Replacing a floor-standing boiler

[MarkScott]

I have an open-vented heating system driven by an Ideal Mexico Super 2 CF125 floor-standing boiler (29-36kW). It must be getting on for 25 years old but it keeps working and the guys who service it for me say "they don't make them like that any more". But it is sited in what used to be an open car-port next to the house, which has been closed off with walls and a roller door so it's now an enclosed garage -- and of course the boiler gets an "at risk" warning every time an engineer sees it. Also for efficiency's sake I would like to replace it.


The boiler backs onto what is now an internal wall and the flue goes up vertically inside a brick chimney emerging at (2nd floor) roof height. It would be really hard to relocate the boiler to an outside wall - minimum of 4 metres of new pipework through the uninsulated garage. So I would like to fit a new floorstanding unit such as the Worcester FS42CDI as a "drop in" replacement. There's a nearby drain for condensate so that bit's easy. I'm not so sure about the flue arrangements. The existing boiler connects to the chimney via a 150mm flue pipe, and there's what looks like a 150mm cowl on top of the chimney. Would it be a reasonable assumption that there's space inside the chimney to run a new 80/125 flue pipe up it, and if so, does that sound like a workable option?

 

[kirkgas]

You can't fit the new flue inside the chimney as you can't clip it
Someone will survey and advise you of the options

 

[mfgs]

Worcester do a flexible flue liner you can drop down the chimney in certain circumstances.

 

[GasManMike]

Get a few Gas Safe Engineers in to quote and advise, there are boilers available that use a flexible flue liner.

 

[buckley plumb]

the Worcester is rear entry chimney flue so if the old boiler was top flue then it wont fit baxi back boiler needs the electric fire infront

 

[snowhead]

The new boiler doesn't need to be on an outside wall.
You just need a clear route to run a horizontal flue to outside.
Put a new wall mounted boiler above where the existing one is.

 

[vern]

Just to be clear WB DO make a flue for this situation, it has expanding spider spikes that self centres the liner as you drop it down the chimney (assumes 9"x9" standard construction) if a 6 " liner fits the new WB flue will and you can fit it off the top of the boiler too as your mexico it comes with an inspection flap too.

the FS 42 CDi ain't cheap neither is the special flue kit comes in set lengths 12m max vertical and upto 3m horizontal to 12 m vertical run

 

[buckley plumb]

Just to be clear WB DO make a flue for this situation, it has expanding spider spikes that self centres the liner as you drop it down the chimney (assumes 9"x9" standard construction) if a 6 " liner fits the new WB flue will and you can fit it off the top of the boiler too as your mexico it comes with an inspection flap too.

the FS 42 CDi ain't cheap neither is the special flue kit comes in set lengths 11m max

I wanted this option but they told me not available rear connection elbow only

 

[vern]

I wanted this option but they told me not available rear connection elbow only

Sorry Ant you were told duff info, the kit comes with a tee that comes off the top, concentric I.e pipe in pipe using standard WB FLUE EXTENSIONS upto 3 m then connects to flexi plastic liner in chimney, the boiler air is drawn from the chimney, it comes with a special terminal that has an air inlet to the chimney and flexi for POC!

Used one in York building listed up to the hilt absolute no new wall penetrations, we got round it taking out an Hideaway in cellar out using this flue and an FS 30 CDi we got the job as 5 tendered but only we quoted......be careful the boilers and this flue ain't cheap!

 

[buckley plumb]

is there a min dimension centre of chimney to back wall was only 6" thanks worth knowing for next time mate

 

[Aquazone]

Ain't the flue kit for this about 600 notes? Looked into this for a custard a while back, but cost is just outrageous. If its not impossible to run flue clearly to external wall in garage, then a regular boiler would probably be the best bet.

I am sure these are probably only fitted in listed buildings as vern said, due to the cost, and if you can't penetrate walls, you don't really have a choice but to pay it.

 

[vern]

Ain't the flue kit for this about 600 notes? Looked into this for a custard a while back, but cost is just outrageous. If its not impossible to run flue clearly to external wall in garage, then a regular boiler would probably be the best bet.

I am sure these are probably only fitted in listed buildings as vern said, due to the cost, and if you can't penetrate walls, you don't really have a choice but to pay it.

not sure now pal....could be, we got a deal on boiler and flue due to other external factors, but even that was not cheap imho but the only solution apart from electric of course

 

[MarkScott]

The new boiler doesn't need to be on an outside wall.
You just need a clear route to run a horizontal flue to outside.
Put a new wall mounted boiler above where the existing one is.

OK, but I'd have the same problem with routing the flue (or worse) as I'd have with new pipes for the water: there's no obvious outside wall to use. We're too close to the boundary on the one side, there are rooms on two other sides, and the garage door on the last side. The roof is pitched the wrong way and a flue emerging from it would look awful.

Wall mounting the boiler would be an option, but realistically the flue is going to have to go up that chimney.

 

[MarkScott]

Just to be clear WB DO make a flue for this situation, it has expanding spider spikes that self centres the liner as you drop it down the chimney (assumes 9"x9" standard construction) if a 6 " liner fits the new WB flue will and you can fit it off the top of the boiler too as your mexico it comes with an inspection flap too.

the FS 42 CDi ain't cheap neither is the special flue kit comes in set lengths 12m max vertical and upto 3m horizontal to 12 m vertical run

This sounds promising. TBH the cost isn't really an issue - I know what that boiler costs and a couple hundred more for the flue won't break the bank.

 

[on31ll]

This sounds promising. TBH the cost isn't really an issue - I know what that boiler costs and a couple hundred more for the flue won't break the bank.

That is what you want to hear for a customer ! Good on you that you are looking up your options and that your willing to pay for it ! Alot of people want everything done for free these days and it just cant work like that ! To be honest sounds like a quality install

 

[tamz]

As long as you are not in Scotland your Mexico is breaking no rules by being in a garage. It is breaking the building regs if you are in Scotland.

If you are not bothered by the extra cost of the flue then go for it but there may be other viable siting options you have not thought about if you speak to an installer.

 

[Whyme]

Sorry Ant you were told duff info, the kit comes with a tee that comes off the top, concentric I.e pipe in pipe using standard WB FLUE EXTENSIONS upto 3 m then connects to flexi plastic liner in chimney, the boiler air is drawn from the chimney, it comes with a special terminal that has an air inlet to the chimney and flexi for POC!

Used one in York building listed up to the hilt absolute no new wall penetrations, we got round it taking out an Hideaway in cellar out using this flue and an FS 30 CDi we got the job as 5 tendered but only we quoted......be careful the boilers and this flue ain't cheap!

listen to vern, these kits are available and have been round for years in the commercial sector..though expensive compared to standard flueing..