a/c not big enough?

[hamons]

Ok -- last year I had a new Bryant dual-fuel heat pump system put in -- put in July 5th 2005.

Have loved the system so far except for one thing -- it will not cool the house adequately when the outside temp goes above 90. It will run all day long and keep it around 80 degrees or so? When I complained last year the company came out and slowed down the fan so that the air being delivered would be cooler. This made the problem worse.

But... we had a fairly cool summer last year and the temps were no longer in the 90's after about August or so. This year I called on the problem again-- they are going to send a tech out tomorrow -- he will find that everything is fine -- I'm sure -- since they just did the summer start-up a few weeks ago and and everyhting checked out.

Should I require that a better sized unit be put in that wll cool the hose better?

Their gauruantee says that the new system can maintain a 75 degree house on a 100 degree day -- that aint happening and it never has. BUT.... the garuantee expired on july 5th this year --- should I still push to have a .5 ton larger or so system put in?

If I was willing to pay for the difference between my system and the next size up -- what would i expect to pay?


[Edited by hamons on 07-17-2006 at 10:16 AM]

[mjk_na]

How did the AC sized before it was installed?

Check the sizing and duct sizing using Manual J and D respectively. Check if the calculations meet the existing. If it is OK, then you are facing other problems.

If it is not, then changing to the right sized one is the nest step to do.

All the best!

[hamons]

This a/c is 1 ton smaller than my old 25+ year one I had before. They measured sq. footage of house and decided old one was too big for what I needed. They did not do a manual j or d

[dash]

You can do the Manual J on this site for a small fee.

http://hvaccomputer.com/talkref.asp

When doing so ,try using higher R-balue attic insulation then you have,as well as tinted east/west windowsw,if that lowers the load enough the system you may be the correct size,and it'll cost less to run!

[tigerdunes]

hamons

From your description, it does appear that you are undersized. I would not accept a system that can only maintain an indoor temp of 80 degrees. You do have the Bryant Evolution controls? I would contact your installing dealer and ask that they provide a written manual J heat/cool load calculation to confirm correct size Heat pump condenser your home requires. I suggest they use 73 deg inside temp at 95 deg outside temp as your comfort limits that the manual J is based on.

Keep in mind if you upgrade to a larger unit, you need to determine that your ductwork is sized correctly for a 5 ton and that your blower rating on your furnace is a 5 ton rating.Not an easy problem to solve considering you have what is generally regarded as one of the best premium systems around. And BTW, the cost diff between a 4 ton and 5 ton condenser is relatively speaking inconsequential to the dealer.

Post back and let us know what transpires.

Good LucK!
My opinion.

[Shophound]

Slowing down the fan was the wrong answer. All that did was turn your system into a better dehumidifier. The very last thing you want going on when outdoor temperatures are high is to reduce indoor airflow. That reduces the air exchange rate and concurrently the ability of the air to exchange heat with the cooling coil.

If their answer was to slow air speed, I would be leery of their technical expertise. Your system may be undersized, but it also was more than likely not commissioned (started up) properly. Overcharge, undercharge, airflow issues, etc.

A few weeks ago I was on a system with similar complaints as yours. Ran constantly and did not pull down indoor temp adequately. Homeowner had someone out last year and they declared nothing wrong with system. They charged her x dollars and walked away. I arrive and find the system overcharged. Not much, just enough to drive compressor superheat to near zero. I removed the excess and that system started moving heat like nobody's business. Spoke with homeowner recently and she's cool as a cucumber, even with outdoor temps soaring over 100.

All that to say before I'd go pushing for more tonnage, I'd ensure the tonnage you have is working 100% as it should. That, and dash's recommendations to add attic insulation and tinting and/or energy efficient windows could solve your problems without a lot of headache.

[hamons]

The system I have uses a honeywell TH8320 thermostat.

[hamons]

Tech came out this morning. Said system was about a pound low on freon -- he topped it off and said wait a couple days and see how that does.

My guess is it won't make a hill of beans -- luckily we have acouple 100+ dyas to check it.

When I had system installed I went with one of the higher priced companies in the area who I had lots of great references for. SO I do beleive that they know what they are doing - although mistakes have been made on this sytem unfortunately.

As pros looking from the inside -- what do you think my approach shouls be when I call on Friday re: system?

[hamons]

Well that got it down to 77 degrees today with a max temp of 94 degrees

[hamons]

On the news last night they had a n hvac guy onthat said it is not reasonable to expect your homes a/c to lower the temp more than 20 degrees -- so if you can cool your home to 80 then you should feel lucky.

This won't help my case that my a/c is undersized for my house.

- jeff

[tigerdunes]

hamons

A heat pump or AC system is a closed system. You just don't happen to lose refrigerant unless system was improperly charged from the initial install. Did tech even bother to check for a leak?

I suggest you make a list over the next several days with date, time, outside temp, thermostat setting, and run time. Do you have the Evolution controls? If so, also note house humidity vs setting. Facts speak for themselves and I would not accept a premium system like yours if it can not maintain an indoor temp of 75 degree, even with this weeks high temps.

Post back and let us know how system behaves over the next several days.

Good LucK!

[hamons]

Do not have a evolution controls -- I have Honeywell VisonPro 8320. Keeping track of temps is good idea is a good idea.

run time is easy -- from 7 am or so each morning to around 11 pm at night.

When they had sytem stratup in late Aprilthey did not add any refridgerant. They sytem had a drop across coil of 20 degrees -

amp draw on compressor 9 amps

rated run amps 14.7

TXV SUBCOOLING

Subcooling required 9 derees
Liquid line pressure 201 #
convert above to temp - 72 degrees
liquid line temp - 6 degrees
actual subcooling 9 degrees
suction line pressure - 101 #

[tigerdunes]

hamons

If you are saying system runs non-stop for 16 straight hours and you/dealer tech have eliminated any mech type problem, then you are undersized.

You should insist that your dealer perform a Manual J heat/cool load calculation and provide the results in writing to you. You paid for a premium system that basically will not perform at reasonable indoor temps for your particular climate. If this was my system, I would immediately sit down for a face-to-face meeting with installing dealer/owner.

BTW, did your system perform in basically same manner last summer?

My opinion.

[Edited by tigerdunes on 07-19-2006 at 11:08 AM]

[hamons]

yes -- performance is consistent with last year.

[hamons]

Ok -- Here is todays performance

Time -Outside -- Inside --------- thermostat set at 75 degrees
8am --- 87 --- 78
9am --- 94 --- 78
10am --- 95 --- 77
12:30 --- 100 ---78
1pm --- 101 --- 77
2pm --- 101 --- 77
4pm --- 100 --- 78
5pm --- 100 ---79
6pm --- 99 ---79
7pm --- 94 ---79
8pm --- 92 ---79
10:30--- 90 --- 78
11:30 --- 88 --- 79
Current -- 85 -- 79 -- A/c has not shut off since it went ont his morning

What do you guys think?

[tigerdunes]

hamons

This is not normal operation for a properly sized AC condenser and anyone who suggests that it is is either being intellectually dishonest or ignorant. Your dealer should provide in writing a load calculation both heating and cooling. You should sit down face to face with installing dealer/owner ASAP.

IMO

[leapfrog]

Originally posted by hamons
On the news last night they had a n hvac guy onthat said it is not reasonable to expect your homes a/c to lower the temp more than 20 degrees

Don't believe everything you hear on the news. Using this logic you wouldn't find the inside of a home or building in Phoenix under 90 degrees in the peak of the summer heat.

[leapfrog]

Originally posted by hamons
They did not do a manual j or d

There is at least one source of your problem. They guessed at the sizing, and they were wrong.

Take 'em up on that guarantee.

[Shophound]

Originally posted by hamons

Subcooling required 9 derees
Liquid line pressure 201 #
convert above to temp - 72 degrees
liquid line temp - 6 degrees
actual subcooling 9 degrees
suction line pressure - 101 #

Were these numbers from the installer's startup data? Are we talking R22 refrigerant? If so, that suction pressure looks high, and the head pressure low. Those numbers look off to me, but if they're the real deal, I'd be looking at the compressor. As it is there's not enough data to make an internet approximation...would need superheat, ambient air temp, indoor delta T, etc. to get closer.

[hamons]

Yes - that is the start-up data from THIS season.

My sytem uses r-410a

return air temp was 51 - supply air temp was 71 - outside air temp was 60

The superhet part of the form is crossed out -- is this because of the TXV?