Boiler gas consumption

[RichD1]

I have a 35kW combi boiler. Can I assume that is the input energy so if I divide by 10.55kW per cubic metre of gas that equals 3.3 cubic metres of gas per hour.

Am i correct?

 

[gas112]

have a look in your installation instruction book it will have the m3/h figure in a chart

 

[RichD1]

I did but couldn’t see any reference to gas consumption.

 

[MNW67]

Usually the 35KW would be the output. The input would be higher. How much higher depends on the efficiency.

But what are you trying to work out?

The conversion also depends on the calorific value of gas at the time you use it.

What is the boiler?

 

[gas112]

I did but couldn’t see any reference to gas consumption.

read it more carefully every installation manual has the figure

 

[ericmark]

Need to read installation manual not users manual to see output, however in the main gas boilers can modulate, so the amount of gas used varies, I wanted to work out gas use with my mothers house, so I could work out if changes were improving boiler efficiency, but not like electric, with electric I can clip on a meter and read how much used, really easy, shown here testing non contact voltage, but easy to see what is being used, but gas one can't measure so easy, even my oil boiler, I can measure time running which equals the amount of oil used, but that is not true with most gas boilers.

What we want is for the boiler to extract the latent heat from the flue gases, to do that the boiler needs to modulate, (turn down) and run constantly at a varying output rather than on/off. The thermostat I had, was designed to stop hysteresis by using a mark/space ratio as it approached target temperature, really good idea with the oil boiler I have now, but not a good idea with a modulating gas boiler, as the thermostat is only there to turn off boiler when weather gets warmer, the TRV does all the work in controlling room temperature. So I was considering changing the thermostat, however before I got any results, my mother died so house was sold.

 

[RichD1]

I’m just trying to work out what it costs to run hot water. Before the advice was it’s more economical to use a dishwasher. But with the increase in the cost of energy I’m wondering if going back to hand washing is better, especially as there only the two of us now.

 

[Rodders53]

It is not worth the angst.

Dishwasher. We two run ours two or three times a week.

Roughly a kWh of so of leccy and under 10 litres of water, according to Neff. Check out your machine's spec / manuals.

Pop over to the Money saving expert energy forums where the Q has been covered and debated by cleverer people than I; doing the sums for gas, oil etc.,. heating the water ( they even allow for the cold draw off waste water costs).

 

[Ltnman]

Why don’t you just get a smart meter? For me it has been a revaluation, as I was surprised how little gas our family of 4 used just heating hot water. Hot water set at 42C to avoid heating water only to add cold.


Typical summer figure

 

[RichD1]

We have the Octopus Smart Meter app too and it's brilliant. But with the heating on at the moment it's difficult to see what hot water is. Think I will take a reading before and after doing the washing up.

 

[Madrab]

Hot water set at 42C to avoid heating water only to add cold

hoping that it is a combi boiler you are using?

 

[Mottie]

I’m just trying to work out what it costs to run hot water. Before the advice was it’s more economical to use a dishwasher. But with the increase in the cost of energy I’m wondering if going back to hand washing is better, especially as there only the two of us now.

We use our dishwasher once a day, every day and there’s only two of us. When our 20 year old one packed up a while ago we got a new one but in between we washed up by hand. We were amazed by the number of times we used the sink during the day - more so by the amount of water we used too compared to the dishwasher. Way more than we thought we would.