Ac not cooling shop?

[Hobby_Man22]

I have a 30x50-12 red iron steel building and put r30 insulation in. It's about 83 degrees outside and it's barely keeping the shop at 78 degrees. The heater worked fine over the winter. How come the a.c. doesn't work as good? It's a good man 5 ton 14 seer heat pump system 60,000 btu. I used my infrared thermometer to measure the surface temp of the vent and it's at 64 degrees. I didn't measure the actual air temp.

 

[Hobby_Man22]

So I don't think it's the system. The only thing I never did was insulatenthe two steel bay doors. Is that the problem or Is this system undersized?

 

[Hobby_Man22]

It was 87 in the shop when I walked in and turned it on. Cooled it to 79 in about 1h:20min Hasn't cooled much more since then and it's been on for about 2 more hours.

 

[Bert_]

Did you get the walls and ceiling insulated and air sealed? Last I remember there were still gaps you were seeing daylight through...

If it was 87* in there it's going to a good part of a day to cool it down. 64* air from the vents is fine considering the return air temperature is in the 80's

 

[samss]

Is the evaporator coil frozen?

 

[Hobby_Man22]

Is the evaporator coil frozen?

I don't think so. It's putting out cool air. It did finally reach the target temp of 76 degrees after 2h: 45m for a total drop of 11 degrees. So maybe it's not too bad after all. It shut off for 8 minutes and kicked back on.

 

[56Mark]

Do you just turn it on when you are out there? It might be more effective to let it run and bump it up to 78 or so when you leave, then it won't have such a heat load to deal with. Depending on how full the building is with stuff, you can have a lot of thermal mass that has to cool down too.

 

[Hobby_Man22]

Pretty much because It only shuts off for 10 minutes between cycles. Which means it will do two 25 minute cycles per hour. My house doesn't do that, I'm afraid I'll have a $500 electric bill if I just leave it running.

 

[Bert_]

Pretty much because It only shuts off for 10 minutes between cycles. Which means it will do two 25 minute cycles per hour. My house doesn't do that, I'm afraid I'll have a $500 electric bill if I just leave it running.

It only shuts off for 10 minutes because everything in the shop is still hot. It will take most of a day to get it cooled off it everything is almost 90*

Let the thing run for a couple days. Before that happens we know nothing as far as whether it's working right or not.

 

[Terry D]

Is this system new or existing, It is not going to cool it down until the humidity is lowered

 

[Hobby_Man22]

It's a new system installed back in November of last year.

 

[BillK]

Keep in mind that when you shut it off and it is 83 degrees outside, you have a HUGE concrete slab and all of the metal and whtever is in the building that is also at 83 degrees. So when you turn the ac on it has to get all of that mass cooled down. WHen I put AC in my business shop 25 years ago my HVAC guy told be to set the thermostat and leave it alone. I have two seperate stats, one for the heater and one for the ac. They get left alone year round.

Like the others have said, leave it alone for a week and then see what happens.

Insulating the doors would probably help some but even more important is making sure they are very well sealed when closed.

 

[Hobby_Man22]

Yeah I bought some door brushes to seal the doors off. Haven't installed them yet.

 

[American Locomotive]

We have told you multiple times now that you can't assess system performance until you've finished insulating and sealing your building!

Seal the garage doors and give the system some time to cool everything in your building off. Plus, depending on the size of your garage doors, you might have an up-hill battle anyways. Uninsulated steel doors are basically just going to be acting like giant radiators.

 

[Hobby_Man22]

American Locomotive you GOTTA chill bro. This heat pump would heat the building 25 degrees warmer than outside temp, now that things are reversed and it's getting hot outside it's like it can barely keep it 7 degrees cooler inside the shop. So I'm just a bit worried because it gets to be 100 degrees where we are and it's only like 83 so far. Usually it's a lot hotter this time of year, but it rains everyday.

 

[Hobby_Man22]

Did you get the walls and ceiling insulated and air sealed? Last I remember there were still gaps you were seeing daylight through...

If it was 87* in there it's going to a good part of a day to cool it down. 64* air from the vents is fine considering the return air temperature is in the 80's

Yes the only thing left is the doors.

 

[Hobby_Man22]

I checked everything later that night with an IR thermometer and found the slab was still at 80 degrees. So like the other poster said, it may be the slab.

 

[Hobby_Man22]

I have it set to 75 degrees right now and will leave it to see how it does the next few days.

 

[Bert_]

American Locomotive you GOTTA chill bro. This heat pump would heat the building 25 degrees warmer than outside temp, now that things are reversed and it's getting hot outside it's like it can barely keep it 7 degrees cooler inside the shop. So I'm just a bit worried because it gets to be 100 degrees where we are and it's only like 83 so far. Usually it's a lot hotter this time of year, but it rains everyday.

I think I speak for everyone when I say it gets old repeating the same stuff over and over. And let's be honest we've all said the same stuff many times over several of your threads. So I don't think you get to tell anyone to "chill".

Just let the thing run and then report back. If you don't have the doors sealed up and insulated don't expect it to do a great job.

 

[Hobby_Man22]

I think I speak for everyone when I say it gets old repeating the same stuff over and over. And let's be honest we've all said the same stuff many times over several of your threads. So I don't think you get to tell anyone to "chill".

Just let the thing run and then report back. If you don't have the doors sealed up and insulated don't expect it to do a great job.

I kind of disagree. Back 6 months ago when I was asking this question he would bombard everything I asked. I even made updated posts and said hey i got the insulation installed it's a lot better than it was, but still runs often.... Thank you guys for the help on this question. At least 3 or 4 people gave me some helpful info this time before locomotive came in to ruin the party. I'll work on sealing off the bay doors. As far as insulation is concerned I'm not really sure how to go about that. I know they have some 1/8" thick radiant barrier type stuff that i guess I can install and still be able to roll the doors up. I think it will look like **** though.

 

[Hobby_Man22]

Would have been better if roll up insulated doors were installed to begin with, but the building was already there when I bought the place.

 

[Black Oak]

almost comical !`

 

[yeldogt]

As we have said before -- this is all about BTU's -- either going in or coming out.

Just like you can't take a cold building filled with cold objects and have them heat up it an hour -- the reverse is true with AC.

You will be best to set the system at 80 and allow it to get everything down to that temp -- allow it to stabilize and go from there.

You may be able to drop it from 80 and be comfortable with it running. No system is going to be able to take a hot building and drop it much in the afternoon .. that's the hottest part of the day. The building is taking solar gain and the unit is working with the hottest outside air.

Also where are the outlets? --- we seem to have many here who think tall ceiling ... AC and ceiling fans are a good mixture. You want to stratify the AC down to where people are ... not mix all the air in the room. Mixing air = cooling air = more energy used

 

[Hobby_Man22]

almost comical !`

Good it's what I'm here for. Glad you're enjoying yourself

 

[Hobby_Man22]

As we have said before -- this is all about BTU's -- either going in or coming out.

Just like you can't take a cold building filled with cold objects and have them heat up it an hour -- the reverse is true with AC.

You will be best to set the system at 80 and allow it to get everything down to that temp -- allow it to stabilize and go from there.

You may be able to drop it from 80 and be comfortable with it running. No system is going to be able to take a hot building and drop it much in the afternoon .. that's the hottest part of the day. The building is taking solar gain and the unit is working with the hottest outside air.

Also where are the outlets? --- we seem to have many here who think tall ceiling ... AC and ceiling fans are a good mixture. You want to stratify the AC down to where people are ... not mix all the air in the room. Mixing air = cooling air = more energy used

I have a dehumidifier that keeps the building at 60 percent humidity. Turn the a.c. on and it will drop to 48 percent after a couple hours or so.

 

[American Locomotive]

I kind of disagree. Back 6 months ago when I was asking this question he would bombard everything I asked. I even made updated posts and said hey i got the insulation installed it's a lot better than it was, but still runs often.... Thank you guys for the help on this question. At least 3 or 4 people gave me some helpful info this time before locomotive came in to ruin the party. I'll work on sealing off the bay doors. As far as insulation is concerned I'm not really sure how to go about that. I know they have some 1/8" thick radiant barrier type stuff that i guess I can install and still be able to roll the doors up. I think it will look like **** though.

I stated the same things as everyone else.

6 months ago, you came to us with a problem. We told you to insulate and seal. You come back a few days later and say "It's working better, but it's still not great". We then ask you if you finished sealing and insulating. Your answer was "Well no, I can still see some day light around the top of the building". Then we told you to finish sealing and insulating before questioning the system performance. This repeated again. We then told you then that your giant, un-insulated, unsealed steel doors will make conditioning the space a challenge.

Now here we are 6 months later. You're complaining about your system performance, and your doors are still un-insulated and un-sealed. I'm not trying to ruin any party - but you're just not listening. It's like complaining your plumber that your bath tub isn't filling as fast as you want when you still have the drain 1/2 way open.

The door seals will help tremendously, and if you just have plain uninsulated steel doors - there isn't much you can do without changing them out for insulated doors (which you probably should if you want the space conditioned). You can get a plastic curtain to hang in front of the doors which will create a little bit of a thermal barrier.

 

[yeldogt]

I have a dehumidifier that keeps the building at 60 percent humidity. Turn the a.c. on and it will drop to 48 percent after a couple hours or so.

In the summer when you have AC need you should be using the AC to lower humidity. The dehumidifier is lowing humidity -- but it's adding heat that the AC now has to bring down. Total waste ..... more $$ spent.

Only use the AC --- the dehumidifier is only for times of the year when you don't need AC.

 

[Hobby_Man22]

I need to seal the building up more. It's just running non stop. I sure hope it's not the system that's undersized. It puts out 60,000 btu

 

[yeldogt]

A system running non stop on a hot day is normal ... it not using any more energy vs a smaller one running less.

You can't expect a system to bring down the temps in an house or two ... especially in the heat of the day. get that dehumidifier and set the unit to a higher temp .... let it run.

seal up the building .. the heat and any moisture from outside is going to cost you to remove.

 

[Hobby_Man22]

83 degrees outside isn't hot though. The ac in the house will have like 20 minutes in between intervals set at 76

 

[Bert_]

83 degrees outside isn't hot though. The ac in the house will have like 20 minutes in between intervals set at 76

When is the last time you let the house get up to 87*? Guessing never... You can't compare because you need to let it run for at least a day to get all the steel and concrete cooled off.

 

[Hobby_Man22]

I let it run from yesterday afternoon to this afternoon. Once the sun came out and it got up to 83 degrees it ran non stop.

 

[Hobby_Man22]

For at least 2 hrs

 

[Hobby_Man22]

When is the last time you let the house get up to 87*? Guessing never... You can't compare because you need to let it run for at least a day to get all the steel and concrete cooled off.

I don't think it ever would get to 87. It currently gets up to about 80. I'm one of those guys that turns the ac up to like 82 when I leave for the day, then back down to 73 when I go to bed. Takes about an hour to knock it down.

 

[Hobby_Man22]

Makes me wonder if I need more than R30 on the ceiling. I don't think it should be getting hotter inside the building than outside. It showed 80 degrees on the insulation and 125 degrees on the bare steel ceiling so it does something.

 

[Showkey]

What is the temperature of the inside of the metal door is the heat of the day ?

 

[Terry D]

So this is the first cooling season for the system, so you have nothing to compare it to. Was the system installed by a contractor. If so, have him come back out to look at it. There are a lot of things that could be wrong. Is there ductwork. Is there condensate coming out of the drain. Is your suction line sweating outside. Is your filter clean. Maybe post some pictures of the system.

 

[Showkey]

^^^^^^^^^^^^^^^^^^

Here’s a link to just part of the continuing story line referred to several prior post in this current thread.

65 in the shop when it's 33 outside?

I went to the shop today turned on the heat pump and it went from 48 to 69 in about 5hrs I think. Then the temp dropped to 33 and it when down to 66 degrees and stayed there. I have a good man 5 ton unit 60,000 btu. I just about have all the insulation up on the roof. Most is up on the walls...

www.garagejournal.com

 

[Yankeefarmer]

Hobby_Man, two things you have mentioned interest me. The first is that your slab temp was/is 80 degrees. The second is that you mention it’s normally warmer there, but it’s been raining “every day.” When you started this thread, was it the first time in days or weeks that you had used your system in cooling mode? Reason I ask is that when people heat their buildings using in-slab heating, they don’t use slab temperatures nearly that warm, and they are comfortable. I suspect your slab is heat-soaked, and that makes the air temperature you measure feel warmer than it would in the absence of a hot slab. Following the advice others have given regarding letting the system run for a couple days shooting for inside temps in mid to upper 70’s and measuring slab temperature each day may shed some light on this. It’s pretty clear that your unsealed, uninsulated steel days aren’t helping the situation. Are they in direct sun? Does any part of your building ever get any shade from trees, or is it full sun all day long?

 

[Hobby_Man22]

So this is the first cooling season for the system, so you have nothing to compare it to. Was the system installed by a contractor. If so, have him come back out to look at it. There are a lot of things that could be wrong. Is there ductwork. Is there condensate coming out of the drain. Is your suction line sweating outside. Is your filter clean. Maybe post some pictures of the system.

Is that line supposed to be cold? It was sweating and draining out the condensate line, but that copper line was like 80 degrees when I shot it with the temp gun. I thought it's supposed to be cold?