New house, Old furnace, New Plan.

It's doubtful you will see much improvement. With the furnace not having a heat exchanger, you will slow the amount of heat that's transferred to the walls. Lining could improve combustion, but without preheated air, there's only so much that can be done.

Smoke Signals said:

I apologize for stirring up a hornets nest here, I didn't intend for this to turn into a debate over what furnace is better. I was more looking for guidance on the soundness of my plan to get by with the Tundra until I can afford the Kumma.

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Nah, no worries, we are all regulars on here, it's February, the natives are just gettin restless.
You have a good plan there...carry on

Smoke Signals said:

I apologize for stirring up a hornets nest here, I didn't intend for this to turn into a debate over what furnace is better. I was more looking for guidance on the soundness of my plan to get by with the Tundra until I can afford the Kumma. The info about the issue with Tundra is good to know. Thank you to all who have contributed. Let me throw a third option out there for discussion. How much would I gain in performance If I were to line the fire box of my current furnace with fire brick. Would there be a noticeable gain in efficiency?

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Don't get me wrong I'm not saying which is better because there is no unit that is best for everyone. I just don't like how sbi put out a unit that was dangerous and was so ho hum about it. And for a company that has made tens or hundreds of thousands of units they should have known better. I am a bit of a grudge holder so I will always have doubts with the company. I do think the caddy is a very good unit and sbi makes them. I also thought it was brilliant on their part to come on the forums and ask us nut cases what we would want or not in a furnace.

Smoke Signals said:

I will have to give the Caddy a good looking over. Had not checked them out yet.

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HD version of the Tundra basically. Priced about halfway between Tundra and Kuuma

Smoke Signals said:

PSG advertises the Caddy starting price a $3.999 (still out of my price range for the moment), Does any one know if this include the blower box? The closest dealer is over 100 miles from me, a bit of a drive to just window shop but I would like to lay my eyes on one of these.

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Must be with blower, I seen them at the local dealer a year or two ago for ~$2800 without blower

Yeah I believe so since you can only buy from dealer...but could be wrong on that

Smoke Signals said:

OK, I will have to call around a little and see what the prices are around here. One other question, with the Caddy is a professional install required for warranty purposes ?

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PSG has changed their views on their warrantys. If it's installed by a certified dealer, labor costs are covered for replacement parts, otherwise if installed by a homeowner, no labor costs. The furnaces are built well and parts are easily replaceable.

If your central furnace is in good shape, then a Caddy can be installed without the blower in series with the central furnace. No backdraft dampers, just a simple duct to tie the two together and an interlock. Otherwise it's a stand alone install or parallel.

I really haven't a clue. I think the manufacturer lists their prices high, and the dealers usually come in under them. I would expect a Caddy without a blower to come in around $3000, but I could be wrong.

Smoke Signals said:

I apologize for stirring up a hornets nest here, I didn't intend for this to turn into a debate over what furnace is better. I was more looking for guidance on the soundness of my plan to get by with the Tundra until I can afford the Kumma. The info about the issue with Tundra is good to know. Thank you to all who have contributed. Let me throw a third option out there for discussion. How much would I gain in performance If I were to line the fire box of my current furnace with fire brick. Would there be a noticeable gain in efficiency?

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I can tell you that I converted a wood stove to have heated secondary air injection. The original build (1960's) included a flue bypass. The added secondary air was directed to the exit point of the primary firebox. This is where the exhaust took a turn and passed across the top and then back again to the round flue outlet. In addition, I did add firebrick to the primary firebox. That rascal burned plenty hot and smoked zero after switching the bypass. So it was a bonafide updraft gasser. Unfortunately it was originally designed as non-airtight. Therefore fire control was lost once it got hot, steel tends to warp when it is glowing red. If I had converted the loading door to airtight. that unit woulda been the cats ars. Instead, I scrapped it and got an Eko.