How much electricity does an oil boiler use?

Jacqs0304

I'd really appreciate some help with this question (sorry if it's been asked before, I tried searching the posts but couldn't find the answer).

I have a Grant Vortex condensing combi 26 oil boiler and I'd like to work out how much electricity the boiler uses.

Can anyone tell me - or explain where to look to find out - how much electricity is used per minute when the boiler is heating water (i.e. running the hot tap/taking a shower) or when the central heating (radiators) are on?

I obviously pay for heating oil (my local oil club has a rate of 88p per litre this weekend, so £440 for 500 litres which will last me a few months) and of course I use much more oil during the winter months than the summer months, but I don't understand why my winter electricity bills are so much higher than summer bills?

I appreciate I use a bit more electricity during the winter re: having lights on for longer or taking longer showers, but if I'm not using any other heating (i.e. no plug-in electric fan heaters etc.) then it seems to me the only difference can be my use of the Vortex boiler for central heating? But if the central heating is oil fired, how does this use electricity??

Any information anyone's able to help me with (in lay persons terms, without too much technical jargon!) would be very much appreciated, thanks!

(FYI I'm careful about electricity usage in general i.e. I don't use a tumble dryer or dishwasher, I use the washing machine sparingly, there aren't any gaming devices in the house and I switch appliances/gadgets off at the mains etc. etc.)

QrizB

I don't know your boiler specifically (there are some here who will) but as a very rough guide, 100 watts for the circulating pump plus 50 watts for all the other electrical gubbins. So 0.15kWh for each hour it runs, 0.9kWh/day if it runs for six hours a day.

That's equivalent to 0.0025kWh per minute.

One of the Grant owners will no doubt be along shortly to let you know how wrong I am

lohr500

The data sheet for the Vortex Pro internal 26 boiler states the burner motor uses 90 Watts and has an absorbed motor power of 0.15kWh. As far as I can tell from Google, the absorbed motor power is the better indication of the actual power used, but it isn't a term I am familiar with. There will also be some power requirement for the control panel.

The circulating pump could be 100w as QrizB mentioned, but possibly less depending on size. The popular DAB Evosta3 runs at 35 watts.

https://www.toolstation.com/dab-evosta3-circulating-pump-80130/p28753

If the absorbed power is the actual consumption and we assume 35 watts for the pump, then the consumption would be a little higher than QrizB's estimate. 0.185kW/h.

However, unless the house is poorly insulated and the boiler runs permanently, the circulation pump and burner motor will cut in and out periodically once the room thermostat reaches temperature and starts to cycle. So 0.185kWh will be the worst case.

How much more electricity are you using in winter? As per QrizB's calculation, or mine which is similar, the boiler shouldn't be using any more than 1 unit of electricity per day tops, if used for 6 hours. And more than likely less as it will be cycling on and off through the time it is in use.

Have you got any high powered halogen motion sensing spot lights outside, or any other external lighting that operates from dusk to dawn? Lots of traditional 60W or 100W lightbulbs that would be switched on for longer through the winter? Large tropical fish tank with heater?

Jacqs0304

QrizB said:

I don't know your boiler specifically (there are some here who will) but as a very rough guide, 100 watts for the circulating pump plus 50 watts for all the other electrical gubbins. So 0.15kWh for each hour it runs, 0.9kWh/day if it runs for six hours a day.

That's equivalent to 0.0025kWh per minute.

One of the Grant owners will no doubt be along shortly to let you know how wrong I am

Thank you that's really helpful! :-)

Rodders53

Age of boiler?
Grant CH circulating pumps power will vary depending on speed set and age of it.  My Grant-branded one in the (15 year old) boiler housing is 45 / 65 / 90 Watts on the label - running on the slowest speed in my case.  If yours runs faster it'll use more electric.

I replaced an almost identical pump used on my underfloor heating manifold with a modern Wilo Yonos circulating pump that consumes 4-33 Watts depending on need (instead of speed 3 and the 87 Watts that Pegler-branded pump label stated).

The boiler circulating pump will run continuously while there is heating demand (call for heat from any thermostat(s)).  The kerosene burner pump will cycle on and off to maintain hot circulating water to the radiators.  If your CH has zones you can add another 6 Watts for each zone valve that opens to allow water to flow in the relevant zone.

With a combi on HW only it'll likely just be the oil burner running for however long the water is being drawn for.

Gas boilers have similar electricity usage when operating (except they have no need for the kerosene burner pump; instead often having a balanced flue fan).


Now I need to work out if it's worth changing my boiler's circulating pump to save some electricity... 

Jacqs0304

Many thanks Rodders53 & lohr500 for your really helpful advice, much appreciated!

Reed_Richards

Rodders53 said:

The boiler circulating pump will run continuously while there is heating demand (call for heat from any thermostat(s)).  The kerosene burner pump will cycle on and off to maintain hot circulating water to the radiators.  If your CH has zones you can add another 6 Watts for each zone valve that opens to allow water to flow in the relevant zone.
 

I used to have a combi oil boiler but I am struggling to remember what happens if you turn on a hot tap for an extended period, for a  bath or a shower or filling a sink.  The boiler had a buffer tank with a little bit of hot water in so that you can get hot water quickly but when this had run down or just cooled down from lack of use then the boiler would switch to hot water heating.  In my case the pump was integral to the boiler and  I presume at some point during this sequence the central heating pump was turned off, whether or not there was a heating demand.  Of course that's not going to make much difference to the overall electricity usage but the OP did ask the question. 

Alfster

lohr500 said:

The data sheet for the Vortex Pro internal 26 boiler states the burner motor uses 90 Watts and has an absorbed motor power of 0.15kWh. As far as I can tell from Google, the absorbed motor power is the better indication of the actual power used, but it isn't a term I am familiar with. There will also be some power requirement for the control panel.

The circulating pump could be 100w as QrizB mentioned, but possibly less depending on size. The popular DAB Evosta3 runs at 35 watts.

https://www.toolstation.com/dab-evosta3-circulating-pump-80130/p28753

If the absorbed power is the actual consumption and we assume 35 watts for the pump, then the consumption would be a little higher than QrizB's estimate. 0.185kW/h.

However, unless the house is poorly insulated and the boiler runs permanently, the circulation pump and burner motor will cut in and out periodically once the room thermostat reaches temperature and starts to cycle. So 0.185kWh will be the worst case.

How much more electricity are you using in winter? As per QrizB's calculation, or mine which is similar, the boiler shouldn't be using any more than 1 unit of electricity per day tops, if used for 6 hours. And more than likely less as it will be cycling on and off through the time it is in use.

Have you got any high powered halogen motion sensing spot lights outside, or any other external lighting that operates from dusk to dawn? Lots of traditional 60W or 100W lightbulbs that would be switched on for longer through the winter? Large tropical fish tank with heater?

I was just searching this forum to confirm how much electricity my oil boiler uses as shown by my smart meter. I have a Grant Vortex oil boiler (not combi).

If I watch my smart meter before and after switching the hot weater or central heating on the current useage increases by 200-250W. 

Having gone into my basement to check a what else is down there I have a Gransfos pump which I looked up and is about 50W. Which means the boielr uses 150-200W in line with what lohr found. Just thought I would post this to anyone that comes across this post again. 

orbit500

Mine has a consumption meter inline so I can measure oil consumption. It’s a 36/46 utility and averages 140w.

rodmaker

I put a wattmeter inline on the mains feed to my boiler. I did this by repacing the socket    to a  standard  13 amp type  and plugged the watt meter into that.I fitted a 13 amp plug to the boiler cable and that just plugs in to the meter. See here for one of these.
The watt meter measures the use in amps or watts.  I did  this to establish what my boiler actually uses.
 We live in a rural 2 bedroom cottage. The central heating run time pre the heating burner motor kicking in is 29 watts. When on boil or heating the boilers water motor it peaks at 170 watts for the period that it heats the water till the thermostat cuts it off. It runs at 170 watts roughly four times per hour. When domesic hot water is called for again that is 170 watts till the water reaches the required temperature. This can be as long as 15 mins if the boiler is heating up from cold.