You got it!  That has to work better than what you have, IMHO.  Let us know how it works.  I’d be willing to bet that you could shut off your electric elements for the summer and coast along on waste heat!

Chris

I’ll bring this one back.  I got around today to pulling the bottom end of my old/original water heater loop.  There is a picture of the loop a few posts back.  My main concern was how was I going to drain the water heat so that I could do sweat (solder) joints on the copper pipes.  Recalling, I could not get the spigot on the bottom to drain water, all plugged up due to the narrow channels associated with the tap that splits the one drain hole into two channels, one water out to HP, the other water back to the water heater.  One of these channels is also used by the drain spigot As seen the the picture a few posts back the water heater HP loop has individual ball valve shut offs.  So I was able to shut down both lines.  I then drilled a small hole in one of the 1/2” pipes and when I opened the ball valve, very little water came out.  So I drilled a small hole in the other 1/2” pipe and when I turned the ball valve open, water shot out of the hole. So, I cut the pipe there, ball valve closed, and connected plastic tubbing to that pipe coming out of the ball valve and fed it over to my French Tile drain in the basement floor.  It took some time to drain the tank, but it was finally accomplished.  I then pulled the two channel tap, and took some pictures of how it is loaded with calcium (lime) whatever, it is jammed up especially the narrow channel that surrounds the center pipe with provides the other flow direction for water in/out of the tank.

I don’t plan to reuse this two channel tap, so I install the simple drain spigot in the bottom drain hole.  The tank can now be drained/cleaned via that spigot.  As discussed earlier in this trhead, I plan to tap into the cold line in, a 3/4” copper pipe with shutoff, and into the hot line, another 3/4” copper pipe. I will install “T” in those pipes with a 1/2” outlet.  I’ll then reuse the two ball shutoff valves, one in each line and plumb those two lines (from the Ts) to the loop going to/from my HP.  I should get that done sometime this week, and as we are still in heavy air conditioning season I will be able to test to see how much “free” heat I can capture for my hot water system.  My wife is away for a few days, so I can experiment without any worry about a cry for hot water.

Picture, full picture of three way tap, looking at the business end, end that sticks into the water tank, the area around the threads is where one of the water channels is located, it is fully coated over with deposits.  Last picture is a closer look.

EEEEWW.  That’s gross!  Are you on a well?

Looks like you found the problem.  I have never seen a fitting like this.  Have you looked at the circulator for this contraption?  I hope it’s not burned up.  Maybe a drain valve in the HP loop will make future work easier?

Good luck and let us know how it works.  I want temp readings! 

Chris

Hi Chris, with your change in avatar it took a while to recognize you.  That’s why I’m going to tap in with 1/2” in and out.  That should not get plugged.  As for the heat exchanger, it has bee turned off for some time, years.  It could have burned up before I turned it off, but in fact some small amount of water was getting through and the HP is “processor” controlled with some active maintenance programs running. There is an indicator showing the status of the super-heat exchanger, but that may be nothing more than it is “on/off”.

EDIT: the big problems I see now is cutting into the 3/4” in/out to the water heater. These pipes run against the overhead joists, no up-and-down free movement.  Trying to insert a “T” with no space to move the pipe will be problematic, I may have to break into another joint to get the freedom required.

Here are two pictures of the revised plumbing to connect the heat pump DWH via 1/2” pipes in/out of the existing water heater.  I reused the two ball valves, they are needed for “bleeding” the loop.  One picture shows the details of the splice into the cold and hot water pipes of the water heater.  The other picture shows how the two new lines travel to get down to the original loop plumbing going in/out of the heat pump.

The weather is not hot, so no test yet to see how well it works.  I have trouble getting my mind around the fluid dynamics involved, but it seems obvious to me that when the heat pump low capacity pump starts to pump water in the loop, it will draw water out of the cold water feed side, but that will not be water coming from the well/pump/tank as the other side of the pump goes to the hot water side of the tank where it puts “pressure” on the water in the tank.  This seems to be no different than the “factory design” that used the drain hole to talk water out and around the HP loop.  The improvement I’ have is dedicated 1/2” plumbing in and out.

I note in passing I had some problems getting leak free solder (sweat) joints.  Must be old age, seems I didn’t used to have any trouble.  Most joints were new pipe and fittings, a couple were reconnects to existing pipe and they don’t leak.  I did clean, flux and get hot, sill some leaks that had to be redone, three times in one case.

Some operational data.

It hasn’t been the usual hot August in NJ, so the A/C hasn’t been on a lot.  I did run some A/C however, while my wife was out of town, with the electric water heater off.  The HP did provide some warm water, but never got real hot, but then the A/C was running only briefly and periodically.

My wife is home and the water heater is back on, but I did have the “need” for some A/C today so I took some temperatues of the In and Out pipes (1/2” copper - see pictures in previous post) and found with the A/C on high speed (a two speed unit) the delta temperature twas about 5 degrees (example: 105 our and 100 in) and when in low speed the delta was about 3 degrees (example:  103 out and 100 in).  I have no idea of how much water is flowing in the loop, but assume the dedicated 1/2” copper line will allow several gallons per minute.  Thus a Delta T of only a few degrees represent a sizable BTU transfer.

In any case, the design discussed on this forum was implemented and it appears to be working.  Hope the saves me enough KWH to justify the expense (an additional $30 approximately) and time, at least 3 hours given I had some trouble getting two sweat fittings to stop leaking.

http://www.nyletherm.com/waterheating.htm

Design Error!!

After running the connection I have shown above with pictures with the HP in A/C mode it became obvious that for some reason the water delivered to tap upstairs wasn’t hot, in fact it was only warm sometimes.  Thinking on this for a while I came to the obvious, now that I see it, design error I built into the HP loop.  As you can see from the pictures the hot water tank out (hot) and in (cold) are in parallel with the heat pump loop.  So, if the A/C is running when a demand is made on the hot water some of the water delivered to the tap is derived directly from the cold water inlet to the hot water outlet, via the HP, which is not putting enough heat into the water to operate as a instant/demand hot water heater.  I will take the line off of the hot water outlet and instead return it via the drain tap at the bottom of the hot water tank.  This can be done easily by simply cutting the 1/2” copper return line from the HP at any convenient point, attach a hose outlet and put a piece of hot water rubber hose that can be used with a washing machine, for example, between this new hose tap and the hose tap on the drain valve.  If this works well I can later plumb with a more permanent line.  I say this knowing that I have used such rubber hoses on my hot water feed to our cloths washer and they have held up for many years, say 10 or so.