No wood burning appliances should vent into an unlined chimney, which yours seems to be. The bricks and mortar could have sustained major damage from a chimney fire, making things much more unsafe than they were before.

There are two options for lining chimneys. One is a stainless steel liner. I'm not sure how adaptable these are for fireplaces, but they are widely available. The second option is a poured in place liner. There are at least three brands, Supaflu is one (http://supaflu.com)Ahern is, I think, another. The poured in place option will strengthen the chimney and fill in any gaps making it to my mind the better option for an old brick chimney, especially one with fire damage. How available any of the poured in place systems are in the relevant area is a factor. Costs, at least when I had it done, were comparable to stainless liner installation.

Is this an open fireplace? If so what made the renters think they had a chimney fire? Regardless of any myths you may have heard, it's Very Very unlikely they had a chimney fire in an open fireplace (vs. a woodstove chimney where, especially w/ older stoves it's relatively common). If they truely did have a fire, it will be almost impossible to find an honest and intelligent sweep. You need a sweep who's honest enough not to suggest relining or replacing if there isn't any damage, and a sweep who's smart enough to know damage or lack of damage when he see's it. good luck. btw, it seems a lot of people are confused about a few things, one: a liner is usually clay tile, which is perfectly acceptable. another is that a completely (brick only interior) unlined chimney, while not ideal, is not the danger the steel liner salesment would have you believe in CERTAIN circumstances. Although not code- accepted for new construction, such unline chimneys venting combustion products from: Coal (fireplace or stove) oil (furnace/boiler/anything) gas (older, low efficiency furnace/boiler) or wood (open fireplace only)are perfectly safe provided they are not completely deteriorating. missing bricks, gaping holes etc. good luck finding someone to give you an honest and ACCURATE opinion on the condition of your chimney or whether or not they even experienced a chimney fire.

We have 2 fireplaces in the house. Upstairs is open, downstairs is a stove type insert with a blower. The renters were very vague about the details of the fire but, when we arrived at the house after they had moved out, we saw huge black marks up the rock surround of the fireplace (wasn't there when we renter to them). We found birch and pine in their firewood pile near the house. We think this was the source of creosote buildup. They, of course, blamed us saying the chimney hadn't been cleaned in years (lie).

All that said...we are having a difficult time finding someone we can trust and who knows enough about chimneys to help us. We certainly don't want any liability issues or tragic outcomes to the new renters wanting to save a few dollars on propane expenses. We'd also like to maintain property value and feel that a house with 2 unusable fireplaces might not be someone's #1 choice. I will continue on my quest to find another sweep and hopefully the Good Lord will lead us to an honest, knowledgeable one. Thank you all for your input. If there is something else you think of, please let me know. This is weighing heavily on me these days and it's not very comfortable. I'm certainly thankful for the Gardenweb!

I'm going to have to disagree with a couple of things in berlin's post. First, you certainly can have a chimney fire in a fireplace. Second, in my experience, most chimney sweeps are honest and conscientous people with the safety of their clients a primary concern. If there's any doubt about whether a chimney fire took place, someone rom the local fire department could tell you for sure.

I have no idea what sort of landlord liabilities you may face for this house but:
You seem to have a fireplace and a stove venting into a single flue.
The chimney has no lining.
One professional has already told you that the chimney ought not to be used until it is repaired.

All of the above are violations of building codes and common sense.

$6k seems quite high for lining a chimney with either a steel liner or a poured in place liner unless the chimney is especially tall. You may have no choice but to repair the chimney or somehow make it impossible for a renter to use the chimney. Many non code compliant chimneys are grandfathered, but in most areas this changes when the property is rented. Your insurance on this property is another factor.

Sorry to be pessimistic, but better to know the truth.

If you are not in a position to fix the chimney(s), I think you need to protect yourself against liability from a renter. Renters like to sue landlords -- it happens more often than people think. To protect yourself, I would prepare a brief statement for the renter to sign. The statement should state that they have been informed that the fireplace(s) cannot safely be used, and they agree not to use them. It should also state that you, the landlord are absolved of any responsibility in the event that any harm comes to the renters as a consequence of their using the fireplace(s). I would insist that they have their signatures notorized.

well, maingrower, you can have a chimney fire in a fireplace, but it's very, very uncommon; and there are very clear reasons for this, not the least of which is the reduced or nonexistant production of certain types of creosote deposits in the flue vs. in an airtight wood-burning appliance. as far as chimney sweeps being mostly honest and conscientious... well I would say that the opposite is true. and guess what? i sweep, rebuild chimneys etc. for others as a hobby and i see all the nonsense being purveyed by most, but not all, sweeps and "chimney professionals" in my area. sometimes they spew this garbage out of sheer stupidity, but most of the time, it's from their desire to "rip-off" their client.

i do agree w/ haus proud. If you are not able to determine what occured w/ this chimney or are not able to fix any damage that may have occured due to any chimney fire, you should do what you can to physically prevent use of the fireplace/insert and have them sign a document clearly stating the fireplace/chimney may be dangerous to use/damaged and must not be used under any circumstances etc.

I'm thankful to have checked on this post again. Good advice from many people and I appreciate it. We still have not resolved the fireplace issue with the renters. My main concerns is that they will expect us to reimburse them for heating costs or want to move out. Maybe neither would happen but they have been extremely high maintenance to date and we are out-of-state landlords. The house was originally our primary residence until work opportunities dried up in MN and opened up in CA. I want to maintain the value of the property and 2 unusable fireplaces probably don't help any. I looked online at chimney liners but am having a difficult time finding a chimney person in the expert who is willing or able to help us out.

All said, thank you all again and I hope to be able to post a positive outcome to this ongoing stressful situation.

I have the outcome to this situation:

Posted ad on Craigslist for professional chimney guy - asked for a chimney inspection
Several responses. Picked one. He went out and told me we have a draw problem (we know that) and need $600 of work to replace 2 clay tiles in one flue and new cement cap.
Also need a chimney cleaning due to creosote build-up.
Outcome was much more favorable than I had hoped. I worried about this for so long and now realized my ignorance was the root cause of my concern.

Thank you all for you help with this. The answers and suggestions lessened my ignorance which empowered me to move forward. A life lesson AND a chimney fix all in one blow!