Workshop Heat - Natural Gas

[RonB]

Yeah, it is cold is SE Kansas. The kerosene heater + help from an electric cube heater does a pretty good job but looking to upgrade.

When we built the house last year we had the plumber provide a "T", valve and plug in the basement for future routing of natural gas through the basement sill into the garage. I am wanting to put a permanent heat solution in the 1,000 sf. garage shop that will minimize impact on floor space. The garage is pretty well insulated with 6" walls, R-19 overhead and insulated and well mounted overhead doors.

I was wondering what kind of experience is available from rec'ers in the following areas:

- Overhead Furnaces

- Wall-Mounted Ventless

- Overhead infrared

- Anything I have not listed

As usual, cost is important but so is a reasonable fast warm-up rate. My kero unit can pull temperature up about 20 degrees in 1 to 1-1/2 hours on a pretty cold morning (15-30 degrees). Regarding cost I must consider both installation and longer-term cost to operate the system. Operating cost is probably most important.

Any help appreciated.

RonB

[Ed Pawlowski]

Modine Hot Dawg available at many places

[Mike M]

I have a stand alone building with a woodstove no problem with heat. When I built it I did multiple layers of gravel and insulation under a

6" slab, and can heat the 16x32x10' space with a 1500 watt heater most of the year. If not a code problem pellet stoves are great.

Mike M

[Lew Hodgett]

------------------------------------------------ Having lived thru MidWest winters for the majority of my life, can attest to the fact there is nothing like hydronic heating.

If I were to return to cold weather, hydronic heating would be a must.

Higher install cost, lower operating cost than forced air.

Humidity is not a problem as it is with forced air.

Since you are using a hot water boiler, can pull combustion air in from the outside and vent exhaust outside without bothering with make up air problems and the associated heat loss problems.

It's worth a conversation with a good heating contractor.

Lew

[Morris Dovey]

I've bragged on this shop heating set-up before, but I'll extend the old brag...

1200 ft^2 shop has remained above 65°F day and night for more than two years now, and the gas and electricity savings are now more than the original cost of the panels - meaning that for the next 20 winters the shop will be warm 24/7 without spending even a dime for heat.

The indoor/outdoor thermometer here reads -4°F.

[Ed Pawlowski]

Would you use anti-freeze in the system? For the weekend user, it would be expensive to keep it heated all the time even though that would be nice for both the wood and finishes stored there.

[Larry Jaques]

On Mon, 04 Jan 2010 00:56:18 -0600, the infamous Morris Dovey scrawled the following:

Cool, er, warm!

-- Society is produced by our wants and government by our wickedness. --Thomas Paine

[Chris Friesen]

Hydronic has lots of thermal mass, making it slow to heat and slow to cool. Not ideal for quickly heating up on weekends.

I've got a Lennox unit heater (similar to the Hot Dawg mentioned before). At 45K Btu it's oversized for the double garage, but it heats up pretty quick which is good for my own weekend warrior ways.

Incidentally, you can use an old metal coil thermostat to keep the temperature just above freezing. Normally they don't go that low, but if you mount it with a single screw you can just twist the whole thermostat body to get lower temperatures. I have tick marks on the wall to tell me where to set the case corner for particular temperatures.

Chris

[keithw86]

Why would a hydronic system have a lower operating cost? Filters? Forced air has faster recovery but for a shop, filters might be an issue.

Because you can drop a mold maker in the plenum? Raising the temperature of air will "dry" it out. Hydronic shouldn't be any different than forced air.

Forced air systems have a heat exchanger, too. It should be possible to use outside air for combustion. Don't know if it's done, though.

I'd certainly agree with that.

I've had hydronic systems in my previous two houses. I didn't like the recovery time, but with a set-back thermostat I could anticipate temperature changes. We'd have about a 7F delta programmed in, with a couple of bumps per day.

Our current house has forced cold air "heat" (heat pumps). I don't much like them, but we only have half the delta-T to make up (VT vs. AL).

[Nonny]

Fort Wayne, IN, I built a 4 X 8' panel and placed it outside my workshop. It was just an experimental thing, so I didn't do much in the way of a permanent installation. The panel introduced air at the outside top of the panel, where it flowed down a corrugated aluminum separator to the bottom, then back up the backside, where there was a thermostat and small blower. The panel was piped into the top of a double hung window, which was opened about 6", with a plywood header inserted and two ducts running to the panel: air in and air out.

My concern was that without the forced air and NONsyphon-type system, I'd be losing heat when there was no sunshine. Is that a problem or issue with your installation? Have you considered some type of free-swinging dampers on the intakes to prevent counterflow. Is there counterflow at night?

My next door neighbor told me that the coating of the aluminum separator should be on both the front and back: the best collector is also the best emitter. He also reminded me that IR is just another frequency and that a half wavelength antenna is what I want. I don't recall exactly, but 4 mils on both sides rings a bell. What do you do for the coating, coating thickness etc?

[Robert Bonomi]

Nope. he's got that matter solved.

He considered it, and came up with a better solution.

Nope.

That is true.

*THAT* is nonsense. For antenna construction the 1/2-lambda figure is for a _center-fed_ dipole -- oriented _perpendicular to the direction of the radiation. The 'depth' of the antenna (i.e., in the same direction as the radiation is coming)` is irrelevant.

Note: there is nothing 'magic' about 1/2 wavelength. _Any_ odd multiple of lambda/2 will work at least as well.

IR wavelengths are around 600-1000 _nano_-meters. I'll let you work out the conversion, and figure out how far off you are. *IF* it was a meaningful calculation, in the first place.

A 'black body' absorber is good. The right kind of IR-reflective glass may also be beneficial in some circumstances. (when you grok _why_ that latter statement is true, you'll have begun to have a _real_ understanding of how passive solar heating works. :)

[Morris Dovey]

Sorry, Nonny's post hasn't arrived here yet, or I'd have responded sooner. Robert's answers are on the mark - and I'll add a little that I suspect he's figured out but left for me to say...

I'll interject that I don't have a "separator" as Nonny speaks of it - I have an absorber constructed of formed 0.1 mm glossy black aluminum ribbon that absorbs and re-radiates on _both_ sides - formed, oriented, and spaced in such a way that emitted energy is directed almost entirely at adjacent ribbons.

There's a concept (_not_ design!) drawing at

shows how counterflow is prevented and hints as to how the absorber is configured.

I'd take that with a grain of salt.

Etc's aren't allowed. The coating is the thinnest glossy black powdercoat I could order.

Wikipedia has articles on black/gray bodies, black body radiation, temperature viscosity of air, and laminar flow that I found exceedingly helpful - and I'd have had a difficult time sorting a lot of this stuff without some high-quality coaching/mentoring from real physicists over on alt.solar.thermal

Funny thing, tho - every time they "helped" my head hurt for a week. :)

[Lew Hodgett]

================================

Give that man a cigar.

I engaged keyboard before doing a memory scan.

Lew

[Lew Hodgett]

That depends.

The recirc pump is going to operate 24/7.

Base piping is 3/4".

In order to be effective, you need turbulent flow which puts you in at least the 4'-6'/minute flow rate.

Going to take some sustained period below freezing to effect that type of flow.

As I said, that depends.

Given a well insulated space, maintaining 60F shouldn't break the bank while keeping things stable.

Lew

[Lew Hodgett]

---------------------------------

DUH!

Try 4'-6'/second flow rate.

---------------------------------

Lew

[Larry Kraus]

I have a 24'x28' shop attached to the house, hydronic heat supplied by a conventional (30gal?) propane hot water heater circulating plain water. Thermostat is usually at 55F, but I may bump it to a cozy 60F if I expect to have a full day to work in the shop. Weeknights I wear a sweatshirt. At 60F, I might wear a long sleeve cotton shirt, but the sleeves are usually rolled up. Somehow the heat radiating out of the floor just makes you feel warmer. I ran it up to 70F once, it made me want to take a nap... Here in central Ohio, I heat the shop from about mid-November to April. The water heater is set to run at about 90-95F, (between WARM and VACATION). The circulating pump runs only when the thermostat calls for it. I can not say exactly what I pay for shop heat as the propane tank also supplies the kitchen range and clothes dryer.(Home heat and domestic hot water are electric - geothermal) We use about

100 gallons of propane per year. My only regret is that we do not have hydronic heat in the house. I just could not justify the cost of radiant heat plus a separate A/C system.

[RonB]

Thanks for the input.

The garage is attached to the north side of the house so solar is not an option unless we go to the roof. We did build a passive solar addition onto a previous house and will attest to its effectiveness. This place uses good exposure on the living side.

Starting to lean to infrared. The hardest things to warm up, and be comfortable working with, are the metal surfaces in the shop (saws, etc.) I believe IR would start warming them first.

RonB

[DT]

I live in northern Ohio and my garage is 660 sq ft. R13 walls and R19 ceilings, insulated garage doors. I use a 21,000 btu Warm Morning through-the-wall furnace (direct vent) when I need to. It works perfectly and is actually more than I really need and has a fairly low duty cycle when on. I replaced the blower with a heat-rated higher flow model and it help circulation quite a bit.

[Luigi Zanasi]

If it's not going to be heated all the time, antifreeze is a must. And even if it is, a long power failure could result in burst pipes. Water in a hydronic system where temperatures stay below freezing for a long time is pound foolish.

Luigi who has propylene glycol in his heating system.