Re-use Existing Flue??

jon26 · Posted: Thu Aug 14, 2008 10:01 pm

Just a question for you pro's please.
My friend has a 30+ year old Potterton oil fired boiler and is looking to replace it with a new condensing type (possibly Worcester or Grant?)

Although the boiler is very old, the existing boiler flue is quite new, it was only replaced 18 months ago, I believe its a 150mm dia. lined flue which rises vertically through the first floor and second floor through the roof.

Can the new oil condensing boiler be connected to the existing flue?

Cheers

cozzmic · Posted: Thu Aug 14, 2008 10:06 pm

No it can't, flue gasses and condensate more corrosive and special flue matched to the boiler required. Be prepared for big bucks for the flue.

Corgigrouch · Posted: Thu Aug 14, 2008 10:09 pm

Personally speaking, I'd scrap the grease machine and look at a heat pump of some description.

jon26 · Posted: Thu Aug 14, 2008 10:11 pm

Surely a 150mm dia. open flue that is currently there will be the same as the new flue that would be fitted? How will the new one differ?

nickso · Posted: Thu Aug 14, 2008 10:16 pm

jon26 wrote:

Surely a 150mm dia. open flue that is currently there will be the same as the new flue that would be fitted?

no it wont.

Quote:

How will the new one differ?

a combination of voodoo and luck.

rssteve · Joined: 03 Nov 2007 Posts: 467 Location: United Kingdom

condensate more corrosive and special flue matched to the boiler required

also the new flu may have an air in aswell as out. Why ask on here if you don;t want to agree with the answers.

jon26 · Posted: Thu Aug 14, 2008 10:20 pm

rssteve wrote:

condensate more corrosive and special flue matched to the boiler required

also the new flu may have an air in aswell as out. Why ask on here if you don;t want to agree with the answers.

As I said the new flue won't be a concentric flue or air in aswell as air out. It would be an open flue. But I take your point about the condensate etc.

Could the new flue go inside the old one, I know the Grant boilers have a flexible flue system that could be used??

cozzmic · Posted: Thu Aug 14, 2008 10:26 pm

Just let him go ahead and install and not listen to installers, then when the flue corrodes through and the condensate starts to seep into the chimney and disolving the cement/brickwork/old soot and start staining of the wall on the inside and outside he'll maybe think I should have listened.
And no it probably wouldn't go down inside the other flue, quicker to pull the old out and the new tied to the end to pull it in.
The Grant flue is of a special build quality, double thick and has to be put in correct way with the arrows printed on it.

jon26 · Posted: Thu Aug 14, 2008 10:29 pm

cozzmic wrote:

Just let him go ahead and install and not listen to installers, then when the flue corrodes through and the condensate starts to seep into the chimney and disolving the cement/brickwork/old soot and start staining of the wall on the inside and outside he'll maybe think I should have listened.
And no it probably wouldn't go down inside the other flue, quicker to pull the old out and the new tied to the end to pull it in.
The Grant flue is of a special build quality, double thick and has to be put in correct way with the arrows printed on it.

I appreciate you comments, and have no reason to doubt you. I will let him know.
Is there a possibility that a 'non-condensing' boiler could be fitted or is this against regs?

jon26 · Posted: Thu Aug 14, 2008 10:51 pm

Would you recommend another open flue or go for a concentric flue on the new boiler. I don't think there is an available outside wall for combustion air

Agile · Posted: Fri Aug 15, 2008 12:32 am

You seem to be going to a lot of trouble and to be mildly argumentative with replies given when its your friends problem anyway.

The normal advice would be for him to choose an OFTEC registered installer and take his advice!

Tony

sambotc · Posted: Fri Aug 15, 2008 7:16 am

You could also consider fitting an outside boiler if siting requirements are met and re-routing pipework. Depending on the situation it may work out cheaper?

Sam

jon26 · Posted: Fri Aug 15, 2008 12:59 pm

Agile wrote:

You seem to be going to a lot of trouble and to be mildly argumentative with replies given when its your friends problem anyway.

The normal advice would be for him to choose an OFTEC registered installer and take his advice!

Tony

Just remind me of the name of your company Tony, so that I know not to use you. What would be the point of these sites if everyone were to go straight to their installer first?

Thanks for the other helpful comments guys.

Agile · Posted: Fri Aug 15, 2008 3:11 pm

jon26 wrote:

Just remind me of the name of your company Tony, so that I know not to use you.

What would be the point of these sites if everyone were to go straight to their installer first?

Dont worry we dont work north of the border! In any case we only work for the property owner, or whoever is going to pay us and not for their "mates".

The point of this site is to help people understand problems with their heating and boilers. In some cases we can help reasonable competent DIYers to repair their system themselves or at least to get an idea of what might be wrong and how much that might cost to put right.

Safety dictates that gas and oil boilers are installed by competent qualified people. Its normal for an installer to visit and discuss with the owner what is required and how that can be accommodated.

Installation questions can only be answered at the property except when highly detailed pictures and/or plans are submitted.

Tony

nickso · Posted: Fri Aug 15, 2008 4:58 pm

Agile wrote:

Dont worry we dont work north of the border! In any case we only work for the property owner, or whoever is going to pay us and not for their "mates".

you dont have the correct paperwork to get "north of the border".