Recommendations on equipment

10 years ago

Im doing a full house remodel (myself) and thinking of replacing the 25 year old Rheem heat pump and Goodman air handler. They are a 3 ton system that was on a 1700sq ft house. We have added about 500 sq ft of living space (garage conversion and previous patio conversion). We foamed the roof line with 6" of open cell and the walls will be foamed with 3.5" of open cell ($1200 difference in insulation price for the walls).

I have been researching and thinking of doing DIY HVAC. I have rewired and replumbed the house myself. I dont see why I cant do most of the labor side and have a pro come out and braze the lines and charge the system. I did a free load calculation on loadcalc.net and it suggests 22k btu cooling and 19k btu heating which puts me at a 2 ton system for the 2100sqft.

My plans for sure:
Ultraire 70 dehumidifier
New ducting (in rigid metal trunk lines). I will probably have a manual D done
Whole home air filter (Aprilaire or Honeywell)

Looking for input on the condenser and air handler. Im really leaning towards a variable refrigerant condenser like the Mitsubishi Mr Slim. Very nice it doesnt have to run full blast or 50%, it has a wide range from 15% to 100% if Im not mistaken. I want to keep the traditional a/c vents in the ceiling (conditioned space).

A Mr Slim 25k btu 18 seer heat pump is $2000
Rheem 2 ton variable speed air handler is $1000
Manual J/D is $300
Braze and charge $500

I have a local guy who can install a 3 ton Rheem heat pump (assuming 13 seer) for $4k. He also wants to flex duct everything and not use a manual j/d. He has not estimated the ducting side yet.

That being said...is there a reason not to go DIY?

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Comments (4)

mike_home
10 years ago
The one reason for not doing DIY is that most manufacturers will not honor the warranty for equipment sold on line.

If you are getting a variable speed air handler then why do you think you will need a dehumidifier?

The Mitsubishi Mr. Slim is a ductless mini split system. I am curious how you are going to install this with a Rheem air handler and with rigid metal trunk lines and flexible duct work.
tigerdunes
10 years ago
"The Mitsubishi Mr. Slim is a ductless mini split system. I am curious how you are going to install this with a Rheem air handler and with rigid metal trunk lines and flexible duct work."

I was thinking same thing. What's the point?

If going with Mr Slim, I would want it zoned. No expert here though.

IMO
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8mpg
Original Author
10 years ago
Mitsubishi actually makes a standard air handler for their systems. The Mr Slim is usually though of with the ductless mini splits but does not have to be used with them. You could theoretically have 2-8 traditional air handlers on their systems. Check out Matt Risinger's video on it on Youtube. I do not want ductless due to the heads having to be on the wall, hidden in an art frame or in a fur down. I want the variable refrigerant, quiet fan, quality name without the price of the Carrier Greenspeed. Mitsubishi is very affordable. Im not 100% sure the Rheem air handler would work.

The dehumidifier would be to dehumidify the air before it comes into the house. Ultraire typicall is ducted for outside air and put into the return of the system. I live in the hot humid South.
mike_home
10 years ago
The Carrier Greenspeed is high end and very expensive. There are plenty of other heat pump choices from Carrier/Bryant, Trane/American Standard, and Rheem/Rudd which are lower in cost and very efficient.

I assume the reason you are looking at heat pumps is because you have no access to natural gas. Is this correct?

The system you are trying to architect is beyond my expertise so I can't comment whether it will work or not. If high efficiency is important to you then putting together mismatched components is not a good strategy. You will not know the system efficiency since there is no AHRI rating.

Do you have an HVAC contractor which you know and trust? Most good contractors don't want to get involved with DIY projects. You might find someone who is willing to work with you but may not want to be responsible if things don't work well. A good installation is critical. The best equipment will never perform well if it is installed incorrectly.

Keep us up to date on the progress. I am curious about the system you put together and how it performs.