When is it worth replacing gas boiler?

[Cynderella]

I'm pretty good at working out where to reduce the electricity I'm using, but I need to tackle gas. We use a lot. In our old house, we used about 30,000kwh a year, so this one is better - 20,000kwh a year.

But, obviously that's a lot - almost twice the average. We are four adults in a 3 bed Victorian mid terrace house. Windows double glazed, curtains, carpets and rugs, so pretty average there. I do cook a lot and there's four showers a day - between 3-10 mins each. Dishwasher, so only one lot of washing up water.

We're averaging 250kwh a month with no heating on. The boiler was installed in 2008 and is a Vailant Ecotec 831 - with 89% efficientcy and maximum output of 25kwh.

I'm resigned to not having the heating on when I want it this winter - we're on a standard variable rate, so not in a position to do anything else. But would it be worth replacing the boiler - has anyone done this just to save money rather than because it was not working properly?

I don't think your boiler is using excessive energy.

We're a family of 4 in an extended 1930s semi. Boiler is about 7-8 years old. Our usage over the summer, without heating on (and we don't have anything gas other than the boiler, so just showers, baths and hot water) is approx 200-250kwh/m, so in line with yours. Our annual gas consumption is approx 12,000 - which seems pretty average for a family of 4.
So that suggests that the issue isn't with your boiler, it's with the amount of gas that you use for heating - the "heating" bit of our gas usage is approx 9000kwh, the "heating" bit of your gas usage is approx 17000kwh - nearly double. Either you're having the heating on a lot or at a high temperature, or you are losing heat through poor insulation.

We mostly work from home, but only heat the house (to 18/19) for an hour or so in the morning, and 2, maybe 3 in the evenings. This keeps the house at a pleasant ambient temperature throughout the day. If we do feel a bit chilly when WfH we have knock-off oodies we can use, but we only really need them on the coldest of days. We always dress appropriately for the weather with vests, long sleeves, jumpers and warm bootie slippers in winter, but we don't really excessively bundle up. Given that you live in a Victorian house, I would suggest that if you're not excessively using the heating, that you look at where you could add insulation.

We replaced our 20 year old constantly short cycling boiler in January. I was very excited to see our bills reduce with our new efficient condensing boiler. Heating and hot water time schedule stayed exactly the same and the savings were...nil!

So I wouldn't bother replacing

Surprises me a bit. I replaced my 15 year old cheap s**t non condensing boiler (main control PCB blew up) with a new condensing one last December and saw my consumption go down around 15%.

There is a thing where if the return temperature is too high the boiler will not condense, so maybe that is happening. I know mine is condensing because I can see the water it produces.

Yeah I don't understand it. I knowing is condensing too from the water and plume. Plus I got really obsessed and bought pipe thermometers and balanced all the radiators perfectly so they were all heating up together and had the correct differential between flow and return so the heat was being released into the room. Tbh I was really disappointed. I can only assume it's because our 1930s home is really badly insulated (it's a very cold house) and spread over 3 levels. Rads are all correctly sized. Anyway I digress. Just my experience of a new boiler

Really interesting to hear that other people have similar usage to us when you just look at hot water and cooking - that makes me feel better!

I know that I can reduce our annual consumption by cutting back on the heating - I've lost count of the times I've turned it off, realised how warm it is only to find that my barefoot T shirt wearing son has turned it up because 'it's freezing in this house'. I'm also guilty of putting on the heating higher than I need. It's normally at about 19 or 20, but higher when it's really cold. We have a Nest thermostat, and I have already set a brand new schedule for when the heating goes on this year.

I have thought about smart valves. We have downstairs rooms on 'full') which is 5 and bedrooms on 3. There are lots of times we could turn the bedroom radiators off completely, but I'm not sure we would get our money back on those. Loft is insulated - I suppose we could put more in. Not a popular idea as we have a lot of stuff up there. All windows and doors double glazed. When we had front door done, we had a door on the outside porch to make it an inside one. Only one big window curtains not lined - my 'office' not used in the evenings. I have lining material ready to line those. We're mid terrace which should help.