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New widget aims to reduce gas bills

Posted by Cathy Debenham on 12 January 2011 at 10:47 am

I've just received my gas bill and I'm not surprised to find that December's freezing temperatures mean that I've used a lot more gas than usual (and quite a lot more than the supplier has estimated too).

I've been recording weekly readings from my gas and electricity meters for the past 2 and a half years using imeasure, and you can see from the graph that the worst week this year is quite a lot more expensive than the coldest spike last year (it beats 2009's worst week too). The orange bars show weekly spend on energy - and the blue section is the proportion spent on gas.

Of course, this nasty spike isn't a surprise. We kept the heating on all day (I work from home) during the cold spell, and still weren't all that warm. That's something we never normally do, as we've divided the house into an upstairs and downstairs zone, and turn them on and off as required. I also tend to put on my special extra warm jumper before I turn on the heating!

I'm always interested in things that will lower our gas consumption - both to keep the bills down and to reduce our carbon emissions, so when I was offered the opportunity to test and review a new gizmo that "greatly lowers gas consumption and lowers your heating bills by optimising the operation of your boiler," I jumped at it. The g-save claims to be able to save you up to 31% on your annual gas bill.

Mine was installed literally the day before the snow came! So, if it works as well as promised, my recent gas bill would have been even higher without it. But because we've had the heating on so much more than we normally do recently I can't do a like with like comparison, so I can't tell how it's performing yet.

Of course, I'll continue to take readings, and compare this year with the past two winters, and will report back on how effective the g-save has been in a couple of months time when I've got enough data for a reasonable comparison.

In the meantime, this is how it works:

The g-save has two electronic timers which pulse at different pre-set times 24 hours a day, seven days a week. One timer is wired into the room thermostat wiring and the other is wired into the hot water cylinder thermostat wiring.

In a standard domestic system there is a time lag in the heating process. The time lag is caused because the thermostat demands heat from the boiler and the boiler responds, but it takes time for the heat to get around the system, and for the thermostat to register that the water or room is now hot enough. The thermostat then stops demanding heat; but the heat that is already in the system still has to work through. In effect, because of this time-lag, the water or room is overheated.

The g-save Economiser pulses the demand for heat so that the latent heat in the system that is still moving around is used to full effect, even when the boiler is not active.


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2 comments - read them below or add one

Cathy Debenham

Cathy DebenhamComment left on: 18 January 2011 at 11:32 am

I've got a five year old Vaillant boiler, so it will be interesting to see if it makes a difference.

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Bunny Man

Bunny ManComment left on: 17 January 2011 at 2:48 pm

This product may make a difference to older boilers/heating systems operating with thermostat control for heating and hot water.

Modern boilers such as a Vaillant operate with thermister sensors to monitor both flow (and on some models return) temperatures from the boiler and the room and hot water temperatures and will therefore automatically modulate output as the actual temperature nears the 'target' temperature. If further efficiency improvement is required then a weather compensated control such as the Vaillant VRC430 and zoning controls such as the VR61 and VR81 would be theway forward. (weather compensator also available as a wireless unit VRC430f )

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