size unit for a 14x70 MH

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size unit for a 14x70 MH

Postby waterworld » Tue May 26, 2009 10:08 pm

We have a 14 X 70 MH with attached sun room apx 10X17. We are having our heat pump replaced. Currently have a 2.5 ton. Salesman told us we would need a 3.5 ton, and suggested a 13 SEER, 42,000 BTU. I am concerned that is too much for our small home, though the MH is an older model, 1984, and as such, not energy efficient. We live near Myrtle Beach, SC. Also, salesman said life of heat pump units where we live is only about 10 years....does that sound right? Our current unit is working, but is 10 years old, and does not cool the sun room sufficiently when it is very hot outside. Also, can a 3.5 ton replace a 2.5 ton without any modification. The salesman looked at our electric panel and said it was sufficient. I don't know enough about it to challenge what he has told us. :? Thanks for any input you may have.
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RE: size unit for a 14x70 MH

Postby Robert » Thu May 28, 2009 2:55 am

Hi,

Find an hvac contractor experienced in mobile homes that will do WITHOUT you requesting it, an ACCA Manual J Load Calculation to determine size unit needed.

That is only way to know true size unit needed.


Salt water from ocean always leads to premature failure of a/c units.

Spent many, many days at Myrtle Beach as I'm from Upstate SC, but now living in Tennessee.


Do not increase size unit without a Manual J being done.



Thanks,
Robert
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RE: size unit for a 14x70 MH

Postby waterworld » Thu May 28, 2009 7:33 pm

Thanks, Robert. Unfortunately, we rushed into this "deal" (you know...."you can only get a discount if you sign up today!") and I didn't think to post a question to this website until 2 nights before our install, which was today. We actually did request that they cut the size of the unit from 3.5 ton to 3.0 ton, because we thought 3.5 was just too much for our square footage, even though an older mobile home. I sure wish I had checked here sooner so that I would have known to ask for a load calculation.

However, as I am observing the operation of the unit since they installed it this morning, it seems to go on and off quite frequently, being on maybe 8 or 9 minutes, and off maybe 6 or 7 minutes. I don't notice that the temperature on the thermostat ever changes, so I guess it is good that it is maintaining a steady temperature, but I thought the temperature was supposed to rise/drop above/below the set temp before it would shut off/come on. I guess what I need to do is thoroughly read the manual now.

Thanks again. Hope you are enjoying Tennessee. We love it here in SC....have been here a year, having moved from MD.
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RE: size unit for a 14x70 MH

Postby Robert » Thu May 28, 2009 8:48 pm

Hi,


You're very welcome, happy to help. The on and off frequent cycling can come from unit being oversized.


It should stay on for longer run times in order to maximize on removing humidity from home.


Keep an eye on the temp and yourelectric bill and if not staying within parameters given for unit, call the installer back out.


These are things that are impossible to give a true answer on from here without performing any tests on unit and/or home.


Enjoy the beach and all that area offers.



Tennessee is nice, but I do miss SC, the beaches and the mountains.



Take care and best wishes,
Robert
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