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Getting a new heat pump...a few questions..

Posted by paleo78 (My Page) on
Fri, Oct 21, 11 at 1:17

My current heat pump finally shot craps, so I'm replacing. I got three quotes. I decided to go with a great company that has a great reputation. They were the only quote to measure, inspect, and run calculations on a computer program.

So to the question. We live on the southern Oregon is very moderate (30 - 60 degrees F) is normal and close to the extremes. The home is 3000 square feet (measured by them at 2800). The current system is a 4 ton pump/4 ton handler (Trane). The company quoted a 3.5 ton Trane XL15 pump/4 ton variable speed handler.

Does this sound right for such a large house? I guess it all goes back to the weather here...not that extreme. Just wanted some expert thoughts!

Follow-Up Postings:

RE: Getting a new heat pump...a few questions..


Did your dealer perform a load calculation and if so did he give you a copy of the results on the software letterhead to support his size recommendation?

How did your old system perform? Any problems heating and/or cooling?
Any short cycling?

How would you describe your home's building envelope and insulation qualities?

these are the minimum specs you should be looking for.
both outside and inside units should be replaced to have a properly matched system.

15 SEER, 12.5+ EER, 9 HSPF
best matching VS air handler
full BTUs in both cooling and heating for your rated size
R-410a refrigerant(same as Puron)
scroll compressor preferred
electronic demand defrost preferred
thermostat with "dehumidify on demand" feature
staged backup heat strips
new and correctly sized refrigerant lineset
10 yr warranty on parts and compressor

you want a thorough inspection of your ductwork system. size, overall condition, supply and return lines, insulation qualities, leak test, etc.

any hot/cold spot issues in your home should be addressed.

My personal recommendation is Trane/AmStd, Rudd/Rheem, and Carrier/Bryant.

Depending on your location, I would not purchase a new system that did not have electronic demand defrost.


RE: Getting a new heat pump...a few questions..

How did the old 4 ton handle the extremes in temps? I would think 4 ton for your size home.

RE: Getting a new heat pump...a few questions..

If the size of the old unit was adequate you have ruin the test.

no matter how you run a Manual J to size a system for an existing structure there are numerous places that errors can creep in.

the actual R-value of the walls and ceilings must be estimated, and infiltration losses (often the largest source of loss) must be estimated unless you run a blower door test.

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