My neighbor just got a new 4 ton GSHP, the old Climate Master bit the dust. He invited me over to check things out as the contractor was finishing things up, and to ask questions about the new unit. This is not one of the big name units, I think they're built in SD. This is a two-stage furnace on an open loop pump and dump. The installer adapted the water OUT line to a single 3/4 Taco motorized solenoid valve and then a ball valve to regulate flow. I mentioned my two-stage WF has two solenoid valves and two Dole valves, his reply was "yeah we don't do it like that anymore". He said "you can flow 16 gallons a minute through a 3/4 inch pipe, I only need one even for 2nd stage". Not knowing what I don't know, I shut up and got out of everyone's' way. Later I went to the manufacturers web site and found the install literature for that unit. I thought maybe it had a modulating flow valve like I've seen in higher end furnaces. It clearly states two-stage units over 3 tons should have two solenoid valves and each branch should have a flow control device. There are four more neighbors with aging equipment, we'll be needing replacements pretty soon. Did my neighbor get things done right, or is he just dumping a lot of water for no reason?
Maybe not a "bad" install, but probably not as efficient as it could be. Most heat pump models require only 1.5 GPM/ton of capacity in open loop at normal entering water temperatures. Pumping more water than required uses more pumping power and more water than necessary.
