Leaning Towards Heat Recovery Unit

[omagic12]

Home is in mid-west coast of Florida (Tampa Bay area).

We have a 2 bedroom 1250 sq. ft. single story condo/villa (built in 1985) that we purchased two months ago. The AC unit was old and we knew would need to be replaced within a year or so, but turned out to be much sooner. Last week we got a Rheem 2.5 ton, 15 seer split system heat pump with electrical heat strip backup whole house A/C unit installed. Since downsizing form our 3/2 2000 sq. ft. home (built in the 1950's) in the same area, I am looking for more ways to cut energy cost. Going form a 10 seer / 2 ton unit to our current one in combination with a programmable thermostat should lower our a/c cost by 25% or more.

Now I am turning my attention to the hot water heater and have been reading up today on a/c unit heat recovery systems to heat water tanks.

There is currently a limiter used that is provided by FPL (power company)

that limits use during peak times and I keep a blanket wrapped around the heater. I read that timers don't really help save electricity for water heaters. An HRU seems like a very viable savings especially in Florida where the A/C is needed about 9 months a year and heat about 1 month total. The other 2 months we like to keep the windows open as much as possible. Does anyone have experience with these? What type of savings is expected? Is there one brand or type that is recommended more than others? Any other relevant comments or suggestions towards energy savings are welcomed.

[Marc]

I've installed a few and worked on several. Are you sure the Rheem heat pump can accommodate a water heater recovery unit? Aren't the heat pump and WH heat recovery features mutually exclusive?

If you want to save on energy costs on an 85' condo, don't forget to look at the attic insulation, windows and perhaps invest in a Home Energy Rating to expose drafts.

Use to live in an 80's condo myself, bout same size as yours, in coastal Louisiana.

Marc

[David Meiland]

Can't answer your specific question, but in your climate you could look at a heat pump water heater.

[omagic12]

I've installed a few and worked on several. Are you sure the Rheem heat pump can accommodate a water heater recovery unit? Aren't the heat pump and WH heat recovery features mutually exclusive?

I'll have to look into that, call Rheem tech support.

If you want to save on energy costs on an 85' condo, don't forget to look at the attic insulation, windows and perhaps invest in a Home Energy Rating to expose drafts.

Good idea. It does have R30 in the attic the windows are single pane, aluminum sash. The ducts are in the attic would it help to cell foam spray the flex air ducts for more insulation?

Use to live in an 80's condo myself, bout same size as yours, in coastal Louisiana.

I never lived in a condo or apt before and didn't think that I ever would, but in my area SFH's are expensive and we couldn't even find a comparable one in good shape, less than 50 years old for twice the price we paid for our condo.

Marc

[John Kogel]

If you have gas, a demand water heater is your best choice.

The GE hot water bank? Google it. In all my years, I've seen one in a crawlspace, connected to the refrigerant lines from a heat pump. The home owner had turned the water off to it. My guess is it was robbing heat from the heating system.

I think since you do not have gas(?), look to installing a small electric storage heater in a closet near the bathroom. For the kitchen sink, a small under the sink water heater. Then turn your big water heater down so it is just preheating for the small heaters.

Talk to your neighbors about putting solar panels up on the roof.

[omagic12]

Electric only, no gas. According to some posts, on the various sites I browsed, an HRU is more efficient than solar and can be used year round. However, with HRU it takes about 5 years to recover the initial cost:

http://www.homedepot.com/p/ZeroEnergy-H ... c=17588969 This one is on the expensive side, but supposedly very efficient.

http://www.olivetreeenergy.com/residential/

[David Meiland]

Interesting item... a refrigerant-to-water heat exchanger. The water piping would be fairly simple, but you would need someone to evacuate your AC system, modify the lines, and then recharge the system. Also looks like it depends on a convective loop to move the water from the exchanger into the tank. According to their promo video, a housing authority chose to install several hundred of them, so they must have done some research to determine that they were cost-effective, and/or they got rebate money from the electric utility to apply to the project. What would the total installed cost be for you?

I agree with Marc that you would look at typical weatherization measures for a building of that age. What can you get in terms of a free or subsidized energy audit from the utility companies?

[John Kogel]

In the 80's, the GE Water Bank was given as a free accessory to people that bought an AC.

It makes a lot of sense where you have 9 mos of AC. Keep your conventional heater in the loop for the winter months.

http://news.google.com/newspapers?nid=2 ... 13,2105156