I am installing an "on demand" pump (to get hot water my upstairs bathroom) as well as a drain water heat recovery (DWHR) system. I need some help with sizing the pump for the "on-demand" system. My 2nd floor bathroom (where the pump will be istalled) is about 70 ft away from the hot water tank which is in the basement. The 70 ft includes the vertical height. I have 1/2" pipe. I am looking at either the Medlund D'Mand pump (http://www.gothotwater.com/D'MAND/) or the Taco equivalent. Normally I should get the mid-side models (either the Medlund S70T or the Taco 008-DM-PK) which are good for 100 ft. However, I wonder if these are still the appropriate models once I add my DWHR system. My DWHR system will likely be the Powerpipe 60" model (R4-60). Can anyone tell me if the added resistance of the Powerpipe R4-60 means I need a more powerful D'mand pump? I'd appreciate any advice. Thanks.

I am not famiiliar with the specific models you list, but do have 2 questions.

As this is domestic hot water, I assume each of these pumps is one of the bronze pumps, which can be in contact with potable water?

Why place the pump upstairs so it pulls instead of downstairs where it pushes? Pushing provides good head pressure. I would think the pump placement upstairs would accentuate any water or pressure loss by quickly spurting, whereas if downsatirs it would be less likely to spurt or pump erratically?

I originally set up my ICF house to heat with a 30g OF HWH, which also provided the DHW. I had less head room/run vertically, but I had other reasons for using a Bronze Taco #11. It now only does my heating zones.

Jim,
Yes, the pumps are bronze and they are intended for DHW. They are also intended to be installed under the the sink in the location that is farthest away from the hot water tank. When you activate the pump, it circulates the water from the upstairs hot water pipes back down the cold water pipes to the water heater. When the hot water arrives at the upstairs faucet, the pump automatically stops. Typically, the hot water arrives to the upstairs faucet faster and there is no wasted water going down the drain. the system can be activated by a button switch, motion detector or wireless remote. It is quite well explained on the Advanced Conservation Technology website (www.gothotwater.com).
The nice thing about these models is that they only circulate the water when you need it (i.e., on demand) so the water is not circulating needlessly and wasting energy in the process.

If you're looking at recirculation pumps the vertical head factors out of the equation, it's just head from flow & the raw plumbing distance to & from the HW heater. Going smaller/larger just means shorter/longer delays, but with just about any 50-80W pump the wait should be "short 'nuff".