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do i need the existing flu lining replacing to change from a back boiler to a gas fire? thanks?

mary-jo c - 2008-01-21 00:44:23 - Maintenance Repairs

we are removing a back boiler and were told we must change the flu before we can fit a gas fire.Is this true?

Best Answer:

There could be a problem with it being to large, and having to much draft. To much draft will suck all of your heat out the chimney. Material wise you should be OK.

Answers:

I don't see why, unless the existing one is damaged

There could be a problem with it being to large, and having to much draft. To much draft will suck all of your heat out the chimney. Material wise you should be OK.

The most common chimney liner typically seen is the orange clay tile, usually from the ground you can seen a few inches of the orange tile sticking up out of the top or possibly you could view up from the bottom with a mirror. This type of liner doesn't hold up well with gas appliances especially if it is oversized which they usually are. The older coal, oil, or wood burning units needed larger flues than what gas appliances do. Also the gas exhaust is extremely acidic. It will (slowly) eat away the liner (spalling) and eventually go through the brick or block. It's pretty common to find but if you drive around and see white patches on the side of masonry chimney's; this is efflorescence and is a sign the flue gases are leaking through. I've "heard" for stainless liners the flue gases from the gas appliances will create pitts and eventually fail also. The best liner for a gas appliance is aluminum (cheap) or a solid cast in place liner (expensive). When a new liner is put in they will then re-size the flue to properly match the appliance.