New Home In-Floor Heat

[mitchstockdale]

Hey Everyone,

I Plan to do a future OWB install in the next couple of years for my new house, currently under construction.  I want to get all the radiant tubing installed now since it will be inaccessible once the sheetrock is installed.

The question is... do you think i should install radiant tubing on the underside of the second floor?

I have been leaning towards not doing the install of the second floor tubing since i will have a large woodstove (jotul f600) and ductless heat pump units (needed for insurance) heating the centre cathedral sections of the house (all rooms are accessed from this center cathedral section).

My thought is if i install radiant tubing under the first floor only, coupled with the wood stove and ductless heat pumps there would be enough heat from those sources to heat the rooms on the second floor. 

Basement is only A crawlspace and will be insulated and heated once the OWB is installed most likely with a fan radiator of sorts, and electric backup.

Has anybody come across this predicament before any advice would be much appreciated.

Thanks
Mitch

[KamHillbilly]

After you get use to the heated floor on the first floor I think you'll be disappoint you didn't do it on second floor while you had the chance . The tubing isn't the expensive part put it in while it's easily done

[50 Acre Jim]

I agree wholeheartedly with KamHillbilly.  We put radiant heat in all our rooms except the bedrooms.  The thought was that we sleep in a cold room so no need to heat it.  Wrong decision.  Now we have a granddaughter and the room is too cold for her.  Install it now cuz as you noted, you won't be able to go back and add it later.  Radiant heat is awesome, you'll love it! 

Edit:  Add as many zones as you can afford.  That's what we should have done for the bedrooms instead of leaving them out of the loop.  Also, our kitchen and living room are on the same loop but the kitchen has more windows than the living room so on a cold night, the kitchen is always a few degrees colder than the living room.  If we had put it on a loop of its own we could have just raised the temp in that room a few degrees. 

[peterpaul]

We have radient in my basement slab and first floor.  The second floor we went with Radsen Radiators which are individually controlled.  We have 7 zones, each with either power heads or zone valves controlled by a thermostat.  The entire second floor (3 bedrooms and bath) is controlled by a thermostat located in the bathroom.  Works well, allows us to shut down 3 bedrooms when not in use, keeps the MBed cool, Mbath warm by keeping door closed.  In the basement, I did not run tubing in one small storage room (cold cellar) and insulated from the heated space.  We have a lot of south facing glass, so get good solar heat gain as well.
Zones are: basement, hearth room(first floor), liviing room/dining room/kitchen (open floor plan), master bedroom (incl. master closet), master bath, second floor, attached 24 x 26 garage.
We have a masonery heater to reduce propane consumption.  I'm please with the performance.  FYI, -12 this morning, if your feet are warm, your warm.

[KamHillbilly]

I agree with lots of zones I have my bedrooms and bath zoned individually , kitchen and living area zoned together . My walkout basement is unfinished but pipe is laid out so it is easily zoned in future .

[mitchstockdale]

Thanks for the insight guys..looks like i should be getting geared up to install the second floor tubing.

What is yours guys opinion of installing the aluminum heat transfer plates to hold the pex tubing...I have read things  arguing installing them and not installing them.  The way i see it is if I install adequate insulation to direct the heat upwards the transfer plates are really only to hold the pipe, which can be done with those black pipe clamps.

There seems to be various ways to install the tubing, I see 250ft of pipe is max for a loop.  Do you guys know of a good comprehensive source that you could point me towards for the install and what equipment is typical.  I have had some exposure to this stuff but that was a few years ago now and cant seem to remember anything.

Thanks

[Crusarius]

I have radiant floor in the downstairs of the house. It is a concrete slab. That and a wood stove downstairs is how I heat my house.

I like having just the downstairs heated cause all the bedrooms are upstairs and I like it cold when I sleep. There are very few times I want heat upstairs. The primary times I do is when it has been below 0 for a week. Then it starts to get kinda chilly in my room. When that happens a well placed fan in the open loft area will warm the room right up.

The wood stove just heats the air since I have a loft area that is open right to the roof. Without the wood stove I get a cold draft rolling off the loft floor onto the couch. It really is not bad but the wood stove makes it very nice.

[sprucebunny]

I skipped the transfer plates and glued down vinyl plank floor for best heat transfer. Tile in bathroom.
I used the special clips that keep the tubing 1/4" away from subfloor as it is recomended and I would be nailing 1/4 smooth plywood before vinyl. It works well even with quite a few windows.

[John Mc]

When we built our house, we did radiant in the basement slab, and radiant on the first floor. On the first floor we poured a lightweight concrete slab under hardwood floors in most areas, with tile in the entrance hall and kitchen. (The tile transfers heat much quicker, but the radiant heat still works well under the Ash wood floors.) We wanted to get a little thermal mass, so these zones weren't cycling on and off all the time.

The upstairs we used baseboard hot water. Our thinking here was that we wanted a quicker response time than on the main floors, since the bedrooms would be turned down when not in use. The concrete slabs do take a while to warm back up if we turn them down (but then that's what thermal mass is all about).

This is all fired by a propane boiler. However, we have a wood stove in the center of the first floor that is our primary heat unless we are away, sick, or we get a really frigid spell. We have a cathedral area that is open to the second floor, if we open the bedroom doors, we can heat the whole first & second floors with the woodstove in all but the coldest weather (we've been below 0˚F for about a week - the wood stove keeps up for my comfort level, but my wife kicks on one of the radiant zones on the first floor occasionally - she likes the warm feet).

If you are doing radiant heat in a slab, be sure to include provisions for a thermocouple in the slab. Our thermostats for the slab areas have two inputs: one has the normal air sensor, the other senses the slab and keeps it above a minimum temperature. (This basically keeps the slab from going stone cold in between times when the air sensor is calling for heat.)

[Crusarius]

The thermal couple in the slab would be great. I get quite a bit of temperature fluctuation with just the air sensor. Especially with the wood stove running.

[John Mc]

The thermal couple in the slab would be great. I get quite a bit of temperature fluctuation with just the air sensor. Especially with the wood stove running.

Yeah, that slab thermocouple really helps prevent the large swings. It is possible to add one after the fact, but you need an infrared device to see where the radiant tubes are - and then just drill into a spot where the tubes aren't. It's a whole lot easier to just do it when you are pouring the slab, since you can run the wiring in the slab as well (we capped the end of some tubing and used it as a conduit for the wiring and thermocouple - that way if the thermocouple brakes, we can just pull the wires back and replace it.)

[Crusarius]

I do have access to thermal imaging cameras. That thought had just crossed my mind. Just not sure how I would wire it into the system.

I really need to learn alot more about electronics and controls. Especially with what I am dreaming of for my mill. Lets just say arduino cutset v1.0?

[John Mc]

I do have access to thermal imaging cameras. That thought had just crossed my mind. Just not sure how I would wire it into the system.

When I finally get around to adding the one that I should have put in my basement slab, the wiring is going to run down a column in the center of the basement. It's a metal column enclosed in wooden trim, so it will be easy to hide the wires. Once it gets into the ceiling, would be easy to run it over to the wall to the utility room. That wall is where my air thermostat is mounted. However, I'm thinking I may put the air sensor thermostat out on that column as well.

[50 Acre Jim]

I bought some infrared night vision 5-6 years ago.  Everyone asks about the floor heat and I break them out and let them see the loops under the floor.  That's always a hit!   ;D

[E Yoder]

Back to whether or not to run the tubing now or not I would agree do it while you can. And as long as you loop it so each room is as much as possible on its own then you can run multiple zones or at least throttle flow to adjust temps from your main manifold.
Running suspended tube v. transfer plates means you'll need to run hotter water (suspended) but that's not as much of an issue with an wood boiler that runs constant hot anyway. If you have storage then low temp water is important. Definitely insulate underneath.

[shinnlinger]

I installed pex in my second floor but have yet to hook it up, but this past week I wish I had!  As for the aluminum plates, I bought a 4 foot roll of armafoil, which is basically aluminum tyvec and cut it into 8 inch lengths on my metal cutting chop saw.  I took those small rolls and use them to staple the pex to the underside of my main floor.  It was quite fast as the roll would cover the whole width of the house and pretty inexpensive.  The main floor heats well.

[mitchstockdale]

Back to whether or not to run the tubing now or not I would agree do it while you can. And as long as you loop it so each room is as much as possible on its own then you can run multiple zones or at least throttle flow to adjust temps from your main manifold.

Ok, I figure I need approximately two loops of 300ft for each third of the floor area... total of 6 loops for the second floor. 

What is most common practice for getting to the second floor?  Have a central set of 1/2" manifolds in the crawlspace to run the loop lines back to?

Is there any benefit to installing electric valves vs the manual valves at the manifold?  other than convenience of temperature control via a thermostat.

[E Yoder]

You could run 1" Pex up to manifolds in a closet or pull them all down to the bottom. Insulating the lines down to the bottom will help keep the heat only where you want it.
Electric zone valves v. manually throttling each loop would depend on how many zones/thermostats you want upstairs. If the loops are planned carefully you can adjust a particular room cooler just by throttling it down.
I'm curious what other guys think.

[Crusarius]

you are correct about the throttling I have 1 thermostat in the house and throttle all my rooms.

[Holmes]

  the extruded aluminum plates are good, quiet, help heat transfer a lot and are expensive. The stamped aluminum plates are expensive , but cheap, and are very noisy from expansion and contraction. I do not recommend them unless you want to do a constant circulation system , which is an added expense but much more comfortable, no heat swings.  Do not exceed 300' total loop lengths with half inch pipe. Suspended system is fine just make sure you insulate below the pipes well.
My house is 75% radiant heat. I did the bedrooms with baseboard heating now I wish I had done them with radiant.
I f you are going to install hardwood floors make certain the nails , staples are short enough to not penetrate thru the hard wood and sub floor. Other wise you could end up with a sprinkler system, holes in pipes.  Quarter sawn flooring is much better to use over radiant than flat sawn flooring. Flat sawn shrinks more. Shrinking is not totally related to the radiant heat is is more related to the lack of humidity in the house in the winter. It may be wise to plan on a humidification system. 

[overclocking]

My theory on the plates is run them if you can. If there are nails all over from hardwood floors or the backer board you might not be able to run the plates.

Its really two different but acceptable forms of transferring the heat.

If you run the plates its likely you wont need to insulate under the ceiling drywall because the plates transfer the heat mostly by conduction. I would run some type of vapor barrier under the ceiling drywall though to keep it from discoloring from the temperature changes.
If you just run the loops and no plates your going to want to add at least tabbed foil foam radiant barrier to trap the air into a 2 inch void in order to promote convection.
Its not wrong either way, they both work as long as the loops aren't over length.

As far as getting the heat upstairs, I would suggest 1 inch pex to a center mounted manifold if you can and zone control them electronically.

My main floor is heated, but my upstairs is not and I wish it was. There is nothing more comfortable than that type of radiant heat. I would absolutely spend the money now, and not wish you had later.

[shinnlinger]

I used armafoil and there is no noise from expansion/contraction and it was cheap and easy.  I nailed my air dried flat sawn pine into the joists so as to avoid the pex with ring shank nails in my air nailer. I painted the heads black first and turned up the air to get a nice countersink.  Again, cheap and easy.  I even put them down rough sawn and then floor sanded in place.  8 years later and held up pretty well.  In winter the cracks open up a bit but not too bad.

[mitchstockdale]

I used armafoil and there is no noise from expansion/contraction and it was cheap and easy.  I nailed my air dried flat sawn pine into the joists so as to avoid the pex with ring shank nails in my air nailer. I painted the heads black first and turned up the air to get a nice countersink.  Again, cheap and easy.  I even put them down rough sawn and then floor sanded in place.  8 years later and held up pretty well.  In winter the cracks open up a bit but not too bad.

I may see what i can find that is similar to Armafoil around here the hardware stores typically only deal in the basics.  Will most likely end up using the plastic clips with pre loaded nail.

I have been thinking of doing the same type of floor but since my joist are running the same  direction that i would like the flooring to run I have been considering gluing it down with Mapei adhesive.

[mitchstockdale]

My theory on the plates is run them if you can. If there are nails all over from hardwood floors or the backer board you might not be able to run the plates.

Its really two different but acceptable forms of transferring the heat.

If you run the plates its likely you wont need to insulate under the ceiling drywall because the plates transfer the heat mostly by conduction. I would run some type of vapor barrier under the ceiling drywall though to keep it from discoloring from the temperature changes.
If you just run the loops and no plates your going to want to add at least tabbed foil foam radiant barrier to trap the air into a 2 inch void in order to promote convection.
Its not wrong either way, they both work as long as the loops aren't over length.

Most likely not doing the plates unless i get a heck of a deal.  As a minimum for insulation I plan to use 1" or 1.5" EPS foam with a reflective face

As far as getting the heat upstairs, I would suggest 1 inch pex to a center mounted manifold if you can and zone control them electronically.

I have been looking at this for a couple weeks now and I dont have a good spot for the manifold upstairs on the second floor....will most likely be bringing all the 1/2" leads down to the crawlspace.

My main floor is heated, but my upstairs is not and I wish it was. There is nothing more comfortable than that type of radiant heat. I would absolutely spend the money now, and not wish you had later.

Great advise thanks...have really come to this realization since the thread was started... everybody has been very helpful.

Will try and post a layout for people to see what I am up to.

[mitchstockdale]

Sorry for the quality if you squint really hard you can sort of make things out.  I attached a PDF also has better quality.



  



 



 

[Corley5]

  I bought a pex stapler to attach my lines to the sub floor.  I used pex-al-pex because it is supposed to transfer heat better and isn't noisy like regular pex.  I've got two runs of 1/2" tubing in each 16" space between the 2X10s and installed 8" thick foil faced fiberglass insulation with the foil up to reflect the heat up and leave a two inch air space.  My supply manifolds are in the basement with flow meters.  We didn't insulate the tubes going upstairs.  They're in the wall between a closet and the stairway.  Both are very warm.  We leave the closet door open.  The system is set up for thermostat controlled pumps and zone valves but we never installed the thermostats and adjust the temp with isolation valves on each zone.  The components are on the shelf in the mechanical room.  It's on my list to finish that part but until it then it works very well ;D   
  I'm considering putting some tubing in a wall of each room in the old part of the house to supplement the baseboard.  It would be hooked into a separate loop and pump and only used on the very coldest days when the baseboard falls behind.  I've got enough tubing left over and taking off the T&G and putting it back on wouldn't be too bad.
  I got my supplies online.  Shop around.  Pex Universe and Pex Supply were two sites that come to mind.  They offered free shipping with a minimum purchase 8)  I ordered some 1/2" ball valves a while ago because they were way cheaper than Lowe's or Home Depot.
  I don't know what you've got for a crawl space but I'd seriously consider putting your manifolds somewhere you can easily access them like a utility room or a closet on the ground floor if possible.  Installation as well as maintenance will be much easier.  If a pump or something needs replacing it would a whole lot more pleasant and it's easier to monitor the system.  Not that it needs much

[Stoneyacrefarm]

Great input guys.
I'm currently working on the same kind of project.
Radiant heat in the basement floor and the first floor as well.

[Corley5]

 

 



 

This is the pex stapler I've got.  Worth every penny.  It was used to install the potable pex as well.  We use the standoff clips.

https://www.supplyhouse.com/Peter-Mangone-RB-5-Manual-Clip-Gun-5226000-p?gclid=EAIaIQobChMItpC56-vS2AIVFb3sCh1AIQ39EAQYASABEgJ_3fD_BwE 

[KamHillbilly]

I have an 1 1/2" of concrete ( regular concrete with smaller rock and an additive which name I can't think of ) on my main floor covering pipes I just added an extra bottom plate on walls , most of main floor is 3/4" maple hardwood glued directly to concrete with Bosticks Best urathane adhesive . Wood has been down for 15 years with no issues , My friend has his stapled underneath sub floor with radiant plates and it seems to work well also but he ADL-Org insulated the under side between floors . Mind you we may be in a different climate we are in our 3rd week of -30C temps .

[John Mc]

KamHillbilly - mine is a similar setup to yours: A lightweight concrete slab poured on the subfoor (like you, I can't remember what was added to the concrete). I had sleepers nailed down before the slab was poured. The tubing runs in the gaps between the sleepers (the sleepers were left a bit short on the ends to create a gap fo the tubing to go through). Slab was poured on that between the sleepers. Instead of gluing, my hardwood flooring was nailed to the sleepers. It's been working well for 15+ years now, and I really like the thermal mass of the slab.

[Crusarius]

that is a great idea. I just don't want to add anymore to my existing floor

[mitchstockdale]

This is the pex stapler I've got.  Worth every penny.  It was used to install the potable pex as well.  We use the standoff clips.

https://www.supplyhouse.com/Peter-Mangone-RB-5-Manual-Clip-Gun-5226000-p?gclid=EAIaIQobChMItpC56-vS2AIVFb3sCh1AIQ39EAQYASABEgJ_3fD_BwE

Wow!  I need this stapler... running the pipe is going to be a horrible enough job, this would sure make things go a little easier instead of swinging a hammer overhead.  Thanks Corley5 much appreciated.

Any particular reason you would use the stand off clips as opposed to the flush clips??

Does anyone know of an online supplier that carries this product and will ship to Canada I tried the online portal at supply house and it seems they don't ship to Canada.

[Corley5]

http://www.petermangone.com/Canada%20Distributors.php

The standoff clips hold the tubing away from the surface so it doesn't wear with expansion and contraction from rubbing.

[Corley5]

https://www.pexuniverse.com/peter-mangone-rb-5-manual-pex-clip-gun

http://www.blueridgecompany.com/radiant/hydronic/249/peter-mangone-rb-clip-gun-system

https://www.pexsuperstore.com/pex-accessories/peter-mangone-staple-clips/manual-pex-clip-gun-rb-5-by-peter-mangone-w-pex-clips.html

http://www.houseneeds.com/heating/radiant-heat-pex-tubing/peter-mangone-pex-tube-clip-gun-rb5

Amazon has a listing too but it's more $$$ than the others.  One of these suppliers should ship to Canada :-\

https://www.amazon.com/Peter-Mangone-RB-5-Manual-Clip/dp/B003QSO0E0

[clerkick]

I have an ICF home, actually my first house, radiant heat on both floors, in slab and stapled to second floor subfloor with what is basically foil faced bubble wrap placed between the joists. This seems to work well, aside from the master bed/bath zone. Master bed has the only carpet in the house and is on the north wall of a home designed for passive solar. This I think costs me more money than the type of tubing attachment would. Carpet and padding provide a lot of resistance to heat transfer. Currently 14 degrees and this is my slab vs bedroom temps.  Edit: the original owner ran tubing in the garage slab but never hooked it up. Something the wife and I think about adding every winter. A lot easier to add a thermostat and a tyco valve than to add tubing after the fact. 

  

 

[50 Acre Jim]

What's your boiler set at? Temp sure looks low coming into the house.

[mitchstockdale]

Does anybody have any recommendations on whether insulation is needed on the zone piping that runs from the manifold to where the zone loops start.  In my case the approximate pipe length is going to be about 20+ft from the manifold outlet to where the loop starts. Is this something to consider or does it matter in the grand scheme of the system?

[mitchstockdale]

What's your boiler set at? Temp sure looks low coming into the house.

I wonder if this is because he has an ICF house? my friend built an ICF home and he can literally heat the place with a candle...lol

[Corley5]

  When I was in the planning stages for my in floor heat it was recommended that I read Dan Halohan's books.  I got these  "Pumping Away"; "Hydronic Heating, Practical guide for the Nonengineer"; and "Primary-Secondary Pumping Made Easy".
Dan's website https://heatinghelp.com/about-us/

[E Yoder]

What's your boiler set at? Temp sure looks low coming into the house.

This is mixed down water, correct? Not the full temp boiler water.

[E Yoder]

  When I was in the planning stages for my in floor heat it was recommended that I read Dan Halohan's books.  I got these  "Pumping Away"; "Hydronic Heating, Practical guide for the Nonengineer"; and "Primary-Secondary Pumping Made Easy".
Dan's website https://heatinghelp.com/about-us/

Agree, great info- well worth the money and entertaining too.

[E Yoder]

Does anybody have any recommendations on whether insulation is needed on the zone piping that runs from the manifold to where the zone loops start.  In my case the approximate pipe length is going to be about 20+ft from the manifold outlet to where the loop starts. Is this something to consider or does it matter in the grand scheme of the system?

depends on whether it heats the area you are trying to heat or somewhere else. It will reach off some heat, not a lot.

[Randy88]

I'm not sure what climate you guys are living in, but I'd have a basement under any home I own, put in floor heat in the cement floor, then forced air ducts in the house for both forced air heat and also cooling in the summer.     I'd run a radiator in the plenum off a boiler to heat the house.      

This gives options for other heat sources, and cooling sources later on down the road.  

With any in floor or under floor hot water heat system, you only have a certain amount of BTU's per square foot and in severe extended weather conditions, depending on the insulation and a host of other factors, many in my area found out it wasn't enough to keep the house or shop warm without an added heat source.     

[John Mc]

With any in floor or under floor hot water heat system, you only have a certain amount of BTU's per square foot and in severe extended weather conditions, depending on the insulation and a host of other factors, many in my area found out it wasn't enough to keep the house or shop warm without an added heat source.

It sounds as though the radiant heat systems to which you are referring were improperly designed or sized for the house in question. In a well insulated house, with a properly designed system, you will have no problems.

I have radiant heat in the floor of my home here in Vermont. I have zero problems keeping my house warm with my radiant floor heat. In fact, my first floor is a mostly open floor plan made up of two zones. I can keep it comfortable (by my wife's standards - which is 72˚F) running just one of the two zones in all but very unusual circumstances. When we have a couple weeks in a row of -10˚F or lower, I might have to kick the second zone on.

I will grant that my house is very well sealed and insulated.

[Randy88]

Yes your right with proper sizing, but you didn't take into account when a problem arose with the in floor heat, forcing a shut down of a part of the house, or most of the house or in a few cases, the entire house.

You also never took into account something most heating experts neglect to discuss, its called heat recovery.

A few years back we had a long cold snap, wind chills 80 or more below zero, weeks on end, little to no snow cover, frost pushed 8 and some cases 9 feet deep, far deeper than any water lines or buried utility lines, water lines were simple to keep from freezing, just leave the water run, till the frost heave sheared them off, same for electric and even heating and gas lines, private septics froze solid, many municipal sewer lines sheared off or froze up as well.    

About every heating person known at the time became public enemy number one overnight, they never took into account heat recovery in any heating equation, from houses to shops and everything in between.    Many were abandoned or froze up because there were not enough man power to go around soon enough to get everything hooked up in time to keep the house from freezing up, top that off and those not affected, had their heating equation changed from the inside to outside temps or what some called heating differential or degrees of heat rise were more than doubled, meaning even running 24/7 most heating systems could not keep up, add in complications even slight ones and houses froze up with properly operating heating systems and even additional electric heaters hooked up and running.       

Electric, gas and even heating lines were easy to hook back up and get going, most were laid over the top of the ground, which is what was done, the issue that came apparent very fast was the time factor, coupled with the sheer volume of work needed doing for everyone everywhere and in hours, houses, shops and livestock buildings froze up, those that didn't, used every possible heating option and source available to keep them above freezing.     Myself, I used electric, forced air propane, wood boiler and even in the shop, diesel fired torpedo heaters to keep things thawed out.

Most heating equations are figured at a certain degree's heat rise, then once there, its a maintenance heating requirement.     Run the figures but double or triple the heat load, then recalculate it with that same heat load starting at zero or below in the house, see if your heating system can not only keep up, but get it above zero and if so, how many hours will it take to do it.    

After that ordeal, I'd recommend having options, one being forced air heat, so instead of using 100 degree water in the in floor heating, you have the option of using 180 plus degree water with forced air to hasten the heat recovery in the house, or have a backup gas furnace to kick in to help recover or maintain if needed, especially if a portion of the heating source needs to be shut down for repairs or even if the whole system has to be shut down for a day to do repairs.    Just tossing out problems some of us have encountered and never saw coming or were told not to worry about, after all its never happened before.......................

[E Yoder]

I would agree that having multiple heat sources is good. A backup plan is always a good idea. The other thing is that with two (or more) you can size them for the normal load so they don't short cycle, then turn them both on once in a blue moon for quick recovery. One system sized for recovery would run in short bursts and not function well quite a bit of the time.
Of course two systems adds cost.. most folks feel like they can't afford it.

[John Mc]

Randy -

What you are describing sounds like a problem with any type of heating system: if it's not sized to handle the load (including recovery, if you lose heat for a time), you are going to have problems. It's not just a matter of the temperature of the water you are pumping, it's also a matter of the surface area. With my entire floor warm, I'm able to put just as much heat into the room as I could with baseboard heaters running at 160-180˚.

Our boiler and radiant floor heat is probably oversized for how well the house is insulated, given that most winters if we are not using the wood stove we can heat the two main stories with just half the first floor's heating area turned on. I suspect the guy doing the calculations for the design used calculations based on stick-built 2"x6" walls. (We have a timber frame enclosed by 6" thick SIPS, which insulates far better than 2x6 walls, since there are no thermal breaks - except for windows.)

We did have a winter as you described several years ago. We had repeated instances of well below 0˚F for extended periods (my recollection was regularly in the -20's and staying there), bare ground, so no insulating effects from snow cover, high winds. We are on a deep well, and had to keep a slow drip going to keep the line from our well to the house flowing. Two neighboring towns have city water. Some of their main lines were freezing up - lines that had never frozen in anyone's memory. During that spell, we turned on both our downstairs zones. Upstairs bedrooms ran occasionally (programmable thermostats were set to give them a little kick before it was time to get up each morning). I may have also turned the basement slab on during that spell, just as insurance so we'd have some thermal mass up to temperature to buy us time if the power went out when we were away.

We are fortunate that our house is extremely well sealed and insulated. Most of the time, we're using a 60,000 BTU Hearthstone woodstove to heat the two upper floors (about 2200 sq ft, though some of that floor area is "missing" since we have a cathedral ceiling area). If I'm around to keep it stoked (I do a fair amount of work from home), it will keep the house comfortable in all but a prolonged very cold spell. We don't heat the basement much - occasionally we'll kick the heat on in that slab, if someone is going to be down there for a while.

[Randy88]

So how do you cool the house in the summer?

[John Mc]

So how do you cool the house in the summer?

We don't really need to. Typically, we get a week or so that is above 85˚. If I leave the awning extended over our big south facing window, and pull the other shades/curtains during hot, sunny days, the house will stay cool enough through that spell. If it gets too bad, we have an 8 or 10,000 BTU window air conditioner that we put in to take the edge off. Most summers, we don't need it. The last two, we did pull it out - the couple of weeks in the 90's, with occasional highs around 100 were too much for us, and the house eventually absorbed enough heat to get uncomfortable.

[Randy88]

Here the norm is pretty much central air for the whole house and to cool it to at least the mid 70's or lower, we try to keep the house in the low 70's year round.      Forced air is the only way to achieve it, guess there is a huge difference in area's and their needs.      

    

[John Mc]

Here the norm is pretty much central air for the whole house and to cool it to at least the mid 70's or lower, we try to keep the house in the low 70's year round.      Forced air is the only way to achieve it, guess there is a huge difference in area's and their needs.      

 

There sure is. We keep our house about 70+ in the winter (not by my choice, my wife likes it warm. I'd keep it mid 60s if it were up to me), and it stays below 75 most of the summer by itself, if we do things like manage the curtains and awnings on hotter days.

[Holmes]

Randy88 I remember your problems from back a few years ago. What I did not know back then was when you go below zero all standard heat loss calculations become totally inaccurate to the tune of 2 to 4 times more heat loss than what the original calculator came up with.

[John Mc]

Randy88 I remember your problems from back a few years ago. What I did not know back then was when you go below zero all standard heat loss calculations become totally inaccurate to the tune of 2 to 4 times more heat loss than what the original calculator came up with.

Sounds like a pretty flawed calculator. Heat loss should be a linear relationship between the inside temp and outside temp, though wind chill will have an effect as well.

[Randy88]

Yes to an extent, heat loss is linear, and yes wind chills are a variable not really anyone can give an answer for in terms of heating needs, wind chills affect buildings differently depending on how they are built, where they are located, how protected they are and the list is endless.          

All the heating experts told me and everyone else in my area, a certain sized furnace was needed to heat the space to conformable temps, running say for example 50 percent capacity, well when you double the heating needs and run it constantly, it'll keep up, when you triple the heating needs, there's no way it can keep up and its a slow and steady decline in temps inside the structure.      

The only choice I had then was to increase the size and capacity of the outdoor boiler, add on a waste oil burner in the shop to help with recovery when I opened the door to bring in equipment and when we needed fast warmup in the shop, we fired up a salamander heater as well.      

The other issue I had was, the more stuff we put in the shop, the more floor space was covered with low belly clearance machines and that cuts heating capacity of the building, which also lowered inside temps to the point of being critical and near freezing in the building as a whole.    We're planning on installing forced air radiators off the wood boiler as well, to help solve this issue, just haven't had time yet to do so.

[John Mc]

The other issue I had was, the more stuff we put in the shop, the more floor space was covered with low belly clearance machines and that cuts heating capacity of the building

I had not thought of that one. I've often wished I had in-floor heat in my workshop. It's currently unheated. I just use an electric space heater when it's not frigid out, and a portable propane heater when the mercury really plummets. Eventually I'll put in a permanently installed heater - either a propane heater, or perhaps a split off of a cold climate heat pump, if my wife ever decides to put one of those in for her workshop upstairs.

[Randy88]

John, not sure what you have for a shop or what you do in it.     But the more floor space you cover with machines that sit on the floor, like cabinet saws, or stack wood on the floor or even have work benches that sit on the floor, all take away from the square footage of heating space for the room or building.     In floor heat is great, especially if your sitting or laying on the floor to work on things, keeps your feet warm and gives a much more even heat from the floor to the ceiling, with forced air heat, its far warmer at the ceiling that on the floor, whereas with floor heat, there's only about five degree's difference from the floor to the ceiling.

The downside is that you really need to heat the space all winter long, from cold to warm in the dead of winter, it'll take days or even longer to get the building warm, in frigid temps if the floor is cold, it could take a week to warm it up and get the building warm.    There are a lot of variables in this equation, how thick the floor is, what the outside temps are, how much heating space there is left in the building that doesn't have the floor covered with something and the list keeps going to factor everything in.    

My shop is for heavy equipment and tooling, lathes, mills, welders and the like, our wood shop is in the house basement.     What issues I have is when I bring too many low to the ground things in at once, like trailers, vehicles and things like that where the heat can't get out from under, skid steer loaders with buckets sitting on the floor are another issue, all those cover the floor and limit the overall heat output to the building itself and if there are too many of these things in at once, my floor heat will never shut off and the building will be below freezing in the morning, but the underside of those things will be over a 100 degrees to the touch or whatever temp you have the floor heat set at, in my case its 120.    

The same is true with warming up a house, most kick the heat when it gets chilly inside, about 50 or so in the fall, only needing to warm it up about 20 degrees with the outside temps about the same, or the difference between inside and outside of only 20 degrees, then form then on, its just got to maintain the temp, when you have to do that in the dead of winter, you might have 70 degree's difference from outside to inside.     When its frigid out, and something has happened to knock out the heating system and the outside temps are 50-80 below and inside its cooled to zero and your trying then to heat up the house with a partial system working is when things take a lot longer and gets a lot tougher.    You then need to warm up the system with 150 degree temp difference and no heating system is designed to do that, most are not even capable of that at all.

What got many in my area is when backup systems could not work, electric lines sheared off with frost heave, along with gas lines, leaving the house without any options to keep it warm, by the time something was done to get any option working, the house was too cold to get warmed up with a system designed to supplement heat, not a stand alone heating system, so in the mean time, things froze up many forgot about, washing machines froze and were not discovered till later, toilets froze and cracked, in floor heat lines froze and many burst or were cracked, water pumps froze with water in them due to no electricity to pump the water out and the list was endless, so once back warmed up, the main heating systems still didn't work properly and couldn't maintain the house temps or causing more issues once warmed up again, water lines leaking, walls, wood floors, carpets, insulation soaked and the list went on and on.

We initially wanted to heat my shop with in floor heat exclusively, after some years of issues and learning, we now use it to do a portion of the heating, in mild weather it does it all, in frigid weather maybe 50 percent, with too many of the wrong machines inside, it'll do maybe 20 percent of the heating and that changes daily depending on variables.   

[mitchstockdale]

Finally started on the install yesterday.  This is a 300' loop used "j-straps" plastic clip with a ring nail to attach the tubing to the underside of the sub-floor.... surprisingly not as difficult as i thought it would be. Will try and keep posting pics as I progress through installing all the pipe and insulation.

[E Yoder]

Nice pics.

[Hilltop366]

Randy88 I remember your problems from back a few years ago. What I did not know back then was when you go below zero all standard heat loss calculations become totally inaccurate to the tune of 2 to 4 times more heat loss than what the original calculator came up with.

Sounds like a pretty flawed calculator. Heat loss should be a linear relationship between the inside temp and outside temp, though wind chill will have an effect as well.

Read a article a few years ago about how fibreglass insulation losses its insulating effectiveness as temperatures drop, apparently due to it's lack of density it will allow air to move inside the wall cavity (even if completely sealed)

As the temperature difference increases when outside air cools the outside of the wall then the cold side of the wall cavity will have air next to it that wants to drop and the warm side of the wall cavity has air in it that wants to rise causing air movement in the wall cavity that is now colder than the inside of your house causing the same effect inside your house = heat less.

So the colder the outside temperature the more of this effect takes place = a non-linear relationship.

Apparently foam board, cellulose and other more dense insulation significantly reduces this effect.

[Rebarb]

We recently built a home, a daunting task for old folks like us.
We live in the mountains with lot's of access to firewood so i already knew a wood furnace would be a viable option plus we've burned wood our entire lives including childhood. 

Well my wife kept pushing hydronic / radiant heating, glad i listened. 

It's been the best and most efficient heat we've ever had.
We have it in the finished basement and garage and it effectively heats the entire house.
The downstairs is set at 73 and upstairs stays 69......4800 sq ft.
This is VA with typical 30's in winter. 

[mitchstockdale]

All six loops are installed and insulated.  Ended up using 4 loops of 300' and 2 loops of 250' worked out perfect.

Used 1" Silverboard insulation with a reflective facer on each side and cut to fit tight between the floor joist diagonal webs and pushed it up tight against the top chord of the joist to give me 1-1/2" airspace. Secured the insulation with a shot of spray foam in the crotches of the webs seems to have worked well.

[E Yoder]

Nice.

[Hilltop366]

Well done, looks like a lot of work!

[mitchstockdale]

Ya it turned out really well and went much smoother than anticipated.  I did however leave a couple joist bays un insulated since this was in a location where there was a wall upstairs and had several wires and pipes coming through the floor.  It was easy enough to run the pex but not the insulation. 

I hope it makes the system perform better than not having it, and reduces the operating temperature.

Thank you all for your comments and input. Will keep posting pictures as the system progresses.