Are my radiators too small?

[RadiatorBTUQ]

OK, not me but my brother 😂. He's just moved into a new house and it's cost them £80 this week in gas and electric when they are used to spending half that in a slightly larger property. ...

We're trying to work out of whether the radiators may be insufficient for the space, so the boiler is struggling to heat the house and working overtime.

Does anyone have an idea on how to work out the BTU of a radiator that's already fitted? So we can calculate whether they are up to the task!

When was the boiler last serviced?
I would seek a recommendation from a neighbour or other local for a local heating company then book a service with them and ask them to review the system at the same time.

The review will add a bit to the cost of the service but it can save money if they can pinpoint eg water tank at the wrong temperature, a couple of radiators needing replacing/flushing.

I’m a big advocate of finding good, local trades and keeping them rather than going with the giants who just sub out the work to any random on their books.

Depending on where you are, it was much colder last week so I'm not surprised that the fuel bill has increased. Comparisons are obviously difficult in rentals, I can easily compare the corresponding week/month in previous years or my annual usage, but I would agree £80/week sound high for a normal sized modern house.

If you are using a lot of gas, it's unlikely that it is because the radiators are too small.

In fact too small radiators should in theory mean you use less gas.

Probably if you took into account the boiler efficiency (condensing/non condensing), radiator flow balancing (whether the return temperature is set up correctly on a condensing boiler) and poor loft insulation that could easily account for double the gas required in otherwise identical houses.

But houses are different and leak heat differently. A modern new build 3 bed semi might need hardly any heating at all. Whereas a 60s house of the same size and format might need significant more.

If you are interested in getting the BTU of your radiators, the easy way to do it is to measure them up, and note down whether they are single (one panel with one set of fins) double (two panels with one set of fins) or double plus (two panels with two sets of fins). I think the types are 11, 21 and 22 respectively.

Then just go to somewhere like Screwfix and find the equivalent type and sized radiator and the BTU will be approximately the same as that.