Roughly how many kW does a boiler use when ticking over?

shortchanged_2

Just a quick question for those in the know.

I have a Vaillant ecotec 428 and I am wondering roughly how many KW of power the boiler is using on heating when it is ticking over to maintain the set system temperature.

lstar337

shortchanged wrote: »

Just a quick question for those in the know.

I have a Vaillant ecotec 428 and I am wondering roughly how many KW of power the boiler is using on heating when it is ticking over to maintain the set system temperature.

A lot of variables in there. I don't think anybody will be able to give you a precise answer.

shortchanged_2

lstar337 wrote: »

A lot of variables in there. I don't think anybody will be able to give you a precise answer.

Thanks, I understand I was wondering roughly what output the boiler has when it is ticking over quietly.

matelodave

As said, there's lots going on.
Vaillant reckon it's 60watts but that assumes that the pump, burner and fan are all running at the same time. The electronics probably takes about 5watts continuously and the other 55watts will be intermittent.
Even if the boiler runs for 50% of the time(which is unlikely) that's about 30watts/hour which is about 1kwh every 33 hours if you have the heating on continuously.
If you've got a thermostat and timer then multiply your on time by 30watts and you'll get some idea - alternative get an energy monitor and measure it.

The boiler's gas usage is much more difficult to predict as it's a modulating burner which outputs anywhere between 5.5-30kwh depending on your flow and return temperatures. Assuming a 90% efficiency it will consume anywhere between 6kwh and 33kwh of gas whilst it's heating.

However it doesn't run continuously at full output except when it's heating the house or hot water from cold, it will reduce the output (and thus ithe input) to compensate and will also turn on and off under the control of it's internal thermostat, the room thermostat, timer and any other system controls. Again all you can do its go and read the gas meter on an hourly basis to try and determine how much it uses when running

DTDfanBoy

shortchanged wrote: »

Thanks, I understand I was wondering roughly what output the boiler has when it is ticking over quietly.

According to the specs output is between 5-30kW, I guess it all depends on how you define ticking over quietly.

The easiest way to measure it's average output is to monitor how much gas it uses.

lstar337

DTDfanBoy wrote: »

According to the specs output is between 5-30kW, I guess it all depends on how you define ticking over quietly.

The easiest way to measure it's average output is to monitor how much gas it uses.

Though it isn't obvious, I think the OP is asking about the electrical power consumed by the boiler.

Cardew

matelodave wrote: »

As said, there's lots going on.
Vaillant reckon it's 60watts but that assumes that the pump, burner and fan are all running at the same time. The electronics probably takes about 5watts continuously and the other 55watts will be intermittent.
Even if the boiler runs for 50% of the time(which is unlikely) that's about 30watts/hour which is about 1kwh every 33 hours if you have the heating on continuously.
If you've got a thermostat and timer then multiply your on time by 30watts and you'll get some idea - alternative get an energy monitor and measure it.

I read the OP's question differently. They asked:

I am wondering roughly how many KW of power the boiler is using on heating when it is ticking over to maintain the set system temperature.

You are talking about the electrical consumption, but the OP surely means gas consumption when 'ticking over'.

OP, Your boiler will modulate(turn down the output) from 28kW to 5kW, but of course if it doesn't need 5kW it will shut off.

Your best bet is to simply monitor your gas meter which will give you an accurate measure of how much gas has been used in, say 1 hour.

lstar337

Cardew wrote: »

I read the OP's question differently. They asked:

You are talking about the electrical consumption, but the OP surely means gas consumption when 'ticking over'.

OP, Your boiler will modulate(turn down the output) from 28kW to 5kW, but of course if it doesn't need 5kW it will shut off.

Your best bet is to simply monitor your gas meter which will give you an accurate measure of how much gas has been used in, say 1 hour.

And I read it differently to you.

Perhaps the OP needs to clarify the situation.

Cardew

We should have a virtual pint on this:beer:

Pincher

As a house, it is leaking heat to the outside ALL THE TIME.
If you had the timer on continuous (24/7), and the thermostat on 18 degrees, the heat generated is simply what you lost to the outside.


Obviously, you lose more heat when it's zero degrees outside, as opposed to ten degrees.


The typical boiler set up is just clicking on and off all the time.


A weather compensation controller should try to simmer continuously to match the heat loss, so it will produce 5kW to match a 5kW loss.

matelodave

A weather compensating controller has to be incorporated into the boiler controls so that the boiler output is modulated to accommodate the heating load - once you bung an external thermostat on the outside (even a weather compensated one) then the boiler is switched on & off which causes it to go full blast when it lights and then turn it's self down as the house warms.

My heating system varies it's output temperature in relation to the external temperature so when its 15 outside the flow temp is 25 degrees and when it's zero the flow temp is 40 degrees. The pump is controlled by the internal thermostats (one in each room) so the heating unit just maintains sufficient water temperature to compensate for the heat loss.

It does take ages to get the house up to temperature from cold though so instead of turning it off we turn it down a bit (night setback) and can boost it if required to attain a faster warm up.