Consistency of the water law with cast iron radiators

[Johannm]

Hello everyone,

Small reflection level energy saving.

In the case of cast iron radiators, to follow the law of water (temperature the most stable and low possible of the radiators to obtain a constant internal temperature while referring to the outside temperature ...) is it a good thing economic level, knowing that cast iron radiators have better performance at high temperatures?
Should not it be better to have a heating water temperature setpoint at max 70 ° all the time and regulate thanks to the indoor thermostat?

I have the impression that I consumed less before regulating the law of water when this one was overvalued ...

I have heard that cast iron radiators have better performance at high temperatures

Ps: I have a pellet easypell boiler 12kw house 110m² poorly insulated

[Bardal]

Cast iron radiators, apart from a slightly stronger inertia, have no heat emission quality superior or even different from other metal radiators. They emit mainly by convection, and a little by radiation, depending on their surface, their shape and (a little) of their surface state ...
It is strictly useless to seek a better "yield" than for other radiators by injecting them with hotter water (which will not be the case with the assembly that you propose); the only thing you will get is an unbearable room temperature ...

The impression that you have the ability to save by this means is false; good regulation (and regulation by water law can be excellent if well set and adjusted) is one of the ways to optimize heating consumption; the other means, very effective, is to respect a set temperature below 20 ° (or less if you support), and to avoid heating spaces that are not used.

The royal road remains of course the insulation and the fight against the air leaks. No hope on the matter of the radiators ... Sorry, the laws of the thermal leave little room for miracles ...

[Johannm]

Thank you bardal for your clear answer.

In fact I managed to find my law of water that it is a 20 ° I consumed 120kg of pellet by 48h with an average of 4 ° outside, I thus re-calibrated my law of water for 17 °, but I consumed castionnaire the same (interior thermostat deactivated of course)

Although 17 ° at home, and my order down 10 ° I had no impact on my consumption.
This may be due to the fact that I have a bad insulation and that although the setback decreases the amount of hot water to inject into the circuit remains substantially the same because the loss would be greater at lower temperature setting and that of has very bad insulation?

I have an old house, stone walls of 80cm semi-buried and no insulation attic for now (I isolate the attic in R7 in February).

Another amazing fact, or not; it is that in the face of this overconsumption of pellet I re-ignited my turbo wood insert (which distributes hot air in 80% of the rooms of my house) and I do not use my boiler any more than 3h a8h of the morning ( the boiler consumes much less it is on) but the surprising thing is that I can heat the whole house between 20 ° and 22 ° consuming 2 stere per month with the insert against 3 tons of pellet per month with the boiler ...

The only explanation I can see is that having a lot of heat loss because of my rotten insulation, the "turbo" insert which pulses hot air constantly is a more appropriate heating method because it renews the heat. air, hot air much faster and decreases humidity ... What do you think?

[Exnihiloest]

There is almost no relation between the type of radiator and the energy consumption. The only difference is its ability to dissipate more or less quickly the heat of the water which circulates there. An aluminum radiator will dissipate heat faster than a cast iron radiator, as will a radiator with a larger surface area than anything else being equal. These differences can be compensated for by the water flow and temperature settings. For comfort and efficiency, it is better to favor solutions operating at the lowest temperatures (therefore large and "warm" radiators rather than small and very hot).

The only explanation I see is that having a big loss of heat because of my rotten insulation,

That's it, yes.

[Johannm]

There is almost no connection between the type of radiator and the energy consumption. The only difference is its ability to dissipate more or less quickly the heat of the water circulating there.

if the logic is the same when going from a radiator to an insert, then indeed the insert that pulses hot air dissipates the heat velocity V large which can counteract my poor insulation.

so I'll have to wait to have isolated the attic so that my pellet boiler becomes my main mode of heating?

my 1er floor being under roofing, after insulation of my attic I would have fully insulated 50% of my house ... I confess that I freak a little because in the state I consume 1,5T pellet a month with instructions around 45 ° ... going from my current rotten insulation to an all-round 7er R1 floor in frivolous insulation what can I expect in gaining grosomodo consumption? a halving?

[Ahmed]

Johannm, you write:

The only explanation I can see is that having a lot of heat loss because of my rotten insulation, the "turbo" insert which pulses hot air constantly is a more appropriate heating method because it renews the heat. air, hot air much faster and decreases humidity ... What do you think?

It is perhaps hazardous to compare an insert and a boiler because the latter knows losses that the first does not have to support: production of DHW, room of the boiler room (even basement) and passage of the pipes possibly to proximity of thermal bridges in line with the floors ...

[Did67]

A parameter to take into account: the thermal inertia, with stone walls 80 cm ... It is a thermal liner. And not a zodiac! No need to tire yourself down - you will need 48 to go up!

What has been said is correct:

- the nature of the radiators plays little; it is possibly the exchange surfaces; the disadvantage of cast iron radiators is that they are usually old, with very little surface exchange; therefore, you can regulate what you want, you will not have too much choice, to heat enough it will cause you to send water at high or very high temperatures

- automatically, if you regulate your law of water, you will come out with rather high parameters: temp at the foot of the curve, slope ... And you can not do anything about it.

- unless it was heavily insulated, in which case your radiators would be oversized, which would allow you to work with lower settings.

- so yes, set the lowest setpoint temperature that is bearable; limit the parts ...

- and one day, isolate; ideally from the outside, in which case the inertia will provide you an unthinkable comfort (especially in summer: the freshness is preserved!).

- especially do not think that an insert will bring a plus, even if indeed, we blow the hot air, you can put in the flow and leave the rest much colder; it's a little misleading, and it's extremely uncomfortable ... And the insert has a deplorable performance - often 50% - for catastrophic emission rates (unlike your pellet boiler, which has an excellent performance and a controlled combustion very clean!)

- do not rely on records for very short periods; they do not have much meaning - it's enough that your night temperature drops 2 or 3 ° more, that you have pulled a little more hot water (many people forget it, hot water is a sinkhole energy: in well insulated homes, which is not your case, it exceeds the consumption for heating! That is to say).

- It will remain that the better you will regulate your heating, including your water law, to have just enough hot and never too much, and the less you will consume; this "less" being able, in a thermal colander (no insulation, air leaks) to be a lot! Even a lot - and you can pay until next Christmas, that won't change a thing. It's like filling a leaky barrel. And want to maintain the level (20 °). If there are a lot of holes, you have to pour a lot of water !!!! You can adjust your spray all over the place - no miracle possible, once you have adjusted the flow to the leaks! I am well aware that the regulators advertise so many "miraculous" things - I sometimes wonder why we still sell boilers!

[Johannm]

Thank you did67 for this synthesis!

especially do not think that an insert will bring a plus, even if indeed, we blow the hot air, you can put in the flow and leave the rest much colder; it's a bit deceiving, and it's extremely uncomfortable ...

My insert 11kw and its heating ducts were very well installed, because it alone, boiler off it heats the whole house between 20 and 22 ° according to the rooms and in each room the heat is relatively homogeneous, relatively comfortable and all this by consuming 2 stere per month. I warmed up like that all last winter.

I took a pellet boiler for comfort and ecology but given what it consumes for now ... I regret a little.

and one day isolate; ideally from the outside, in which case the inertia will provide you an unthinkable comfort (especially in summer: freshness is preserved!
.

I'm going to think about isolating the walls too from the outside, on the beautiful stone, too bad ...

In the meantime, I'm going to isolate the roofs, besides, you do not think it's going to be bad enough to fill the barrel? Given the configuration of my house; 50% of my surface is under the roofs (old attic arranged but not isolated at the time)


For now I have ironed 90% on my insert and no longer uses the boiler for the purposes of night and ecs.

I hope I could, after insulating the attic switch back on my boiler by having decreased my pellet consumption by 2.

[izentrop]

In these conditions, the wood comes back at least 2 times cheaper, it makes sense, less waste and cost in the first way.

[Did67]

In the meantime, I'm going to isolate the roofs, besides, you do not think it's going to be bad enough to fill the barrel? Given the configuration of my house; 50% of my surface is under the roofs (old attic arranged but not isolated at the time)

You can indeed start there, the "heat rises" is not entirely false: the ceilings are more exposed to hot air than the floor or the bottom of the walls ...

A second "easy" parameter is the door frames if this has not already been redone: tightness and emissivity [but be careful with the tightness in the absence of CMV: condensation / mold!]

Your insert is amazing. But indeed, with a network of ducts, we achieve much better performance and a better distribution of energy by aeraulic route (air circulation; there is not only water as a vector!). And it is well dimensioned, which allows you, I suppose, to run it at good power, without smothering the fire by regulating the air inlets (it is this regulation by suffocation that generates the "ecological catastrophe" - incomplete combustion at too low a temperature, therefore emission of CO, VOCs and particles - and drop in efficiency). Perhaps it has a post-combustion (secondary air supply)?