Is this an insane idea?

Cavallo

Gravity furnaces. They seem to be regarded as a dated concept. However, what would be the disadvantages to the following scenario?

An old 1920's foursquare, located in upstate NY, two stories, about 1400sq ft. not including the attic. The entire envelope is very tightly insulated with 2lb, closed-cell spray foam, full depth on the true 2x4" frame (6" in the attic for the roof deck.) Work has progressed over the winter, during which time a temporary, forced-air gas furnace was located in the basement with no ductwork leading anywhere. That furnace - an old, inefficient model - managed to heat the entire house very evenly from basement to attic with only a few degrees difference between the floors. I was kinda surprised, actually. Although - there are currently no interior walls, so convection can proceed very easily.

This got me to thinking.

What if a more efficient, modern, modulated gas furnace were placed in the basement, maybe with just a few ducts to insure even delivery to spots on the exterior walls of the first floor. Then, what if ducts were placed strategically to encourage convection from central locations of the first floor ceiling, between floor joists, to spots on the exterior walls of the second floor, then likewise to the attic (which for purposes of this discussion should be considered conditioned space)? Basically, all this would amount to is an official codification of something that already seems to have worked rather well over the winter. Sort of an update of the gravity furnace concept, with the benefit of simplicity that that brings.

Downsides I could imagine; difficult zoning, encouraging the spread of fire in the event of disaster, codes issues?

Is this a stupid idea? Is it already being done? Is it utter madness? Tear it apart. It's just a concept, and I won't be offended at being called naive.

Paul48

Wow.......You used that much 2lb? You will have to make provisions to bring fresh air into the home. I'd put a hydronic system in there. Scorched air is really unhealthy, especially in a place that tight.

Bob Bona_4

Yeah it is kind of nuts . I'm thinking how you gonna cool the place? Convection ain't going to cut it.

Cavallo

The original plan was for hydronic. Cost has become an issue, so I'm considering other ideas.

As for cooling - last summer, one single, smallish window air conditioner was positioned upstairs. Did it cool the whole place to perfect comfort? No. But it dried the air out, and kept things relatively comfortable in the entire building. Again, I was kinda surprised. It did spike the electric bill, though.

The plan for fresh air is currently spot ERVs in strategic locations.

ChrisJ

Many people heat their houses with a single wood stove.

My house originally had two grates in the floor on the first floor and a coal stove in the basement. It also had two stoves on the second floor.

I'd think your idea could work but I have no idea how well as far as comfort or efficiency.

If you spent that much on insulation, is a little extra for a good heating system that bad? I realize when the till is empty it's empty, but another option could be to use what you have until you get some money to put in a good hydronic system.

Cavallo

The trouble with that is that there is some pressure to finish. Putting in a good hydronic system later would require tearing out ceilings. I can't leave the ceilings unfinished and still get a certificate of occupancy. And I've discovered that I *really* hate dealing with drywall. Once the ceilings go up, they are not likely to come down. And don't even bring up baseboard radiators. I'm really not a fan of them at all. (Yes. I'd rather resort to forced air than have to put up with baseboards.)

ChrisJ

Cavallo said:

The trouble with that is that there is some pressure to finish. Putting in a good hydronic system later would require tearing out ceilings. I can't leave the ceilings unfinished and still get a certificate of occupancy. And I've discovered that I *really* hate dealing with drywall. Once the ceilings go up, they are not likely to come down. And don't even bring up baseboard radiators. I'm really not a fan of them at all. (Yes. I'd rather resort to forced air than have to put up with baseboards.)

It's ok, you're entitled to your opinion even if it's wrong.

Ok, seriously, I agree, never liked baseboard but I do love cast iron rads. But I'm also steam so maybe those two go hand in hand, I don't know.

If you really want to try this I'd say your next step is finding out if it'd pass code in your town.

Bob Bona_4

There's something to be said for keeping the mechanicals to standard. We are just temporary stewards to our abodes.

Looking ahead then, as a seller, it is far easier offering an up to date hvac system to the masses than a one off, possibly dangerous, exotic Frankenstein home grown. Just food for thought.

Cavallo

Hmm. Resale. Good point.

ChrisJ

Cavallo said:

Hmm. Resale. Good point.

I'd finish everything I could and wait until you have the money to put a hydronic system in. And I know you're not going to like it but if I was you I'd do baseboard and run all the piping through the livingspace like they did years ago.

Yeah, the pipes are in the room but look at the pros of doing it this way.

• The piping is in the conditioned space, no lost heat.
  
• Easy to maintain
  
• Low cost to install, no dealing with drywall.
  
• Less likely to freeze during a power outdage
  

Your house is insulated like a chest freezer, this heating system is consistent with the idea.

Cavallo

Well, the insulation is complete, and one of my original design goals - no plumbing in exterior walls - has been adhered to. So freezing is equally unlikely no matter what I do. From a purely aesthetic standpoint, running all the piping through the living space sounds completely ghastly, but could be survivable, I suppose, with a bit of clever design.

BUT - I get your point. Waiting on my dream heating system need not be as traumatic as I fear it might be. In the meantime, I could put in vents to encourage the convection I was describing in my original post, and simply close them off someday in a glittering future where I'm not broke from remodeling. Or even leave them. Maybe they'd still help.

Cavallo

Now that that's a bit clearer in my head - who knows of a modulated, forced-air furnace that can be interfaced with a microcontroller?

RobG

Doing drywall isn't too bad if you pay someone to do it.

ChrisJ

Be glad you're not dealing with plaster. I have tons of fun in my house, although the more I do, the less I hate it.

Once I learned my Kirby could sand walls / ceilings and actually leave close to zero dust on me and everything I became a whole lot happier. I'm going to be looking for a similar attachment for the shopvac as I really don't like using the Kirby for that. But, it did do an awesome job.

Cavallo

Plaster removal, or putting in new plaster? Because I removed *all* the plaster in mine. It took a month, four dumpsters, and all the house-help-karma I had in this lifetime. Never again.

Rich_49

You don't need a modulating furnace .

http://forum.heatinghelp.com/discussion/154490/troubleshooting-not-providing-enough-heat#latest

Look at the second page for why

ChrisJ

Cavallo said:

Plaster removal, or putting in new plaster? Because I removed *all* the plaster in mine. It took a month, four dumpsters, and all the house-help-karma I had in this lifetime. Never again.

No, plaster repair.
Removal is just, not happening anytime soon.

I've got some drywall also. It's fun swiss cheesing a wall and ceiling to run wires and then repairing them so no one can tell it ever happened.

Paul48

If hydronic isn't in the budget, how about roughing pex and documenting where it falls behind the baseboard in each room. You could piece-meal the system one emitter at a time, as the budget allows. With a compound miter, you could even leave access panels for the pex. Only you would know where they were.
Just to give you an idea....I read an article about an installer putting less than 2" of foam on the exterior of a refrigerated warehouse. They reduced their refrigeration by 1/3. You could probably heat that house with a candle in each room. Oh.....and I'm pretty sure they used 1/2 lb.
My brother was a contractor, when he found out how much it cost for pros to do the drywall, he sold his screwguns. The price was dirt cheap, then take into account the speed at which they can hang it, and mud it. It just didn't pay for him to do it.

vaporvac

Well, there's nothing as beautiful as a plaster wall and easier to fix cracks than one might think, but that's not helping this post. I like @Paul48 's suggestion of roughing things in. You could always box the pipes inside drywall if you go in that direction. Go with rads...they really complement a house of that vintage.

@ChrisJ , I need more info on the sanding Kirby! Mine will plish my floors, but it's so heavy. It's an old one, so maybe yours is newer.

Cavallo

I'd have loved to keep the plaster walls, but they were in too poor a state, and there was too much burst copper inside them to justify it. Down to the studs it went. Literally. And it's a damned good thing. The framing was pewp.

As to not needing a modulating furnace, will read the thread ASAP. Although, I *like* the idea of modulating to keep things quiet.

Cavallo

Also - I have not yet done my heat loss calcs, but I will soon. Yes, my joke with friends is that I could heat it with a candle. The required BTUs should be stunningly small.

Cavallo

OK, Rich, I think I see your point. Keep it Simple, Stupid. That's actually kinda what is driving me to consider hot air. My original idea was to run pex-al-pex in the ceilings and heat the drywall up there (as little as possible to maintain desired ambient temps,) letting the heat shine down from above. You have no idea how many people (who should know better) said "but heat rises!" Ugh. Anyway, it became apparent that the parts to put together such a hydronic system would be more expensive to acquire, repair, and replace than a hot air system, even though I hate hot air. This got me thinking about long-term maintenance, and has driven me in the direction of simplicity.

Although, it's only going to be so simple. I already have my own, homemade temperature/humidity sensors on the walls in a couple rooms. They also sense motion, have cameras, and can talk, but that's way outside the scope of this thread. The point is that simplicity does not come naturally to me. I'm having to work on it.

RobG

You would be surprised how many ways there are to hide PEX piping. You could run it up the corners of the rooms and put a piece of crown molding vertically to cover them. Go up in one corner and down in the other corner. There are many ways to give it a finished look, you just have to think outside the box.

Cavallo

All true. But, dammit - I have the interior walls open still. I could do so much better if only I had unlimited resources...

ChrisJ

Cavallo said:

All true. But, dammit - I have the interior walls open still. I could do so much better if only I had unlimited resources...

We all have those same exact thoughts very often.

There has to be another option other than forced hot fudge.

Cavallo

I kinda like the idea of building in the pex and sealing it up for later. Still have to buy the pex, but that would probably be the cheapest part of the system.

I better get to doing my heat loss math.

Rich_49

How are you gonna ventilate ? You left out so much .

How many square feet is the insulated roof ? How many sq ft is the ceiling ?

Cavallo

I briefly mentioned spot ERVs. I think a couple Panasonic FV‑04VE1 units, carefully positioned, would work well. Although they're damned expensive too, and I'm not sure they'd operate well in my climate.

Anyway, the house is about 700 sq ft per floor. A short basement, two real floors, and the attic, which is now essentially a big room. It's a hip roof with a pretty steep pitch. I'm not sure the rise/run, but I'm sure someone more experienced than I am could make a fine guess. It's essentially a big cube with a pyramid on top.

MikeG

Have you looked at a couple of small mini splits strategically placed for heating and cooling?

Cavallo

I've thought about it, but I don't know enough about them.

ChrisJ

Cavallo said:

I've thought about it, but I don't know enough about them.

For what they are, and what you need they're awesome.
I think they have units that are something like 25 SEER.

Cavallo

Also, I'm highly disinclined to heat with electricity. I have a gas line and I'm going to use it to its fullest potential.

ChrisJ

Cavallo said:

Also, I'm highly disinclined to heat with electricity. I have a gas line and I'm going to use it to its fullest potential.

It sounds like you've already made up your mind.

RobG

If the walls are open you should do a heatloss and determine the type and size of emitters you will need for each room, that will determine the spacing of your piping runs. Just stub them out of the floor or walls and install the rads when you can afford it.

Spence

If you keep insulating and sealing, you won't need anything more than a mini-split, and you won't use it for almost all of the winter anyway.

As you so aptly said, you can heat with a candle. Yet you must install ERVs, and hopefully you have lots of southern and western glazing with overhangs for summer. East and west OA dampers with humidistats are nice to catch cool breezes.

Cavallo

ChrisJ: I've made up my mind inasmuch as I want to use gas as the primary fuel, since electricity is more expensive in my area. Apart from that, I'm willing to consider lots of things.

I'll get off my butt and do a heat loss ASAP. I'll get a friend, a measuring tape, and get some numbers. I think I have the Slant/Fin app. Is there something people generally like better, or will that one do? Or should I do it longhand on paper?

Spence: The idea of OA dampers had occurred to me, though I hadn't yet looked into how to properly locate and use them (or indeed - even what they were properly called.) Thanks for the clue.

And this raises a question that may be a topic for another thread. I'm natively an IT geek. As I hinted at above, I'm rolling my own automation system of sorts. Each room will have a small box on the wall that performs a variety of functions from security to entertainment to environmental monitoring. As it stands, the very first function I built in was air quality. Each unit measures air temperature and RH, and calculates dewpoint, once per minute and dumps it into a database. If you guys had that much data coming in, what would you do with it?

One thing I had imagined was outside monitoring as well, and having the system bring in outside air, say, on a cool summer night, and stop in the morning, before the day heated up.

Cavallo

Also, I may be willing to consider a mini-split if I could figure out how to estimate monthly operating costs.

SWEI

If you really want to maximize your use of outside air for free cooling, consider installing a whole house fan (or at least an exhaust fan) at the top of the house. We do this using Greenheck Vari-Green EC motors which consume very little electricity and feature native 0-10V control.

Now for the fun part: Install motorized OA dampers at strategic spots around the perimeter near the ground (above the snow level.) Have your tinner put filter holders on the inside of each inlet (for dust control.) Install a personal weather station and use the wind speed/direction info together with OAT and dewpoint to manage what gets opened and closed as well as fan speed (if any.)

Cavallo

That sounds brilliant.

ChrisJ

Cavallo said:

ChrisJ: I've made up my mind inasmuch as I want to use gas as the primary fuel, since electricity is more expensive in my area. Apart from that, I'm willing to consider lots of things.

I'll get off my butt and do a heat loss ASAP. I'll get a friend, a measuring tape, and get some numbers. I think I have the Slant/Fin app. Is there something people generally like better, or will that one do? Or should I do it longhand on paper?

Spence: The idea of OA dampers had occurred to me, though I hadn't yet looked into how to properly locate and use them (or indeed - even what they were properly called.) Thanks for the clue.

And this raises a question that may be a topic for another thread. I'm natively an IT geek. As I hinted at above, I'm rolling my own automation system of sorts. Each room will have a small box on the wall that performs a variety of functions from security to entertainment to environmental monitoring. As it stands, the very first function I built in was air quality. Each unit measures air temperature and RH, and calculates dewpoint, once per minute and dumps it into a database. If you guys had that much data coming in, what would you do with it?

One thing I had imagined was outside monitoring as well, and having the system bring in outside air, say, on a cool summer night, and stop in the morning, before the day heated up.

You're going to have all this, without a proper heating system?
Now I'm confused.

Cavallo

No. I'm building this anyway for a variety of reasons. The air quality sensor was the easiest thing to implement, so I did it first. But the data could be used to control just about anything with serious finesse.