Registration: 10/02/03, 14:06
Location: Greenhouse planet
x 10976




by Christophe » 14/08/10, 22:57

Well yes especially that the house is apparently not yet built ...

Insulate well and think about climate control and free contributions brings much more than increasing the efficiency of a boiler ...

Using only solar for DHW in summer also optimizes consumption and operation and limits wear and fouling of the boiler ... (a boiler that only runs for DHW wears more fast because it does very small cycles) ...
0 x
sspid14
I understand econologic
I understand econologic
posts: 141
Registration: 28/12/08, 22:11




by sspid14 » 14/08/10, 23:15

A condensing boiler only condenses if the return temperature is below a certain temperature and therefore a very large exchange surface is required.
If the return temperature is too high, you might as well take a low temperature boiler, not a condensing boiler. The return will be the same and the investment cheaper.
0 x
gisier
I learn econologic
I learn econologic
posts: 27
Registration: 16/12/08, 22:26




by gisier » 14/08/10, 23:31

sspid14 wrote:A condensing boiler only condenses if the return temperature is below a certain temperature and therefore a very large exchange surface is required.
If the return temperature is too high, you might as well take a low temperature boiler, not a condensing boiler. The return will be the same and the investment cheaper.


Thank you, but what is a "low temperature" boiler?

What ideal return temperature to answer the yield question?

How to lower the return temperature?

Thank you
0 x
dedeleco
Econologue expert
Econologue expert
posts: 9211
Registration: 16/01/10, 01:19
x 10




by dedeleco » 14/08/10, 23:43

Fun to focus, pinayer and get tired on the performance of a boiler, we gain 20 to 30% max (factor 0,8 to 0,7) between a low-cost boiler (but adjusted so that the gases do not leave too hot in the 120 ° C chimney) and a very expensive condensing boiler with everything else, low temperature underfloor heating, or large surface radiators, casing, maintenance, etc.
While burning free wood and vegetable waste (collected everywhere among what we all throw away), combined with additional solar heating, save a lot more. Factors 2 to 4, even enormous, of decreasing heating costs are possible.

When the water is at very low temperature, the surface of the radiators must increase as much as more than this water is close to 20 ° C, to keep the heating power. For 1m2 with water at 60 ° C in a typical radiator, we go to 4m2 for a radiator with water at 30 ° C (60-20) / 30-20), and 2m2 for 40 ° C and the efficiency of the condensing boiler changes by about 10%. .Also it is not certain that it is a very interesting investment.

Solar and wood heating with free wood, vegetable waste crushed or recovered, dried in the sun is much more interesting, because it can reduce heating costs to zero, and not an unfortunate 10% !!!

By recovering and cutting from my hands the wood of chablis abandoned from the storm of the end of 1999, I had enough to heat for free for 10 years, apart from the subscription to EDF which I had to keep to light up !!
In addition it is a physical exercise that helps to keep in shape and health.

I would tend to invest in a beautiful automatic boiler burning all wood, logs, chips, grinds free recovered, even badly dried, rather than a condensing boiler and all that goes with it for a price can be comparable ???
0 x
dedeleco
Econologue expert
Econologue expert
posts: 9211
Registration: 16/01/10, 01:19
x 10




by dedeleco » 15/08/10, 00:33

Thank you, but what is a "low temperature" boiler?

What ideal return temperature to answer the yield question?

How to lower the return temperature?

It is clear that a theoretical basic course is necessary to light the lantern !!
Any heating with fuel (fuel oil, gas, wood) gives very hot fumes which include water vapor and CO2 created by combustion.
A heat exchanger allows these fumes to cool by heating the heating water that heats the house.
The more the heat gives off the smoke, the lower the smoke coming out of the heat exchanger and the better the efficiency, since the heat lost in the chimney is reduced with less hot smoke !!.
It is 100% if the fumes come out at 20 ° C, but the water comes out at 20 ° C to heat the house. !!
The ideal is 20 ° C with an infinite surface of radiators, the house being a huge radiator !!
The problem is that the water vapor from the fumes condenses into liquid water if the fumes come out below 100 ° C! We recover the condensation energy of this water but at the cost of a lot of water which drips and makes it rust, imposing a much more resistant boiler and a casing of the chimney.
For this reason we call this condensing boiler !!!
http://fr.wikipedia.org/wiki/Chaudi%C3% ... ndensation

The old boilers gave combustion gas temperatures from 200 to 300 ° C towards the chimney (in pure losses) while by cooling the combustion gases by a condenser, one can lower them to 45 - 70 ° C! The efficiency of the boiler increases and the losses to the chimney drop. In theory, in fuel, we should count on a saving of 6% and in gas of 11% (PCS / PCI ratio). In reality, in fuel, we reach values ​​around 4% and in gas around 8%. It is also prudent to inquire about the performance values ​​announced ... Indeed, a condensing boiler will have the best performance at low temperature, that is to say 40-50 ° C. This corresponds approximately to the dew point where the water vapor deposits its maximum energy via the condenser and redistributes it to the heating circuit. Above these temperatures, the energy recovered in the condenser drops.


However, the gain is less than 10% max compared to non-condensing (fumes slightly more than 100 ° C).

Finally, on an old boiler with poor efficiency (smoke at 300 to 200 ° C), the efficiency can be greatly improved without changing it, by reducing its heating power to have smoke coming out a little above 100 ° C!, With the gas, it suffices to partially close the tap to reduce its flow, checking that the combustion remains good !!
Without any investment, or change of boiler, with just a thermometer, you realize a significant saving, even price of the heating divided by a factor 2 if the temperature of the fumes after exchanger is more than 300 ° C. !!!

Finally I think it is better to take a free fuel (wood discarded and recovered) or solar than to spend to recover 10%.

Sawdust for making pellets was free, but the current selling price of pellets is barely more attractive than fuel oil or gas.
The free is a max of profit for those who take advantage of it to resell it as expensive as possible !!
0 x
sspid14
I understand econologic
I understand econologic
posts: 141
Registration: 28/12/08, 22:11




by sspid14 » 16/08/10, 00:08

Thank you, but what is a "low temperature" boiler?

The temperature of the return water is low and therefore allows you to take in more heat which will not escape into the chimney. However, there is little or no condensation.

The condensing boiler has a more efficient exchanger which allows the latent heat of vaporization and therefore high condensation to be recovered.

What ideal return temperature to answer the yield question?

For a condensing boiler to have an interest, the return water must be less than 46 ° C, because the dew point temperature is around 46 ° C for fuel oil.
http://www.cstc.be/homepage/index.cfm?c ... t9&art=143

How to lower the return temperature?

See "possible combinations" from the link above
0 x
oiseautempete
Grand Econologue
Grand Econologue
posts: 848
Registration: 19/11/09, 13:24

Re: Increase the efficiency of a boiler and decrease its cost




by oiseautempete » 16/08/10, 09:42

gisier wrote:Hello,
I think I will not have the means to invest in a heated floor


A heated floor is hardly more expensive than large radiators with the advantage of clearing the walls, no maintenance and no cold feet in winter: think carefully before dismissing this solution ...
0 x
User avatar
chatelot16
Econologue expert
Econologue expert
posts: 6960
Registration: 11/11/07, 17:33
Location: Angouleme
x 264




by chatelot16 » 16/08/10, 13:48

why would the underfloor heating be expensive?

in a new house you need a concrete floor anyway: putting a few pipes in it does not cost much more

of course the classic method, big cold concrete slab + special and rigid insulation with pipe fixing + more very special thin concrete so as not to crack seems to me too complicated

in my house it will be rather polyethylene, loose insulator like pouzolanne, polyethylene, ordinary concrete with pipe attached to the scrap

the total price is almost identical to a floor without heating

each slab must be independent of the foundations and walls because of expansion

for the floors the underfloor heating is less simple ... but still remains the best solution
0 x

 


  • Similar topics
    Replies
    views
    Last message

Back to "Heating, insulation, ventilation, VMC, cooling ..."

Who is online ?

Users browsing this forum : No registered users and 309 guests