A/C issues

[Gonavy]

Question...We brought a new house in 2017...and seem to be having issues with the MUNNS A/C. WE have had the service people out several times and they can not find an issue and said the house temp will only be 15 degrees lower than it is outside. Is that a true? So if the outside temp is 100 degrees, the house temp at 85 is acceptable? Also, our A/C will not come on u until the outside temp hits 85 degrees...is this also acceptable? WE like the house to remain at 76 degree. We average 79... seems like it turns off or will not kick after 11pm thru 9;30 the next morning even if we turn temp down from 76. both units garage and outside are running but house is not cooling. 79 is about where we stay

any thoughts, suggestions, experiences? thanks

[ColdNoMore]

That sounds nuts. :oops:

No, it's absolutely not true that an A/C can only keep a house...15 degrees warmer than ambient.

Something is seriously wrong here, either with your unit...or the people MUNNS' is sending to you. :ohdear:

[villagetinker]

I heard on the news (I think) typical A/C units will keep the house at least 20 degrees cooler than outside. So a few questions, have you or the A/C people changed the filter, this needs to be changed at least twice a year, be sure it is installed in the correct direction. Also make sure you have the correct MERV rating. Is your controller programmed correctly, we keep our house at 78, and A/C works just fine, 5 years old this month. Did A/C people check that all the vents are open? When the A/C is operating can you go room to room and check individual registers to see if all are getting cold air, if you have one (not a return register) that is not putting out cold air see if you or A/C person can look at the duct, in case it has separated.
This is all of the ideas I have for now.

[DangeloInspections]

You should easily be able to cool your home to the temperature and humidity level you desire, within common sense limits. Despite what the temperature is outside, anyone should be able to keep their home in the low 70's 24/7.

Studies have shown that most folks say the "perfect" inside temperature is 75 degrees at 50% humidity. Some like it colder than that, some higher. The point is that it should be easily achievable with a properly running A/C system.

Is your filter clean? What is your Delta T reading? We look for a Delta T of between 14-22 degrees typically, with some variation allowed under certain circumstances. Is your unit icing up? Are the fans working, etc,etc...?

If you bought your home in 2017, this should still be under warranty. This is one of the many things that are thoroughly checked and documented during a warranty inspection. You must get this addressed during the first year to have the cost of repair covered. If you have not dealt with this through the Warranty department, you must do this without delay.

Frank

[Wiotte]

No one here is reading you correctly. You said the AC is not coming on until the outside is 85 degrees ?
That’s problem #1
That and that alone demands a call to the service manager so he sends a tech that knows what he’s doing.


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[golf2140]

That's a bunch of crap. I set ours a 77 and it stays there even when it's 97 outside.

[pbkmaine]

We keep our house at 74 and our 20-year-old AC unit has no problem maintaining it. Call Chuck Farrell and have him check it out.

[DangeloInspections]

Re-reading the original post, there seems to be multiple problems here that cannot be diagnosed without being there. Your A/C of course is designed to come on and off based on your inside temperature, so the outside temperature, time of day or night, etc., would have nothing to do with it's operation. Any normal, currently running A/C unit should maintain the temperature you are seeking.

Since the home is less than one year old, it should be under warranty. For homes no longer under warranty I often recommend Chuck Ferrall...I have never met him, but he has many positive reviews here. In this case, this being a new house, it seems that the homeowner should not have to pay for anything....he just needs someone out there with the skill set to troubleshoot and remedy the issue.

[graciegirl]

Question...We brought a new house in 2017...and seem to be having issues with the MUNNS A/C. WE have had the service people out several times and they can not find an issue and said the house temp will only be 15 degrees lower than it is outside. Is that a true? So if the outside temp is 100 degrees, the house temp at 85 is acceptable? Also, our A/C will not come on u until the outside temp hits 85 degrees...is this also acceptable? WE like the house to remain at 76 degree. We average 79... seems like it turns off or will not kick after 11pm thru 9;30 the next morning even if we turn temp down from 76. both units garage and outside are running but house is not cooling. 79 is about where we stay

any thoughts, suggestions, experiences? thanks

Call Warranty FIRST. Always call Warranty first.

[village dreamer]

sounds like it could be a thermostat problem , set it on manual for 76 and see what happens

[biker1]

There are two warranties: the 1 year home warranty and the 10 year parts/5 year labor warranty on the HVAC equipment. For homes still under the HVAC warranty, they should work with the original installation company and escalate as needed to have the issue addressed. Unless another HVAC contractor is an authorized dealer for your equipment and is going to honor the 10 year parts/5 year labor warranty, I would stick with the original installer. I have found Munns to be very responsive and competent.

Re-reading the original post, there seems to be multiple problems here that cannot be diagnosed without being there. Your A/C of course is designed to come on and off based on your inside temperature, so the outside temperature, time of day or night, etc., would have nothing to do with it's operation. Any normal, currently running A/C unit should maintain the temperature you are seeking.

Since the home is less than one year old, it should be under warranty. For homes no longer under warranty I often recommend Chuck Ferrall...I have never met him, but he has many positive reviews here. In this case, this being a new house, it seems that the homeowner should not have to pay for anything....he just needs someone out there with the skill set to troubleshoot and remedy the issue.

[Brandigirl]

Had the same problem with our brand new home. We expanded our home and I told them to make sure we had the correct tonnage (BTU's ) for expanding the home. They put in a 4,000 ton when I think it should have been 5,000. Was told by the A/C people the same thing that GONAVY said in his post. The A/C guy said that The Villages has a calculation they use to determine this. He said someone took them to court on this and LOST. We are in the same boat. Can't get the temp below 75-76 degrees when it is extremely hot outside.

[Nordy]

The industry standard when designing the size of your air conditioner is to maintain 15 degrees cooler than the outside temperature. Sounds silly but it's true. The result is an undersized or borderline sized unit that will have trouble cooling your house on the hottest days. With this design it is imperative that your undersized unit is giving you 100% of it's capacity. A master technician can field verify how many BTU's your unit is producing. If it won't come on until it is 85 degrees outside then they must have programed your thermostat to do that. Your unit must cool regardless of the outside temperature otherwise it will never catch up when it gets above 85. Until you get resolution I suggest removing any programs and use the thermostat in its "manual" mode. You don't want some "ghost" program turning you unit off.
Good luck,
Bruce
Florida State Certified Central A/C Contractor

[Wiotte]

Had the same problem with our brand new home. We expanded our home and I told them to make sure we had the correct tonnage (BTU's ) for expanding the home. They put in a 4,000 ton when I think it should have been 5,000. Was told by the A/C people the same thing that GONAVY said in his post. The A/C guy said that The Villages has a calculation they use to determine this. He said someone took them to court on this and LOST. We are in the same boat. Can't get the temp below 75-76 degrees when it is extremely hot outside.



It’s called a manual J calculation which errs on the side of minimum rather than maximum tonnage. Sometimes all it takes is an extra half ton which will prevent the house to exceed the tipping point which can’t be recovered until the sun goes down. The courts do not have expertise in engineering matters and will rely on the testimony from HVAC “experts”.


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[biker1]

The state of Florida mandates that the so-called Manual J calculation be done for all new construction. Manual J is a heat gain/heat loss calculation for the entire home and takes into account such things as the size of the home, orientation, amount of window and the quality of the windows, the insulation in the home, etc. The calculation will essentially come up with the required number of BTUs to maintain a certain indoor temperature and humidity assuming a certain outdoor temperature and humidity. The actual equipment sizing in BTUs will typically be a bit larger than the Manual J calculation since the nominal performance of the equipment as measured in a lab is somewhat greater than when it is installed in a house plus other inefficiencies such as heat gain through the ducts in the house. Equipment sizing is typically on half ton increments. On days where the outside temperature and humidity exceed the figures used in the Manual J calculation and/or your desired indoor temperature is below the Manual J design point, then it is possible that the system will not be able to maintain your desired indoor temperature. The Manual J calculation typically won't be based on outdoor temperature and humidity values that rarely occur. There are other possible issues such as the quality of the duct installation.

Your Manual J calculation for your home is available on-line. I can't remember the exact county website but with some googling you should be able to find it. You can check the indoor and outdoor temperature and humidity assumptions and other inputs that went into the calculation of the number of tons of cooling you need. By the way, a ton is 12,000 BTUs. The size of your system is 4 tons, not 4000 tons.

Had the same problem with our brand new home. We expanded our home and I told them to make sure we had the correct tonnage (BTU's ) for expanding the home. They put in a 4,000 ton when I think it should have been 5,000. Was told by the A/C people the same thing that GONAVY said in his post. The A/C guy said that The Villages has a calculation they use to determine this. He said someone took them to court on this and LOST. We are in the same boat. Can't get the temp below 75-76 degrees when it is extremely hot outside.

[Nordy]

Silly but true. Mechanical Engineers when designing your a/c system design as a minimum 15 degrees cooler than the outdoor design conditions. For Ocala that is 93.2 degrees. So that is 78.3 degrees inside. Many developers install the minimum size to save $$. If your unit is undersized or borderline it is imperative that it be working to 100% capacity.
A master technician can determine how may BTU's your unit is producing. But he is probably not going to want to spend a couple hours doing that. He will need to measure entering and leaving dry bulb and wet bulb temperatures and the CFM or amount of air being moved by your unit.

Definitely contact the developer.
If your unit won't come on if it is cooler than 85 degrees outside then they must have programed your thermostat do do that. Though I'm not aware of any t'stat having that capability.
Until you get resolution I would advise using your thermostat in the manual mode to avoid any "ghost" program from limiting your units "on time"
Good luck,
Bruce,
Florida State Certified A/C & Mechanical Contractor, Retired

[retiredguy123]

If you determine that your A/C system is undersized, adding insulation and mechanical ventilation to the attic "may" be enough to solve the problem.

[Topspinmo]

It's not working right call home warranty NOW! It should easily cool to 75 on hot days. It may run longer, but the temp is house should maintain 75. Do you have Honeywell relative humility option? IMO it has to be set on ON. Not on any of the numbers on the dial.

[Brandigirl]

Thanks for all the great info! Will pass it on to my husband as he is the technical one!

[graciegirl]

Listen to Frank DiAngelo (above) and always.

Call Warranty first. They are the ones that have the power. They represent the people who hired the contractors and who want to see that things are working right.

[DangeloInspections]

Well, some very good A/C guys posted some good info here....they are correct. But the point is here is that the unit is less than one year old, so this is 100% a warranty issue.

Contact warranty directly and get this problem documented. It could be something as easy as a thermostat problem, ( the newer wifi ones can be tricky and are new enough that many techs do not know them well ), or something more serious.

In any event, this is a warranty issue. That being said, we do sometimes find rare things, like insufficient insulation, no insulation, etc. that could exasperate the issue.

Frank