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OT: Gasification boilers, tankless heated water, and radiant floors?

SND

Diamond
Joined
Jan 12, 2003
Location
Canada
So I'm hoping that a few of you here may have experience with this variety of systems. All input in welcome on what may be the most efficient/cost effective system.

We're pretty much set on the idea of having a heated slab in the house we're building next year as it won't have a basement. Just 2 levels, and a slab(4ft footings/frost wall around)
I like the idea of the heated slab so that I can maintain an even shop temp around 20C for my work and machines.

Now I'm searching for which heating system may be best. So for starters, here's some data.
Aprox 1850sq/ft main floor/shop and about 1600sq/ft on second floor. We would probably use 3 or 4 water baseboards to heat the 2nd floor if not enough warm air made it up from the slab. 6"walls, very well insulated it'll be. But very open design inside for good air flow and such.
There will also be a normal wood stove in the house, its a must.
About 3acres of trees, so there's wood for quite many years and I'll plant more as I go which is why I'd like so sort of wood system, if it is indeed the most cost efficient long term. So far it looks like most of those furnaces are 8-10K $, but needs some "other stuff"...


So I'm searching into indoor wood furnaces and the gasification systems came up, appears to be the most efficient in wood burning and clean. I'm not overly interested in the outdoor systems.

Here are some brands I've found so far.
http://www.greenwoodusa.com/
http://www.woodboilers.com/wood-boilers.aspx
http://www.alternateheatingsystems.com/Multi-Fuel_boilers.htm
http://www.newhorizoncorp.com/

This is where things get fun, the "other stuff". Some of these furnaces can have a water coil for home use. Realistically we may need to heat for what, 4 months? and it doesn't get all that cold where I live the recorded average is of -5C for Jan and Feb being the 2 coldest months.
Which means we'd still need a way to heat the house water the rest of the year. Other problem is what if I leave for a few weeks in winter and nobody is home to put wood in it? They make some dual fuel furnaces, but I don't want to also have to buy an oil tank, plus add-on just for the possibility of someday having a few weeks vacation somewhere. Doesn't sound cost effective at all.

I haven't yet found a wood furnace that also has an electric element in it as back up. Which is making me wonder if I should just use Tankless water heating for home use(only 2 people). And perhaps have a similar system tied between the furnace and the slab, so that if I leave it can keep just enough heat going? I'm just not sure if there's a tankless system compatible with the Glycol used for the in floor heating. Maybe just build my own? Any ideas?

Other option is to just go for the plain electric system that heats the slab and house water. Perhaps try to heat mostly with the stove in the house, and maybe also add one to the shop so we're not using up more electricity than needed to heat a slab? I don't really think that just 2 stove would be quite enough for good heat all over the house but could had maybe an electric baseboard in the bathroom or other areas which may require more heat. The shop will be 24x48 with a loft/studio above it, though I could perhaps locate the stove right in the middle lengthwise?

I had the idea of using a good wood stove and running some pipes to get heat into a slab, but since my contraption wouldn't be ASME and CSA approved, it would have to be done after inspections, etc, and I don't want problems...

Should we skip the heated slab idea altogether? How much cost does it usually add, have most of you found it to be worth the investment?

Heat pumps or similar things don't appear to be that great around here, doubt I'd go for it.

Other things is Stainless Vs Carbon steel water boilers. Some say SS is great, some says its Bad because of heat fractures over time. Of course its just plain 304, not 310/316/321 which would be more capable of high heats I think. So, whats the verdict? ask for 321?

All input is very welcome, thanks.
 
6"walls, very well insulated it'll be.

You might want to check your local energy code for guidance on this. A nominal R19 in the walls is the bare minimum here in central Vermont and may be marginal in your area too, depending on the insulation (foam, fiberglass or cellulose) and how it's installed. 20 years from now the standards for insulation will likely be much higher.

Heat pumps or similar things don't appear to be that great around here, doubt I'd go for it.

A water source heat pump might be the ticket for you. Their efficiency drops to that of straight resistance heating at low temps but are considerably more efficient than resistance heating at higher temps. Higher initial costs, certainly, but maybe cheaper in the long run, especially if you use it a lot. kWh costs will prob continue to climb, too. They're good backup heat and come with air conditioning at no cost, too, if that's of any use to you.

I'd suggest taking your building plans to someone (energy consultant, heating and insulation company, etc) who knows local practice and codes and can calculate your annual heat loss and make recommendations for sizing the heating system, which would be useful info for the expensive choices anyway. And the numbers will help you make choices, too. For instance, "fuel" costs for resistance electric heating are higher than for oil or propane so the payback period for more insulation would be shorter for electric resistance than others. It's a complicated guessing game without numbers but a lot easier, more certain and cheaper in the long run with them.

Neil
 
As for the issue of electric heater / glycol -- I don't think you'd plumb the glycol directly into the hot water heater; instead, you would have some sort of heat exchanger loop.

What about a system that had an electric tank for hot water (house use), with two heat exchangers in it -- one to go out to the slab when needed, and the other to bring heat in from your wood furnace. When the wood furnace is running, you could turn the electric elements off -- otherwise, they would come on whenever you ran a shower, I think. But whenever you're going to be gone, or when it is no longer heating season, shut down the wood furnace and turn on the electric.

Here's a web site that might give you some ideas. I have not used this company and have no affiliation with them -- no recommendations implied, etc. -- just a site that I stumbled on a while back when I was wanting to find out more about radiant systems. IIRC, they have solutions that allow for something like I described in the previous paragraph:

http://www.radiantcompany.com/

On edit -- I went and browsed around that link a bit to refresh my memory -- click on the "Heat Sources" link in the menu bar along the top, and you'll see a variety of systems, including tankless water heaters. From the way the site is presented, I suspect you could get their help in designing a custom solution, but no idea how much that might cost -- and again, I've never worked with this company, so they may or may not be good ...
 
I have a system from Radiant Floor company, and love it. Radiant heating in the slab is wonderful in a shop. I will elaborate about my experiences further when I am not on my iPhone. Do NOT buy a Polaris water heater.
 
Another question about water heated floors. I see that a lot of people put the tubing at the bottom of the slab just over the Styrofoam, while I've had a friend who's quite knowledgeable in nearly all things carpentry/construction related tell me that they should be placed closer to the top. He got to see it done both ways, and apparently it was better that way. Can anyone here add to that one way or another? Should they perhaps be placed midway into the slab? I'm a bit worried about machine weight, although I guess with the rather small size of the tubes and their spacing it may not matter much?
 
I'm just not sure if there's a tankless system compatible with the Glycol used for the in floor heating.

My radiant heating system just uses a 50 gal. water heater as the heat source, and it circulates water. Why are you considering glycol? Is there a possibility that the entire system may get shut down and freeze or something?

I have tankless water heater for the domestic hot water supply and I am 100% happy with it. This is the fifth year of service, and it has been very consistent. I would like to use it for radiant heating, but the flow rate through the heater is low and I am not sure it would work. It is not rated for that use.

Should they perhaps be placed midway into the slab?

Our tubing was tied to the rebar in the slab every 8 ft. It ended up being midway and works fine. We only put styrofoam around the periphery of the slab and down along the retaining wall.
 
Another question about water heated floors. I see that a lot of people put the tubing at the bottom of the slab just over the Styrofoam, while I've had a friend who's quite knowledgeable in nearly all things carpentry/construction related tell me that they should be placed closer to the top. He got to see it done both ways, and apparently it was better that way. Can anyone here add to that one way or another? Should they perhaps be placed midway into the slab? I'm a bit worried about machine weight, although I guess with the rather small size of the tubes and their spacing it may not matter much?

Placement of the tubing will change the responsiveness of the slab temperature. If the heat will be turned off for a period of time when it is turned back on, there will be a delay as the slab heats. If the tubing is near the top of the slab, the delay is short - near the bottom the delay is longer. If the heat will remain on all the time, position of the tubing doesn't matter.

My tubing is at the bottom attached to the foam with clips. But I haven't finished connecting the system since I insulated the heck out of the building with spray foam and am able to heat it pretty well with sun shining in the South windows and a 1500 watt portable electric heater. Tubing and manifolds cost about $1200.

On the electric heaters, the radiant heating folks make a fair size deal out of the difference between a water heater and a water boiler, that being how much water they are capable of heating. In a building with a high heat demand (Unless you are talking about 6" Structural Insulated Panels in Canada, I'd call 6" wall with fiberglass high heat demand) don't try to use standard water heaters.

Steve.
 
Glycol was mostly for the corrosion aspect in a closed system, heat transfer is supposed to be good but perhaps a bit less than water, unless the water lines start to scale which rapidly reduces their efficiency. But I'd go with whichever was recommended for the system to get the best life out of it.

I just did some more reading on the geothermal heat pumps and it doesn't look very cost effective for this area, and being its a smaller house. It'll cost enough just to drill the water well without having to do a bunch of other holes. The air to air type heat pumps says a back up would be needed for the cold winter temperatures, plus I don't know if they actually tie into a water heating system. Only saw the heated air type.

I want as few pieces in the puzzle as possible to get the job done. I'll check if there's any non biased consultants around here, so far I only ran into people selling one thing and saying the rest is junk, of course.
 
Number 1) Insulate under the slab by all means- That cold ground will sap the heat right out of that slab.
Number 2) go to this site- http://www.heatinghelp.com/wall_forum.cfm and ask them questions about what you asked here. They are all pros, and the only thing they won't talk about is price.
I bet ya they will also tell you to purchase a book about Hydronic Heating (which is what you are talking about) by that websites' sponsor. I have it and it is worth the money and shows all the different ways to plumb a system like this. It doesn't show anything about wood fired stuff- just basic hydronic systems and how they work and should be plumbed.

What is great about slab floor heat is that you don't need to run the temp of the water in the floor any hotter than you want your area heated. They make special types of boilers called "mod-cons" which means modulating condensing which like to run at low temperatures and they automatically modulate the amount of fire coming from the burner to save fuel.
I heat with wood thru finned tube baseboard heaters, and I have a Munchkin brand Mod- Con boiler (google HTP - Heat transfer products) plumbed into the system with heat exchanger to keep the water in the two systems separate. When the wood fire dwindles down, the Munchkin takes over.
 
Couple of quick things....I lost a post earlier due to my own timing problems and an IE crash.

- I would definitely insulate under your slab as Joe E. posted, they have products designed for the same application in airport runways which I believe has a higher loading than your shop floor. Also insulate the footings to prevent sideways heat transfer.

- I don't think 3ac even thoroughly wooded is enough timber to be sustainable. I'm not an expert woodsman but if it is thickly wooded it's bound to be thin-stick fast-growing trees without much heating value. Older hardwoods are desirable...but they might take 50 years for a single tree to be replaced.

- Cutting, stacking and splitting wood is "cheap" and gets you off the petroleum price swings, but man does it eat up the time.

- Lastly, transferring heat via heat pumps is IMHO the most efficient way to go. It will keep you from freezing to death but probably won't keep the place toasty warm either...so you need some sort of backup/boost system. Also can double as A/C.
 
In a building with a high heat demand (Unless you are talking about 6" Structural Insulated Panels in Canada, I'd call 6" wall with fiberglass high heat demand) don't try to use standard water heaters.

The key is the number of btus the heater is rated for. We've had excellent results keeping the house 69 deg. F when it is sub-freezing outside, and we have a 40,000 BTU 50 GAL water heater. We have 5" of rigid foam insulation in the ceiling and R16 in the 2x6 walls, with 1" styrofoam along the retaining walls and below the edge of the slab (4 ft. wide). The only downside has been the life span of the water heaters. In 16 years we have had to replace the water heater twice.
 
First question , where in Canada are you , makes a big difference in what is needed for the system .
Glycol in an area that freezes more than a few times every hundred years or so is a good idea . If for some strange reason you were not at "home" for a few days and the power fails and the house freezes the lines in the concrete will also freeze and this makes for broken concrete . I worked on a friends "investment house" that had copper tubing in the garage floor for heat , the house was siezed by the bank and set for two winters before it was sold to my friend and he ended up replacing the concrete . Everywhere the tubing ran the floor was cracked or broken . Now pex might expand and contract but concrete doesn't one has to give and it will not be the pex .
A back up boiler is a good idea also , for times when it is a little chilly with warm weather in between the cold snaps . Radiant heating is more efficient then regular hot water because you are putting the heat where you need it at your feet . If you are going to have a second floor add tubing to the floor there and heat the whole place with it , you will be happier in the long run . One of my buddies had been set on heating his shop with forced air until we fired up the used furnace in his old 8' X 16' storage building shop and the dust went flying everywhere :crazy: , I talked him into a oil fired boiler with heat exchangers running the radiant floor and two runs of fin tube in the bay where he keeps his classic car . No work is done in the bay and the concrete was already there so this was the most cost effective for him , but he does say that the bay is colder feeling then the shop . He has been in his new shop for two winters now ( going on three) and is really happy with the system . Recently he added an outside hot water stove to this system and runs it all the time , he makes his domestic hot water with it for both the shop and his house all year round .
Three acres of woods will yield three cords of wood ,sustainable , every year . Once you get above that yeild you start to get into the downward curve for sustainability , the more you cut the small the acreage gets the more you cut , so on and so forth .
Gasification Technology has come a long way in just a few years that I have been hearing about it , but have not looked into them much so all I can say is you will have to do your research on them .
Stainless steel verses Carbon steel , with proper care I would go with the carbon steel models as they seem to be a lot less likely to crack . Stainless steel does not like being cycled hot to cold , so +1 for carbon steel .
I will be doing the whole house and shop with radiant heat when I do my remodel and build the new shop , also have done a lot of radiant floor heat as a pipefitter . The initial cost is higher but will return the cost in fuel savings over time . Dan
 
I have both central gas that blows in my duct work and a radiant heat set up on the main floor. The initial cost of the radiant floor isn't excessive if you do it yourself. It doesn't matter where in the concrete you put your tubing once it's up to temp. Boilers are a lot more expensive than demand water heaters. I know most heaters aren't rated for this but I know a lot of guys that use them and they work fine. I have 3 in my house. They are all Rheem nat gas demand heaters. I have one for the kit/main bath&b laundry, one for the master bath and basement and one for the floor heat. I could have done it with just 2 but I like the back-up should one break and leave me with out hot water for a while. They were no more expensive than a tank-type other than the stainless vent piping which is criminally expensive.

I would suggest having a wood stove to utilize your free wood and a main heat system that can keep you from freezing out if you have to go away- either gas fired or electric.

Generally, electric water heaters are going to cost a lot more to heat with than gas. You need to have your utility companies run the cost comparisons for you- they all have software to do this.

The floor heat is only good when you have low temps that are going to stay low for a while. It isn't a system where you can change the temp quickly.

R19 is marginal in walls these days. I would shoot for R22 or so by using some foam or something creative in the walls. All this is wasted if you don't use good insulated windows etc.
 
My neighbor has a floor radiant system in his house, and he kept scratching his head as to why his propane bill was so high. Finally I had to stick my nose in the problem and came to the conclusion that the only way to get a grip on the beast was to break everything down to BTU load. Once that was determined, it was fairly easy to make a choice on how to heat it. His system is styrofoam insulated, both slab and footer, using PEX pipe and straight water. What we found was a major surprise.

Our test area was a zone of approximately 1500 sq. ft., residential house, 9' ceilings, R28 walls, new construction. Yes, Spencer, I'm sorry to say we were using a Polaris propane heater. In the first 24 hours, we consumed 1,250,000 BTU's dropping to just under 900K for the next 24 hours. It finally settled down to 750K/24hrs. to maintain an inside air temp of 72º. Outside temp at the time was around 40º. This was a house of about 4500 sq. ft. sectioned into four zones (not equal). The heat we were generating in our test zone was obviously leaking into the non-heated zones, so we have a lot holes in our test. In any event, it was enough for us to quantify exactly what kind of BTU's we had to generate and then figure out the fuel to do it.

It was pretty apparent that for those in wooded country, a gasification boiler was the only way to go, but as Matt pointed out, there is a labor/aggravation factor involved that may sway the decision. For those of us in the high desert, we're screwed in all depts....solar, electric, propane, natural gas.....and cactus doesn't burn.
 
SND - A couple of concepts: balance point and HDD.

Balance Point is the temperature at which a standard heat pump (air source) can no longer get heat from the air, seems to be around 25-28 degrees F for the newer units. At this temperature, the heat pump just runs and runs until hell (or you) freezes over because there isn't enough thermal energy in the air for the heat pump to extract. Heat pumps are efficient at heating a building when the air is above 40-45 degrees F. Below that the efficiency gets worse and worse until the balance point. At this point you get your house heated on "Auxiliary heating", think "Really large toaster with a correspondingly large electric bill". This is why you don't see heat pumps in Canada.

Ground Source Heat Pumps (sometimes called Geothermal) get around this problem by extracting heat from deep underground. The monkey wrench in the works for GSHPs is the rather substantial cost of getting the pipe put in the ground.

HDD is Heating Degree Days, which is the sum of the daily temperatures below 68 degrees F added together for the year and is a measure used in heating requirement calculations. More detail here:

http://en.wikipedia.org/wiki/Heating_degree_day

With all due respect to RimCanyon, Salinas shows 2800 HDD; and assuming Slugger is in Flagstaff he has 1700. I'm in what's called the Hot Humid South and I'm at 3600. Toronto shows 7400 and Fairbanks Alaska is 14000 so depending upon where in Canada you are it is either a heck of a lot or a giant f%#$ck of a lot colder than where we live.

For most water boiler manufacturers a 40000 BTU water heater is less than half the output of the smallest units they make. They make dual fuel units which might be an option.

The folks who can really help you are construction pros in your area. This might help:

http://www.cagbc.org/index.php

The strategy that I used was: insulate the building well past what any sane person would do in that climate, then add whatever minimal heating (and cooling) is needed.

Steve.
 
SND

My house is 3 years old, mostly self built and is a work in progress for details.
It is a 40' x 60' single story w. 9' ceilings. Full walkout basement, 40 x 60, 10' ceilings. Roof is a 9 pitch gable which yields an additional 1500sq' area.
The main floor also has a 500sq' worth of cathedral area with 24' total height.
Needless to say, it's big ( at least as far as heating is concerned )
Heating is done only on the main floor, dual heat. The whole area has hydro-air, 2 separate zones. In addition the 3 bedrooms and 2 baths also have radiant floor heating, installed between the floorjoists, totalling approximately 1300 sq'.
I have a Tarm Excel2200 boiler with the 840 gallon storage tank, installed in the basement. Chimney is in a chase smack in the middle of the house with only 4' exposed to the cold at the ridge.

The reasons I'm describing the details that there are a few things I'd like to mention:
1: If you don't absolutely need cathedral, then don't build cathedral. Period.
2: R19 in walls - as mentioned - is marginal. If I could do it again I would build the outside with 2x6, install R19 or R22 as it is now. Then build an additional 2x4 inside wall, offset by 1-2" from the 2x6 and also stagger it by 8" to avoid heatbridge to the outside. Into the 2x4 I'd install R11 with radiant barrier foil.
3: Make sure your rafters are insulated and if you can in addition also insulate the ceiling joists.
4: I know you want slab, I would not. Not for a house anyway.
5: If you go with a wood boiler, the addition of a heat storage tank is well worth the time and expense. Nice thing: You can add the storage later as long as you plan for it.
6: If possible, put the chimney on the inside of the house. You will easily maintain a stack temperature high enough to greatly reduce creosote buildup. I've got a Vermont Casting Sequoia stove which was used for 1 and a half season, totalling approx 8 coords of wood burned. The chineyguy came out in July to clean and had commented that I could have easily gone another 2 years at this build-up rate. As it stands I'm in the process of installing Aluminum sheetmetal fins onto the lower part of the chimneys and the smokepipe as to put some of that heat to better use.
7: If you can definiately install a double heat system. The radiant will easily keep you comfortable down to 20-25 deg outside temp, below that it will struggle. The addition of a fast-recovery heating ( forced air or hydro) will help you during the cold days.
8: Don't believe the setback garbage touted by the government folks. Do your homework and experiment on your own house. I have the thermostats set to 70 and left there. 'Nuff said.
9: Observe the sun during winter days. Try to expose as much of the house to it as you can, install the windows there. For summer a decent size roof overhang with nice pitch will reduce the overheating. Mine has 2', the winter sun shines through all day, elevating the temperature by 4-6 degree even in the 20-s. Summer I get no more than 3' direct hit, easily solved by curtains.

That's it in a nutshell, though there are some more details I can tell you and there are many many more I don't even know yet ( hence the work in progress part...)
As it stands, last winter we've burned about 5 coords of wood in the stove, virtually no oil used for heating purposes. Right now the oil has been completely shut off since thanksgiving. The boiler has burned about 1 1/2 coords, maintaining 70+ degree inside temps and supplying 8+ daily showers worth of domestic water ( got 2 teenage girls and a wife, you figure..)
Loading is done twice a day with one or two days during 35 or above temps and sunlight when we just skip it altogether and exhaust the storage tank's heat.
 
I heat my shop 32x40 with a Siesco electric boiler, PEX tubing and 50/50 anti freeze mix. I know Siesco offers an electric boiler that has a seperate chamber for hot water.

greg
 
- Cutting, stacking and splitting wood is "cheap" and gets you off the petroleum price swings, but man does it eat up the time.


Hey, there is one other person out there that realizes that heating with wood is not cheap, IF you pay yourself something for your time.

Sure, IF you have a lifetime supply of free wood,(3A ain't enough), if you have nothing else to do with your life, Have access to free labor other than yourself, and if you have free access to a lifetime supply of woodcutting equipment.

MAYBE, if you can meet all the above criteria, heating with wood is sorta cheap and makes sense.

Otherwise, anyone who claims that heating with wood is cheap is blowing smoke up your ass.

If heating with wood was the cheapest and most efficient everyone would still be doing it rather than coming up with other methods. Gasoline is the cheapest and most efficient method of transportation, that is why we are still using it.
 
SND: One of the reasons they put the pipe at the bottom of the floor on the insulation is it will not break when the cement cracks or shifts. It can mean lossing a zone if you have a major crack or shift in the floor if installed in the cement, it's also easier for the contractor to put it in the bottm,
 








 
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