Baxi condensing back boiler BBU - any gotchas?

We've been struggling on with the old Baxi gas back-boiler for far too long, largely because of the lack of convenient siting for a modern wall-hung boiler, along with need to completely re-arrangeme the pipe work that it would entail. But - now there is a Baxi BBU, a condensing direct replacement (allegedly) to fit in the fireplace where the old one lives.

It looks promising, well except for the fact it IS made by Baxi!! but there is no other choice as far as I can tell.

Advantages seem to be, apart from the obvious of not having to relocate all the pipe-work, 1) it is room-sealed - the old one isn't, 2) it is claimed 90% efficient, and even if that's an exaggeration, it's surely an improvement over our cast-iron jobby which is no doubt well less than

65%, 3) The bulky gas-fire front which we don't use can go, and be replaced by a flat fire-front or nothing, freeing up some space in the room.

Disadvantages: 1) Needs a condensate drain. Not a problem here as we have an under-floor space and its not a major job to route it to an outside drain. 2) Only one size is available (15kW). I would go for a bigger output if changing to a wall-hung but this should give at least as much as we get from the old Baxi which just about keeps us warm enough, and is probably producing well less than 15kW output anyway.

I would dearly love to rip out all the existing system and replace it with a super-duper sealed system, but for various reasons that's not practical at present, so unless there are any nasty gotchas that I've missed I'm inclined to bite the bullet and give this Baxi a go.

What do the team think?

Phil

Reply to
Phil Addison
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So will need an air supply from outside. How does this fit with a conventionally flued boiler?

Wander over to

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and look your current one up.

Reply to
Dave Liquorice

It has a concentric flue liner that goes up the chimney to replace the existing flue liner (or maybe it goes inside it?*) available in 10m or

12.5m length. I have to find out how tall my chimney is, its quite tall being a victorian property so hope these are long enough. I'll be measuring shaddows next time the sun comes out :)

Thanks Dave, I had forgotten about sedbuk, turns out they reckon its 65% heh-heh, and that presumably was when it was new, its now 24 years old so I'll have a nice fuel bill reduction to look forward to, and I've just done a supplier switch which will save me £400/year too (but less for the new boiler), I oviously stayed with Atlantic too long!

*No, the installation manual says the old liner must be removed.

Phil

Reply to
Phil Addison

Fan-flued with a concentric flue up the chimney.

The real problem in many locations will be the condensate drain.

Owain

Reply to
Owain

Don't most offer a pump as an option now? My MILs pumps up into the attic and vents into the gutter. I thought it was weird but it seems to work, having performed through last winter.

Reply to
Ericp

Most?? Do you know of another make besides this Baxi? They claim to be the only one.

Yes, this Baxi one has a pump. There is a sump at the bottom and the pump pumps it up to an outlet at the top of the boiler. In my installation it can go from there through the side of the chimney brest to join with the existing boxed in pipework. From there it can dive under the floor boards and cross under the joists and through an outside wall where it will emerge a couple of inches above the patio level, and from there a short run to a rainwater drainage grill.

Phil

Reply to
Phil Addison

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