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Xringer 06-28-12 11:51 PM

A7 AirTap install (ASHP hot water heater)
Here's the links:


Web links?
An Affordable Heat-Pump Water-Heater Retrofit- GreenSource Magazine

Airgenerate_AirTap_Installation_Upgreen Store - YouTube

Specifications: (Ambient Temp. 68˚F)
Max Water Temp: 130˚F
Energy Factor 2.2
1st Hour Rating (40 gal tank): 44.5 Gallons
Output kW 6.5 kW (Hybrid average)
Dimensions 18" x 14" x 14" (height)
Weight 50 lbs
Noise 50 db

AirTapô Installation Requirements
Volts 115
Amps 6 operating (12A start)
Phase 1
Frequency 60 Hz
Space (ventilated or ducted) 250 cubic feet
Space (unventilated) 1,000 cubic feet

The goal is to discontinue burning oil for hot water and use the A7 AirTap ASHP.

Step 1. Will be product testing (as described in the manual), hopefully this weekend.
I'll post my findings and some pictures.

Step 2. Select the size and shape of the hotwater storage tank (aka electric hotwater heater), and order it.

Step 3. Install the hardware, when the tank is delivered.

Here's a block diagram of the new system.

Vlad 06-29-12 01:04 AM

I don't really get this concept.

You use oil or gas to heat air inside your house and after you take this heat and steal it for water heating????

In warm climate yes it makes sense because this is your "free" AC. But when you heat your house I just don't get it.

For this reason I am going to use ground loop (closed water loop) as a heat source and I will build water to water 2 ton HP.

Xringer 06-29-12 07:59 AM

ASHP is the new GSHP
The basement isn't heated. We use 2 Sanyos to heat (and cool) upstairs.

The A7 will dehumidify and cool the basement during the summer months without using much power.
But during the colder parts of the winter, when the basement temperature drops,
it's going to take more power to heat the water.

A GSHP would be nice, but digging a deep ditch in the backyard is pretty much impossible.
I might be able to do it someday when they invent a cheap Laser excavator that can cut soild granite.

I have two ideas that might help out with winter power usage.
I may use one or both of these ideas.

1. Vent warm attic air down to the basement during sunny days.
2. Use backyard PV to power the A7 during good sunlight hours.

The basement slab (and walls) get pretty cold during the winter.
About the same temperature as the water main coming into the house.

MN Renovator 06-29-12 10:09 AM

"1. Vent warm attic air down to the basement during sunny days."

Adding high dew point hot outside air to your basement is a great way to bring condensation to your basement which brings mold. Not to mention that the moisture will spread to the rest of your house and you'll be living in wet swampy air.

Xringer 06-29-12 11:37 AM

When it's cold, we do get some humid days (not so much on sunny cold days), but the A7 is also a dehumidifier.

We have metal items stored in the attic, and there doesn't seem to be much of a rust problem up there.
I don't think that pumping attic air to the basement is going to add overwhelming humidity.

The benefits of drying the basement air is one of the things I'm looking forward to.
My machine shop tools are rust magnets.. :(

The fancy new Zenith dehumidifier we got last year is going to find a new home at my daughter's house.

S-F 06-29-12 02:17 PM

The dehumidifier can also be used in the winter. And it probably should be. But they net increase the temperature.

The air in the attic will only be reasonable for a small portion of the year.

All of Vlad's points seem to be reasonable. In the summer the dehumidification and cooling is nice though.

You will have to make a bypass from your attic to the basement. You'd better be sure to insulate and seal that up really well when it's not in use.

I don't think you should do anything to make your house colder in the winter. If you need those two huge monster heat pumps to keep a ranch warm I personally think you have more pressing issues than concern for an extra $1 a day or so on oil to heat your water.

Honestly I see so many issues with this plan that my head is spinning. The amount of work and materials costs will negate any savings you will hope to achieve. We all need hobbies and tinkering with this thing might be a fun project but I wouldn't touch it and I couldn't in good conscience recommend it to anyone.

On a different note, I know a guy who has installed one of these hot water heat pumps and he runs his dryer exhaust through the coil. He coordinates large hot water usage with running the dryer. I have been thinking about using one of these in the summer ONLY! and reverting to gas in the winter.

Xringer 06-29-12 05:47 PM

A7 unboxing..
I didn't really need a second 24k BTUh for the den. 8K BTUh would have worked fine.
But, I didn't have an 8K BTUh unit sitting unused in my garage.. :)

Maybe taking warm air from the attic is just crazy and I should forget it..
So, I'll look into running the unit off PV. That shouldn't be to hard to do.

The package came in this afternoon and it was in pretty good shape.
The test run was good. Took about 3 minutes before the coil got warm.

Geo NR Gee 06-29-12 08:15 PM

How often do you think the Airtap is going to be running?

Xringer 06-29-12 09:54 PM

That's going to depend on a bunch of factors. I really don't have any idea right now.

If it ran 24 hours a day using 368 watts, that would be 8.832 KWh per day..
At $0.1661 per KWh, that's about $1.47 a day.

So if it runs 8 hours during a summer day? That's 49 cents..

If the average daily run time is between 8 and 16 hours a day, that would be nice.
Cheaper than burning $2 worth of fuel oil..

The cost of home heating oil here in MA has been slowly going up for years.
I don't expect it to get any cheaper over the next 5 or 10 years..

Even if the A7 wasn't useful during cold weather, we might still be
able to cut the amount of oil burned by a good percentage.

Ryland 06-29-12 10:11 PM

I don't have a large enough basement for a heat pump water heater, they want a minimum square footage, otherwise I was thinking about going with something like the Air Tap as well, but as I see it, most of the heat in the basement is coming from the floor and walls, that is why in the summer when it's 90F upstairs the basement isn't that much warmer then when it's 50F upstairs in the winter, so in a round about way a water heater like this is a ground source heat pump and from what I read it should cost you about the same to run as the dehumidifier you currently have running if it runs as much as mine does (about half the time), so it's a win win! dry basement, hot water.

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