Electricity spiking using Combi gas boiler

houghton91

Hi all

Sorry if this is a stupid question, as I’ve only just started using both a smart meter and a Combi gas boiler, and I have little experience with either. 

Tonight is the first time since last winter that we’ve turned the heating on (except when the boiler was serviced last month) and I’ve been tracking over an hour to see what the energy usage is. Over the course of an hour since I turned the boiler on, we’ve gone from 6kwh electricity usage for the day up to 7.5kw, and I just wanted to check if this was normal for a gas boiler to use that much electricity? Or could it be down to it being the first time we’ve switched it on for a while? (I did have to turn up the boiler temp initially as it was set too low. The electricity seems to spike every minute or so, up from a baseline of 600w up to 1500w-2000w. 

For reference, the boiler has just been serviced, is around 3 years old and is a 26kw gas boiler. 

grumbler

houghton91 said:

Over the course of an hour since I turned the boiler on, we’ve gone from 6kwh electricity usage for the day up to 7.5kw, and I just wanted to check if this was normal for a gas boiler to use that much electricity?

No, it's not normal. The only part that consumes electric power is the CH pump that is about 50W. You can even check the fuse - it has to be 3A, i.e. ~750W max.

Or could it be down to it being the first time we’ve switched it on for a while?

I don't see any reason for this.

jrawle

50W is a slightly conservative estimate. The separate pump in my system uses 100W, plus you have the fan etc. so let's call it 100W total. To use 1.5 kWh for the boiler, you'd have to run it for 15 hours. That might not be impossible if you have it set to a very low flow temperature (which plenty of people here advocate to gain a few extra percent efficiency, although if it means a large electricity consumption, that may not be an advantage).

However, you say you measured it over an hour, so how do you get a figure of 1.5 kWh extra per day? I'm confused by the slightly inconsistent mixing of kW and kWh. Are you reading too much in a spike in power of 2000W, I wonder? Or does your smart meter give an estimate of your daily usage based on current power?

I would ignore any spikes in the reading. They may be artefacts caused by the way the smart meter samples its data to give an instantaneous power value. If the boiler has been running solidly for an hour, it may well estimate 1.5 kWh per day, but this is unrealistic unless it will run continuously all day. The only way to measure your usage accurately is to note the kWh usage each day for a few days when you are using the heating.

MikeJXE

Have you a fridge freezer running also