Excessive gas use for hot water All aspects of plumbing questions and answers, help, tips and information

[Wintergreen]

Hi all. We live in a leaky old Victorian house, and I have been engaged in a process of making it more efficient and warm for some years. I'm hoping to install a heatpump over the coming months, and have been looking into our gas use. We use around 36,000kwh per year, and that is with a target temp of 18 in the main space, and very little heating anywhere else. I've been looking at the bills over last summer, and we were still doing 130m3 a month; around 1,450 kwh. That is crazy high, and I can't think where the inefficiency might be. 2 adults, 3 kids, one of whom only bathes weekly at most. The other 4 have short daily showers. We have a circulating pump which ticks over, ensuring that hot water gets to the taps quite quickly. No doubt that causes some heat loss, but I wouldn't expect it to be that significant. We have a large 46kw boiler which goes into a low loss header, and heats the water in an UVC. Cylinder temp was probably 60 or 65. I have turned it down to 52 now. Any ideas about the likely explanation would be gratefully received!

[stoneyboy]

Hi wintergreen,
Have a look at the circulating hot water pipe work and check it is well lagged. If it isn’t this is where you are using excess energy.
Regards S

[Wintergreen]

Thanks for the reply. All the pipes - hot and cold - seem to have standard Climaflex-style lagging. I've no doubt it's not perfect, and indeed you can feel a bit of heat coming through the floorboards at certain times, but it seems a huge amount of heat to be losing that way. Is there a best way to set up the DHW circulating pump? The original installation literally had it on 24/7.

[stoneyboy]

Hi wintergreen,
You could check if the hot water system is the issue by turning off the boiler and then see how long your tank of hot water lasts. If the tank looses all its hot water in 3-4 hours then this will be contributing to extra gas usage.
Your consumption for what must be a large Victorian house with 5 occupants is about right.
Regards S