RS15-6SG

My positive rating is for the stainless version I ended up using (RS15-6SB). I had initially purchased a non-stainless version of the same pump under a different "brand" (KolerFlo) and the issues I had are summarized below but I'm 99% sure the issues with that one would also apply to this BokyWox line so I'm including my review for people to hopefully learn from.TLDR: The non-stainless version WILL rust; try different versions (and different "brands") of this pump if yours doesn't seem to pump enough water; ensure your pump comes with the pipe fitting adapters (that have o-rings) because the threads are NOT true NPT-fit threads and will leak; instructions are a joke so read enough reviews/do your own research to make sure you know how to install this (it's not complicated but the instructions make you question your own intelligence); no "on/off" switch so plan to use with a switched outlet or smart outlet for control.This review is for a non-stainless KolerFlo unit I bought (RS15-6 Blue). I intended to use it with the Grundfos-made thermal bypass valve for creating a water recirculation circuit for my tankless water heater system. I saw several reviews that said this worked for people, but it was not always clear whether they had a tankless system or not. Tankless water heaters require a minimum amount of water flow to turn on (typically ~0.5gpm) and after plumbing this pump and the bypass valve, I discovered that I would only get about 0.3gpm through my water heater. I tried all the power settings on the pump, "bleeding" the air with the screw on the front and flushing the lines, nothing helped. "Bleeding" with the air screw did let out some spits of air/water but the way the o-ring seal is designed, there is no way to get it to seal again while the pump is running so beware of doing that and/or be prepared to get wet. I "knew" that the fittings were 3/4" MIP so I also bought all the associated hardware to plumb this into the existing copper hardline on the INLET to my heater (used SharkBite fittings + 3/4" coupling to a 3/4" nipple so that I could have something rigid to use for mounting with 3/4" pipe clamps). The installation was fine except that even with a more-than-typical amount of teflon tape, I was not able to get a leak-free connection between the coupling and the pump. I made the connections quite tight and I was worried I would over-tighten and crack something. I did make a simple plywood base to allow the flat sections of the pump to rest since my pipe situation would not support the pump on its own.Since the pump did turn on and wasn't overheating or making any weird noises (it was very quiet actually), I assumed that I was just out of luck since the Grundfos valve kit I purchased actually did explicitly state that it was not for use with tankless water heaters (though it said the reason was that it was not designed to be used with systems that had a water-return circuit). After a couple of days I uninstalled the pump again to see if I could figure out if there was something mechanically wrong, and that is when I saw the RUST in the pump. I was very disappointed to see that and also very upset that I potentially put my family at risk for having that in our drinking water system. I also read someone else's review about making their own parallel valve circuit with two Grundfos valves and additional hoses/fittings to allow twice the flow through the valves. So in a second round of attempting to get functioning water circulation, I bought all the pieces needed for making the parallel valve setup AND a stainless-steel version of this pump, but under a different name brand (BokyWok).Once I received the new parts, I first decided to just install the new pump and see if that would make any difference. I was surprised to find that there was actually an adapter in the kit that would connect to the pump with a 3/4" female O-RING fitting and then adapted to a true 3/4" NPT thread. I didn't end up using them, though, because I just tried to connect the SharkBite adapter hoses directly (the non-SharkBite end had a 3/4" female o-ring connector) and used some thick cardboard spacers to allow a standard 3/4" pipe clamp to secure the whole thing in place to my plywood base. After this simplified installation was done, I turned on the pump and the heater kicked on!! This was WITHOUT making any changes to the Grundfos thermal valve installation, and I was now seeing about 0.5-0.6gpm flow through the water heater.This has been installed for a couple of weeks and still working fine...returning the crappy pump I received and the now unnecessary additional thermal bypass valve components. Lots of small lessons here, but my biggest suggestion is to try at least a couple of pumps from multiple vendors if yours isn't working. I looked at many pumps and they all seem to be the exact same imported hardware with various branded stickers on them (including the "official" Grundfos ones).

I have a Grundfos recirculation system connected outlet Hot water line of a 40 gallons Natural gas water heater. A Grundfos Comfort Valve were installed under the sink at the far end of a 2nd floor bathroom. The entire system was controlled via voice using WeMo smart switch and Amazon Alexa. The system served our family well and were spoil with instant hot water with Zero water wastage. At our new house, I’ve installed a Whole House AO Smith Filtration and Non-Salt water descaler (Water Softener) and feed into the Cold-water side of a Viega Manabloc whole house distribution system. Each water outlet in the entire house has a dedicated PEX line for Hot & Cold water and can be turn off if maintenance is required without shutting off the entire house water supply. A high efficiency outdoor Takagi Tankless water heater were installed. The installed Grundfos recirculation pump did not work as it was unable to turn on the tankless water heater. All bathrooms and kitchen sink were installed with Grundfos comfort valve. Brought a Watt branded recirculation pump and it did not work. Called Watts support and was told their pump which is made by Grundfos will not work with any Tankless water heater. After reading much reviews on Amazon, decided to buy the more expensive stainless steel Bokywox recirculation pump. The Watts were removed and the new pump was installed by a licensed plumber today on the Hot water outlet of the Takagi tankless water heater. The temporarily connected AC out of the Pump AC to a WeMo smart plug. The speed dial on the Pump control was set to 3. Turn on the pump with “Alexa, turn on Hot water” and the pump start up immediately, next the tankless water heater were turned on. After about 1.2 mins when the LCD display on the water heater were showing 120 degree on the Outlet and a flow rate of 1.2 GPM. The Takagi tankless water heater stops and all the shower hot water supply register a 120 degree. The pumps runs quietly. At last, no more waiting for about 1.5 mins and throwing about 10-12 gallons of water into the drain. Doing my fair share of conserving water in drought stricken Southern California. Very happy with the performance of the Bokywox recirculation pump, is quite when activated. And as always, next day delivery by Amazon Prime. They said Third times a charm, indeed it is. 👍👍👍

Purchased for a hot water recirculation line between master bath and water heater to have instant hot water at sink and shower. Used copper O-ring fitting flex lines to attach to pump and adapt to Poly pipe. NPT threads are not reliable to use and not leak. Major gripe is that there is no place to attach any mounts/brackets/etc. to suspend/mount this under a floor in basement. The only was is to use the pipe as support, mainly at the water heater fill pipe. Due to the nature of how the tank was plumbed, I could not mount in that fashion. Pump operates intermittently via a aquastat to open/close circuit between temp setpoints. 8 months in operation and no issues at this time.

Had this pump for two years now with no problems. I use it to operate my tankless water heater. I turn it on and off using Alexa which really makes it easy to operate. I would most certainly buy it again.

Product arrived this evening. Amazon box was intact but the interior styrofoam was a bit beat up. Didn't think much of it until I got the pump out.Pump didn't look very good but I did buy a "warehouse" one so I figured it be not new but didn't realize how best up the power cord would be.Didn't think too much of it and installed it after a trip to the hardware store. Within the first hour, I went out to look at it and water was spraying out from the front with the pump in off position and the valve set to 2.Quickly cut power off and uninstalled everything. Luckily I kept bucket under the pump so only about 2 gallons leans into the bucket and probably a gallon into the garage! So lucky this was in the garage and not inside the home.Such poor quality. Be aware and have a backup plan for catching any leaks.