I built a welding shop on my property. It's 196sq ft with a peaked roof with the center beam 3 ft above the 14x14 shop. Hope that makes sense. I bought a 16000 btu ac,heat and humidifier portable unit. I insulated the ceiling with r38 and the walls with r13. I have a metal roof. I figured the ac unit would easily cool the shop to 76-78 even on a 90s degree day because it is strong enough to cool a space 3 to 4 times the size of my shop. But nope. While tig welding for 9 hours the other day the temp in the shop could not get below 82. Would my tig welder and water cooler put off so much heat to stop the ac unit from cooling any lower or do you think my unit is not very good? Trying to decide to take it back or not. It was 86 degrees outside that day. All help appreciated!
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noddybrian
- noddybrian
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There are likely better qualified guys here - but the way I'd look at it is your AC unit is advertised to suit a given size room / building - but that's usually residential which has more thermal insulation properties than a workshop / shed - the tin roof once hot will retain a huge amount of heat - now your adding the welding heat into the enclosed space - you don't mention how much but even a smallish machine is likely 4 > 5 kilowatts - seems unlikely a small domestic AC can cope with that - they are only a heat pump - there will be a maximum heat energy per hour a given size unit can cope with - also the units room size rating tends to be for a given heating capacity & the cooling capacity is generally less - another thing is positioning of the unit & if it's been in a shop setting for any length of time the matrix may have a considerable amount of airborne contamination stuck to it reducing efficiency - if I remember BTU > Kw correctly 16000 is like 4.5kw or close so in ideal conditions the unit will likely cope with removing the welding heat input but have little or no effect on ambient temp - obviously the exact % time your actually welding effects this but on the whole I'd think the unit is probably working close to it's rating - I don't know a scientific way of testing but why not leave the shop shut up with the AC on - no other influences then after say half a day take an inside & outside temp reading - gut feeling is you needed a bigger unit due to how your using it - I'm fairly sure there are at least a couple of HVAC members so with luck someone will chime in - on the bright side it's still better than mine - I leave the door open !
- Otto Nobedder
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Blaze,
I'm guessing you may have "too much" AC... Leaving it off until you're ready to weld, so the humidity builds in the room, then freezing up the evaporator coil when you decide to take the room to 72* because the evaporator get so cold so quick.
When it refuses to cool, try taking the filter and front cover off the machine, and see if it's frosted nearly solid. If it is, you may not be able to remove the cover or filter.
If so, leave it in (or a few hours before you plan to work, set it in) dehumidify mode set at, say 85*, to keep the moisture down.
Steve S
I'm guessing you may have "too much" AC... Leaving it off until you're ready to weld, so the humidity builds in the room, then freezing up the evaporator coil when you decide to take the room to 72* because the evaporator get so cold so quick.
When it refuses to cool, try taking the filter and front cover off the machine, and see if it's frosted nearly solid. If it is, you may not be able to remove the cover or filter.
If so, leave it in (or a few hours before you plan to work, set it in) dehumidify mode set at, say 85*, to keep the moisture down.
Steve S
Ace,
Haier 14000 btu ac,heat and humidifier. Model HPN14XHM. Brand new. My shop is 14x14 with a ceiling peak of 11 feet. No flat ceiling at wall height. It's open to the peak. I have r13 in walls and r38 up on ceiling. R38 is up against metal roofing. Thx!
Haier 14000 btu ac,heat and humidifier. Model HPN14XHM. Brand new. My shop is 14x14 with a ceiling peak of 11 feet. No flat ceiling at wall height. It's open to the peak. I have r13 in walls and r38 up on ceiling. R38 is up against metal roofing. Thx!
Everlast 250EX
Everlast I-Mig275 w/ Alum Spool Gun
Everlast Plasma60
Everlast 300 Water Cooler
Everlast I-Mig275 w/ Alum Spool Gun
Everlast Plasma60
Everlast 300 Water Cooler
So you don't tig weld aluminum? Thanks Blaze. Just a couple more questions if may.
I would like to know where the unit is mounted on your wall. Is it approximately in the middle of the wall? If not what is the distance to the nearest corner from the middle of the unit?
What is the distance from the top of your unit the the top of your vertical wall?
I would like to know the height of your wall too please. Open roof space was good information.
I would like to know where the unit is mounted on your wall. Is it approximately in the middle of the wall? If not what is the distance to the nearest corner from the middle of the unit?
What is the distance from the top of your unit the the top of your vertical wall?
I would like to know the height of your wall too please. Open roof space was good information.
Flat out like a lizard drinkin'
Coldman,
Portable unit. Closest corner 6 ft. Distance from top of machine to top of wall 5ft but no drop ceiling. Wall height 8 ft.
Portable unit. Closest corner 6 ft. Distance from top of machine to top of wall 5ft but no drop ceiling. Wall height 8 ft.
Everlast 250EX
Everlast I-Mig275 w/ Alum Spool Gun
Everlast Plasma60
Everlast 300 Water Cooler
Everlast I-Mig275 w/ Alum Spool Gun
Everlast Plasma60
Everlast 300 Water Cooler
OK Blaze, here we go:
FYI : Gazetted summer design conditions for Norfolk (nearest I could get to Gloucester, but still coastal) is 91F dry bulb/ 76F wet bulb. Nothing extreme here, standard ratings apply.
Your insulation complies with your ASHRAE Standard 90.1 (one less thing...).
The unit you have selected is sufficient in cooling capacity for your floor area if it had a standard 8ft ceiling. Including roof space into the occupancy has increased the room volume significantly and your unit is therefore under capacity.
Also remember that hot air rises and your unit is low to the floor blowing cold air at low level and therefore cooler air returning to the unit. - it never gets the hot air returning to it. Heat builds up at the peak of your roof and as more hot air rises the heat pocket increases and lowers in stratification until you feel it getting hot. This is the time you feel the unit may have lost it plot.
The solution is therefore two fold.
1st. The cooling capacity of the unit has to increase to not less that 20,000BTU/hr
2nd. The unit has to be able to get the hot air to return to it. This is more difficult. Personally I think the portable style of unit is inappropriate for this application, more suited to spot cooling in bedrooms and lounges where people are lower to the floor being either seated or laying down. A better choice would be a split air con mounted as high on the wall as possible. These type of units blow more air around on high speed which would help break up the stratification. A pedestal fan blowing up would also help break up the stratification and allow the the cold and hot air to mix. You can try this as an experiment to see what difference it makes to your existing unit.
Cheers.
FYI : Gazetted summer design conditions for Norfolk (nearest I could get to Gloucester, but still coastal) is 91F dry bulb/ 76F wet bulb. Nothing extreme here, standard ratings apply.
Your insulation complies with your ASHRAE Standard 90.1 (one less thing...).
The unit you have selected is sufficient in cooling capacity for your floor area if it had a standard 8ft ceiling. Including roof space into the occupancy has increased the room volume significantly and your unit is therefore under capacity.
Also remember that hot air rises and your unit is low to the floor blowing cold air at low level and therefore cooler air returning to the unit. - it never gets the hot air returning to it. Heat builds up at the peak of your roof and as more hot air rises the heat pocket increases and lowers in stratification until you feel it getting hot. This is the time you feel the unit may have lost it plot.
The solution is therefore two fold.
1st. The cooling capacity of the unit has to increase to not less that 20,000BTU/hr
2nd. The unit has to be able to get the hot air to return to it. This is more difficult. Personally I think the portable style of unit is inappropriate for this application, more suited to spot cooling in bedrooms and lounges where people are lower to the floor being either seated or laying down. A better choice would be a split air con mounted as high on the wall as possible. These type of units blow more air around on high speed which would help break up the stratification. A pedestal fan blowing up would also help break up the stratification and allow the the cold and hot air to mix. You can try this as an experiment to see what difference it makes to your existing unit.
Cheers.
Flat out like a lizard drinkin'
- Otto Nobedder
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How about a ceiling fan, to recirculate the hot humid air from the top and generally "stir" the space? Set on "up" draw, to disperse welding fumes...
Blaze:
I can't recommend a brand to you in the USA as I am down under. I can tell you what I tell people here that ask, if it is a well known brand that is prepared to put a 5 year warranty onto their equipment, the quality must be there. Other things to look for:
- get an inverter model
- look for lowest noise for both indoor and outdoor units if that is important to you
- look for lowest power consumption
- look for highest airflow from the indoor unit. This may be the most important.
- get a refrigeration technician to install it.
Steve:
ceiling fan would work a treat as long as it shifts enough air to stir things up.
I can't recommend a brand to you in the USA as I am down under. I can tell you what I tell people here that ask, if it is a well known brand that is prepared to put a 5 year warranty onto their equipment, the quality must be there. Other things to look for:
- get an inverter model
- look for lowest noise for both indoor and outdoor units if that is important to you
- look for lowest power consumption
- look for highest airflow from the indoor unit. This may be the most important.
- get a refrigeration technician to install it.
Steve:
ceiling fan would work a treat as long as it shifts enough air to stir things up.
Flat out like a lizard drinkin'
Just one more thought.
If you have gable walls, mount the indoor unit high on a gable and you don't need any other fans. I've done this a few times with great success.
If no gables, mount on wall as previously described and some sort of extra fan required.
If you have gable walls, mount the indoor unit high on a gable and you don't need any other fans. I've done this a few times with great success.
If no gables, mount on wall as previously described and some sort of extra fan required.
Flat out like a lizard drinkin'
Captainbeaky
- Captainbeaky
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A good way to prove out this would be to stir up the air in your workshop with a fan...
Something of decent size, and angled up to stir up the air and stop stratification...
Something of decent size, and angled up to stir up the air and stop stratification...
noddybrian
- noddybrian
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