Another hot water tank heat pump

[berniebenz]

Originally Posted by randen

Thanks for the thoughts AC

I was thinking about controlling the heat-pump water heater system. A better temp controller and delay timer in-case of a power interruption also possibly some "time of use" system for operating the system during the lower cost for electricity. 7:00 pm to 7am
I seen that Hv23t used some Omron timers etc. If anyone could suggest some control Ideas would be great.

Randen

Randen, I have done just that!
In the A7 AirTap install thread, see my 7-16-13 post #314,
“Integrating A7 control into propane DHWH with TOU electric rate schedule.”

Regards, Bernie

[Hv23t]

Originally Posted by jeff5may

OK, I can't help myself. Here's the difference:

The Airtap unit Xringer installed is a pre-engineered, somewhat drop-in unit. The Water heater fitting is made so you can assemble the whole shabang without much chance of anything bending very much. The Heat exchanger coil slides straight in, and can be positioned while the plumbing is somewhat dismantled. It has a swivel fitting, so assembling the plumbing presents no further twisting once the tubing is snaked into the vessel.

When HV23T made his heater, he snaked the exchanger coil through the rather large hole, leaving a few feet of tubing sticking out. He threaded these pigtails through the fitting, then tightened the fitting while the pigtails were still free to not spin the whole assembly inside the tank. If anything, the ends may have spiraled around each other a few revolutions. Once the through-wall fitting was tight, he then tightened the compression fittings for a waterproof seal.

The heat exchanger randy made is all one piece. Besides the wrangling of fitting the tubing through the bung hole, he had to twist the entire assembly multiple revolutions to tighten the through-wall fitting into the bung hole. Since copper is somewhat rigid, more so the larger the tubing diameter, when the exchanger contacted another surface inside the tank, it tried to crease rather than bend.

Rather than force it in and hope for the best, randy wisely decided to stop and re-bend his exchanger so it will fit. I would have done the same thing. Trial and error, man. That's what it's all about.

For what it's worth, I don't think it will make a whole lot of difference what shape the exchanger is, as long as it fits in the tank. Lanky snake or twisty slinky, as long as you put the thermostat down low in the tank it will sense cold inlet water arriving. Once the unit fires up, convection will mix the water pretty quickly.

Jeff is correct on this, I took the 30' of tubing, bent it in half and snaked it thru the hole pre bending it as I fed it in so it would coil up. After all but a couple feet were in I twisted the lines around each other in a counterclockwise direction. I then fed the two lines thru the two compression fittings on the plug , but I didn't tighten them. I then screwed the plug back into the tank in twisting the lines as I tightened. I then snugged down the compression fittings and Waahlaa I had a sealed tank.

Hv23t

[AC_Hacker]

Originally Posted by Hv23t

I then screwed the plug back into the tank in twisting the lines as I tightened. I then snugged down the compression fittings and Waahlaa I had a sealed tank.

Hv23t,

What do you have flowing through the copper lines that you are snugging down the compression fittings on?

-AC

[Hv23t]

Originally Posted by AC_Hacker

Hv23t,

What do you have flowing through the copper lines that you are snugging down the compression fittings on?

-AC

There is r290 flowing thru those lines.

Hv23t

[AC_Hacker]

Originally Posted by Hv23t

There is r290 flowing thru those lines.

How are the lines terminated?

-AC

[Hv23t]

Originally Posted by AC_Hacker

How are the lines terminated?

-AC

They are brazed to the lines on the dehumidifier.

[AC_Hacker]

Originally Posted by Hv23t

They are brazed to the lines on the dehumidifier.

OK, great...

As you probably read, I trusted one of those compression fitting to seal r290 and it failed in a most sudden and unpleasant way.

I just needed to make sure you hadn't made the same mistake.

Best,

-AC

[ThomSjay]

I was curious as well, about the compression fittings after AC Hacker pointed out the differences. It's good to see that in this case, Hv23t was merely using them to hold the tubing and to seal the plug/bung.

[randen]

Its been a couple weeks but have found some time for more work on the HWHP. Decided to mount the compressor and evaporator on top of the tank. I drilled down from the top and between the tank and outside cover through the foam to run the condenser lines to the condenser copper HX coil. It worked very well and was easy. The connections are brazed up.

Further work is needed to finish mounting and connecting the compressor and evaporator. Following that a nice cover. I ordered up a new anode and treated the tank with an acid rinse. Looking though the bungs it looks brand new inside. I tried to take a photo of the cork screw HX in-side but no can-do.

Dad is quite interested now in his new HWHP.

Randen

[AC_Hacker]

Originally Posted by randen

...Further work is needed to finish mounting and connecting the compressor and evaporator. Following that a nice cover. I ordered up a new anode and treated the tank with an acid rinse. Looking though the bungs it looks brand new inside. I tried to take a photo of the cork screw HX in-side but no can-do.

Looks good and geeky.

The new anode sounds wise... but what's the acid rinse all about?

Wow, great work, but, too bad about the cork screw photos... There's a tsunami of web cams flooding into the thrift stores now. I just bet that with the smaller ones, the shell could be removed so that the functional guts could be squeezed inside through the bung hole.

I did something like this when I was drilling my bore holes in the back yard and experienced sudden fluid loss... the web-cam-in-the-hole revealed that I had drilled through an abandoned cess pool.

No, you don't hear much about 'cess' any more... not even the spelling checker knows what it is... and why did a pool of cess end up in my back yard?

Best,

-AC