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11-09-2012, 08:06 PM #1
Professional help with Trane equipment selection.
We recently moved into a home in Northern California, Coastal area 1/4 mile from the ocean and need to purchase and install a Heat pump. Currently the house uses electric wall units in each room. Load Calc calls for 21k Btuh with a 37 degree design td. I am interested in the xr15 4twr5018 matched with the Tam7 air handler. However the smallest Tam7 available is a Am7a0a24. We want the tam7 for the dehumidification capability. Opinions on matching an XR15 in ton and a half with the Tam7 2 ton air handler? Is it better to just go with a 2 ton xr15 for a better match, and not stress over the slight oversizing?
i appreciate any input in advance. I am a fix it guy and do not know a lot about sizing and or installation. Is the dehumidification feature of the Tam7 worth it (keep in mind we have serious humidity problems with moldy shoes etc..etc..etc..) Some locals solutions are to leave a light on in a closet to remove the moisture? I am not able to navigate to a site where I can check the HSPF of the units in the 2 configurations I am considering.
XR15 4twr5018 with an Am7a0a24
XR15 4twr5024 with an Am7a0a024
I need to make my decision quick, before the meter flies off the wall outside!
Thank you for any help!Living the dream !!
11-09-2012, 08:27 PM #2
1.5 ton is 15 SEER, 12.5 EER, 8.40 HSPF
2 ton is 15.5 SEER, 13 EER, 9 HSPF
If the cooling load is 21K, I think I'd be looking at the 2 ton unit personally. I would want a control that has the dehumidify on demand feature. Lots like that these days. And since there will be times when you need dehumidification but not cooling, a whole house dehumidifier would make sense in your climate.
Some will say buy 2 stage for better dehumidification, remember that low isn't that much less than high on almost all of them and some, Trane especially, don't do the greatest job of latent (moisture) removal on low. Save the money and get the dehum.
11-09-2012, 09:06 PM #3
Thanks for the response. I do appreciate it. I will go with the 2 ton I believe. I like the Hspf of 9. It is the heat load that is 21K. The cooling load is 11k.
11-10-2012, 08:00 AM #4
Then I change my opinion. Heat pumps are sized for cooling needs with strips sized for heating. So with the cool load of 11K, I would rather see the smaller unit. Going well over double what's needed for cooling will cause humidity issues. The sucker will hardly run, even on the hottest day of the year. Even the 1.5 ton is considerably oversized for that load. A 1 ton mini split HP is probably more in line.
I should have read the 37K design temp and realized you meant heating loss. Probably need some strip heat in the AH for the coldest morning but even the smaller HP will do most of the work.
11-10-2012, 08:44 AM #5Regular Guest
- Join Date
- Jun 2001
- Oklahoma City
Unless the house is large or poorly insulated I don't see the 1.5 ton having a problem keeping the place warm with a 37 degree outside temp. We don't even turn our heat on until it's less than 50 outside. You will have some internal heat gain which becomes significant when loads are as low as yours are.
11-11-2012, 12:58 AM #6
The 2 ton XL20i with Tam8 would be a perfect solution.
Low stage for cooling to remove humidity much better.
High stage will take care of most of your heating demand.
Of course there's a little more to it."The only true wisdom is in knowing you know nothing" Socrates