Mini split or small port high velocity hvac?

[ezzzzzzz]

I’m building a shop at my new home. It will be 40’ x 50’ with 10’ walls and a peak of 17’ ( trusses). It is dimensionally the same as my old shop but two fewer garage doors. I have a 3.5 ton Unico evaporator and blower from my old farmhouse. This unit has only about 6 months usage so it is practically new (swapped for larger unit after renovations/expansion). I’d have to purchase a condenser unit, lines, etc as well as figure out duct. The alternative is to purchase a two cartridge 4k mini split system which is what I had in my 40’ x 50’ shop at my farm (Daikin). It worked fine year round. Like the old shop, the new shop will be fully insulated including two 12’ x 12’ doors. So, what are your thoughts.

 

[pcmeiners]

The alternative is to purchase a two cartridge 4k mini split system

What is a 2 cartridge 4k mini split. ?
In what year was the Unico unit made ?

 

[NakeDiesel]

I used a 5 ton heat pump in my shop. It's a 40x80 with 4.5" of spray foam with 3 12x12 insulated doors and two insulated man doors as well as 6 windows.

I had a custom canvas duct made for my shop. Gave them the cfm, diameter of inlet and wanted all the holes to go out one side as I have upper storage behind it.

20240217_151125 by NakeDiesel, on Flickr

 

[markietas]

Well the outdoor unit is usually where most of the cost is (compressor, valves, control circuit, ECT..) Unfortunately your indoor unit on its own isn't getting you that far ahead.

And ductwork is expensive, not to mention the few benefits of a high velocity system don't really help at all in a shop situation, and there are several drawbacks.

I am almost certain you can buy a while mini split of similar capacity for what it would cost you to just get a new outdoor unit for your existing system.

The price difference is probably even bigger if you are willing to do a diy install of the mini split (pretty easy if you have some attention to detail).

Also the mini split is going to be way more efficient even if you get a cheap one.

 

[fitter30]

You need to look at you tube cleaning a mini split evaporator. Most heap pumps lose capacity as outside temp drops. Except for a couple of top of the line hyper heat units. All minis use enhanced coils where they have little slits in the fins that can collect dirt.

 

[NakeDiesel]

Probably the biggest question is, what you use the building for. I looked at going the mini split route, but I generate a ton of dust in my shop, sanding on cars, welding and grinding, woodwork, etc... I didn't think a mini split could handle that type of environment. I use 2 24x24 intake filters on my 5 ton unit.

Now in my bee room inside the shop, I'm looking at putting a tiny mini split in there.

 

[danski0224]

I have a 3.5 ton Unico evaporator and blower from my old farmhouse. This unit has only about 6 months usage so it is practically new

I would use the Unico.

If you are going to use it as a heat pump, Unico has specific evaporator coils designed for heat pump use. Then you need an outdoor unit that will work for your load and climate.

Unico has design stuff on their website. If followed, the systems are quiet.

They are very proud of their parts.

 

[brewchief]

I would use the Unico.

If you are going to use it as a heat pump, Unico has specific evaporator coils designed for heat pump use. Then you need an outdoor unit that will work for your load and climate.

Unico has design stuff on their website. If followed, the systems are quiet.

They are very proud of their parts.

Using the unico might not be very easy if it's a r410a unit, finding 410a equipment around me isn't very easy and switching it to use r32 or r454b may require a new txv and will need whatever leak sensing add on **** that required with the A2L refrigerant. One really has to decide if it's the right way to go and not be swayed by the I have so I want to use it idea.

 

[danski0224]

Using the unico might not be very easy if it's a r410a unit, finding 410a equipment around me isn't very easy and switching it to use r32 or r454b may require a new txv and will need whatever leak sensing add on **** that required with the A2L refrigerant. One really has to decide if it's the right way to go and not be swayed by the I have so I want to use it idea.

Yeah, but when venting a unit heater improperly is OK in this forum, I guess "anything goes"...