|
Just moved my company into a new office/warehouse thing. Has what looks to be a heat pump to my amateur eyes. Simple condenser unit on the roof and handler inside above the office. Only 900sqft of space to condition. The space came with a super basic non programmable thermostat. Set it to a temp and it leaves it there 24/7. With this thermo the unit would come on and off as expected and keep the temp around 76, our setpoint. After seeing my first electric bill with the unit just left at 76 all the time I installed a programmable thermostat set for business hours. Since then the following has been observed: - The unit manages to maintain my "away" temp of 85 running ~20 minutes an hour. Seems a bit much but ok... - Despite a setpoint of 76 the unit brings the temp in the office down from 85 to 79 during business hours. - The unit never reaches 76 and ran for 9 hours straight attempting to do so until the biz day was over and it set back to the away temp of 85. - It then maintained 85 just fine running ~20 minutes an hour the whole night with no more than a 1 degree variance from 85. What the gently caress? What the hell could I have f'd up simply changing a thermostat that would have the thing cool but not cool efficiently? Wouldn't it just be i hooked up the wire right and it cools or I didn't and it blows but doesn't cool? How the crap did I end up with it "kindof" cooling? I'd call an HVAC guy out to look at the system except this is 100% correlated with my change of thermostat. On the old one it always reached the set point within reasonable time and would then get to turn on and off only as needed. I'd say maybe the sensor in the thermostat is bad but if that were the case we'd be freezing our butts off. Instead it genuinely was indeed ~79 degrees in the office. We're in texas so we'd know darn quick if it wasn't cooling at all but on the other hand if it was working normally after 9 hours of continuous cooling we'd all be frozen solid. Edit: Fun fact, the AC unit was inspected less than a month ago upon move in and passed, so it's not like it's been on the roof for 20 years without service. chedemefedeme fucked around with this message at 20:16 on Jul 17, 2016 |
#
¿
Jul 17, 2016 20:13
|
|
|
|
| # ¿ Apr 19, 2024 11:42 |
|
|
some texas redneck posted:Make sure you didn't connect Rh or W to Rc or Y; doing that would be calling for both heating and cooling. Can a heat pump even run heat and cool at once? It would make a lot of sense if they were fighting each other except that I didn't think heat pumps worked that way. I did test putting it into heat mode after install and it blew warm air. It also blew cool air in cool mode..or so I thought. Apparently not cool enough...
|
|
#
¿
Jul 17, 2016 23:34
|
|
|
Motronic posted:Only if it's a gas unit. Actually, I take that back......I suppose on a pure heat pump that on some units you could have the electric resistance coils (emergency heat) running along with AC. The unit would not run for 9 hours before the new thermo to hit the temp. It would run, say, 40 to 60% of any given hour during the hottest parts of the day..about normal for a unit that looks to be maybe 5 to 10 years old. When the heat was on it was lukewarm heat pump heat. I have one at my house and am familiar with how they work. Our mild winter (snows for real maybe once a decade..and melts the next day) in Austin, Texas means we have heat pumps installed left and right. My home system does have emergency heat coils. Unsure if the office install does or not. There were very few wires to hook up - less than at my house, if I recall correctly. No gas in this office .All electric appliances and hvac. I definitely did it with my thermostat install I just can't figure out how! angryrobots posted:My suspicion is that the building is poorly insulated, possibly a metal strip mall style structure in full sun with a bank of windows up front, and the change to an 85°F unoccupied setting happened at the same time that the outside temp is getting higher and holding until later at night. It's a tilt-wall style warehouse with insulated structure built inside of it. The high warehouse ceilings (~24ft) are also insulated. In the warehouse it gets up to maybe 95 on the hottest of days since we are on the east side of the building and not getting the worst of the sun. This is an easier job than the vast majority of AC units here in Texas have. It worked reasonably before I came and (apparently incompetently) installed the new thermostat. Lemme see if I was smart enough to take a photo of the old wiring before i screwed it up. chedemefedeme fucked around with this message at 00:50 on Jul 18, 2016 |
|
#
¿
Jul 18, 2016 00:44
|
|
|
Motronic posted:Other possibility: you sure it's not a multistage unit that you didn't set up right? I have no flippin idea if it's a multi stage. I don't even know what that means  Edit: I can tell you it's not part of something else in the building like a central chiller though. There's one small residential looking fan/coil unit on the roof and one air handler smaller than the one in my attic sitting on top of the office inside the warehouse. Between the two run the thin copper coolant lines you'd expect on a residential heat pump/ac. The unit is entirely standalone and serves only my office inside my segment of the warehouse. Found my pre-install pic. This is the back plate of the old thermostat before I removed it. Tell ya much? 
chedemefedeme fucked around with this message at 00:56 on Jul 18, 2016 |
|
#
¿
Jul 18, 2016 00:53
|
|
|
Thanks for looking at it. Good to know for sure I didn't make the wrong assumption about system type. I'd agree his explanation would seem likely except for the type of construction this is. It's an insulated warehouse with a freestanding, also insulated, office structure built inside of it. We're surrounded by other tenants on 3 sides and our one exterior wall faces east and so misses the heat of the day. The warehouse itself is often between 85 and 95. This AC has it easier than what most in texas have to deal with. At this point might it be safe to assume the inspection done by the landlord's contractor that the landlord would have had to pay for repairs from before the system was turned over to my responsibility was bull crap and that I should have the system serviced by someone actually motivated to find problems with it?
|
|
#
¿
Jul 18, 2016 01:13
|
|
|
So I don't get taken by whoever I call out to look at it what justifies undersized for an office of just 900sqft? I feel like I've had window units that could cool this much space faster than this. How might I get away here without buying a whole new/larger system but also not running the current one so hard? Anything I should be asking about? Should know to watch out for (common scams/grey practices)? Thanks for the advice so far.
|
|
#
¿
Jul 18, 2016 01:48
|
|
|
ExplodingSims posted:The other thing to consider, is what's in the building? Is this a store where you have lots of computers or people going in and out? I mean, if you're sucking in hot air every time someone opens the door, then yeah, that's going to contrubute. It's a private office with only 3 desks, one door to the outside world, and no windows. It's literally a 900sqft wood and sheetrock (w/ fiberglass insulation) office built inside of a 24ft high warehouse space, the remaining 2000sqft of which is the high ceiling warehouse. The "outside" unit is on the true roof, not inside the warehouse. ExplodingSims posted:Whenever we program a building's A/C, we usually don't go higher than 80*. Of course, this is in Florida, where the humidity will gently caress stuff up something awful. I went for 85 since that's what I do at my house. My house can recover from this lickedy split. The home probably half as old as this warehouse although the AC unit appears to be about the same age. It is cooler in the warehouse than it is outside my house at virtually all times. The warehouse containing our office structure, facing east and surrounded by neighboring units on 3 sides, never gets as hot as the outside air temp. Humor me this, though. Last night it got down to maybe 70 outside. My wifi thermostat's stats show it ran 30 to 40 minutes of every hour to maintain 85 degrees...is that still normal? I'm fine setting the "away" temp to 80 instead of 85 but I want to be sure I'm not wasting money if something else is wrong. Should it require more than 50% runtime to maintain 85 degrees in a 900sqft space with 3 desks in in the dead of night? There was literally not an hour the past two nights it didn't run at least 30 minutes all night long. chedemefedeme fucked around with this message at 03:34 on Jul 18, 2016 |
|
#
¿
Jul 18, 2016 03:32
|
|
|
Zhentar posted:The hot has to come from somewhere. If it's not from outside, and it's not from the sun, then where? We're big fans of those electric baseboards in Texas There are a few computers inside but nowhere near enough to be making any crazy heat. I'm sure the warehouse retains some daytime heating but I can go in there in the evenings and it's perhaps 80 or 85 in the warehouse. I was simply trying to ask if the system needs to be checked. 50% duty cycle to maintain 85 degrees inside when it is dark out can't be normal?
|
|
#
¿
Jul 18, 2016 07:05
|
|
|
literally a fish posted:What sort of climate control setup does the warehouse have, if any? None, but is surrounded on 3 sides by other tenants, has insulated partitions between tenants and an insulated ceiling, and its only exterior wall faces east. I honestly thought we might have to add something in there for it to be bearable in the summer but it has yet to meet or exceed outside temps even on the hottest day, which has been nice. I can't imagine it's cheap to condition 2000sqft of 24ft high warehouse. angryrobots posted:Could you measure the air temperature while it's running, at the return and at a couple supply vents, say the one closest and the one farthest away from the air handler? I've seen HVAC guys with those really fast refreshing thermomoter probe things. I unfortunately can't think of anything I own that has this capability. I have an analogue meat thermometer I'd have to duck tape to the vent for 20 minutes to get a reading?  What is a reasonable price to pay for having this system checked over by someone independent of the landlord? I don't mind putting some money into it if it's gonna save me paying to run it 18 hours a day just to maintain fairly modest setpoints in such a small space. I ask because I feel like the guys I've hired in the past when the system at my house broke charged me well more than was reasonable just for the initial visit. Don't want to get ripped off again.
|
|
#
¿
Jul 18, 2016 15:42
|
|
|
|
| # ¿ Apr 19, 2024 11:42 |
|
|
angryrobots posted:I'd just call around and see what a service call costs, although they may sell a "tune- up" special, which usually includes cleaning the coils and some other stuff. My luck in life.... Guy came out today from a local AC company. Got half way up the 24ft warehouse roof ladder, said "No way, can't pay me enough to climb this" and left without charging us. Said he would call us back with a referral for someone else. Never did. You'd think an AC guy would have been on a few roofs in his day? The ladder is a month old, made of aluminum with nice grooved footholds, very sturdy, and I've climbed it with all manner of crap in my arms and strapped to me. Of all the janky ladders and ceilings I've worked around in my career this is about as safe as you can get without having a staircase right to the friggin roof. Unit couldn't maintain 80 degrees today. Something is deff going wrong. Guess I'll try the next number in the phone book tomorrow.
|
|
#
¿
Jul 19, 2016 06:05
|
|