gas or electric boiler running costs

themethod

Hi there,
This is a reasonably common topic, but couldn't find a decent enough answer.
Because of various restrictions due to having a gas boiler on a se duct (internal chimney), I am considering an electric boiler.

I have a 1 bed flat (5 radiators), if I get a 6kW electric boiler and get the econ 10 tariff, am I right to assume (using this crude calculation)
on avg for the whole year 5 hours a day = 30kwh a day which is 900kwh a month at roughly 10p a kwh is £90 a month.

If I get a 24kw gas boiler does that run at 24kw, or will it consume less?
IF it is 24kw then again with 5 hours a day that is 3600 kwh a month at say 3p per kwh for gas is £108 a month.

Obviously I should be missing something as the gas option has to be cheaper per month, so even is the boiler outputs at 18kw its still £81 a month, which is higher than my current setup, so wondering what I'm missing and whether electric boiler is affordable?

**my average of 5hours per day for the year assumes 2hours for half the year and 8 hours for half the year.

Many thanks

rogerblack

Both boilers will only provide as much heat as required, using as much electricity or gas as required.

Gas isn't always that much cheaper than economy rate electric.
It'd be useful if you said what rates you're paying for power during the economy 10 periods.

themethod

during the econ 10 periods the rates I got quoted was 8.39p per kwh, but I assumed 10p in my calculation to be conservative

chris1973

Gas can be got on a tier 2 rate for anywhere between 3.4p and 4.3p per KW

Off peak electricity (conventional E7 Tariff) anywhere between 4.9p and 6p

(all based on the recently increased tariffs)

Electricity is supposed to be slightly more efficient than gas. So will narrow the void slightly.

Your tariff of 8.39p doesn't seem all that attractive to be honest, unless you are likely to be a big user of electricity by using other high consumption appliances during the E10 periods?

rogerblack

chris1973 wrote: »

Your tariff of 8.39p doesn't seem all that attractive to be honest, unless you are likely to be a big user of electricity by using other high consumption appliances during the E10 periods?

8.39 is pretty terrible as an E10 rate.

I'm paying 9.79 with n-power, and that's a standard tarrif. (inc vat)

One thing to note.
If you're a light user of gas, the initial unit rate may be a huge component of your bill.
For example - again on my tariff - I need to use 4572 units a year before hitting the second rate. As I have solar-thermal water heating (from ebay, 300 quid) and cook with electricity, this would only be used for heating.

For 4 months of the year, this is 38kWh/day, or about 1.5kW all the time.
This is a large slice - maybe this may be adequate - if all of my insulation performs as expected - to heat my house entirely.

If you use more than this, then you can look at it as a 212 pound a year 'standing charge'.

chris1973

I'm paying 9.79 with n-power, and that's a standard tarrif. (inc vat)

Cool, can I ask what Tariff you are on for selfish reasons (well on behalf of my Parents actually), they are with Npower and have recently been informed that their tariff has gone from:-

16.66p to 18.66p (Tier One 728 KWH / Year)
13.99p to 14.95p (Tier Two)

I know prices are regional, but i'd love to get them one something closer to the mentioned 9.79p, even if it was 11p or 12p!

themethod

thanks for the replies...
I guess the main question is if I get a 6kw electric boiler or a 24kw gas boiler what would be the rough usage of each type?

I have 4.5 radiators which should be about 2kw each = 10kw??
and another 3-4 kw for the hot water, so maybe the gas boiler will only use about 14kw?

How do I calculate my expected gas used in kwh for a gas boiler..?

I just don't know how to estimate running costs? Any help would be appreciated

Ben84

themethod wrote: »

If I get a 24kw gas boiler does that run at 24kw, or will it consume less?

The way a boiler works is that whenever the burner is lit/the heating element is on it is using the rated kW, but the thermostat turns the flame/element on and off repeated every hour giving various minutes use per hour, depending on the temperature difference it's trying to maintain between inside and outside, so that the actual kWh consumption may be anywhere between zero and the maximum (24 kWh in this example). It could for example give you 12 kW over an hour by running a total of 30 minutes in that hour.

So, unfortunately the kW rating on a thermostatically controlled appliance isn't sufficient to predict its running costs. It will give you a maximum - but it's likely to be a massive over-estimate of the real cost.

themethod

ok thanks trying to compare a 6kw electric or or 24kw gas boiler..can anyone have a crack at estimating total kwh used.
Should they both be roughly the same.
I dont understand how a 6kw electric equates to a 24kw boiler?

thanks very much

rogerblack

themethod wrote: »

ok thanks trying to compare a 6kw electric or or 24kw gas boiler..can anyone have a crack at estimating total kwh used.
Should they both be roughly the same.
I dont understand how a 6kw electric equates to a 24kw boiler?

thanks very much

As a first estimate - they deliver as much heat as is required.
If the heat required to heat the property is 3kW, then the 6kW boiler will be on half the time, and the 24kW one 1/6th of the time.
If it's 6kW, the 6kW one will be on all the time, and the 24kW one 1/4.

If it's 12kW, you'll be cold if you've got the 6kW one, and the 24kW one will be on half the time.

rogerblack

chris1973 wrote: »

Cool, can I ask what Tariff you are on for selfish reasons (well on behalf of my Parents actually), they are with Npower and have recently been informed that their tariff has gone from:-

16.66p to 18.66p (Tier One 728 KWH / Year)
13.99p to 14.95p (Tier Two)

I know prices are regional, but i'd love to get them one something closer to the mentioned 9.79p, even if it was 11p or 12p!

Sign online 21 dual-fuel. With the 100 quid bonus for DD, if I spend the expected amount on electricity this year, I'll be paying 8.17 for around 2500 units.

(assuming for the moment price doesn't go up)
I'm in Fife.