floor standing combi boilers

witney1 · 22 Mar 2010

I need to replace our old mexico boiler with a combi boiler.

Problem is that the boiler is in the centre of the house with no direct acess to an outside wall. Mounting on an outside wall would mean a huge disruption to floors and ceilings to reach an outside wall.

Is there a combi boiler that has a flue that can use the old flue /chimney. Current boiler is on grd floor of a 2 storey mid 1930s semi

Any ideas advice welcomed.

Many thanks

Andygasman2010 · 22 Mar 2010

even with a floor standing combi you'll need to get hot and cold pipes to it, a condense waste pipe and pressure relief pipe to outside. Is there any particular reason you want a combi?

witney1 · 22 Mar 2010

None except both heating installers who have been round have both said that I could only instal combi boilers' - there was nothing else because there is insufficient ventilation for the present or a replacemenrt regular boiler - if that makes sense.

The problem is with the present boiler ventilation has been cut off by the draft has been incorporated into an extension so the ventilation has been cut off.

Agile · 22 Mar 2010

The reality is that you will have enough cost/difficulty to replace your boiler without having a lower performance combi.

The obvious replacement is one of the very few heat only boilers which allow flexible flue pipes like the baxi back boiler replacement. They include a condensate pump which can pump upwards about 3m.

Even so this would still be a very expensive solution!

Whats wrong with mounting the boiler in the loft?

Tony
.

sambotc · 22 Mar 2010

Does the old boiler use a built chimney or does it have a vertical flue made from metal up through the roof?

You could install any boiler in the same place, providing there is a wall to mount it on, and run a vertical flue through the roof.

Wether or not you choose a combi makes no odd's to the flue arrangement.

HTH Sam

witney1 · 22 Mar 2010

Agile - the engineer said that there was insufficient space in the loft - its a standard pitched roof 1930s style - so Im not sure why not. for sambotc - the old boiler has a vertical metal flue going into the old chimney- apparently there is insufficient ventilation to allow a non combi boiler to replace the old one.

numpty1 · 22 Mar 2010

witney1 said:
Agile - the engineer said that there was insufficient space in the loft - its a standard pitched roof 1930s style - so Im not sure why not. for sambotc - the old boiler has a vertical metal flue going into the old chimney- apparently there is insufficient ventilation to allow a non combi boiler to replace the old one.

i would suggest you get a heating person around to discuss your requirements rather than the bovine manure spouting fools you have spoken too already.

Agile · 22 Mar 2010

I have successfully fitted a boiler in the loft of a modern low profile roof with trussed supports.

I used a roof ladder hired by the customer to access the outside to ensure the vertical flue was adequately waterproofed.

A typical three bed semi has tone of space. You only need about 1.2m of space vertically.

Tony

witney1 · 22 Mar 2010

Tony

Thats very useful thanks
There is 1.3m in the loft - acess is available through the trap door- working space would be difficult but not impossible. I suspect that getting the gas pipe up would be the difficult bit - need to take floors up, etc. Are there any other problems I should be aware of before I get another engineer in?

Roger

numpty1 · 22 Mar 2010

Access and lighting are part of the requirements,getting a gas pipe to the roofspace would be relativly easy.

D_Hailsham · 23 Mar 2010

witney1 said:
None except both heating installers who have been round have both said that I could only install combi boilers' - there was nothing else because there is insufficient ventilation for the present or a replacement regular boiler - if that makes sense.

No. it does not make sense.

1. You do not have to install a combi boiler; but you do have to install a condensing boiler. But as all new domestic boilers are condensing, you don't have a choice.

2. Virtually all modern boilers are room sealed - it gets its air directly from the outside, not from the room it is in. The flue pipe is actually two concentric pipes; one carries the air in, the other the fumes going out.

3. Boilers are available which allow you to use very long flue pipes. For example the Remeha Avant boilers can have a maximum flue length of 5 to 8 metres (depending on the boiler) if a standard 60/100mm flue is used. If an 80/125mm flue is used it can be between 29 and 34 metres long.

Flues can be expensive.

DP · 23 Mar 2010

OP, depends which boiler you select. 1.3m space will NOT be sufficient if vertical flue is specified. A Vaillant combi needs mininum of 1780mm (being 180mm under boiler space+ boiler at 720 + 880 for flue section below roof flashing

Open vented which would be like for like for you boiler (but would need to be a sealed system if fitted in the loft) would need a height of 1670mm measured from floor level.

If the flue were to be horizontal, then you could fit above boilers in the loft.

My option would be to fit the open vented Vaillant in a room and fit verticle flue through the loft space to the outside. Vaillant condensate pump connects to boiler electronics

witney1 · 23 Mar 2010

d hailsham - this is the solution that I was looking for. The cost of the flue will be offset by the huge disruption and cost of having to lift boards and running new pipework into the loft or onto an outside wall as has been suggested by visiting engineer.

I get the feeling that they were both prepared to suggest only what they wanted to do / could do.

I feel far better informed now and better prepared to tell engineer exactly what we want.

DP - do you need a condensate pump on all such vertical flues or only with Valiant boilers - are the pumps costly

Preumably old liner has to be removed first or can the new liner be installed within the old flue

Many thanks again

D_Hailsham · 23 Mar 2010

witney1 said:
DP - do you need a condensate pump on all such vertical flues or only with Valiant boilers - are the pumps costly

Presumably old liner has to be removed first or can the new liner be installed within the old flue

When a boiler is condensing it produces water (condensate) which has to be disposed of. Normally this is done by a pipe from boiler to, say the sink waste pipe. But if the condensate will not drain away naturally (i.e there is a downhill gradient from boiler to the connection with the house drainage). You will need a pump, which will cost about £120.

Condensate pumps is not connected to the type of flue. It's the location of the boiler and availability of a suitable drain point which is relevant.

The flue is not just a liner, it is two pipes, one inside the other. Provided there is a straight drop down the chimney that the flue can use, I can't see any problems. You must use the boiler manufacturer's own flue.

numpty1 · 23 Mar 2010

I can't see any problems. You must use the boiler manufacturer's own flue.

Not quite true,the flue must have the manufacturers approval.plenty of flues about that are not made by manufacturers for this type of installation.

diynot

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floor standing combi boilers

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