Shop Heating

[7milesup]

To note:
An oversized air conditioner is a no-no. An oversized AC unit will have short cycle times, which does not allow it to properly dehumidify the air and therefore the comfort level will be much lower.
With an oversized heater, much larger temp swings will be experienced, also resulting in lower occupant comfort. Probably not a big deal in a shop but certainly noticeable in a house.

This is not at all a jab at you Bruce, it was just a best-practices standard that came to my mind while reading through this thread.

 

[RJSakowski]

To note:
An oversized air conditioner is a no-no. An oversized AC unit will have short cycle times, which does not allow it to properly dehumidify the air and therefore the comfort level will be much lower.
With an oversized heater, much larger temp swings will be experienced, also resulting in lower occupant comfort. Probably not a big deal in a shop but certainly noticeable in a house.

This is not at all a jab at you Bruce, it was just a best-practices standard that came to my mind while reading through this thread.

I installed the 18K unit rather than the 12k unit, largely because the 12k was on a long backorder and the 18k was actually less expensive than the 12k at the time.

My MrCool mini split uses a VFD-like technology that slows the compressor down rather than cycling it on and off. As I understand it, the heat pump varies it's output according to demand. The only time that I hear the compressor kick in is when I make a change in temperature. The interior fan remains on all the time the unit is powered on but slows to a crawl as well. The exterior fan will cycle off and on depending upon compressor and condenser cooling demands. Room temperature remains constant at the set temperature.

Presumably, other state of the art mini splits use similar technology.

 

[Winegrower]

The ceiling fans go from blowing up in the winter to down in the summer.

Here is a very minor controversy. I recently installed a ceiling fan in the shop, and the manual said to blow up in summer, down in winter. Which is right? Is there a correct answer for this, does it depend on shop geometry, etc?

 

[BGHansen]

Here is a very minor controversy. I recently installed a ceiling fan in the shop, and the manual said to blow up in summer, down in winter. Which is right? Is there a correct answer for this, does it depend on shop geometry, etc?

I've always run them just the opposite; down in the summer, up in the winter. Key thing is keeping the air circulating. I prefer the up in winter so I'm not feeling a draft. Here's an answer from Google asking "ceiling fan up or down in winter".

Bruce

 

[rabler]

Yep, ceiling fan direction is a question of wind chill.

 

[7milesup]

I installed the 18K unit rather than the 12k unit, largely because the 12k was on a long backorder and the 18k was actually less expensive than the 12k at the time.

My MrCool mini split uses a VFD-like technology that slows the compressor down rather than cycling it on and off. As I understand it, the heat pump varies it's output according to demand. The only time that I hear the compressor kick in is when I make a change in temperature. The interior fan remains on all the time the unit is powered on but slows to a crawl as well. The exterior fan will cycle off and on depending upon compressor and condenser cooling demands. Room temperature remains constant at the set temperature.

Presumably, other state of the art mini splits use similar technology.

Correct RJ. I should have been more clear that I was referring to conventional heating and cooling systems. The mini-splits utilize inverter technology so have that wonderful ability to ramp up and down.
I built a new house in 2019 and the whole house A/C does not have that ability. My furnace has a two level burner in it that will adapt to some extent for changing conditions, but not like a mini-split will.

 

[Winegrower]

On fan direction: Well, there you have it, I suppose. I'll switch it around and see which I like best. Perhaps it doesn't make a lot of difference, just having a fan stirring things up is most of the solution.

 

[rabler]

I installed the 18K unit rather than the 12k unit, largely because the 12k was on a long backorder and the 18k was actually less expensive than the 12k at the time.

My MrCool mini split uses a VFD-like technology that slows the compressor down rather than cycling it on and off. As I understand it, the heat pump varies it's output according to demand. The only time that I hear the compressor kick in is when I make a change in temperature. The interior fan remains on all the time the unit is powered on but slows to a crawl as well. The exterior fan will cycle off and on depending upon compressor and condenser cooling demands. Room temperature remains constant at the set temperature.

Presumably, other state of the art mini splits use similar technology.

It is also interesting to note that at least the Pioneer brand mini-splits can actually put out more BTUs of cooling than their rating. For example, my 18000 BTU unit can put out between 7592-24806 BTUs of cooling, and some very similar range for heating. I believe above 18000 BTUs you don't get the rated SEER efficiency.

The remote has a rapid cool-down mode in the extended settings that allow you to make use of the maximum capacity without tapering off as you near the set temperature. It would be interesting to know the control algorithm, whether it has a PID component, or just a temperature differential algorithm.

 

[ddickey]

I always thought you wanted to pull up in summer because the cool air is lower.

 

[DAM 79]

A shop that size wouldn’t take that much it all depends on how well insulated it is how many windows doors r-value of insulation and so on a have a old pole barn with tin on the outside 20x40 very little insulation I have a wood stove and also a propane gas furnace with straight AC coil on top ( it was free and only a year old ) I can heat it quickly and cool it quickly I have lots of trees also to shade it all my machines very rarely get any surface rust . It all boils down to what you can afford for install and electric/utility bills wood stoves heat up nicely and are cheap to run propane is nice will deliver heat in the 130-140 degrees out the vents a heat pump will run good down to around 40 degrees give or take them they start to struggle but that’s why the have electric back up heaters in them to help out and also when unit goes into defrost .a ductless or (Mini Split ) they are the next choice again all depends on what you get (Mitsubishi) would be my choice they have the best warranty and never have any problems they will work well down to around 30 degrees or so if you step up to the Hyper Heat Models there good down to -13degree and still keep a high seer rate but there not cheap !!!!! If it were me I would do a ductless unit and be done and have a wood stove to help out when it gets really cold !!!!! Been in the trade for 28 years just my two cents