Heat Pump Sizing and Sound

[codywatkins]

Hi All,

This forum has turned out to be a great resource.

First off:

1) Sound Related Question: Does the Carrier 25HCA3 come with a sound hood installed from the factory? I'm seeing conflicting info on that. Would it cut compressor noise in half if added?

Second:

A follow up from http://www.hvac-talk.com/vbb/showthread.php?t=137066, I've now completed my own Load Calc.

Quick overview: Both HVAC companies wants to put in Carrier 25HCA 2ton, just by eyeballing the house (built July 06'). They did not do a load calc. Already have 45,000BTU 80% builders grade furnace, would be dual fuel.

My load calc based on default design conditions shows the following: (See attached images)

The Carrier Comfort 25HCA3 2ton per spec will provide: 22,800 BTUH cooling, and 24,400BTUH heating (High temp) and 15,100BTUH heating (low temp).

2) Is it correct to size a heat pump for air conditioning only?
3) If load calc calls for 18,000 BTUH cooling, is 22,800 too much?
4) With our recent hotter than usual summers, if I bump up the summer design temperature 3 degrees F, I'd need about 1,500BTUH more cooling. Is this reasonable to take into consideration?


Thanks!

[BaldLoonie]

1. yes
2. yes
3. not in my opinion
4. if you go "2 ton", you have plenty of reserve

[tbox8098]

1- Yes
2- Yes- now you may get conflicting answers here that will recommend oversizing a 1/2 ton or a full ton for more heat. THis will hurt your a/c performance. I always size for hte cooling load of the structure.

3-No, it is nto too much it is the correct size for your house. A 1 1/2 ton will not have the cooling performance to give you a full 18,000 btu

4- If you feel you need to take this into consideration by all means do so. But you will be covered by reading response to # 3

[codywatkins]

1- Yes


Thanks for the replies so far!

1. Is this yes to "It comes with Sound Hood" or yes to "It will make it half as quiet". (This was my bad...two questions in one). It's probably a "Yes Yes"?

I wouldn't go with oversizing it for heat since it'll be dual fuel and I can always turn on emergency heat if it's not keeping up to my liking.

It looks like it'll be the 2 ton then.

[BaldLoonie]

Yes it has a sound hood. They do help don't cut the sound in 1/2. Scrolls tend to be pretty quiet anyway. The unit you are considering is 74db. That's about average these days. But the db rating only tells part of it. In a critical situation, I tell people just to listen to the unit they are considering.

[codywatkins]

Yes it has a sound hood. They do help don't cut the sound in 1/2. Scrolls tend to be pretty quiet anyway. The unit you are considering is 74db. That's about average these days. But the db rating only tells part of it. In a critical situation, I tell people just to listen to the unit they are considering.

What's the best way to listen before purchase? Ask for a reference of some kind? I don't believe they have a show room that I can go to and see it in action. I did see the infinity series in action at a "Home Show" last fall, but not the comfort series im looking at.

Also, would a short waist-height hedge on the curb facing side of the unit help with sound at all (allowing for minimum clearances)?

Thanks.

[BigJon3475]

You could keep an eye out while out and about. If you see one ask the homeowner if he minds you taking a listen to it. Just an idea. Or you could ask your installer if he knows of any of these units close to you and if you could possibly check them out...But I will tell you this 74 db is quiet and if the hood makes it any quieter...they won't be loud enough to be a bother...

[codywatkins]

You could keep an eye out while out and about. If you see one ask the homeowner if he minds you taking a listen to it. Just an idea.

That might be a good idea. I know there are one or two Carrier A/C's within walking distance.

[rickhall]

Most htg and cooling systems are oversized until you meet design anyway it's just a matter of how much. Remember the systems are rated at btuh the h stands for hour. If od design is 93 and actual temp is 82 then unit wouldn't run entire hr anyway. Just some food for thought when sizing.