Question... Dealing with Clay Flue liners

[DSGStang]

... first post here.

I'm not real knowledgeable on fireplaces/flue liners/etc so bear with me.

I'm installing a gas insert into my fireplace. I climbed up on the roof to look at the top on the chimney and found the the terracotta on the top was damaged. (see the attached picture if it works). What would be my easiest option to fix this.

- break out the top block and drop in a new one and then mount the new cap on? (how hard is this, could I do it with a hammer to break up just the top block, then just drop the new one in place ???)
- break it down flush with the top of the chimney and mount the cap on there?
-or something else?

Let me know, any suggestions/help is much appreciated.

Thanks,
-Ryan

 

[DAKSY]

Your best bet would be to remove the top section of the terra cotta flue tile & replace it with a new one.
It'll take some elbow grease & mortar mix, but it'll be worth it in the long run.
If you decide to sell this house & move, at least that part of the chimney will be in good shape.
It's also easier to bend the cap adapter plate to fit the size of your flue tile than it is
to attach it directly to the mud cap...It'll be easier to remove, as well...
HTH

 

[jtp10181]

Can't see a lot because the picture is so close. Does not look like the crown is very smooth on there. I assume the rest of the old SS double cap is coming off? Is the old bioler / dwh flue still in use?

If the top of the crown was smooth I would just bust it off and silicone the top plate from the insert right to the crown. It looks pretty lumpy so it might work better to replace the top flue tile as DAKSY said.

 

[DSGStang]

Thats what I was thinking too. Whoever repaired it last time and put that double cap on did a horrible job. It is very lumpy and the concrete that is holding that cap on is starting to chip off. I think I'm going to go ahead and take that cap off, break out the old and put in the new terracotta piece, and go with two single caps (and yes the other flue is still used, furnace and hotwater heater vent there).

When putting in the new terracotta is there something that I have to put in place to hold it there or is it just slide it in and gravity holds it there?

 

[tiber]

You'll find that there's a vault (as in the archatecture term) at the top of the chimney under the cap. I had to rebuild my cap when we bought the house also. What strikes me about your particular chimney is that it's not covered in creosote, ash, and general chimney disgustingness. I'm inclined to think someone used the wrong sized steel brush when they cleaned the chimney and beat the hell out of the whole thing. I would make sure the flu itself is in good condition and not blocked.

That being said, you don't really need the four inches or so above the crown, especially if this chimney is already two stories tall. To add to the safety-factor - most of the gas units are direct vent or ventless. If you're going with a gas log set that's ventless, I would just throw another inch of quickcrete on the crown and forget about it.

 

[Hurricane]

Thats what I was thinking too. Whoever repaired it last time and put that double cap on did a horrible job. It is very lumpy and the concrete that is holding that cap on is starting to chip off. I think I'm going to go ahead and take that cap off, break out the old and put in the new terracotta piece, and go with two single caps (and yes the other flue is still used, furnace and hotwater heater vent there).

When putting in the new terracotta is there something that I have to put in place to hold it there or is it just slide it in and gravity holds it there?

You need to use mortar in the joint between the bottom block and the new one. Just put a little cement ( mortar ) on the top of the bottom one before sliding the new one in, push the new one to leave maybe 1/2 " of mortar in place. Reach inside to smooth out the bulge of cement, then run a mortar joint around the top outside of the cap making sure it slopes away from the terracotta pipe so water runs away and not toward the pipe.

 

[DSGStang]

You'll find that there's a vault (as in the archatecture term) at the top of the chimney under the cap. I had to rebuild my cap when we bought the house also. What strikes me about your particular chimney is that it's not covered in creosote, ash, and general chimney disgustingness. I'm inclined to think someone used the wrong sized steel brush when they cleaned the chimney and beat the hell out of the whole thing. I would make sure the flu itself is in good condition and not blocked.

That being said, you don't really need the four inches or so above the crown, especially if this chimney is already two stories tall. To add to the safety-factor - most of the gas units are direct vent or ventless. If you're going with a gas log set that's ventless, I would just throw another inch of quickcrete on the crown and forget about it.

It's not covered in ash because the previous owner propbaly only used the fireplace once or twice in the 40-50 years that they lived here. And it looks like it was redone (just the top) at some point and not done well. We had a home inspection on the house and the guy that did the inspection was a certified fire inspector. So he inspected the chimney and liner with a video system on a long telescoping flexible pole. He basically said it was not safe to use because of all the gaps/crack in the liner (no blockages though). So we have not had a fire in there for the three years that we have owed the house. Rather than repair/replace the liner we decided to get a gas insert (it helps that my wifes parents are giving it as a christmas gift this year). The insert has a 3" intake and 3" exhaust line that tie into the cap to place on top. (It's the Napoleon GDI44)

 

[DSGStang]

Thats what I was thinking too. Whoever repaired it last time and put that double cap on did a horrible job. It is very lumpy and the concrete that is holding that cap on is starting to chip off. I think I'm going to go ahead and take that cap off, break out the old and put in the new terracotta piece, and go with two single caps (and yes the other flue is still used, furnace and hotwater heater vent there).

When putting in the new terracotta is there something that I have to put in place to hold it there or is it just slide it in and gravity holds it there?

You need to use mortar in the joint between the bottom block and the new one. Just put a little cement ( mortar ) on the top of the bottom one before sliding the new one in, push the new one to leave maybe 1/2 " of mortar in place. Reach inside to smooth out the bulge of cement, then run a mortar joint around the top outside of the cap making sure it slopes away from the terracotta pipe so water runs away and not toward the pipe.

Thanks, I'm going to give this a shot today. I already picked up a new piece so I'm going up there right now to break out the old one. We'll see how it goes

 

[webby3650]

Just so you know, If you are putting in a vented gas appliance, the flue has to be in the same condition as it does for a fireplace. Carbon Monoxide is produced from gas and wood but you can't smell it at all with gas. If you are having the flue relined for the insert, re-cast the crown and be done with it.

 

[DSGStang]

Just so you know, If you are putting in a vented gas appliance, the flue has to be in the same condition as it does for a fireplace. Carbon Monoxide is produced from gas and wood but you can't smell it at all with gas. If you are having the flue relined for the insert, re-cast the crown and be done with it.

a 3" inch exhaust line runs up the entire length as does a 3" intake line and will be sealed at each end with high temp silicone therefore I am not worried about CO.

I just smashed out the old and put in the new terracotta top piece. Was not too bad getting it out but getting the new one up and in was a bit of a pain in the ass... heavy and not so easy to slide down in there. But it ended up not going too bad. I'm definteley not a mason but it will serve its purpose. I still have to touch it up a bit and take off the double cap but that's for another day.

 

[webby3650]

Good job, the new tiles are rarely the same size, if we do this, we measure the new ones to find one that is the same or even a bit smaller. Looks good

 

[jtp10181]

Hmmm under all that rubble I see there is no crown up there.... odd. Or... is there. Looks like possible that ring of bricks on the outside was added on top of the crown to make a base for the double cap. If those are left there its going to make a little pond up there when it rains. Again... picture is so close I can't really see much. People (in general) really need to learn to take some pictures from afar so one can see the full perspective.

If it is as it seems, I would take off the cap and that top course of bricks which seems to be on top of the crown. Then the crown probably needs a good coating on top, I think I have seen some crown repair stuff at the hardware store.