Plumbing Efficiency - Bypass Heater

[da2434890]

Is it better to bypass the heat pump for the summer thus reducing the number of 90 degree turns from 7 to 2 to gain efficiency or better to keep the water flowing thru the heat pump? In addition, I assume that the heat pump itself causes some extra load on the pump. See picture for how the valves are currently set to bypass the heat pump.
[attachment=0:2y7925qw]P5270351.JPG[/attachment:2y7925qw]

 

[JasonLion]

The most efficient setup, as long as you have the heat pump turned off, is to open all three valves. The way you have it now is very nearly as good, but it is best to have a little flow through the heater so the water in there doesn't get stagnant.

With the bypass line open there is noticeably less flow resistance, so more total flow. That should allow you to run the pump a little shorter than you would otherwise need to run it which saves money. It is very important that you don't turn on the heat pump while the bypass is open.

 

[da2434890]

Thanks for saying the correct option was the one I did not consider. I just checked the pressure gauge on the filter and it is 5 psi lower with the valves set as shown. Needless to say, I also turned off the breaker to the heat pump at the same time I changed the valves so that I did not accidentially turn on the heat pump if it gets cold here in Mexico in the summer. Since it has been in the 80's for weeks and since I use a black pool cover to absorb heat (or reflect heat with the white side up) before I use the heat pump I am sure that the heat pump will probably not be needed until sometime in Octoer.

 

[no-mas]

....It is very important that you don't turn on the heat pump while the bypass is open.

Jason -
why is that? I'll need to double check, but I thought the instruction manual for my heat pump requires the bypass for pool pumps greater than 1.5 h.p.

 

[Melt In The Sun]

With all the valves open, there probably wouldn't be enough flow for the heat pump. It should shut itself off in that situation, but stranger things have happened...

 

[JasonLion]

The heat pump needs a minimum flow rate or it won't work. With the bypass turned on in da2434890's system the heat pump won't get enough flow. However, with all three valves open, the heat pump will see enough back pressure and might turn on if it has a pressure based flow sensor (many of them do). If it did turn on it would likely damage it's self due to the low flow.

That is not the same as saying that all bypass systems will cause problems. In a high flow bypass, the flow is split between the heater and the bypass, and the heater is still getting enough flow and is fine. But da2434890's system isn't setup that way.

 

[no-mas]

Thanx guys. You're correct.

I have that same Rheem/Raypak 5100 heat pump pictured by the OP and re-read my manual. It says that for a pump greater than 1.5 hp, the bypass is required, but should be set to mostly closed, so that most of the flow is forced through the heat pump.