replaced furnace - pcv vent - now chimney bricks falling off

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May 1st, 2018 7:08 am

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Apr 29th, 2018 5:40 pm

sk1001 [OP]: Deal Addict; Nov 28, 2013; 1326 posts; 507 upvotes; London, ON

Apr 29th, 2018 5:40 pm

replaced furnace - pcv vent - now chimney bricks falling off

Weird story. Maybe not related but I thought i'd ask to see if anyone has seen thing happen.

We had our old furnace and water heater go through the chimney , but the furnace was replaced and now is going through the venting pvc pipe side of the house.

The water heater is still going through the chimney.

How the bricks from the chimney are popping off. WELL not the WHOLE brick , but 1cm thick portion of the brick like a veneer or something - but our bricks are full style bricks which is confusing the crap out of me.

It seems that it cracking 1cm from the face of the brick :S
so confused

7 replies

Apr 29th, 2018 5:48 pm

mathu83: Deal Addict; Jul 8, 2010; 1230 posts; 923 upvotes; White Bear, ON

Apr 29th, 2018 5:48 pm

It's old damage caused by your old furnace and heater. It's common since the liner becomes brittle with time and erodes allowing hot air to basically eat away at your chimney. Good HVAC companies replace the liner but when there is damage caused by the old liner/equip the chimney has to be repaired, replaced or removed.

+1

Apr 29th, 2018 9:35 pm

fusion2k2k: Deal Addict; Apr 6, 2008; 1807 posts; 1170 upvotes

Apr 29th, 2018 9:35 pm

Did they change the liner when doing the furnace? If not then you've got condensation issues...causing the chimney damage most likely.

Apr 30th, 2018 12:01 am

sk1001 [OP]: Deal Addict; Nov 28, 2013; 1326 posts; 507 upvotes; London, ON

Apr 30th, 2018 12:01 am

No they didn't - probably still have the original in there.
Sheer fact that had good BBB records etc we went with them and plus other peoples reviews.

They said because the chimney won't be used just for the water heater we don't need to replace it

Apr 30th, 2018 9:11 am

Pete_Coach: Deal Expert; May 10, 2005; 36613 posts; 10982 upvotes; Ottawa

Apr 30th, 2018 9:11 am

sk1001 wrote: ↑ No they didn't - probably still have the original in there.
Sheer fact that had good BBB records etc we went with them and plus other peoples reviews.

They said because the chimney won't be used just for the water heater we don't need to replace it

Not associated.
Your furnace company just re-directed the intake and exhaust of your furnace. They have nothing to do with your chimney.
Your chimney brick spalling is coincidental and from something else. Probably a long time problem just showing up now. I suggest you get a bricklayer or restoration company to have a look and see if it can be halted.

Apr 30th, 2018 10:55 pm

fusion2k2k: Deal Addict; Apr 6, 2008; 1807 posts; 1170 upvotes

Apr 30th, 2018 10:55 pm

Pete_Coach wrote: ↑ Not associated.
Your furnace company just re-directed the intake and exhaust of your furnace. They have nothing to do with your chimney.
Your chimney brick spalling is coincidental and from something else. Probably a long time problem just showing up now. I suggest you get a bricklayer or restoration company to have a look and see if it can be halted.

When houses were built several decades ago, they would size the chimneys for a low/mid efficiency furnace and direct vent water heater, both converging together and sharing the same chimney flue. So, they would both get used fairly regularly (especially during cold/freezing temperatures in the winter) and this would burn on the excess condensation.

If you remove one of these appliances - in this case the bigger of the two, you now are putting much less heat through the old chimney and it is unable to burn off the excess condensation. This causes cracked bricks, sprawling, etc damaging the chimney.
A reputable HVAC contractor should have installed a smaller liner which resized it for just the water heater. If this isn't clear maybe a HVAC professional can chime in.

OP - was the water heater touched at all?

Apr 30th, 2018 11:17 pm

sk1001 [OP]: Deal Addict; Nov 28, 2013; 1326 posts; 507 upvotes; London, ON

Apr 30th, 2018 11:17 pm

fusion2k2k wrote: ↑ When houses were built several decades ago, they would size the chimneys for a low/mid efficiency furnace and direct vent water heater, both converging together and sharing the same chimney flue. So, they would both get used fairly regularly (especially during cold/freezing temperatures in the winter) and this would burn on the excess condensation.

If you remove one of these appliances - in this case the bigger of the two, you now are putting much less heat through the old chimney and it is unable to burn off the excess condensation. This causes cracked bricks, sprawling, etc damaging the chimney.
A reputable HVAC contractor should have installed a smaller liner which resized it for just the water heater. If this isn't clear maybe a HVAC professional can chime in.

OP - was the water heater touched at all?

Negative . the water heater was not touched at all. still attached to the chimney flue - house was built in the 60's we bought are the second owners, so not sure if was changed or whatever at any point.

I asked some people via the calls to and told them what happened and they said something similar to what you said - less heat is moving and thus gave the chimney less heat.

- I am going to try to get someone to come do the new liner - not sure how much that will cost - luckily i have matching bricks - so far it is only four - and then I am going to apply a water proof agent on it .

May 1st, 2018 7:08 am

Pete_Coach: Deal Expert; May 10, 2005; 36613 posts; 10982 upvotes; Ottawa

May 1st, 2018 7:08 am

fusion2k2k wrote: ↑ When houses were built several decades ago, they would size the chimneys for a low/mid efficiency furnace and direct vent water heater, both converging together and sharing the same chimney flue. So, they would both get used fairly regularly (especially during cold/freezing temperatures in the winter) and this would burn on the excess condensation.

If you remove one of these appliances - in this case the bigger of the two, you now are putting much less heat through the old chimney and it is unable to burn off the excess condensation. This causes cracked bricks, sprawling, etc damaging the chimney.
A reputable HVAC contractor should have installed a smaller liner which resized it for just the water heater. If this isn't clear maybe a HVAC professional can chime in.

OP - was the water heater touched at all?

I disagree with your assumption that condensation causes spalling on the outside of the brick chimney. Yes, condensation could occur in the flue (liner) but that does not transmit to the outside of the brick even if the flue had some cracks (and if there was damage, th brick damage would be localized).
Having said that, I had a high efficiency furnace installed in my house 10 years ago and have my hot water tank vented out he existing chimney without any problems to the outside of the brickwork.

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