Hi,

Looking for a little help selecting a pump to drive domestic hot water recirculation in my home (I am the home owner). I have a tankless hot water heater and no-dedicated return line. I don't have power available under the furthest two sinks!

As far as I can tell none of the systems on the market will help me... requiring either a dedicated return line or power under the furthest sinks.

So I got to wondering...

What if I use the "return" values from Amstrong's new Astro Express System (looks much more well constructed than the grundfos comfort valves.) These valves create a return path for the water from the hot to the cold pipes at the furthest two sinks - but don't require power.

Then get a suitably sized pump to trigger the tankless water heaters - which I would mount near the tankless heater in the mechanical room.


So the question is what pump to buy...

I see from the Laing ACT-909 model designed for tankless applications, without a dedicated return but mounted under the furthest sink has a head of just over 25ft and max flow of 8.5GPM.

So what I think I need to try (yes I recognize this is an experiment and it may fail!) is a "simple" pump (no timer, no temp sensor, no check valve - all of which the Laing ACT-909 has) with the following specs:

- 25ft of head
- max flow of 8.5GPM
- 3/4" connections
- Thermally protected (in case the pump ends up dead-heading against the closed Astro valve... I plan to only turn the pump on* for just long enough to get hot water to the faucets)

Can some one give me a part number for a Laing, Armstrong or Grundfos pump which would meet these specifications?

Also... should I mount the pump before the tankless (on the cold water inlet - i.e. the pump is pushing water into the tankless) or after the tankless on the hot side - i.e. the pump is pulling water into the tankless)...or doesn't it matter?

Thanks

* I will be controlling the pump using a computer controlled timer I already have (actually an X10 control system).