Need advice for 2500 SQ foot shop

[bdog]

I have a 50x50x14 steel building that has closed cell spray foam insulation. We have had the building ten years with no heat or AC but I want to add for sure heat and maybe AC.

I am in the Texas Panhandle. It gets cold, but not super cold. The shop has a restroom with a toilet and sink and with no heat whatsoever they have never froze up. How I don't know but they haven't. Whenever it gets below 15 degrees we get some freezing pipes in our house but the shop is fine. I think the coldest I have ever seen it here was around 5 degrees and in the summer it gets over 100. Typically lows are in the 30s and highs in the 90s.

We used to just have electric but ran a large gas line to our house for a pool heater last week. I had them run a gas line to the shop as well.

What would you recommend for the shop? Cost really isn't a factor. I did some research and was thinking maybe something like a Modine Hot Dawg but then thought what about a heating and cooling unit? Could something like a residential unit work?

I am not in the shop all the time I spend maybe 10 days a month out there and those days I am out there all day doing things for my small business.

 

[HoosierBuddy]

If you want to put in duct work, you could run a residential style split system or even a heat pump...but that's not what I would recommend.

For heat only, a unit heater like you suggest is a "no brainer" given you have natural gas available. In west Texas, aren't they pretty much giving natural gas away right now?

What I like about gas fired unit heaters for part-time heating is you can oversize them a bit and they will really thump out the BTU's and get that space up to heat when you want it warm to work out there.

Your other choice would be some sort of heat pump based solution like a mini-split or multiple mini splits given the size of the shop. The big upside is they would also provide cooling. They would likely be more expensive to operate than natural gas (you'd need to look at your power and gas costs to know for sure).

The downside would be a lot more up front expense...but you said that wasn't an issue anyway.

Wait a minute. Cost is not an issue? Is your last name Ewing by any chance?

Phil

 

[Jim greengo]

For that big of an area I'd probably do a couple of split systems to simplify duct work/air flow issues.
You could install an A coil in each system,then add linesets and condensing units later if you want Ac.

 

[nsula_country]

I have an example in my signature. 40x60x17, 2400 ft/2. Ducted Heat Pump.

I didn't have gas, so used electric furnace. You could use a gas furnace air handler in place of the electric furnace in the example.

Don't think mini splits are cost effective in this application. Unless budget is really unimportant.

CT

 

[bdog]

Thanks guys.

Having the option to cool would be nice.

I called a local heat/AC place and they give me two quotes.Both Mitsubishi mini splits two 2.5 ton / 30k BTU units. $10,400 installed for 15 SEER units or $12,800 for 20 SEER units.

I have never messed with heat/air but am an avid do it yourself person. I have rebuilt engines, wired houses, plumbing, etc. Checking on Google I can buy two of the units 20 SEER units for 8k or two 15 SEER units for 6k. How hard are these to install? The cost is within my budget but if it isn't that difficult I wouldn't mind tackling it myself.

nsula_country I read through your build thread and am jealous. That is an amazing job. Being that yours is a 5 ton setup what are the pros/cons of something like yours vs the two 2.5 ton mini splits?

 

[yeldogt]

With natural gas and 2500 sf .. why not do a simple split system. Typical furnace AC .. do a load calculation. my 1700 sf studio w/ foam has such a low load .. it cheap to heat and cool.

Mini's are great -- I have them ... but you have the space for a simple conventional system. get it sized correctly .. most are going to recommend a bigger size than needed

 

[theoldwizard1]

50x50x14 - You will never get anything close to even heat with only one heat source.

Cost really isn't a factor.

Well, then, why not go all the way !

2 mini-split compressor each feed in 2 air handler (4 total). "Slave" them together. You'll be warm in the winter and cool in the summer. (Personally, I would install some electric heat in the bathroom.)

 

[930dreamer]

I use an oil filled heater in my shop bathroom during the winter. I open the vanity/sink doors and just leave them open. Where in the Panhandle are you?

 

[nsula_country]

Personal opinion.

I don't feel mini splits will distribute air evenly, even with 6 heads let alone 4. Cost per ton minis get expensive with multi head systems. Not to mention the management of multiple linesets, conduits, ect. More points of failure. More maintenance.

I installed EVERYTHING (100% new) for less than your price of 2, 15 SEER minis. And it moves 2000 cfm of air.

Split system or package system with ducting is how I would go. 1 line set, 1 conduit, 1gas line. Duct layout would depend on building layout. Package system can be DYI.

I would think for <$12k you could get a turnkey 5ton 16 SEER ducted system installed. Filtration is one plus. Simplicity another. Gas furnace will have MUCH FASTER temp rise over mini. Minis don't have aux heat. Only heat pump, which looses capacity the colder it gets.

Fans will be a must with the ceiling height. I have 4, 60" Industrial fans.

This evening worked in shop. Had tstat at 58*. Cranked it to 70* for a few hours. Was cycling within an hour. Then set it back to 58* when I left.

CT

 

[bdog]

Thanks guys. I am in Lubbock. I thing you are right in a more conventional system. The mini splits seem nice and perfect for smaller areas but adding multiple units just kind seems like cobbling it together.

If I went with a 5 ton unit what would be recommended for the duct layout? The shop is just a 50x50 square with 14’ tall sidewalls and a 16’ peak. A walled in bathroom is located in a corner that measures roughly 8’ square and is 8’ tall. Other than that there is no dividing walls or anything like that in the shop. If I divided the shop in to four 25x25 zones and had a duct going to the center of each one from above would that be adequate?

The shop is pretty much worked in all over except for a 8x32 enclosed trailer is always parked in there. The shop has three 12x12 insulated doors on the front wall. The trailer is always parked in the south side bay.

 

[nsula_country]

If I did it again...

I would have hung air handler from ceiling.
Ran a trunk line down the center.
4-5 supply registers per side.

Only negative is filter maintenance would require a ladder or scissor lift.

Fans keep the air from stratifying.

Your building is 10' wider than ours. I don't have an issue with the air throwing to past center line of building. You would benefit from a central trunk line.

Mind you I'm an Engineer, not an HVAC installer. These are my suggestions of how "I would do this".

CT

 

[yeldogt]

In a large open space ... Single point source heating and AC works in a well insulated space -- with low air infiltration. Having ducts all over a house is because of the walls and the often poor building performance.


Do a proper load on the building -- you don't want an oversized system .. especially with AC.

And remember when you have high ceilings -- the key is to only cool low down .... ceiling fans just take all that hot air at the top and mix it up .. making the load on the building higher. You want to leave the heat up there.

Industrial buildings are often conditioned with systems up high -- but, that's for packaging. Make sure if you have vents up high that the system has the velocity to get the air where you need it. Down at the floor

 

[theoldwizard1]

Personal opinion.

I don't feel mini splits will distribute air evenly, even with 6 heads let alone 4. Cost per ton minis get expensive with multi head systems. Not to mention the management of multiple linesets, conduits, ect. More points of failure. More maintenance.

There is a lot of truth there, but mini-splits are still a viable option IN SOME CASES !

Multi-head, single compressor units have lower efficiency. 1 or 2 head per compressor is best, but much more expensive.

A "central" HVAC system will need a very large fan and a lot of duct work to get anything close to even distribution and they are much less efficient for cooling.

It is very difficult to calculate the "pay back" time, especially with the low cost of natural gas for heat.

 

[theoldwizard1]

The mini splits seem nice and perfect for smaller areas but adding multiple units just kind seems like cobbling it together.

That is where they shine !

The best thing is that multiple units (even with separate compressors) can be slaved together to act as on unified system.

 

[theoldwizard1]

Fans keep the air from stratifying.

This is very true in ANY large open area. You will likely need 4 ceiling fans.

 

[nsula_country]

There is a lot of truth there, but mini-splits are still a viable option IN SOME CASES !

Multi-head, single compressor units have lower efficiency. 1 or 2 head per compressor is best, but much more expensive.

A "central" HVAC system will need a very large fan and a lot of duct work to get anything close to even distribution and they are much less efficient for cooling.

It is very difficult to calculate the "pay back" time, especially with the low cost of natural gas for heat.

SEER is SEER... Much less efficient?

CT

 

[yeldogt]

You don't want to move air around when doing AC ... you want the air to stratify. Why cool all the volume of air? ... that's what happens when you bring hot air down from the ceiling.

When you AC a church -- you only worry about the first 8' ...

It's very easy to cool a large open space with only one output -- I do 2500sf w/o any issues.

Multi head mini splits look to be less efficient .. but lots of that has to do with how they are measured. In reality -- they goal with one or more is the same .. proper sizing. Multi allows for zoning and keeping the unit in it sweet spot.

A single always running at 40% is not efficient as a multi running at 80%

 

[bdog]

I pulled the trigger on a 5 ton 16 SEER system. They are going to mount it on the ceiling and run a trunk line down the center of the shop with six vents. Three facing each way. It has a 10 year parts and 10 year labor warranty and I am getting it installed Monday for $9,500. I am doing the electrical work and having the gas line ran over to where the unit will be but they are doing the rest of the labor.

The electrical turned into quite an ordeal. I bought the wire, disconnect, and breaker and started running the wire and then realized my panel was full and couldn’t accept any more breakers. So I went and bought a bigger one. Got it bolted to the wall and found out my service entry wires aren’t long enough to reach to the mains on this bigger panel. So I went and bought more wire and got it pulled and hooked up. It’s always fun how simple projects turn into something bigger.

 

[bdog]

I guess I will find out once it gets going but any ideas on what I will need for fans and recommendations? I also bought a nest thermostat so I can control things from my phone before I head out there. Any recommendations on where I should mount the thermostat?

 

[nsula_country]

ANYTHING BUT A NEST THERMOSTAT!!! I have actually seen one kill an AC.

Emerson Sensi is a good choice.

CT

 

[bdog]

ANYTHING BUT A NEST THERMOSTAT!!! I have actually seen one kill an AC.

Emerson Sensi is a good choice.

CT

Really? It is actually what my HVAC contractor recommended. He said we have all kinds of brands and stuff we can sell you but we have seen the Nest work the best and you can get one yourself at Best Buy cheaper than we can sell you one for so go pick one up and we will install it,

 

[nsula_country]

Nest are overpriced for what they are. But people who like Iphones seem to like Nest thermostats.

Non touch Sensi is about $90 on Amazon.

And now I think about it. It was the furnace control board that the Nest ate. Not the AC condenser.

CT

 

[dcg9381]

40x60x16 here. Central Texas. Open cell foam, 3 big, crappy-insulation doors.

I run 2 x 2 ton Ductless split systems by Daikin. They're focused on about 600 sqft of the shop, but do cool the whole thing down in the summer. Cost me about $2500 all-in.
What they don't do is cool the entire shop evenly - to do that, I need to move the air a bit more or add a 3rd unit toward the rear of the shop.

These units heat also - they're heat pump. I'd start there... You can always add a 3rd or move to an aux gas heating system.

 

[bdog]

Got it installed today. Waiting on plumber to finish hooking up gas to test it out. He was short one fitting and had to run and go get it.

 

[nadogail]

Enjoy a warm or cool shop in the appropriate season.

 

[nsula_country]

Got it installed today. Waiting on plumber to finish hooking up gas to test it out. He was short one fitting and had to run and go get it.

Looking good!

Decide on a thermostat?

CT

 

[bdog]

Yes I ended up with the nest. I was going to order a sensi but picked up the nest for $169 at Lowe’s locally since it was a rush deal.