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  • #16
    Originally posted by reggie_obe View Post
    Heat pumps become inefficient and switch to resistance heating only below 35F. Some units can be found that switch to Nat Gas below 35F. What type of heating does your home have, hot air, hwbb, steam? No chance of extending ductwork or if hydronic, adding a loop out in your workspace?
    That was true years ago but modern mini splits like the one RB211 posted are MUCH more efficient. There are models that output full rated heat down to 0F and continue producing useable heat to -15F. I never seen one with backup resistance heat strips, they just are not needed. Larger whole house heat pumps are not as efficient as the mini splits and do commonly have backup strips, even so, the heat pump itself produces decent heat well below 35F. That 35F cutout was many many years ago, things have advanced.

    I think RB211's recall of his mini split being a 12 SEER was not right, I am betting it is MUCH higher than that ! I have never seen a mini split with that low of a seer rating. Some go as high as 24SEER !

    A modern high performance mini split is quite capable of doing the job in the northern states.

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    • #17
      Keep in mind that any heater that does not exhaust outside (e.g., the salamander ones) will put a lot of water vapor into the shop air. Which will condense on your cold machines.

      Comment


      • #18
        Originally posted by Sparky_NY View Post

        That was true years ago but modern mini splits like the one RB211 posted are MUCH more efficient. There are models that output full rated heat down to 0F and continue producing useable heat to -15F. I never seen one with backup resistance heat strips, they just are not needed. Larger whole house heat pumps are not as efficient as the mini splits and do commonly have backup strips, even so, the heat pump itself produces decent heat well below 35F. That 35F cutout was many many years ago, things have advanced.

        I think RB211's recall of his mini split being a 12 SEER was not right, I am betting it is MUCH higher than that ! I have never seen a mini split with that low of a seer rating. Some go as high as 24SEER !

        A modern high performance mini split is quite capable of doing the job in the northern states.
        I think you're right about the SEER, the darn thing works very well and isn't noticeable on the electric bill.

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        • #19
          I've successful heated an insulated 24x34x9 space with a simple 5000 watt electric unit heater. Used to keep it 60-65 degrees pretty easily. In space your size I'd set it and let it run. So nice to have a warm shop to work in any time you want. Insulation at Menards is also pretty reasonable.

          https://www.menards.com/main/heating...750-c-6328.htm

          Mike
          Central Ohio, USA

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          • #20
            Originally posted by Sparky_NY View Post

            That was true years ago but modern mini splits like the one RB211 posted are MUCH more efficient. There are models that output full rated heat down to 0F and continue producing useable heat to -15F. I never seen one with backup resistance heat strips, they just are not needed. Larger whole house heat pumps are not as efficient as the mini splits and do commonly have backup strips, even so, the heat pump itself produces decent heat well below 35F. That 35F cutout was many many years ago, things have advanced.

            I think RB211's recall of his mini split being a 12 SEER was not right, I am betting it is MUCH higher than that ! I have never seen a mini split with that low of a seer rating. Some go as high as 24SEER !

            A modern high performance mini split is quite capable of doing the job in the northern states.
            Interesting..........
            Looking at replacing an electric HVAC unit in a condo with (hopefully) a gas fired unit as the old A/C condenser and evaporator were deemed too old to repair economically. Started looking at heat pump, gas fired assist units. Supplier literature said (in heat mode) the heat pump cuts out at 35F. Haven't stared collecting contractor proposals yet.

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            • #21
              Green Bay climate gets pretty tough in Winter
              My friend Tom took 8 feet of his unheated garage and used 2 inch thick foam panels on 4 walls (the ceiling was plasterboard) - even his door was a hinged foam panel
              Put in his Rollaway, Mill and Lathe and some old carpet on the floor and heated it with a 1300 watt heater . Was warm as toast when he needed machine work. Had one double 40 watt fluorescent
              Light.....Had to turn down the heater it was so warm, even when 10 below outside His shop was 8 x 14 or 16 ~

              Rich
              Green Bay, WI

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              • #22
                Originally posted by reggie_obe View Post

                Interesting..........
                Looking at replacing an electric HVAC unit in a condo with (hopefully) a gas fired unit as the old A/C condenser and evaporator were deemed too old to repair economically. Started looking at heat pump, gas fired assist units. Supplier literature said (in heat mode) the heat pump cuts out at 35F. Haven't stared collecting contractor proposals yet.
                Look at the spec sheet, the COP ratings at various temperatures. COP=Coefficient of Performance, this is the heat produced for the amount of electricity consumed. Electric resistance heat is a COP of 1, that means all the electricity is converted to heat with no losses. Heat pumps can have COP ratings around 5 depending on the outdoor temp. I just looked at a goodman heat pump split system for kicks, it had a COP of 2 at 0F outdoors, meaning it produces twice the heat of a resistance heater at that temperature. I would be interested to know the make/model of the unit the supplier literature says cuts out at 35F. Last few nights here were in the mid 20's and my heat pump didn't break a sweat, no backup heat required, its a 10yr old goodman which is certainly nothing special.
                Last edited by Sparky_NY; 12-27-2020, 02:35 PM.

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                • #23
                  Originally posted by wdtom View Post
                  If your shop space is 10' x 10' x maybe 8' high and you do a good job of insulating it you could just plug in a portable electric heater, and the smallest window AC in the summer would do it too for that mater if heat is a problem in in the summer.
                  Hi,

                  Yep, I had a 8'x15' insulated room in my garage. I used this heater https://www.menards.com/main/heating...775395&ipos=35

                  I plugged into this style 120v thermostat https://www.amazon.com/Voltage-Mecha...096900&sr=8-34

                  I added a cheap 110v room air conditioner for summertime needs and was happy for years.

                  I since we have moved north of Frostbite Falls in out old age, I now need to build a new shop. Fortunately it doesn't need to be any bigger than what I had. So, the same heating and cooling requirements will be pretty much the same.
                  If you think you understand what is going on, you haven't been paying attention.

                  Comment


                  • #24
                    Originally posted by Ohio Mike View Post
                    I've successful heated an insulated 24x34x9 space with a simple 5000 watt electric unit heater. Used to keep it 60-65 degrees pretty easily. In space your size I'd set it and let it run. So nice to have a warm shop to work in any time you want. Insulation at Menards is also pretty reasonable.

                    https://www.menards.com/main/heating...750-c-6328.htm
                    That is a hell of a good deal on a heater that size. I just ordered one for my 24x24ish insulated garage shop for just under $125 delivered.

                    I have been getting by with one or two 110v heaters, but this will work better for me.

                    Thanks for the heads up.

                    Comment


                    • #25
                      In the past threads like this folks offer up a lot of low to high cost options for a heat source to start out and then from there it gets down to all of them being farts in the wind if you don't insulate first. So I'd say strongly that step #1 before you even consider any heat source options is that you MUST insulate. It all comes down to working in comfort vs the option of only taking enough of the chill away to survive. Without insulation the shop would still be a place for "emergency repairs only". Just not quite as much swearing about the cold unless you heat it with enough BTU's to melt a pot of brass.

                      The fact that you found a gas line in a wall while removing some existing insulation suggest that it is an attached garage? If so then there's some escaped heat from that common wall. Not enough for comfort but enough that if the exterior walls and ceiling were insulated right off the bat you would see the temperature in the garage rise by a small but significant amount.

                      The cheapest but perhaps not easiest source of heat from there might be extending one of the forced air lines to the shop. How easy and practical depends on the layout of the system in the house. Since the house is, hopefully, better insulated than even your newly insulated garage the furnace in the house won't run often enough to keep your garage/shop toasty warm. But once you slip in there and open the vent to warm the garage for the day it'll likely get up to and keep it warm enough to work in an OK sweater with warm shoes and perhaps a "block heater".

                      For heaters actually in the garage with you I'd agree with the others that you don't want anything in there that burns fuel of any sort with no exterior vent for the exhaust. The issues with exposed ignition source and water vapor and just general poor air quality from the exhaust being inside with you makes this just a bad idea. Big space heaters in construction sites that are open to the outside is one thing. But even a leaky garage doesn't qualify in my books. And even if you crack the door to get enough air circulation there's still the issue of the exhaust moisture.

                      One option that springs to mind if possibly you're only there for a couple of more years might be to just use a 3500 to 4000 watt electric "box" heater with a fan on it and suck up the added electrical cost. Yes you'll likely need to run a 30 amp 220 line out for it. Or if you already installed a plug to power a welder perhaps you could use that and just don't weld while heating.

                      Look up your local cost for a Kw-hr of power and figure out what it costs per hour of run time. For example, if it's 12c per Kw-hr then a 4000 watt heater is 4 x 12c=48 cents per hour of run time. Provided you insulate first a likely scenario for your situation would be running almost steady for the first couple of hours then tapering off to half on half off for the rest of the day. So for an 8 hr day something like $3.50 to use electric heat. A 3600 watt heater is what I'm using in my attached garage. The garage is well insulated but it has a fairly leaky roll up door. During the cold snaps locally the temp gets down to -5 to -10C or 23 to 14F. So a not bad day by Michigan standards. My heater runs almost steady for the first hour, 2/3's of the time for the second, 1/2 for the third and then settles down to about 20 minutes an hour for the rest of the day. If it were more like the 0F temps you likely get I'd expect this to go up a little from that point. But I'm thinking it's still within the idea of $3.50 a day.

                      A gas fueled option that you might consider if you don't use the shop super frequently might be an RV heater running off a propane tank. The advantage there being that it doesn't need anything other than a little cutaway panel in one of the walls for the through wall intake and exhaust access. And a shelf or other to sit the main unit onto. And depending on how you feel about connecting a line to run to the propane tank perhaps no gas tech needed. Plus it would need a 12v power supply and perhaps battery to float the supply from. And there's still the cost and bother of getting the bottle(s) filled. But depending again on how many days a month you use the shop it might be a viable effort to time remaining in the house option.

                      And if you're willing to put in a chimney up through the roof or through a wall there's always the option of a small wood stove. It does steal inside air. But at least the exhaust is sent outside.

                      After these or similar lower cost options I think you're looking at the ones offered by the other guys. And if you would be in there 20+ days a month I'd say that even if you move out in the next 3 to 5 years it would be worth doing it right with one of those proper options.

                      Oddly enough a small house size furnace may not be a proper option. In doing the research on using a smaller house unit I found out that they have a minimum volume as well as max volume. Something to do with needing to run for long enough once lit to properly heat up the system so it didn't get damaged from condensation or something like that. So you can't just take a house sized furnace and stuff it into your garage and let it burp out a short burst of BTU's. The outcome of looking into various direct connection gas options for my own two car garage came down to a small size ceiling mounted unit which still needed a chimney vent through a wall or roof. And of course because it is a gas heater it needs a permit and inspection.
                      Chilliwack BC, Canada

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                      • #26
                        Originally posted by Sparky_NY View Post

                        Look at the spec sheet, the COP ratings at various temperatures. COP=Coefficient of Performance, this is the heat produced for the amount of electricity consumed. Electric resistance heat is a COP of 1, that means all the electricity is converted to heat with no losses. Heat pumps can have COP ratings around 5 depending on the outdoor temp. I just looked at a goodman heat pump split system for kicks, it had a COP of 2 at 0F outdoors, meaning it produces twice the heat of a resistance heater at that temperature. I would be interested to know the make/model of the unit the supplier literature says cuts out at 35F. Last few nights here were in the mid 20's and my heat pump didn't break a sweat, no backup heat required, its a 10yr old goodman which is certainly nothing special.
                        Initial exploration started here: https://hvacdirect.com/dual-fuel-hea...e-systems.html
                        Snipped from Trane:

                        A heat pump may be right for you if you live in a mild climate.
                        If your winters average around 30-40 degrees F, heat pumps could be the perfect fit for your home. A climate like the Southeast that has milder winters works well for a heat pump. In addition, locations with low electric rates are prime candidates for heat pumps.
                        A furnace may be right for you if you live in a cold climate.
                        If your winters are bitterly cold and have temperatures consistently below freezing a furnace may be the best choice for you. Furnaces fare better in cold-weather climates because they don’t depend on the outdoor temperatures to convert to heat.
                        Last edited by reggie_obe; 12-27-2020, 03:03 PM.

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                        • #27
                          If the gas line is downstream of the meter, all well and good, if it is upstream, you should keep your mouth shut.

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                          • #28
                            Originally posted by reggie_obe View Post

                            Initial exploration started here: https://hvacdirect.com/dual-fuel-hea...e-systems.html
                            Snipped from Trane:

                            A heat pump may be right for you if you live in a mild climate.
                            If your winters average around 30-40 degrees F, heat pumps could be the perfect fit for your home. A climate like the Southeast that has milder winters works well for a heat pump. In addition, locations with low electric rates are prime candidates for heat pumps.
                            A furnace may be right for you if you live in a cold climate.
                            If your winters are bitterly cold and have temperatures consistently below freezing a furnace may be the best choice for you. Furnaces fare better in cold-weather climates because they don’t depend on the outdoor temperatures to convert to heat.
                            Notice it says if your winters AVERAGE 30-40F, that alone pretty much shoots down the idea of them cutting off at 35 degrees. Also, they are talking about practicality, meaning efficiency and energy cost to operate. They certainly operate outside of that range, just the efficiency varies with temp. That is where the manufacturer performance charts come into play and the COP ratings at various temps. They are also talking about the average heat pump, high performance mini splits are a different beast altogether.

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                            • #29
                              " if it is upstream, you should keep your mouth shut." Caution if it's upstream the gas pressure is higher an will need to be regulated.
                              John b. SW Chicago burbs.

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                              • #30
                                I use Floor heat & forced air for my shop,Shop is at 50F with floor heat all winter except when working in there then forced air bumps it’s up.I was amazed how efficient it was when Feb 2018 was near coldest in history here,25 days with warmest days -29 c and numerous morning colder than -40 with coldest morning at -48c

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