Electricty used by gas heating

lohr500

MikePh said:

Thanks Victor

I can place the In-House Display right next to the boiler so I will be able to see both ar once (to see if boiler is firing)

A 10 second update on power consumption will be handy

Regarding pump ....  I read somewhere that they only kick in at the beginning of a "session" and then let gravity do the heavy lfting. Do you know if that is true?

Arriving late to this discussion and don't intend to get drawn into the discussion over kW, kW/H, Joules etc.

 You seem fairly confident that the increase in usage is directly linked to the heating system and that there is no electric immersion heater linked to the boiler. So on that basis I agree with your logic that something is wrong with the heating system. 

And as others have said, the pump is most likely to have the highest electrical consumption in the system. 

As far as I am aware, in most conventional systems, the pump runs whenever the room thermostat or water tank thermostat (if fitted) call for heat. On some older systems, the pump wasn't used in the hot water heating circuit, with the hot water circuit relying on thermal action to circulate hot boiler water around the heating coil in the storage tank.  

The boiler has its own internal thermostat which monitors the water temperature in the boiler jacket.

So the sequence of events is :

Room or tank thermostat call for heat and this switches on the pump.
Pump causes a flow of cooler water around the boiler.
Boiler thermostat detects a drop in core temperature and fires up.
Pump continues to run so long as either the room or tank thermostat continue calling for heat.
Boiler may cycle in and out, or moderate heat level (if the boiler is capable of moderating), even with pump running continually, as the boiler thermostat reaches temperature.
Pump stops once room or tank thermostat reach temperature.
With pump stopped, boiler core temperature increases to the point where boiler thermostat kicks in and switches off the burner.
Boiler may run on for a short period with no burn if it has an extractor fan fitted to purge any remaining flue gasses. 

Well that's how my oil boiler system works anyway.

Once you get your IHD it should be easier to monitor what's going on as each of the above events happens.

You could set a low room thermostat temperature and allow the system to get fully up to temperature.
The pump should then not be running. You can hear the pump running or sense it by touching the case. (Perhaps not wise to touch it if it has a possible fault, although it should be well earthed). 

Turn the room thermostat right up which should cause the pump to run. Shortly afterwards the boiler should fire up.

If you switch off all other electrical items before conducting a test (ideally at the consumer unit, or unplug the higher usage items) then either with the IHD, or by carefully observing the meter, you should be able to see the increase in usage firstly as the pump kicks in and secondly as the boiler fires up.

The challenge in switching of circuits at the consumer unit could be that things like fridges and freezers could be on the same ring main that the boiler and pump power are spurred off, so you may have to physically unplug some items 

The time window between pump starting and boiler firing could be quite short, so I 'm not sure if that will be visible on the IHD. But it should be possible to see something on the meter. Particularly if your meter has a pulsing LED to show consumption.

 
 

 

Reed_Richards

lohr500 said:

So the sequence of events is :

Room or tank thermostat call for heat and this switches on the pump.
Pump causes a flow of cooler water around the boiler.
Boiler thermostat detects a drop in core temperature and fires up.
Pump continues to run so long as either the room or tank thermostat continue calling for heat.
Boiler may cycle in and out, or moderate heat level (if the boiler is capable of moderating), even with pump running continually, as the boiler thermostat reaches temperature.
Pump stops once room or tank thermostat reach temperature.
With pump stopped, boiler core temperature increases to the point where boiler thermostat kicks in and switches off the burner.
Boiler may run on for a short period with no burn if it has an extractor fan fitted to purge any remaining flue gasses. 

Well that's how my oil boiler system works anyway.

 

I don't think that's quite how my oil boiler worked.  More like:

Room or tank thermostat call for heat and this switches on the pump and starts the boiler ignition sequence.
Boiler fires up unless return water temperature exceeds the preset maximum.
Boiler did not moderate (domestic oil boilers don't).  Continues to run until thermostat calling for heat is satisfied or return water temperature exceeds preset maximum.  In the latter case I'm not sure if the pump stopped or continued (probably the latter).
Pump stops once room or tank thermostat reach temperature.

MaryNB

MikePh said:

Thanks for the reply @victor2

First of all I don't want to get into a discussion but kiloWatt/hour is a measure of how much energy you're using per hour (kilowatts per hour). The total amount of electricity I have taken from the grid in a day is measured and charged in kilowatts. (e.g at 4 pm I was consuming 4 kwh but only until 4.30. Therefore I had consumed 2 kw)

MikePh said:

Thanks Gerry1

Not confused at all... yesterday I consumed 11.4 kilowatts of power

But as I said "I don't want to get into a discussion"

You are confused. First you say kW/h is energy per hour, then you say kW is power. 

Watt is a unit of power. Power is the rate at which is energy (SI unit is Joule) is consumed or generated. You can't consume a rate, you consume something at a rate for a period of time. 

1 kW/h = 1,000 Joules of energy per second per hour
1 kW = 1,000 Joules of energy per second
1 kWh = 3,600,000 Joules of energy.

At 4pm you were using energy at a rate of  4kW which is equivalent to 4000 Joules per second . Over half an hour you had consumed 2 kWh (4 kW x 0.5 h) which is equivalent to 7,200,000 Joules. 

Have you ever actually read you energy bill? What energy company has charges pence per kW??

Astria

MaryNB said:

At 4pm you were using energy at a rate of  4kW which is equivalent to 4000 Joules per second . Over half an hour you had consumed 2 kWh (4 kW x 0.5 h) which is equivalent to 7,200,000 Joules. 

Have you ever actually read you energy bill? What energy company has charges pence per kW??

Does it matter? We know what they mean, it seems that you are just nit-picking.

MikePh

Thanks everybody

I will take some readings when smart meters installed next Wednesday and return to this thread then

What I did not emphasise in my original post is that the 6 and 10 figures are the daytime use. I know my 'background' night costs (fridge, freezer, alarm, router etc etc) to be around 2 kWh used every single night of the year. Added together my 24 hour average with no heating on is therefore around 8 kWh . This gives an annual figure of a little under 3,000 kWh which I am told is about right for a two person, medium use, household.

But last year it was 5,100 kWh (which is what prompted my investigation with careful night and day readings)

So what is guzzling electricity when the heating is turned on?     I will be back next week after interrogating smart meters

zagfles

Astria said:

MaryNB said:

At 4pm you were using energy at a rate of  4kW which is equivalent to 4000 Joules per second . Over half an hour you had consumed 2 kWh (4 kW x 0.5 h) which is equivalent to 7,200,000 Joules. 

Have you ever actually read you energy bill? What energy company has charges pence per kW??

Does it matter? We know what they mean, it seems that you are just nit-picking.

Yes, it does. If someone says "I used 5 kW" that means a different thing to them saying "I used 5 kWh", both mean something and mean different things so it's not a case of pedantry, using the wrong term causes confusion as both are possible. Like if someone said "I drove at 30mph" when they really meant "I drove 30 miles".

[Deleted User]

jrawle said:

The main electricity usage will be the pump, which could be up to 100W.

I just looked at the power being used (via my IHD for 'usage now') by the pump when demanded by hot water and this is about right - in the order of about 100W and I see no difference when it fires up to supply CH.  I guess the OP will see almost instanteously what the spike in electrical power is as soon as the pump starts working.  If it is in the order of 100W then not an issue with the pump.

If it proves not to be the pump, the OP is adamant that no additional electrical heating is happening (or has ever happened) of his hot water tank.  But I know that folk in the past have been caught out by unknown timers etc.  Sorry if this is blindingly obvious but with this Greenstar boiler being an indirect mains fed domestic hot water requiring (I think) a separate HW cylinder ........

theoretica

zagfles said:

MikePh said:

@zagfles  Thanks for reply.   Are you saying that freezer and fridge drawer significantly more in a colder room?

No, I'm saying the opposite! Think about it. A fridge or a freezer is a heat exchanger. They take heat from the inside and transfer it to the outside (the rails at the back get hot). They will consume power to run the heat exchanger, which will only be on when the temperature inside exceeds 4 degrees/-18 degrees or whatever you've set the thermostat to.

So the hotter the outside, the greater the temperature difference, the faster the inside will gain heat, the more the motor will have to run to keep the inside the required temperature.

Although I can't see it making the difference in usage you observed. Unless you have very inefficient fridge/freezer or seals are worn etc.

When I was looking into a new fridge freezer last year I discovered some are much stupider than that.  You think you have set it to -18 (or whatever) but it has actually set itself to 36 degrees below the outside temperature.  So when it is cooler outside it doesn't use less energy, the inside gets even colder instead and it can come out of its optimum working range.  No idea why some work that way - maybe it is very efficient in a nice controlled room environment.

Cardew

theoretica said:

zagfles said:

MikePh said:

@zagfles  Thanks for reply.   Are you saying that freezer and fridge drawer significantly more in a colder room?

No, I'm saying the opposite! Think about it. A fridge or a freezer is a heat exchanger. They take heat from the inside and transfer it to the outside (the rails at the back get hot). They will consume power to run the heat exchanger, which will only be on when the temperature inside exceeds 4 degrees/-18 degrees or whatever you've set the thermostat to.

So the hotter the outside, the greater the temperature difference, the faster the inside will gain heat, the more the motor will have to run to keep the inside the required temperature.

Although I can't see it making the difference in usage you observed. Unless you have very inefficient fridge/freezer or seals are worn etc.

When I was looking into a new fridge freezer last year I discovered some are much stupider than that.  You think you have set it to -18 (or whatever) but it has actually set itself to 36 degrees below the outside temperature.  So when it is cooler outside it doesn't use less energy, the inside gets even colder instead and it can come out of its optimum working range.  No idea why some work that way - maybe it is very efficient in a nice controlled room environment.

How does it know(detect) the outside temperature.

lohr500

Reed_Richards said:

lohr500 said:

So the sequence of events is :

Room or tank thermostat call for heat and this switches on the pump.
Pump causes a flow of cooler water around the boiler.
Boiler thermostat detects a drop in core temperature and fires up.
Pump continues to run so long as either the room or tank thermostat continue calling for heat.
Boiler may cycle in and out, or moderate heat level (if the boiler is capable of moderating), even with pump running continually, as the boiler thermostat reaches temperature.
Pump stops once room or tank thermostat reach temperature.
With pump stopped, boiler core temperature increases to the point where boiler thermostat kicks in and switches off the burner.
Boiler may run on for a short period with no burn if it has an extractor fan fitted to purge any remaining flue gasses. 

Well that's how my oil boiler system works anyway.

 

I don't think that's quite how my oil boiler worked.  More like:

Room or tank thermostat call for heat and this switches on the pump and starts the boiler ignition sequence.
Boiler fires up unless return water temperature exceeds the preset maximum.
Boiler did not moderate (domestic oil boilers don't).  Continues to run until thermostat calling for heat is satisfied or return water temperature exceeds preset maximum.  In the latter case I'm not sure if the pump stopped or continued (probably the latter).
Pump stops once room or tank thermostat reach temperature.

Might not be relevant to the OP's issue but with our system, when the timer for heating and/or water kicks in, this energises the boiler control system and powers the room and/or tank thermostats. If the boiler temperature is below the boiler stat limit, then the boiler fires up regardless of the room or tank temperatures until it reaches core temperature. If the tank or room stat temperatures are lower than set, then the pump starts running and the motorised valves for the CH and/or HW circuits open. The valves are also controlled by the room and tank stats. I believe our set up is what is known as an "S" plan.

ps. There are now some domestic oil boilers which can modulate the output and the installer we used had fitted a couple in the previous year. I can't remember the manufacturer's name. But he advised against them as both of the ones he had installed had problems with the electronics controlling the burner modulation.