Grundfos MQ series

Not familiar with the Grundfos MQ line, but currently using the BMQE pump (220v). It's a booster pump that uses the same pumping technology as the Grundfos submersible SQE. Works fine for me. Slow starting, so not much power surge. I have it connected to a 60 gallon pressure tank and the pump only runs about 2-3 times durin

Edit: website went down in the middle of my comment. This is complete version.

Not familiar with the Grundfos MQ line, but currently using the Grundfos BMQE pump (220v). It's a booster pump that uses the same pumping technology as the Grundfos submersible SQE. It's mounted on the wall in my "control room" next to the water heaters. Water source is above grade water tanks (3,000 gallon) higher in elevation than the pump, so there is about 7-8 psi head at the intake.

Works fine for me. Slow starting, so not much power surge. I have it connected to a 60 gallon pressure tank. During a shower, it runs 2-3 times for about 45 seconds each time and draws maybe 800 watts when at full speed. I'm not sure that the 60 gallon tank is necessary, Grunfos recommends using a much smaller one. When using a 5/8" garden hose, the pump will run pretty much 2/3 of the time it's in use.

Paul 
in Georgia

Dave, yep I do like long showers, but the cycling of the BMQE pump probably isn't a result of modifying the set points. It seems the BMQE is billed as a "constant" pressure pump with a very narrow on/off operating range. The owners manual states that the pump will start when sensing a 3 psi drop in pressure. This suggests to me that it never gets to sensing a low of 35 psi. The only pressure settings I've been able to discern is the operating pressure in increments of 10 starting at 40 psi with an upper limit of 100 psi. I haven't found a cut-in setting control. Wish I could.

I'm beginning to think that the conventional wisdom to install a large capacity pressure tank to minimize the pump cycling does not apply to the BMQE pump. Grundfos recommends only a 2 psi pressure tank with the BMQE. Looks like I installed and paid for sometime I really did not need. I caulk it up to the trials and tribulations of learning about off-grid living.

Paul
in Georgia

Aguarancher said:

You could always control your pump with a 30-50 psi square-d pressure switch at the bladder tank.. They are rated for 220V. Fairly easy to install.
Forgot to add, square-d makes different pressure ranges on their switches. I have older plumbing so I use the 30-50, But whatever switch you would use, make sure the pressure on your bladder is set to the same psi as the cut-in pressure on your switch.

Good point!  I sent an e-mail to the guy who I know  using the bmqe and I bet that is what he did. Back later.

Here is a pic of the switch with the cover off. two outer terminals are line (power in) the two inner terminals are load (pump) The switch is available at Homedepot. http://inspectapedia.com/water/Two_Harbors_2011_0426_DJFs.jpg
The pressure switch shown is the Square-D 9013
This is the 30-50 http://www.homedepot.com/p/Square-D-30-50-PSI-Pumptrol-Pressure-Switch-FSG2J21BP/100183740

Wheelman, go on line and check-out the BMQE. It's a little over 4" in diameter, 40+ inches long, and can be installed vertically or horizontally. The controller is a small box that is also mounted on the wall and does not have to be right on top of the pump. It's not loud, only a whirring sound. Using flex piping at the intake and outlet helps keep down noise created by vibration. The unit can be wrapped in sound insulation and can be mounted on sound deadening blocks, if need be. Very simple install with a lot of safety features (dry run protection). I read somewhere that by dialing up the pressure to the max 100 psi, you can use it as a "mini" pressure washer (I've never tried it, so I'm not saying it's something that can be done). Download the BMQE users manual for the most complete info.

You may already know this, but the rain water must be properly filtered or the pump will not last. Filtering is so important that without it from the very "git-go" and up until the day the pump finally "dies", you will be fighting the system.

I use this pump for domestic water, and as posted above, it will cycle on/off for about 30-40 seconds when showering, washing dishes, and occasionally, during a toilet flush. I have not taken any accurate measurements, but in a 24 hour period with only me and my wife at home, I think the unit may run a total of 10-12 minutes a day.

Dave & Agua; I'm still not convinced that this pump (with its controller) can be configured with a conventional 30-50 pressure switch. However, the jury is still out for me on this as there may be some way it can done. It would seem that you would use one, or the other, but not both pressure sensing devices in the set-up. Wouldn't two switches in the configuration create conflicting pressures in the system? Am I looking at this right or trying to complicate it?

If the advantage of a 30-50 pressure switch is primarily to cut-down on the cycles, I'm thinking that the pump cycling "as-is" ain't so bad. The noise is not too loud and if I replace the floor mounted 60 gallon tank and install the Grundfos recommended 2 gallon tank (11" X 8") on the wall out of the way, I would have more room in my "control room" for more stuff. 

Paul
in Georgia

Agua, thanks for looking over my shoulder and offering your advice.

Under normal operating conditions (i.e., my wife and I), the pump far exceeds our demands. However, we have a total of 5 baths, 2 indoor kitchens, and 2 outdoor sinks that is supplied by the pump. This place can get crazy when family and friends decide to visit at the same time. 

Paul
in Georgia

Thanks Dave, you input is appreciated. One good thing about the BMQE and night time pump running, it won't run unless it senses an open tap. Luckily, the pump is barely audible where I sleep, thus I won't hear it. And, if I'm the one that starts it running, it means I'm using the facilities, I'm already awake, it's only for 45 seconds, and, thank goodness, it does not run every time you open a tap!

Paul
in Georgia

Yes Zoneblue the strainer is nice on the input for rain. For me it is best to have a clear filter so that I can see that there is nothing in it.
I put the strainer on 10 years ago and it still looks the same. I find it a little amusing when someone says you have to filter the rainwater.
In most offgrid homes the water sits in tanks for months and is really only moved around when transferring water. The filtering off the roof and the first flush really do it all.

Rainwater is just so different than stream, lake & well water. If there were any particles, I doubt they would be hard enough to hurt a decent pump. You do have to manage the PH though.

Inetdog, indeed.

Hey Dave: When you get rainwater from a roof run-off that is out in the boonies and around any decent size hardwood and pine trees, you have to deal with leaf residue, leaf stains, sap, spring-time catkins, pine and grass pollen, acorn strains, dusty roofs, bird droppings, and lots of other nasty looking stuff that I have yet to identify. Of course, I don't live in California either, but I reckon it's all real pure out there.

Paul
in Georgia

americans are funny about rain water. I guess NZ being a maritime nation it rains a lot, and that rain all comes off the ocean and largley from the sub antarctic so is about as clean as rain water gets. we have no nuclear, no real heavy industry, and a somewhat vigilent environmental regulatory.
Yes as Dave said it requires some maintenance. I do 4 monthly gutter clean outs and annual tank drain and cleans. Then theres a primitive first flush device and a panty hose strainer. And then the 0.5 micron drinking water filter.

One thing to watch is to try to isolate the roof facet with any wood stove flue, as under some fire and wind conditions can generate roof soot.