Advise: 40x60x17 GOING FULL HVAC!

nsula_country · Oct 25, 2018

Hello all,

I have decided to pull the trigger on HVAC in our shop. A thread with pictures will be made when I do this.

The specs:

40x60x17 All steel, All welded. Think of a pole barn but with 5" pipe, I-beams and red iron instead of wood posts, trusses and lumber. 4/12 pitch roof.

Standard metal building insulation. White backing, silver radiant barrier towards the metal sheeting.

3 roll ups (insulated) Two 12x14 and One 8x8. Need to put the seals in at the top (gap at top of roll). Two steel 3070 man doors. East wall (60 ft) is shaded by trees. West wall (60 ft) is shaded by 30x60 lean to. South wall (40 ft) is exposed.

4 Emerson 60" heat fans. Over 10000 cfm each on high.

NO GAS. 200 amp service, single phase.

Here is my plan. Use residential split system. Ruud 14 SEER 5 ton condenser, Ruud 24" air handler with ECM blower and 5 ton coil. Build a return plenum mid way down east long wall (60 ft). Will use 2 filter grills for intake filtration (two 20x25 or larger will flow 2000 cfm) Set air handler and use a 4 ft supply plenum vertical.

As for ducting, not sure if I just want to use a couple of large, wide throw registers on the plenum? Or run about 10-15 ft of snaplock each way and use register boots and registers?

Next decision is:
AC/20kw heat (68240 btu)?
AC/25kw heat (85300 btu)?
Heat pump/20kw backup heat?
(Heat pump specs 47* 57000 btu, 17* 35800 btu)

I have 2 heat pumps at the house. Love them. But heat pumps are a "gentle heat" and not a quick temp rise like resistive. Also more expensive up front, cheaper to operate... I'm thinking keep this simple and just go resistive.

Also in the scope of work is to setup Ubiquiti Nanobeams for a point to point connection to the house (700 ft). This is so I can use a WiFi thermostat to control the system remotely. Example. I want to work in shop after work. 4 pm, ramp heat up. Arrive at shop at 5:30 pm, its warm but haven't had to run the heat all day...

Let's see what y'all think!

CT

nsula_country · Oct 26, 2018

Bump...

Any input to this plan of action? Has anyone installed a similar split system all electric or heat pump in their 2000-3000 sq/ft metal building?

If so, how does it perform?

CT

matt_i · Oct 26, 2018

Initially 85k BTU seems low for 2400 sqft and high ceilings.

But then I saw you are in LA and its more about taking the chill off than heating it in 20F ambients all day and night.

How do you use the shop, is it a business where you are out there 40+ hours per week or is it more "nights and weekends"? Also would be useful to know what the target temp will be? I am usually good at 50-60F in my shop in winter but I work in a sweatshirt and sometimes long underwear.

u3b3rg33k · Oct 26, 2018

what about one (or two) of these?
https://www.budgetheating.com/Bosch-4-5-Ton-Heat-Pump-Inverter-BOVA60HDN1M18M-p/52047.htm

probably cheaper to leave it near your setpoint 24/7 than to use electric heaters that pull 125A...

fyi, that above linked unit will maintain a coil temp of 47F/108F based on the load across it. slow the fan down, it'll ramp the compressor down. stage your fan and it'll do the rest. looks like it'll do 40kBTU down to 5 F if you have enough airflow across the coil.

PWC Repair · Oct 26, 2018

In your area, definitely go heat pump with backup. The heat pump will keep up fine, It's not like a house where you will be trying to maintain 72*. Maybe a few times a winter the backup strips will come on, unless you turn it way down then crank it up. Then of course the strips will come on until it satisfies temp. In the summer it will probably be enough to keep humidity down and keep you from roasting but that's about it. To actually keep the whole thing cool you would need twice that much.

dcg9381 · Oct 26, 2018

So I have almost exactly the same building:
40x60. 14' eves. 3 x 14'x14' roll up doors, one man-door.
I've foam insulated 3.5 - 4" all the way around, R-13 to R-15.
I found that roll up doors **** and the right way to do them is to install them 2' higher to get them to fit flush. As such, I had to install wiper seals (just like you) - the gap is huge, 1-2" at the top of the door.

Here's the bad news: I haven't put in HVAC yet.
My plan is 48K BTUs. Shop is only used very part time, otherwise I'd need R-30+ insulation. The most cost effective way to do it - that I know about is ductless split because I can install those myself and get to 16 SEER easily.
The wiring is pretty simple and relatively low draw.. I've only got 100A to my building right now of 320 available.

I'm planning on installing 2 x 24KBTU Pioneer systems. These are $1k each:
https://www.highseer.com/high-seer-inverter-mini-split-ductless.html

If 24k won't get it done, I'll add a third.

Note, my experience with heat pumps says that they will **** below 32F - so for the, maybe 10 days that Texas gets those, I'll live with it.. Or supplement with stand-alone heat if necessary - heating just isn't a big deal in Texas.

nsula_country · Oct 26, 2018

matt_i said:
Initially 85k BTU seems low for 2400 sqft and high ceilings.

But then I saw you are in LA and its more about taking the chill off than heating it in 20F ambients all day and night.

How do you use the shop, is it a business where you are out there 40+ hours per week or is it more "nights and weekends"? Also would be useful to know what the target temp will be? I am usually good at 50-60F in my shop in winter but I work in a sweatshirt and sometimes long underwear.

This will be nights and weekends use. Not a commercial business... Yet. Winter freeze control at 40's* SP and working 50-60* SP.

u3b3rg33k said:
what about one (or two) of these?
https://www.budgetheating.com/Bosch-4-5-Ton-Heat-Pump-Inverter-BOVA60HDN1M18M-p/52047.htm

probably cheaper to leave it near your setpoint 24/7 than to use electric heaters that pull 125A...

fyi, that above linked unit will maintain a coil temp of 47F/108F based on the load across it. slow the fan down, it'll ramp the compressor down. stage your fan and it'll do the rest. looks like it'll do 40kBTU down to 5 F if you have enough airflow across the coil.

I appriciate the link to the Bosch unit. I am a part time HVAC contractor. Full time engineer. I will use Rheem/Rudd due to supply house that I use. Contractor pricing... I can get 5T cond, 5T airhandler, heat strips and lineset for the price of the Bosch inverter. Thanks again.

20kw draws 107 amp. I think 25kw draws 132 amp... Have 200 amp dedicated service.

PWC Repair said:
In your area, definitely go heat pump with backup. The heat pump will keep up fine, It's not like a house where you will be trying to maintain 72*. Maybe a few times a winter the backup strips will come on, unless you turn it way down then crank it up. Then of course the strips will come on until it satisfies temp. In the summer it will probably be enough to keep humidity down and keep you from roasting but that's about it. To actually keep the whole thing cool you would need twice that much.

I thought that too. Friend/manager of the supply house has about talked me out of HP. Its a shop... I would have to get creative to lockout heat strips unless temp is below x* ect. I can do it, but I worry about trying to get 10-20* temp rise quick with only HP. Maybe use resistance to get temp rise and HP to maintain.

Will continue to think about this. Less than $500 difference in materials.

dcg9381 said:
So I have almost exactly the same building:
40x60. 14' eves. 3 x 14'x14' roll up doors, one man-door.
I've foam insulated 3.5 - 4" all the way around, R-13 to R-15.
I found that roll up doors **** and the right way to do them is to install them 2' higher to get them to fit flush. As such, I had to install wiper seals (just like you) - the gap is huge, 1-2" at the top of the door.

Here's the bad news: I haven't put in HVAC yet.
My plan is 48K BTUs. Shop is only used very part time, otherwise I'd need R-30+ insulation. The most cost effective way to do it - that I know about is ductless split because I can install those myself and get to 16 SEER easily.
The wiring is pretty simple and relatively low draw.. I've only got 100A to my building right now of 320 available.

I'm planning on installing 2 x 24KBTU Pioneer systems. These are $1k each:
https://www.highseer.com/high-seer-inverter-mini-split-ductless.html

If 24k won't get it done, I'll add a third.

Note, my experience with heat pumps says that they will **** below 32F - so for the, maybe 10 days that Texas gets those, I'll live with it.. Or supplement with stand-alone heat if necessary - heating just isn't a big deal in Texas.

Hopefully this build can help you. Mini splits are out. Not going to use them. I have all tools and knowledge to commission a traditional split system. I was more on the fence straight resistive or heat pump.

Roll ups do ****. Had I known this, I'd had it framed at 14 ft and used a 16 ft door!

CT

u3b3rg33k · Oct 26, 2018

nsula_country said:
This will be nights and weekends use. Not a commercial business... Yet. Winter freeze control at 40's* SP and working 50-60* SP.

I appriciate the link to the Bosch unit. I am a part time HVAC contractor. Full time engineer. I will use Rheem/Rudd due to supply house that I use. Contractor pricing... I can get 5T cond, 5T airhandler, heat strips and lineset for the price of the Bosch inverter. Thanks again.

20kw draws 107 amp. I think 25kw draws 132 amp... Have 200 amp dedicated service.

I thought that too. Friend/manager of the supply house has about talked me out of HP. Its a shop... I would have to get creative to lockout heat strips unless temp is below x* ect. I can do it, but I worry about trying to get 10-20* temp rise quick with only HP. Maybe use resistance to get temp rise and HP to maintain.

Will continue to think about this. Less than $500 difference in materials.

Hopefully this build can help you. Mini splits are out. Not going to use them. I have all tools and knowledge to commission a traditional split system. I was more on the fence straight resistive or heat pump.

Roll ups do ****. Had I known this, I'd had it framed at 14 ft and used a 16 ft door!

CT

i said 125A because of the 80% continuous deal. 200A gets you 160A - 100A = 60A left for all your stuff while the heat is on. that's workable... but not ideal.

you can get a complete 5 ton system sans labor for $2500? that's sweet.

re: lockout controls: look at the honeywell prestige stat with OAT. stat configurable recovery and customizable aux heat lockout/dual fuel config. it basically does all the things for 3H/2C setups.

nsula_country · Oct 27, 2018

u3b3rg33k said:
i said 125A because of the 80% continuous deal. 200A gets you 160A - 100A = 60A left for all your stuff while the heat is on. that's workable... but not ideal.

you can get a complete 5 ton system sans labor for $2500? that's sweet.

re: lockout controls: look at the honeywell prestige stat with OAT. stat configurable recovery and customizable aux heat lockout/dual fuel config. it basically does all the things for 3H/2C setups.

Load management may be required. 25kw gets up there... Other electrical loads are 24 four lamp T8s inside, 12 four lamp T8s outside. 5hp compressor. Welder. Proposed 18kw or 27kw tankless water heater. 1 freezer, 1 keezer, 2 fridges... Thats about it. Should have went with a 320 amp service like the house. Those with cheap and abundent gas service look at a 320a service like its a distribution substation!

If I use the 3 into 1 jumper it will require a 150 amp 2 pole 4 space breaker and 2/0 Al or 1/0 Cu (or was it 3/0 and 2/0?). If I run 3 separate circuits it is 50a, 45a, 45a. 20kw requires 60a and 50a or a 2 in 1 jumper and a 100 a bkr. 5T condenser specs a 50a bkr. Going to spend some coins on THWN...

If 25kw is used, will probably wire in a selector switch to toggle between 2 or 3 strips. Reserve 3rd strip for **** cold days.

Rheem/Ruud actually has a part number for a 30kw 1ph heat strip... :shocking:

That will stretch the legs of a 200 amp service! Local branch or the warehouse of the supply house we use don't even show a 25kw or 30kw in stock. 20kw most common (in the south) for a 5T system.

When I said creative that was including a OAT sensor. Not sure if the RP14 condenser has one on board standard. Can be field installed I'm sure. If I go heat pump, will definatly use an adjustable OAT switch to lock out strips. Except for defrost to prevent cold air sandwich.

Haven't used the premium Honeywell stats. Mostly use PRO1 and Emerson stats. Really wanted to use an Emerson Sensi, but 50* is lowest SP

A little higher SP than I want for freeze control.

Looked at quote again. A little over $2800 WITH about 9% tax.. Can use a lot of electrons before LP gas installation would break even. Natural would possibly cost over $10k just to get a line to the shop, over 1/2 mile run from street.

Still questioning HP vs straight resistive.

CT

rtz · Oct 27, 2018

Would 1/2 mile of plastic pipe cost $10k?

nsula_country · Oct 27, 2018

Due to pressure drop over about 3000' of run, I calculated either 2" or 2.5" pipe required to support a large furnace. Gas co requires the piping be run by contractor only. I have had it quoted in the past when we built our house in 2011. It was well over $10k. Shop is 700 ft further.

In 2006 we bought our 1st rental unit and moved it to one of our lots. We were quoted about $2000 to install about 120 ft of gas line and $800 meter deposit for a 16x80 MH. I replaced the NG furnace with a 15kw furnace. Never looked back. Tenants like having 1 less deposit to put down.

Not to mention one of our rental houses (existing service) is the last meter on the line. A small line. NG is a luxury in some areas...

CT

u3b3rg33k · Oct 27, 2018

nsula_country said:
Load management may be required. 25kw gets up there... Other electrical loads are 24 four lamp T8s inside, 12 four lamp T8s outside. 5hp compressor. Welder. Proposed 18kw or 27kw tankless water heater. 1 freezer, 1 keezer, 2 fridges... Thats about it. Should have went with a 320 amp service like the house. Those with cheap and abundent gas service look at a 320a service like its a distribution substation!

If I use the 3 into 1 jumper it will require a 150 amp 2 pole 4 space breaker and 2/0 Al or 1/0 Cu (or was it 3/0 and 2/0?). If I run 3 separate circuits it is 50a, 45a, 45a. 20kw requires 60a and 50a or a 2 in 1 jumper and a 100 a bkr. 5T condenser specs a 50a bkr. Going to spend some coins on THWN...

If 25kw is used, will probably wire in a selector switch to toggle between 2 or 3 strips. Reserve 3rd strip for **** cold days.

Rheem/Ruud actually has a part number for a 30kw 1ph heat strip... That will stretch the legs of a 200 amp service! Local branch or the warehouse of the supply house we use don't even show a 25kw or 30kw in stock. 20kw most common (in the south) for a 5T system.

When I said creative that was including a OAT sensor. Not sure if the RP14 condenser has one on board standard. Can be field installed I'm sure. If I go heat pump, will definatly use an adjustable OAT switch to lock out strips. Except for defrost to prevent cold air sandwich.

Haven't used the premium Honeywell stats. Mostly use PRO1 and Emerson stats. Really wanted to use an Emerson Sensi, but 50* is lowest SP A little higher SP than I want for freeze control.

Looked at quote again. A little over $2800 WITH about 9% tax.. Can use a lot of electrons before LP gas installation would break even. Natural would possibly cost over $10k just to get a line to the shop, over 1/2 mile run from street.

Still questioning HP vs straight resistive.

CT

the minimum heat setpoint on the honeywell I have is 40F. that's on the thermostat or via the app. it's the reason I chose it for my garage. mine's a bit smaller, so I'm re-wiring a window heat pump/AC to have defrost controls (came with heat strips too). total output will be about 10kBTU.

meathooker · Oct 28, 2018

rtz said:
Would 1/2 mile of plastic pipe cost $10k?

The local gas company quoted $10,800 for 1,000’ of 2” line. This included a bore under a two lane road to connect the main.

yeldogt · Oct 28, 2018

For the small cost difference HP is going to be 3x cheaper to operate over resistance .. so it's math that determines the route you go.

The need for ductwork is directly related to the variations in the building envelope -- typically in a garage the doors are the big leakers and unless you have conditioned air by the doors you will notice .. if you work in that area. With a very tight well insulated open space the need for ductwork drapes .... there are just too many variables.

My curet space is SIP's with single point heating .. my other uses conventional split with spiral ductwork.

nsula_country · Oct 29, 2018

meathooker said:
The local gas company quoted $10,800 for 1,000’ of 2” line. This included a bore under a two lane road to connect the main.

Thanks meathooker for providing this. Shows that gas is only cost effective if the structure has gas service in place. I would need about 3000' of 2"+ line. ($20-$30k+)

This weekend I performed a swap out consisting of a 100k 80% furnace and 5T A/C. Original equipment was early 80's vintage. If gas is in place, no brainer...

Gas is one of the cheapest heat options, in certain locations. It's not cheap if it's not already in place. It's easy to throw stones at electric heat. But if the only infrastructure in place is electric service, sometimes it is the best option. $10,800 will buy A LOT of heat produced by electricity.

yeldogt said:
For the small cost difference HP is going to be 3x cheaper to operate over resistance .. so it's math that determines the route you go.

The need for ductwork is directly related to the variations in the building envelope -- typically in a garage the doors are the big leakers and unless you have conditioned air by the doors you will notice .. if you work in that area. With a very tight well insulated open space the need for ductwork drapes .... there are just too many variables.

My curet space is SIP's with single point heating .. my other uses conventional split with spiral ductwork.

HP is more economical, at certain temps, much more economical! I am leaning that way. It's not a hardware cost matter. It was just more of a if its not used daily is it worth the added complexity. I have installed several HP's. Once charge is balanced between both modes, they are trouble free.

I just did not know how a HP would handle trying to raise temp 20*-30* at once. Electric will do so no problem. Haven't ever seen a HP in a shop or barn before!

I have contemplated using spiral down center or snaplock... Eventually. For this season though I believe we just need heat. 4 ft supply plenum and some large registers.

Thanks guys!

CT

u3b3rg33k · Oct 29, 2018

I can't see a reason why a heat pump would have operational problems bringing up room temp 20-30F - if you're going from 40F room temp to 60F or 70F, it'll have better efficiency when it starts out due to lower delta T, so keep that in mind. best to do a load calc, find out what your loss is at your idle setpoint and your ideal setpoint, then figure out how fast you want to heat it up.

if you're looking at 5 ton heat pumps, I would suggest two stage units if you're not looking at some sort of inverter system. being able to switch down from 60k to 40k or so would be nice. you could probably get away with two of those on separate thermostats if 60k isn't big enough. that'd give you capacity from 40k to 120k, depending on how you manage your thermostats.

I've always maintained that too much capacity (i.e. a 60k-80k 80% NG heater in a small home garage) will not heat items fast enough and do a lot of short cycling once the air reaches temp (meanwhile your 8000+ lbs worth of vehicles need another hour or two to reach temp. unless you've got a big shop or lots of door opening, oversizing is just as bad in a garage as it is in a house.

nsula_country · Oct 30, 2018

Understand where your coming from. This building is about 42,000 cubic feet volume. 5T and 57k-85k heat is marginal (HP only through 25kw incuded). Not looking to condition like a house, just temper the envelope.

I have ran numbers on load calc. Variables with doors, insulation, and leakage put AC between 5T and 12T.

I plan to install a 5T HP with 20-25kw strips to start. See how this performs for a heat/cool season. Also going to frame in a 18×24x9 room inside main building within a year. This reduces cubic footage by 4300 (37700 cu/ft)... If needed, I'll add another 3-5 Tons of HP (without heat strips). Conditioned room will have separate split or mini split HP.

If space was better sealed, I'd look into 2 stage and variable speed. This building is drafty. 14 SEER equipment vs 20 SEER equipment will not have ROI vs monthly statement. I'd be better off with a 14-16 SEER 5T/5T or 5T/3T for close to same price as 5T VS or Ultratech compressor Premium SEER system... Price jumps almost 2x.

Don't get me wrong, VS and 2 stage have a place. In a tight structure... In a drafty envelope, they would never modulate. Negating the possible energy savings. I will never leave the Tstat at 75 year round.

Last, I completely agree on oversizing. Cools/heats too quick. Short cycles without conditioning the objects in the space. Wish i had 3ph. 7.5-10T HP would be ideal...

Thanks. I'm going HP. If it cannot keep up with demand, I'm only out several $100 over initial investment. Heat strips will heat at expense of Kwh.... Add 2nd split HP later.

CT

nsula_country · Nov 1, 2018

Going to buy the equipment next week or 2 for the project. HP is about $200 more...

SO, going with 5T 14 SEER HP, 20kw heat strips. It's in stock and the best bang for the buck. I can get 25kw heat strip online, but at almost 3x what I can get the 20kw for. Not to mention I really don't want to run a 150A circuit for the 25kw...

The 20kw will output 68k. HP will output 47* 57000 btu, 17* 35800 btu. I doubt I will be in the shop much below freezing! Not going for 70* 24/7. Just comfortable while working.

I'll start a new thread in "Heating and A/C" to document the build and post the results of how it performs as an intermittent cooling and heating source.

CT

nsula_country · Nov 3, 2018

Jimmy2kan said:
Any input to this plan of action?Would 1/2 mile of plastic pipe cost $10k?

I'm not sure how what you quoted and what you are asking are related?

Yeldogt was comparing effectiveness of electric useage between resistive heat pump. Also that ducting options are determined by the building and its useages. Also his space built of SIP panels.

As for piping, yes. If I hired out running Natural Gas to our shop it would be over $10k. Maybe as high as $30k. Now if I bought the materials, rented a ride on trencher, did it myself, maybe under $10k. Distance is about 3000 ft. Would require 2"-3" piping.

But I'm not even concerned. NG Gas is off the table. Not going to even think about it... Don't want to deal with LPG either. Something eles to mow around and price swings too much.

Thats why I installed a full 200 amp service to the shop. Even though most people think 60-100 amps is all that a small shop needs.

Decision is 5T HP, 20kw heat strips (68k btu). Starting on it next week. I am installing it. Should be under $3000 total for all new hardware and electrical. Will have pictures.

CT

dcg9381 · Nov 5, 2018

nsula_country said:
SO, going with 5T 14 SEER HP, 20kw heat strips. It's in stock and the best bang for the buck. I can get 25kw heat strip online, but at almost 3x what I can get the 20kw for. Not to mention I really don't want to run a 150A circuit for the 25kw...
CT

What this run you?

nsula_country · Nov 5, 2018

I figure equipment, build return plenum, conduit, wire, supply plenum and about 20 ft of duct work with registers should be under $3500. I am the labor.

CT

dcg9381 · Nov 6, 2018

Thanks.. Look forward to reading more about it!

Advise: 40x60x17 GOING FULL HVAC!

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