3 mini split heat pumps, first day.

Scruffy887 · Jul 11, 2022

3200 sq ft metal building, black rubber roof, 82 degree day. My HVAC friend said I would need much more than 6 tons based on machines inside. Yeah, almost needed a jacket inside. 3 Pioneer Mini split heat pumps at 24,000 btu each. VERY quiet inside and out. Liking it a lot. The space is 40' x 80', but one catch. A 20' wide opening ( x12' high) on one side leads to a very much larger space and is currently still open. Still cool and dry. Tomorrow I will tarp the space off to 40 x 60 and see what happens. Meat locker?
My electrician wired and mounted the units inside and out. This weekend I broke out my Junior HVAC starter kit and got all 3 running. Pre charged is awesome. And I am now a wizard with a flaring tool. It was easier than I thought.
Chilling
Scruffy

Gordon Heaton · Jul 11, 2022

Guess you came out alright! My shop is 850 sq. ft., has one 24,000btu mini and if I leave it on 24/7 it holds 72F if I don't open the big door too much, weld or cut. Then again, it was 108F here today.

BOB-OO · Jul 11, 2022

I'm looking at doing the same in a bigger space, let us know what temp you can hold inside vs outside.

Gordon Heaton · Jul 11, 2022

Another thing is that most minis have very poor filtering and shop air plugs it up pretty fast too.

FamilyTradition · Jul 11, 2022

Why not tarp off the whole opening (assuming you don't need to go back there or walk through), and you could probably save some $$$ on your electric bill. If you have to, crank the dial back a few notches so you don't freeze to death!

I have heard good things about mini splits. I was considering going that route if the opportunity ever arose to get my own space.

doug925 · Jul 12, 2022

I have 3900/sqft, shop, in a 30 x130' space.
The shop is divided into:
Office space 30 x 20'
-----dividing wall----
Manual equipment room 30 x 35'
----- 12 x 12' restrictive opening---
CNC area 30 x 55'
Secondary work/ grinding/ deburring / sawing area encompassing the remaining 30 x 20'

The office and manual area share a 10 year old, 3 ton AC. (36K btu)
The CNC and secondary area share a brand new 5 ton (60K btu)

The new 5 ton unit has a standard 1 x 25 x 30" air filter acting as a pre-filter, and then a 4" thick super filter for oil and other particulate matter.

We are running between 100-104 in Houston right now, and the shop is a comfortable 72°.

Prior to the new 5 ton (just 2 months old) we could barely keep the shop at 83° in the summer.
It was not ~hot~ per se, but it darn sure felt cold when coming back in from outside!

Last month's electric bill was $756.00
Not the worst for a machine shop in H-town.

Doug

Scruffy887 · Jul 12, 2022

FamilyTradition said:
Why not tarp off the whole opening (assuming you don't need to go back there or walk through), and you could probably save some $$$ on your electric bill. If you have to, crank the dial back a few notches so you don't freeze to death!

I have heard good things about mini splits. I was considering going that route if the opportunity ever arose to get my own space.

Baby steps. Get them running first. Proposed machine space is 40 x 60 but that room is 40 x 80. But cooling almost all space 3 times that. 2 more verticals arriving next month, still think no problem. Tarp goes up in the morning, 90 degree day Wednesday. Bring it on!

david n · Jul 12, 2022

Gordon Heaton said:
Another thing is that most minis have very poor filtering and shop air plugs it up pretty fast too.

↑↑↑ This............what keeps the unit from plugging with coolant and dust?

latheman78 · Jul 12, 2022

Gordon Heaton said:
Guess you came out alright! My shop is 850 sq. ft., has one 24,000btu mini and if I leave it on 24/7 it holds 72F if I don't open the big door too much, weld or cut. Then again, it was 108F here today.

But isn't that dry heat?

Strostkovy · Jul 12, 2022

david n said:
↑↑↑ This............what keeps the unit from plugging with coolant and dust?

Regular maintenance

Garwood · Jul 12, 2022

david n said:
↑↑↑ This............what keeps the unit from plugging with coolant and dust?

So what if they do?

Have you ever cleaned out a heat pump coil pack in a 5 ton air handler? Have you ever cleaned out a min split head unit?

The mini split head unit is just a heat exchanger and a squirrel cage fan. Inside a simple plastic box that comes apart to expose all the guts. That's it. The filter is usually a little screen you pull out and blow off. If the coil gets packed with crud every few years it would still be considerably easier to hose the mini split coil down with coil cleaner and blow it out than to tear your air handler apart to clean those coils.

IME, the mini split coils stay clean in my shop. The filters catch a lot of shit and need cleaned every season kinda just like a big boy air handler does. The mini splits tend to attract spiders and shit that lands on top of the head unit where you don't notice it. That shit builds up and chokes off the air intake causing poor performance worse than anything else.

Blast off the head units with air every couple months and I bet they last 20 years no problem.

Gordon Heaton · Jul 12, 2022

It's not always that easy in a shop environment. Oil mist/smoke requires soap & brushing to get off the screen and eventually it coats the exchanger fins as well. Then its a messy, dirty and difficult job. Better filtering would keep the coil cleaner but the minis don't have enough zip to pull air through a decent filter.

Still, I like mine. It doesn't take up much room indoors or out, its quiet and fairly efficient (16 SEER). New ones will be better.

Scruffy887 · Jul 15, 2022

Tarp went up at days end Wednesday and I left 1 unit running all night. Tarp has an opening just big enough to walk through so not a full seal yet. Space now 40 x 60 and 85+ degree yesterday. Ran only 1 unit up to about 1 in afternoon. Lathe and mill both in full production, lathe puts out a lot of heat. So at 1:00 I turned a second unit on. Staying 70 inside.

Not worried too much about cleaning them as all machines run plastic, no coolant at all. One of the new machines coming will make dust cutting Phenolic, already have a Torit waiting for it.
I do monitor the coil temps a few times a day. Between 50 and 54 as best as I can read with IR pistol.

ernieflash · Jul 15, 2022

What is the ampreage draw on one of those units ?
I have a wall mount 25000BTU unit and its Killing me
plus I have roll up doors that face east and i dont know how I can Insulate them

Scruffy887 · Jul 15, 2022

ernieflash said:
What is the ampreage draw on one of those units ?
I have a wall mount 25000BTU unit and its Killing me
plus I have roll up doors that face east and i dont know how I can Insulate them

Good question and I need to monitor that. Amazon is my friend there. I opened up the tarps to move some big clamp thingies out so I started a second unit to compensate. These units vary output by space needs. Where I am stationed (sit on my chair) I can feel direct air movement. It does change, at least I think it does.
#10 wire if that helps.

Mark Rand · Jul 16, 2022

My home shop is only 300sft, but that's big for the UK. It's got a 9,000 Btu mini split that keeps it comfortable all year, the heat in winter is good as well as the cool in summer. This January, I had solar panels mounted on the roof and a battery with the inverter inside. Now I'm not actually paying for any electricity at all. The sunnier it is, the more electric there is for cooling!

With energy prices having gone up due of the war in Ukraine, it looks like the system will pay for itself in less than five years.

Houdini16 · Jul 16, 2022

We just cut the walls and went from a 1200sqft to 2400sqft shop, We added (2) 3ton(36k) units and they barely keep up.
We run 5 CNC machines and a screw compressor, all machines have mist collectors, the humidity is what kills us.
We can stay at 75° 30%Humidity with all machines running hard, but we also have to run (2) Quest Dual225 Dehumidifiers
and this is in arid Utah.

Scruffy887 · Jul 17, 2022

Houdini16 said:
We just cut the walls and went from a 1200sqft to 2400sqft shop, We added (2) 3ton(36k) units and they barely keep up.
We run 5 CNC machines and a screw compressor, all machines have mist collectors, the humidity is what kills us.
We can stay at 75° 30%Humidity with all machines running hard, but we also have to run (2) Quest Dual225 Dehumidifiers
and this is in arid Utah.

Screw compressors are a major heat source. My screw compressor is not located in the conditioned space. Is there a way to duct the heat out?

Houdini16 · Jul 17, 2022

Scruffy887 said:
Screw compressors are a major heat source. My screw compressor is not located in the conditioned space. Is there a way to duct the heat out?

On my list of to do's, there is a 18" ceiling vent capped off from a CNC plasma from previous tenants, I actually just moved the compressor under it when we rented the next door shop.

M. Moore · Jul 27, 2022

Houdini16 said:
We just cut the walls and went from a 1200sqft to 2400sqft shop, We added (2) 3ton(36k) units and they barely keep up.
We run 5 CNC machines and a screw compressor, all machines have mist collectors, the humidity is what kills us.
We can stay at 75° 30%Humidity with all machines running hard, but we also have to run (2) Quest Dual225 Dehumidifiers
and this is in arid Utah.

Just wondering why you would run at 30% humidity? Normal comfortable range for humans is 50-70%. If you are thirsty all the time it is probably because the air is too dry.
Very lucky here where I live as the indoor humidity level is in that range all year.

3 mini split heat pumps, first day.

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