Zenex boiler efficiency

In today's Sunday Times there is an item about a company called Zenex. Zenex has built a pre-heater for the cold water feed into combi boilers which is designed to extract the last "bits" of energy from the exhaust and dump it into the cold feed to the HW feed.

When I looked for Zenex on this site, so as to check, all I found was a lot of stuff in 2006 which was a tad dismissive. Lots of science, pseudo or near-science about it.

3 - 4 years on, what are the real experiences? Alpha have rites to the technology and have built an integrated unit.

It seems that the technology is a tad obvious but the value depends on the cost benefit ratio.

Ideas... Comments.

Reply to
naffer
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'Rites' - Freudian slip there!

I think Baxi have now picked up on it too.

Depends on the cost of the unit and the type of existing HW system, but I suspect that in most real-world instances the return on investment will be less than for measures like better draught-proofing, insulation, architectural improvements (like building porches to buffer external doors) etc.

Reply to
YAPH

I've got a alpha gassave fitted - I think this is the thing you've seen.

I was impressed at the amount of preheating it does to the incoming cold - much more than I expected but obviously, it's only for hot water. It does nothing to help with the heating circuits.

So, yes, it does work (better than I thought it would). Is it cost effective? I doubt it if you had to pay normal rates - we got it as part of a pack with a boiler and a store so it was a lot cheaper that way. We figured it was worth a punt.

At the 800 quid list price forget it IMO

Darren

Reply to
D.M.Chapman

These are superb when used with heat bank/thermal store. The GasSaver has its own pump, at the heat bank, and continually pumps heat into the thermal store, so it works at all times. The pump is on when the boiler is running. The pump can be eliminated by looping pipes around. The coolest part of the heat bank goes into the Gassaver for preheat then into the boiler.

They will make back their cost quite quickly using them this way - depending on heavy usage or not, it can be a quick payback. The bigger the house the more it makes sense.

Reply to
Doctor Drivel

In modern highly insulated homes (especially the coming regs) the heating costs will be far less than the DHW costs, so then they make sense. With a largish family using much DHW, they make economic sense. One of the few eco devices that do give a reasonable payback period.

A store. What kind of store?

Reply to
Doctor Drivel

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