I have 2 masonry flues in my house currently, in addition to the Class A that the Kuuma is on. I would have happily demolished them long ago, were not the structure holding up part of the house and the roof. But I do have plans... Flues made of stone and earth are a stone age solution that should have been abandoned long ago.
Did you try to run the kumma on the stone ones? Was the class a put up special for the kumma?
Hi Gary,
First off, congratulations on having the hot thread on Hearth! You asked me this question many pages ago, so I feel obliged to respond:
My house was built with a massive central block/faux stone 2 flue central chimney. In addition to this mess, they also put in a
Clayton 1600 on a separate class A Metalbestos flue, at the bottom of a walkout lower floor, upper floor, and vaulted ceiling/partial finished attic scenario. I replaced the Clayton with the Kuuma, so no, I never tried to run it on the masonry flues.
This might get long from here, so if you don't like reading, scroll down - don't complain! What's below is mainly intended as food for thought for the next guy pondering their next move.
My dislike for masonry chimneys stems from the fact that I've lived with both. I currently have problems with the cat stove on my lowest floor that's attached to the masonry. In the past, every masonry chimney I've lived with had problems with draft, durability. or crud buildup. I've never had a problem with a Metalbestos class A flue. I started as an apprentice firefighter at 16, I'm now 55. I've been a paid firefighter, and I've also volunteered a lot of years. I've never seen a class A flue that set a house on fire where somebody didn't do something really stupid. I've seen many a masonry flue setup where it set the house on fire, and yeah, it might have been stupid, but stupid or deteriorated seems to have been incorporated into all the masonry setups I've been called to. I'm going to catch hell for that from the masons, and maybe I deserve it, because I never got called to the ones that were built right. I'm just going to say that there's a lot more leeway to do a masonry chimney wrong, than there is to do a class A wrong, and stainless steel doesn't deteriorate much! Plus a class A is inherently better insulated so it will work better and collect a lot less creosote. I should say my love for class A does not extend to the multi-wall versions that use cold outside air in place of insulation. Insulation= clean. Cold air=creosote and less draft.
If you're rolling with the liner and such, go with it, but at the temps this time of year, I wouldn't think that the properly constructed, even outside chimney you have, would be the problem - if you don't have leaks. I'm lost at where you're at with the liner, and this and that, but I would think that an unlined masonry chimney would work. I've read that your baro damper is now opening, and you don't need more than that. More is just pulling heated air up your chimney - and begs an outside air source.
The change from the Clayton (1600) to the Kuuma (VF100) has been a big plus for me so far. Both were (are) providing not only my space heat, but all of my DHW. I don't know if the Kuuma is up to heating adequately in -40 or more temps, but the Clayton wasn't really up to that alone either. I have a big, leaky, multistory log house. I don't try to fully heat it all, and I prefer to heat the living part of my house to around 56 to 58 f this time of the year. The other approx. 50% of the house comprises work areas or marginally used areas that don't have to be as warm, but constitute insulation. For the last few snowy days (no sun), with temps of around 0 f at night to +10 during the day, I've been running the stove between low to + 2 lines at night, to med+2 lines during the day. Granted, I'm not trying tp get anywhere near 74, and comparisons of different houses and their unique heat losses, are so meaningless.
My impression, so far, is that if I had an unlimited pile of wood, and unlimited time and effort to throw that wood into a box, I would be able to generate more heat with the Clayton 1600 than with the Kuuma. For me, though, slow and steady is winning the race! I have other things to do in the winter than to feed the Clayton every 2 or so hours during the day, and than to get up in the middle of the night to feed the stove with creative wood stacks to hopefully have something burning in the morning. I could have fed the Clayton less frequently, but 2 hours seemed to be what was best for a clean burn that didn't run away either. I was regulating the fire by the amount of wood in the box, rather than limiting air. My Kuuma is heating when I get up in the morning, when my Clayton mostly wasn't. The Clayton 1800, that you removed, I'm sure is capable of quite a bit more heat.
If I (we) wanted the house at 74, I'm sure I could do it this time of year with the Kuuma. I (we) just don't see the need. This time of year, when temps are ranging from -10f to +36f, I'm feeding from 1 1/2 to 3 times a day. It's easier, actually, if it's colder, because stretching out the coals to avoid a cold start, on the warmer days, is more of a pita. I know, if I get behind the heat demand, it's a lot harder to catch up than it was with the Clayton. The Kuuma has a lot more mass, and it just isn't built to run at the draft roaring, chimney glowing, kinda thing, that the Clayton does so well. I can't prove it, yet, but I think the Clayton was wasting
at least 1/3 of the wood I put into it.
If you go out and look a the lack of smoke coming from you Kuuma chimney, then consider the difference between touching the stove pipe from the Clayton, and the Kuuma, you'll know that you're working with different system. So far, it seems like setting the stove to what you would want based on the weather 12-24 hours from now is best.
Can't say the switch is going to work for you, but so far it's working for me.