Wanted - Advice on radiant heat install

[xrdad]

For some reason, I'm not getting many replies on my build thread.. I don't think the thread is coming up under 'new posts'? (Sutton Shop)


Anyway, here's the deal:

30x40 shop, 13' ceiling, one 12x12 door, one 16x8 door, 2 man doors, one 4' window, 6" slab in central Ontario Canada.

I'd like to go with radiant heating in the slab, which will be poured next spring. The shop should be standing in about 2 or 3 weeks. Frost walls (8" CMU, 8 runs, 4' deep, 1 run above grade) are in.

An insulated shed will be attached to/behind the garage for the heating system.

In the house, there is currently an oil fired boiler and baseboard type radiators.

The garage is approx 40' behind the house.

What to do?
I've had many a great plans, and each one has gone for a ...
Instead of rehashing all the ideas, here's the directions and if anybody can advise on the different issues, I would much appreciate it.

1 - insulation and vapour barrier: I feel this is the best insulation product in my area = Insta Panels
I'll be going with the steel sided under the floor, fiberglass on the foundation walls. I only intend to install the panels horizontally on the foundation walls (or 20" deep) which mean about 12" will be exposed above the floor and 2" will be lower than the concrete effectively meeting the insulation panels under the floor. The slab would be completely insulated.

However, I'm a little unsure this is right? Do I need to insulate the entire frost wall? Do I add a vapour barrier between the frost wall and the insulation? I'm told to use "Air Bloc 21" only.

Vapour barrier is a given under the floor (although the heating company I "was" going to use said it's not needed!!). But where do I tuck the ends of the vapour barrier? up and under the insulation on the walls, or down and away?

2- Heat supply = I'd wanted to save $$ by trying to heat both the house and shop off the same system. That's not working because the house radiant won't match the shop radiant. And, the insulated pex is $$$.
So now I'm looking at heating the shop on it's own.
There are many great thread on GJ, but none seem to fit my situation?
Electricity is ridiculously expensive here, and propane is worse. Oil is OK, but it take a lot of space and the tank can be expensive.

I like the idea and simplicity of an on demand water heater, but am afraid of the monthly bill. I haven't figured out my heat load or loss yet, and am unsure how to do it right. So far, I don't trust ANY of the contractors in my area, as they contradict each other and what I have learned on GJ.

Boilers can be found pretty cheap on CL or Kijiji. Since I already have oil to the house, do I go boiler and oil? Do I chance an electric on demand system? The simplicity of this system was described in a post on GJ... I don't know much about heating water, but it seems I know as much as some of the contractors here

 

[Denwood]

First of all, given the size of your shop, and costs in Ontario, you want the most efficient envelope possible. We finished a 9500 square foot renovation project 18 months ago, involving a slab over pour, radiant heat and furred airspace assembly for inner walls. It's incredibly efficient, with heating costs max last winter at $242 to heat 9500 square feet. Gas, on demand (like a triangle tube unit) is likely the most efficient and cost effective. Do you have access to natural gas? I do have friend with on-demand electric in slab (2 car, 2 story) and he's had some large ($800) hydro bills.

 

[theoldwizard1]

Under slab insulation and vapor barrier is key to a comfortable floor. The further north you are, the more insulation is required. 2" minimum, 4" preferred.

Your foam board should be install vertically on the inside of the foundation wall to the depth of the frost line (probably 48"). Some types of foam board also act as a vapor barrier if sealed with the proper tape. Check with the manufacturer. If you are doing layers, maker certain to stagger the joints layer to layer.

Electricity is ridiculously expensive here, and propane is worse. Oil is OK, but it take a lot of space and the tank can be expensive.

What are your "typical" high and low temp in Dec, Jan, and Feb ? If your typical lows are above -20C you could use a Mitsubishi Hyper Heating Inverter Heat Pump. These are very efficient.

View media item 43975
They "officially" only support radiant heat (via a refrigerant to water heat exchanger) in certain parts of the world (NZ and AU for sure).

A very well insulated building (R15+ in the floor and walls, R30+ in the ceiling, triple glazed) could also be heated at a reasonable monthly cost by a high efficiency electric boiler. Also much lower installation cost compared to a heat pump.

 

[xrdad]

Insulation ordered, expected next week. No one argued the quality of the materials I suggested, so I'm assuming all is OK.

The specs looked OK for my build, although I still don't get the skinning on them. But it shouldn't hurt anything and the price was definitely right. I ended up ordering steel skinned for under floor, and fiberglass skinned for the walls.
On that, I'm not going to insulate the whole foundation wall. I can't understand why I would?
Instead, from the base of the stick wall (or top of the block wall if you prefer) I'll glue the fiber panels before back filling. These panels are 20" wide which means I should be somewhere around 4" under the horizontal insulation (under floor). This will mean the slab is insulated on all sides but UP.
Insulating below that (on the walls) just didn't add up to me?

Moving on, now I have to pick my heating system.
Denwood, we don't have NG here. My options are LP, Oil or Electric (and maybe wood).
I looked at a wood boiler = $$$$$$$
I looked at oil fired boiler = $$$$$
I looked at an LP boiler = $$$$
and the electric on demand = $$

Installation of electric is easiest, and in an open direct system, I'd get hot water for other uses (sink).
I am concerned about operating cost though.

There's no clear winner here. Electric is cheap to buy/install, but may have high operating costs.
Gas requires tank rental, fluctuating prices, high install cost.
Oil is expensive, tank is a risk and home insurance increased ($400 rider for the current oil tank)

Anybody know of other electric on demand boiler users that can comment?

 

[mygarageone]

Here's a web site that can and will answer every question any has about radiant heating systems


www.radiantdesigninstitute.com

 

[theoldwizard1]

I ended up ordering steel skinned for under floor, and fiberglass skinned for the walls.

Steel in an area that is exposed to moisture ? What does the manufacturer recommend for that application ?

On that, I'm not going to insulate the whole foundation wall. I can't understand why I would?

Amy foundation wall that is exposed to the outdoors needs an R15+ (R30+ better) insulation. Why the whole wall ? Because the frost can go that deep and "steal" the heat from below your floor. You under floor insulation (also R15+) is not perfect and will allow some heat into the soil under it. You want to keep it there.

There's no clear winner here. Electric is cheap to buy/install, but may have high operating costs.

Which is why you want to spend as much as you can afford on proper insulation. Think of it this way. Every dollar you spend on insulation up front will save you pennies every day for the rest of your life in heating cost !

Anybody know of other electric on demand boiler users that can comment?

They work well, but are expensive if you want them to be the source of radiant heat AND provide domestic hot water. Probably cheaper and easier to plumb in a separate small on-demand potable water heater.

A high efficiency, low temperature, inverter mini-split heat pump would be more efficient to operate on days above -10C. Below -20C could be a problem !

 

[xrdad]

From the vendor:
INSTA-PANELS™ are insulated R-11 foam panels made of rigid polyurethane foam, covered in steel or fiberglass on both sides. INSTA-PANELS™ are designed to be used as an affordable and durable slab insulation and have all the benefits of regular sprayed-on polyurethane foam but in a portable solution. Panels measure 1 ¾" thick and weigh 1.99 lb/ft2.

USES
Intended for residential, commercial, and agricultural applications where insulation is required or desired, under concrete, in radiant or non-heated floor systems. INSTA-PANELS™ can be used in a variety of applications including: under concrete floors of houses; garages; commercial workshops; warehouses; office buildings; cold storage and freezers; agricultural drive sheds; poultry barns; and other specialized applications.

Wizard, the supplier claims that the panels have been used for over 10 years now with no corrosion issues.


Back to the wall... since the floor will be insulated horizontally (the entire floor area), then what heat can be robbed from underneath? My pad will be basically in a bowl of insulation.

Just reading the "picts of your in-floor heat set ups" thread... again.