Need Help With Heating System

[Al Bundy]

I've spent the last few months mulling over what to do for my new garage and I just can't come up with an answer. I'm hoping all the expertise on this board can finally help me with the decision.

The specifics are as follows:

Location is upstate NY temps below 0 are not unusual
Building is free standing 30x40 with 11' ceiling. Two 9x9 insulated overhead doors. (R12 if I remember correctly) The ceiling is insulated with R38 fiberglass, the walls are R19. There is 1 inch of styrofoam under the 6 inch concrete floor. There are no windows. The building is tight by any standards.

My goal is to maintain at least 50 degrees with warmer temps during use. I plan to do some painting so open flame is a concern. I also would prefer not to give up a lot of floor space. Natural gas is not available and electricity is relatively expensive. I don't consider a/c to be a necessity, but I certainly wouldn't complain about it. The initial cost of a system is not a big issue, but I probably wouldn't be willing to consider anything over $7500.

I would appreciate any and all input. The more I try and come up with an answer on my own it seems the further I get from being able to make a decision.

 

[Al Bundy]

Anybody have any advice? Even if it's bad?

 

[mrobins297aaa]

corn/pellet burner

advantages: would be cheaper than propane or electric at least when using pellets, I'm not sure about corn anymore its been going thru the roof.

disadvantages: the stoves are expensive probably at least 2k and needs a special corn/pellet chimney maybe another $500. It can be a bit messy and you have to have a way to get the fuel and the stoves require attention. but l a lot less work then wood.

just a thought

 

[BadgerBoilerMN]

Start with a heat load and put tube in the floor so you will be Radiant Floor Ready®

Radiant floor heating will not require the movement of air and is not a source of ignition nor fuel for any fire. If you tell us what your fuel costs are a boiler can be matched up and sealed combustion specified.

I have been a little late to many a woodworkers shop and had to tell him that the cheap unit heater is not the real deal.

 

[darkk]

There are so many different ways to approach this....but for $7500 I would think you could get a really nice heating/cooling system for this size building.

 

[phbsales]

Quick load calculation I did tells me you need about 80,000 btus to maintain 50*-65* indoor temperature at 0*F. My suggestion is to get a propane tank and suspend a sealed combustion 90% LP unit heater from the ceiling.

 

[Al Bundy]

Quick load calculation I did tells me you need about 80,000 btus to maintain 50*-65* indoor temperature at 0*F. My suggestion is to get a propane tank and suspend a sealed combustion 90% LP unit heater from the ceiling.

Any idea of the what kind of usage cost I should expect with an LP system? I'm not familiar with the consumption of one of these units, so I can't really calculate what the heating costs would be.

 

[phbsales]

Any idea of the what kind of usage cost I should expect with an LP system? I'm not familiar with the consumption of one of these units, so I can't really calculate what the heating costs would be.

Here's a link that may be helpful when making your calculations:

http://risenabove.com/client/hotsy_parts/images/uploads/Machine%20Fuel%20Usage.pdf

 

[chickenhauler]

75k btu 95% AFU LP furnace. Costs less than $1000 installed, pulls combustion air from outside, and should heat your garage for under $1000 a year.

 

[phbsales]

75k btu 95% AFU LP furnace. Costs less than $1000 installed, pulls combustion air from outside, and should heat your garage for under $1000 a year.

I'd like to know what brand and where to purchase such a furnace for that price, and I'll buy 10 of them.

Sorry dude, gotta call B.S...........

 

[chickenhauler]

I'd like to know what brand and where to purchase such a furnace for that price, and I'll buy 10 of them.

Sorry dude, gotta call B.S...........

You can pick up a Rheem on eBay delivered for that price, what makes you think a local guy can't do an off brand cheaper? I was actually quoted $900, but I figured a bonnet would add a few bucks.

If you seriously are interested in 10, let me know.

 

[phbsales]

You can pick up a Rheem on eBay delivered for that price, what makes you think a local guy can't do an off brand cheaper? I was actually quoted $900, but I figured a bonnet would add a few bucks.

If you seriously are interested in 10, let me know.

That's interesting. My local Rheem distributor's best price to my company for an RGRA 95% AFUE, 75K furnace is $1165.00.

I've looked at other manufacturers prices as well, and none of them are below a grand.

So, back to your original statement and pricing. What fool, even if you could buy the furnace at $900, would install it for $100? And at that price, what kind of installation do you think you would get? I can provide and install this furnace for just over $3K, and that includes venting it and running new gas line from the propane tank to the unit.

Gas appliances kill people every day because they were installed improperly, so think about that the next time you decide to offer information that you're not qualified to give.

 

[crazy wheel]

That's interesting. My local Rheem distributor's best price to my company for an RGRA 95% AFUE, 75K furnace is $1165.00.

I've looked at other manufacturers prices as well, and none of them are below a grand.

So, back to your original statement and pricing. What fool, even if you could buy the furnace at $900, would install it for $100? And at that price, what kind of installation do you think you would get? I can provide and install this furnace for just over $3K, and that includes venting it and running new gas line from the propane tank to the unit.

Gas appliances kill people every day because they were installed improperly, so think about that the next time you decide to offer information that you're not qualified to give.

well duh.....apparently ebay installs them

 

[mrobins297aaa]

Nobody would install that furnace for $100, even $500 that is BS.

But i will say I bought my comfortmaker 100k 95% from the wholesale house last January and I think it was $893.......I had to add a lp kit because I have lp so if I remember right it added about $60 to the bill. And that was for a 100k, 75k would have been cheaper.

 

[mrobins297aaa]

also propane is expensive, I don't see how you could ever get by with $1000 a year unless your never out there.
You haven't said if you have a house on the property?.....if so what are you using for heat in there?

 

[Al Bundy]

also propane is expensive, I don't see how you could ever get by with $1000 a year unless your never out there.
You haven't said if you have a house on the property?.....if so what are you using for heat in there?

Good point. My house has an oil fired boiler. Unfortunately the house and garage are about 60 feet apart so tying them together seems like it wouldn't really be feasible. Here's a link to the build if you want to check it out:

http://s940.photobucket.com/albums/ad246/Al_Bundy_cny/Garage/

 

[brewchief]

I can think of a few options,
#1 Ceiling hung sealed combustion unit heater, likely the least expensive initially but will go though some propane.
#2 95% gas furnace, more efficient then the unit heater but will take up more space(can be hung from the ceiling) and will need a drain for it's condensate, draining outside is not the best plan in 0 degree weather. A simple duct system should be used and you will need to have a filter that needs to be changed on the return air.
#3 Oil furnace, there are some models with sealed burner boxes but you are looking about 80% efficient, no drain needed but a simple duct system would be as well as filters. Yearly service is a must with oil as well to keep from sooting and to keep efficiency up. Would use the same fuel as the house so only one delivery truck to deal with.
#4&#5 same as #2&#3 but with an air to air heat pump added, this would keep you off the propane or oil until the temp got down to say 35-40 degrees depending on your fuel and electricity costs. This would also give you A/C.
#6 Mini split heat pump, may not be able to keep up in the real cold weather but might make a nice addition to a unit heater, I don't think I'd want one with the electric strip backup heat in your climate unless power is real cheap.

 

[BadgerBoilerMN]

These "free" heat loads estimates are too high, the results of using heating equipment too big for the design load is are: the equipment will cost more than it should, operate at lower than listed efficiency and be unable to keep the structure as comfortable as it could by not properly dehumidifying in the case of AC or short-cycling in the heating mode.

If the slab in your new garage in already poured (and the insulation below the slab a little light) the next best thing for comfort, without blowing air around, is an infrared radiant tube heater. Infrareds are another form of radiant heating and though not quite as efficient, will perform better than schorched air, with good response time and superior warmth.

The last infrared heating system we designed and installed was for a pole building converted to woodworker's (cabinet maker) shop...loves it.

You will likely have to have it professionally installed, but your budget is reasonable (more than $900.00) and your expectations can grow with the budget.

The other common application we prefer if the slab it "tubeless", is the use of european panel radiators with as sealed combustion condensing boiler. This system is most efficient (next to radiant floor) and again will not blow a lot of air around - good for cooling, always bad for heating.

 

[Milton Shaw]

If you go with propane, buy your own storage tank. The fill ups in the summer for owned tank are half the price of leased tanks. I bought LP last summer I think it was 1.65 a gallon. In the winter its $3 plus a gallon. My propane is used for a backup generator. My generator runs once a week for 15 minutes and then we had two power outages during April storms here that lasted almost all night two nights. My unit has used less than the width of the gauge neetle from the full mark in a year. Less than 30 or so gallons.

 

[Al Bundy]

Purchased a Reznor UDAS-100 with the horizontal vent kit. I think I made a good choice, but I guess I'll know for sure in a few weeks.

Thanks for all the advice.

 

[phbsales]

Reznor makes a decent unit. Wondering how you came up with the idea to go with a 100,000 Btu unit?

 

[JackB]

For your budget I would get a air/air heatpump and a propane burner for extra heat when the heatpump can't keep up. That will provide very cheap heating down to at least -5 degrees C. I imagine the heat pump will keep your shop hot enough at least 90% of winter days if correctly sized.

 

[Al Bundy]

Reznor makes a decent unit. Wondering how you came up with the idea to go with a 100,000 Btu unit?

Actually had analysis done. It came out to 75,000 BTU pretty much what you were figuring phb. The hitch was I had decided I wanted a Reznor sealed combustion unit. The sizes available were 75,000 and next 100,000. It was suggested not to go with the bare minimum, so I went with the 100,000.

 

[phbsales]

Actually had analysis done. It came out to 75,000 BTU pretty much what you were figuring phb. The hitch was I had decided I wanted a Reznor sealed combustion unit. The sizes available were 75,000 and next 100,000. It was suggested not to go with the bare minimum, so I went with the 100,000.

You will be replacing heat exchangers regularly then. The unit can't dissipate all the heat it's producing, since it's grossly oversized. The heat it retains will rot out the heat exchanger from the inside. Flue gasses and condensate are acidic. With a rotten heat exchanger the possibility of being exposed to carbon monoxide is very real.

I would seriously reconsider and toss the 75K in. It'll do the trick nicely and help you avoid the problems I described above.

 

[Al Bundy]

You will be replacing heat exchangers regularly then. The unit can't dissipate all the heat it's producing, since it's grossly oversized. The heat it retains will rot out the heat exchanger from the inside. Flue gasses and condensate are acidic. With a rotten heat exchanger the possibility of being exposed to carbon monoxide is very real.

I would seriously reconsider and toss the 75K in. It'll do the trick nicely and help you avoid the problems I described above.

According to the info provided by Reznor maximum output of the unit is 87,000 BTUs. Would you consider that to be grossly over-sized? The output for the 75,000 unit is only 62,000. It seems that would be as much under-sized. You are obviously in the business and more knowledgeable than I am on the subject. But I would like to have a better understanding before I rush off and change what the HVAC guy told me that did the calculation.

 

[Al Bundy]

I don't know that I would say the climate is radically different, but where I live the average winter temps are at least 6-7 degrees colder than Chicago.

I can't say what method was used because I didn't ask. Although based on reading your post, I can probably guess. I had no reason to question since the result agreed with others I already had. If you keep getting the same answer, it appears that to be the correct one.

I have enough doubt now to call first thing tomorrow and have my order placed on hold. With all the effort I've made up to this point it would be kind of foolish to get this wrong.

 

[phbsales]

According to the info provided by Reznor maximum output of the unit is 87,000 BTUs. Would you consider that to be grossly over-sized? The output for the 75,000 unit is only 62,000. It seems that would be as much under-sized. You are obviously in the business and more knowledgeable than I am on the subject. But I would like to have a better understanding before I rush off and change what the HVAC guy told me that did the calculation.

I would be willing to bet that his calculation was based on comfort heating, that is, finished space like the rest of your home. For a garage, most calculations are based on desired temperature. All the heater in the garage needs to do is bring the space temp up to about 60* in the winter, which is more than comfortable. It's almost better to undersize the equipment slightly and allow the system to do it's job efficiently, than to oversize the system and have it short-cycle. Short cycling is what will eventually cause the HX to fail because it won't get the proper run time, and therefore the flue gasses will condense and eat up the HX from the inside.

 

[phbsales]

Rotted out heat exchangers and flue piping is a sign of improper combustion, not oversizing- unless the unit is so oversized that it does not stay on long enough to cook off the moisture in the heat exchanger.

Oversizing heating equipment, to a point, is not as detrimental as oversizing cooling equipment. But, you can still have short cycling, poor indoor comfort and shortened equipment life due to on/off cycling.

That's pretty much the point I wanted to make, but not everyone has or knows how to use a combustion analyzer, let alone how to interpret the readings.

I have changed out a lot of oversized furnaces in my 17 years in the HVAC field. All of them had cracks in the HX due to years of expansion and contraction due to the fact that all the heat the furnace produced wasn't being dissipated from the HX, therefore heat retention and condensation.