Zenex GasSaver

[djh]

I'm not sure that this is an appropriate topic, so please moderate it if not ...

The makers make some pretty bold claims for the Zenex GasSaver. Does it work?

I accept it can work with old, inefficient boilers but what about modern condensing ones?

I haven't spent long thinking about it, but I thought the whole point of a condensing boiler was to extract heat from the flue and that they have an extra heat exchanger to do just that. If it were possible to extract more energy, why don't the boiler manufacturers already do it?

[gb484]

Condensing boiler only condenses when return temp is below dew point. If return temp is above dew point, it will not condense, this is no doubt why you might fit a gas saver, for those times when the boiler is not condensing. I would have thought it makes more sense to fit weather compensation controls to make sure that your boiler is in condensing mode as often as is possible but maybe that's just too sensible. PS, most condensing boilers do not produce maximum efficiency as they only ever get to condense on start-up, as when they have been running a while, the return temp to boiler gets too hot, so in answer to your question, yes, the technology does work, but it seems fairly pointless, as you suggest.

[dinitro]

Probably a better solution is to force the boiler into condensing mode by

1) by fitting a buffer tank between the system and boiler therefore maintaining condensing mode as long as possible
or
2) fitting a zone valve under the control of a pipe stat of the boiler return to recirculate the system water and shut down the boiler
or
3) a combination of 1) and 2)

I believe the Gas Saver peak efficiency is only in older conventional boilers or those that cannot be forced into condensing mode as above

dinitro