RTU's not cooling the building enough

[Six]

I'm not attacking anybody, the point you missed is that your broad/general comments give the entire industry a black eye. The outcome? Building owners go with the cheapest guy because, according to you, we are all crooks...why not go with the cheapest and save some money for the next crook to fix the last crooks problems. Use your head.

I am using my head, where has yours been buried for the last 3 years ???


They are CURRENTLY going to the cheapest bidder. It has nothing to do with me calling out the crooks and I doubt lil' ole me could do any real damage to our industry anyway.


It has to do with the fact that we are in a economic nose dive or as the President calls it ( Summer of recovery....lol ! )


I lost a 2 year old account last week to a company that "does it all" when the general manager was replaced.

He said we did great work but they're cheaper. Well, you get what you pay for then. You see he's new and hasn't had the pleasure of getting ripped off by a company that goes in low bid and then makes up a bunch of repairs or through their incompetence damages a lot of equipment.

He'll call us back when he goes through the last 3 years of invoices and realizes he spent more than that in the first 6 months with the new and improved company.

I have to say that people are twisted. To think someone would come to the conclusion that keeping their mouth shut and telling others to keep their mouth shut is the obvious solution to corralling the organized theft that some companies practice on a daily basis.

[zartangreen]

Today and the past few ones have been scorching hot outside and the temperatures inside our facility have been suffering badly.

We have several 7.5 ton units each serving one wing of the building. On days with outside temps of up to about 95F, the building seems comfortable enough and the units seem able to cope up. But when it gets to about 100F out, the hallway temps begin to rise to about 78 to 81 and everyone will of course start complaining about it.

We clean the coils regularly and we have the HVAC contractor doing regular PM's on the units. I know that these units were not designed based on these very high temperatures but I would think they should also be able to keep the building comfortable at all times.

We have replaced older units with new ones, and the contractor have just changed them with the same sizes. With these new ones being used, we're always still having this issue of not enough cooling inside on really hot weather and we would at times end up renting portable ones to supplement the cooling.

Do you guys think we should get bigger units? I don't remember our contractor having done any load calculations inside our facility, and we'll soon need to replace another one. Would appreciate any suggestions.

Several units and replaced with new units yet still Problem. That tells me to look at location of these condensers are they close to each other and most importantly are they all in shaft/alley. Basically The Removed heat does it have free range or is all the hot air being Pocketed. Common problem in the city,, landlords only allow condensers in a certain area so u get a tunnel of hot air,, so when its 90 degrees its more like 100 and so on. If so I have a solution,
surprised that wasn't asked first

[btuhack]

I am using my head, where has yours been buried for the last 3 years ???


They are CURRENTLY going to the cheapest bidder. It has nothing to do with me calling out the crooks and I doubt lil' ole me could do any real damage to our industry anyway.


It has to do with the fact that we are in a economic nose dive or as the President calls it ( Summer of recovery....lol ! )


I lost a 2 year old account last week to a company that "does it all" when the general manager was replaced.

He said we did great work but they're cheaper. Well, you get what you pay for then. You see he's new and hasn't had the pleasure of getting ripped off by a company that goes in low bid and then makes up a bunch of repairs or through their incompetence damages a lot of equipment.

He'll call us back when he goes through the last 3 years of invoices and realizes he spent more than that in the first 6 months with the new and improved company.

I have to say that people are twisted. To think someone would come to the conclusion that keeping their mouth shut and telling others to keep their mouth shut is the obvious solution to corralling the organized theft that some companies practice on a daily basis.

Like I said, preoccupied. Your agenda was brought up by you and doesn't address the thread objectives.

Your high post count for a newer member leads me to believe that you're short on hours and have an axe to grind. It's gotta be easier to blame the competition rather than address your own shortcomings. Maybe you got canned from your account because the property manager didn't care for your desire to make foolish remarks. Maybe they got wind of you bad mouthing their decisions in front of tenents, that seems very plausible.

I hope you can turn things around.

[abcando]

Several units and replaced with new units yet still Problem. That tells me to look at location of these condensers are they close to each other and most importantly are they all in shaft/alley. Basically The Removed heat does it have free range or is all the hot air being Pocketed. Common problem in the city,, landlords only allow condensers in a certain area so u get a tunnel of hot air,, so when its 90 degrees its more like 100 and so on. If so I have a solution,
surprised that wasn't asked first

They are actually spaced far apart from each other. The closest they could be would be at least 15ft., and they are all rooftop units so surroundings are wide open.

We're having a new replacement installed early next week, same size but maybe not too late to get a larger one if we can agree that it can be done without too much additional expenses.

[12andstilllearning]

ok seems like your getting partial answers and a epeen waving contest. if at 95 degrees and below your equipment does the job they are sized correctly and working properly. most equipment is designed to maintain 20 degree between outside and inside temp sounds like they are doing all they can do close outside air dampers if you can in a nursing home i would watch it. use water as needed and when the heat is over put everything back to proper settings. Good luck and take care in the heat

[beenthere]

ok seems like your getting partial answers and a epeen waving contest. if at 95 degrees and below your equipment does the job they are sized correctly and working properly. most equipment is designed to maintain 20 degree between outside and inside temp sounds like they are doing all they can do close outside air dampers if you can in a nursing home i would watch it. use water as needed and when the heat is over put everything back to proper settings. Good luck and take care in the heat

Its not the equipment that is designed to only maintain a 20 degree difference. It the system may have only been sized to maintain a 20 degree difference.

Grocery stores have no problem maintaining 30 or more degrees below outdoor temp. The systems are sized to be able to do it. The equipment doesn't care.

[12andstilllearning]

ok that is the heart of the issue how it was designed. and not all grocery stores will do 30 degrees if they did my life would be a lot simpler when it hits 110 or more.

[mcewans]

Excessive use of city water to cool the coils will RUIN your condenser coils.

What is the difference between city water and rain water?

[hvac69]

What is the difference between city water and rain water?

Minerals, rain water doesn't have a high concentration plus it isn't being sprayed direct, 24/7.

[John Markl]

It's very common in some parts of the country to use water assist on condensers during hot weather. Actually, a fine mist will leave heavier mineral deposits that a mild stream will.

When we hit 105+ (common in Texas) we will put water sprinklers under the condensers on supermarket rooftops. Keeps the head pressures down, and washes the coils at the same time....

Avoid "misting" coils. If you're going to use water, use a good stream.

[sdt1104]

John Merkyl is correct it is common the place srpinklers under coils in Texas. Had a facility with an 8 foot wall arouund the roof to hide equipment and block any breeze. When it hit 105 the rooftop temps were 115 to 125 the 70 ton McQuays would not run without water assisted cooling on the condenser coils from abouot 13:00 to 19:00 (thats 1PMto 7PM).

[Six]

Actually its not. Not on the commercial side anyway.

People realize that its short term and will eventually damage the coils. Of course I speak for Houston but working on roofs and in mechanical rooms for 20 years Ive seen it only a few times.

That doesn't qualify as common.

[John Markl]

Actually its not. Not on the commercial side anyway.

People realize that its short term and will eventually damage the coils. Of course I speak for Houston but working on roofs and in mechanical rooms for 20 years Ive seen it only a few times.

That doesn't qualify as common.

We've had water hooked up with a pressure control to the rooftop condensers on 150 tons of AC on a five-story office building for years without damage to fins.

It's a matter of maintaing enough flow for the water to carry the minerals off with it, as opposed to "misting" or soaker hoses.

Most of the water evaporates on the flat roof, but some runs down the gutters....In fact, the building owner will call us (A CPA who offices there) if he doesn't see water coming out of the gutter during hot weather.

Conversely, We service a retirement home with 200+ units....we replaced about 30 of them last year under a capital expenditure, because the facility irrigation system sprays a fine mist which DOES eat the coils out over time.

I used to listen to Mark Davis on WBAP in the mornings, and would cringe when he would advertise those misting systems for home AC units. I even sent him an email about it, which of course, he never answered.

[Six]

You're in North Texas ? We provided water for a old Carrier Chiller used the perforated garden hoses.

We told the customer it would ruin what was left of those coils and in about 5 months and sure enough it did.

They're not designed to have city water run through them but I wonder if the environmemt plays a factor too.

We have to deal with serious humidity down here so there is not much evaporation going on at all.

[John Markl]

Might want to consider going to 2 stage 10 ton units, with the blower slowed to 320 CFM per ton. If your 7.5 ton units are moving 400 CFM per ton, that comes out to 3,000CFM. A 10 ton at 320 CFM per ton comes out to 3,200 CFM. Not a big increase in CFM.

We have been recommending that a lot on replacement quotes....Go two-stage....get good, even cooling and humidity removal during moderate weather, with the capacity to "pour it on" when things get tough.

Automobile manufacturers are offering the same thing.

[abcando]

if at 95 degrees and below your equipment does the job they are sized correctly and working properly. most equipment is designed to maintain 20 degree between outside and inside temp sounds like they are doing all they can do close outside air dampers if you can in a nursing home i would watch it. use water as needed and when the heat is over put everything back to proper settings. Good luck and take care in the heat

Its not the equipment that is designed to only maintain a 20 degree difference. It the system may have only been sized to maintain a 20 degree difference.

Grocery stores have no problem maintaining 30 or more degrees below outdoor temp. The systems are sized to be able to do it. The equipment doesn't care.

This is actually the point of my inquiry here. There are a lot of areas where higher than 95F temps are common (including ours) during summer time, then these equipment or systems that are mostly designed to maintain 20 degree temp difference are not ideal to use in a lot of situations.

I go to other larger buildings and it still feels comfortable inside even cooler than normal despite the extremely hot condition outside. It would be nice to be able to have something that can do 30 or more degree temp. difference in our place.

The pictures show our temporary sprinkler setup on the roof. To be honest, I don't really feel any better inside the building by doing this, but I know it's because of the extreme heat outside. I'm sure the units are getting relieved somehow and I just imagine it would feel worse inside without doing this.

I'm considering doing the pvc setup soon, it sucks to have to pull hoses on top of the roof whenever we need to do it.

I appreciate the discussion about the good and bad of it.

[John Markl]

Well, your equipment looks plenty "new enough"....but from the pics, it looks like you have some serious ductwork issues.

[abcando]

I agree with you John, we have some ridiculous ductwork setup above the roof.

[Six]

Well, your equipment looks plenty "new enough"....but from the pics, it looks like you have some serious ductwork issues.

As long as they're insulated well enough to withstand the extreme roof temps I don't see a problem with them.

It's a sloppy application of foam type insulation. He should take a split at the unit and then take a split at the entering and leaving ductwork inside the building and compare the numbers.

I wonder how much heat he's picking up through that ductwork ??

Maybe he needs to run a sprinkler set up for the duct work ?

[John Markl]

As long as they're insulated well enough to withstand the extreme roof temps I don't see a problem with them.

It's a sloppy application of foam type insulation. He should take a split at the unit and then take a split at the entering and leaving ductwork inside the building and compare the numbers.

I wonder how much heat he's picking up through that ductwork ??

Maybe he needs to run a sprinkler set up for the duct work ?

I'm more concerned about the size and configuration. By the time you allow for all that foam and cool-seal, and presumably some internal insulation, the actual air space for 7.5 tons looks pretty shaky.