A7 AirTap install (ASHP hot water heater)

[ctgottapee]

What do you think the heat loss is like up through the copper refrigerant lines?? It is kind of the cost of doing business

If in the winter, I can't run the airtap and have to rely solely on electric resistance in the tank, how significant will the heat loss be of heat up those refrigerant lines, and that refrigerant transferring heat up into the unit?

With hot water pipes, you can put a loop in them to cut the heat movement...

[Xringer]

It might be useful on some configurations. But, it seems superfluous to me.

What I think might be useful is that AC output socket (1A limit).
That can be used to control stuff. I used it on very cold nights
to control a 1500w space heater (via a 20A SSR).
It kept the area from being too cold while I was working down there. (near the tank).

It could also be used to control a ventilation fan, if the outside temperature is warmer
than your basement, (and not too humid) a fan could pull in fresh warmer air..
(Like in the spring time when we use the dryer).

Before I decided to connect both my solar arrays to both of the heating elements,
I was thinking about using that socket to feed in AC power from a 200W
GTI connected to a single 200W PV panel..
It would be a more effective way of using my PV..

I'm sure it wouldn't be legal, but since the GTI power would be totally
consumed by the A7, no power would ever back-flow onto the grid..

[Xringer]

Originally Posted by ctgottapee

What do you think the heat loss is like up through the copper refrigerant lines?? It is kind of the cost of doing business

If in the winter, I can't run the airtap and have to rely solely on electric resistance in the tank, how significant will the heat loss be of heat up those refrigerant lines, and that refrigerant transferring heat up into the unit?

With hot water pipes, you can put a loop in them to cut the heat movement...

Mine have pretty good insulation on them. Where it was deficient, I added some more on.

My tank is currently at 127F. It's was sunny, so the A7 hasn't run yet today. (it's set to 115F).
I just went down and put my fingers on the two little copper tubes,
where they come out of the tank. I was amazed. They are COLD!
The whole A7 is at room temper.. About 60F today.
Of course there is loss, but it's not enough to warm the refrig tubes.

I think my loss rate is posted here somewhere. If IIRC, it's around 1deg F per hour.

I was open to the idea of adding loss-saver loops in the water lines,
but decided not to use them. (Even dumped the check-valves in the tank nipples).
The free-flow loss is not really that noticeable. 1 deg F per hour is fine in my book.

The A7 is a dang good little machine. Good investment so far..

[Xringer]

The solar assist is working okay. We've used 14 kWh (from the grid) during the last 30 days.
466.66 watt hours per day.

At this rate of power use, I could easily run the A7 off my solar battery bank/back-up system.
But, since MSW inverters are hard on motors, (That's what I've heard from the off-grid guys).
I'm just going to keep on paying $2.36 every month. Way cheaper than oil at $2 a day.
It's 16.88 cents per kWh now.. Was 16.66 last time I checked.

[Daox]

Out of curiosity, how much would it cost to go to a full sine wave inverter that is big enough to just run the A7? ROI would probably be horrendous, but I'm curious.

[Fordguy64]

I used my 1500watt 3000 surge inverter and it ran my a7 just fine.. Well I did it once anyway

[Xringer]

Originally Posted by Daox

Out of curiosity, how much would it cost to go to a full sine wave inverter that is big enough to just run the A7? ROI would probably be horrendous, but I'm curious.

1500W Modified Sine Wave DC 48V to AC 110V Power Inverter | eBay Abt $183 USD.. (6.5 years ROI)?

These things are getting cheaper all the time..
I might have to buy one some day..


Those new A7s are still on ebay.. Power Mizer H2O Heat Pump Water Heater | eBay

[Xringer]

Originally Posted by Fordguy64

I used my 1500watt 3000 surge inverter and it ran my a7 just fine.. Well I did it once anyway

I used my MSW inverter on my A7 for a few hours without any problems.
It's 2.5kw 5kw surge.

When I ran the little basement freezer, using it, the compressor motor sounded a little buzzy..

[Daox]

Do you really need 1500W?

[ctgottapee]

Originally Posted by Xringer

Those new A7s are still on ebay.. Power Mizer H2O Heat Pump Water Heater | eBay

I got one and it was working and appears to be identical to the A7, there is a bit of risk involved, although the price to risk ratio is good.

The power mizer company and its subordinates are a 'shady' group and they have all gone bankrupt, etc. Hence why pallets of these units are being offloaded. While the company may not be the best, they happen to carry a good product, and my ebay transaction and correspondence with them was great.

Shipping was ok, but could be better. It comes slow postal service and it took a beating. Original packaging is used for shipping and it was never designed as such (the company direct sold/installed, the didn't sell to the public). I imagine a proper boxing would be costly due to weight.
It also came insured, so unless you are at home when the postman comes, you have to go get it.


Xringer: Have you ever thought about getting an efergy unit for few of your solar panels to supply base/phantom load to your house? That's what I do. Solar to hot water element is pretty inefficient unless the panels are free to you. It may not be totally legal, but as long as you don't cross that base load line, it shouldn't be a problem.