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Grundfos MQ Booster

TomTom Member Posts: 455
Hey Guys,

I have a customer who has purchased this pump online to bump his PSI from the 70 he's getting now to 90psi. I explained that the problem is not the current pump and expansion but the super cheap shower valves he did not want to change during his remodel. Regardless, I was hoping I could find someone who can tell me if this style pump will work installed with a well and a pump in it and expansion tank.

Can this pump be put on after the expansion tank just to boost the pressure as the customer wants?
Montpelier Vt


  • icesailoricesailor Member Posts: 7,265
    Make it work:

    I'd be telling that customer who purchased that pump on-line to install and make it work for him. Because there is no way that is it is hot and humid in Florida, that's going to work. Unfortunately, you  know it and he is smarter than you.

    All the plumbing codes that I am aware of have a maximum potable water pressure of 75#. All water storage tanks have a listed MAXIMUM WORKING PRESSURE of 75#. Bladder type tanks have a manufacturers requirement of a 75# pressure relief valve installed or the warranty is voided. So is the manufacturers liability. You might be liable for not installing a 75# relief valve. Someone wants to raise the water pressure to 90#? Municipal water systems put pressure reducing valves on water services to individual homes that are over 75#.

    He wants more pressure in shower heads? And he is running 75# in the system? I doubt it if it is a well. You have to keep a 20 # differential between the cut-in and the cut-out pressure (range). They don't sell a 75#/55# pressure switch. If you want that range, you have to but a 60#/40# switch and adjust it yourself. If Roger Rocket the scientist tried to raise the system pressure with the standard Square D PS 104 type pressure switch, he probably turned the middle screw and it shuts off at 75# but probably comes back on at around 40#. Unless you are experienced at changing the pressure of PS104's, you can't do it. And if it was a 20#/40# switch, you can't adjust it because the springs are wrong. But, there's always a way for someone to fluck something up.

    Cheap shower valves? Are you kidding? What kind is that? Unless it was made in Viet Nam, and shipped illegally into the USA, they all meet standards. If it was recently installed, and they are 8" Center valves, as opposed to a single lever pressure balanced valve opening in the cold position with an adjustable limit stop, it will pass more than enough water to blow the skin off your back or the hair off your head at 90#. 75# just plain hurts. If he can stand under a shower head that is delivering 90# pressure for more than 5 minutes, he has some serious nerve sensitivity and needs to consult with a Neurologist. All shower heads sold in the USA must meet the Standard of 2.25 GPM. That's mixed down to not more than 106 degrees. If he can stand under a shower head, spraying 106 degree water for 10 minutes or longer, and not pass out from heat stroke, he is not of this world. Even those "Sunflower" shower heads sold by specialty stores and Lowe's and Home Depot only pass the restricted amounts. Even with the flow restrictors removed, the nozzles in the heads are tiny. The cheapest of cheap

    "Water Saver" shower heads do a better job of getting soap off than some more expensive heads. Even those big Speakman heads, the size of a 2 liter Pepsi bottle will blow the make-up of a woman's face and maybe some skin too. Might pay for itself by cutting the time between the plastic surgeon for the next Face Lift.

    Then, there's the well pump. What is it sucking off? What is the well yield? Is it a single stage jet pump sucking as a shallow well where it is less than 25' to water? How many GPM/GPH is it delivering out of the head? Has Rocky put a hose and a 5 gallon bucket and timed how much water comes in 60 seconds (GPM). Another pump in series won't increase the water that comes out of any well. It can only boost the pressure with what is available. If it is a "Deep Well, Twin Type", all bets are off. The only thing that might happen is the pump will stop pumping because Rocky interfered with the hydraulics of the pumping.

    If it is a cased well or submersible, what is the well yield and what is the GPM rating of the pump? What is the developed flow of the well?

    YOU may or may not understand what I am saying. Rocky doesn't. I could explain it to him, but it is my experience in life that he is so much smarter than the rest of us, that he won't listen and will be looking for someone to agree with him. That's why I usually just wish the Rocky types of the potential customers, Health, Happiness and LONG distance.  
  • TomTom Member Posts: 455
    Sorta on board with you


    It's a drilled well with a submersible pump, it's feeding the house with 4 full baths with 1' pipe. During his newest renovation this customer spent 10K on tile and labor but neglected to replace the dual Moen Chateau shower valves one that feed a rainmaker and the other feeds a hand rail. He also decided no glass door which means his wife feels cold unless the entire bathroom is filled with steam. The valves aren't junk but not what I spec when I do a new shower like this. I like to feed rainmakers with 3/4 and typically do 3/4 thermostatic valves and volume controls. I was not brought into this project until after the tile was done and now it's not going to change. My thought is the same as yours just walkaway, but was curious if I could come off the expansion with a regulator which ensures the proper psi to the booster and then pipe to the booster from there feed the rest of the system just so there is a less noticeable pressure drop as you typically have with well systems.
    Montpelier Vt
  • ZmanZman Member Posts: 3,476

    Ice is on track.

    You will never increase the flow much without reducing the restrictions.

    You might want to show the owner the performance curves on the MQ.

    It doesn't go above 62 psi.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • icesailoricesailor Member Posts: 7,265
    Pressure Drop:

    Those Moen "Chateau" valves are dinosaurs. Is one fed to the other?

    Pull the supply off the toilet (as long as there is no toilet tempering valve on the toilet) and put a pressure gauge on the supply. Check the static pressure and then turn on the shower and check the flow pressure. If it drops appreciably, that's what you are going to have to overcome. If the shower is on the second or top floor, there will be a pressure drop from just the increase in elevation. Decrease the range differential but don't go above 75#. Try 50# on and 70# off. Even 55# on. Put a hose on it to the outside and see what the maximum flow pressure is. If it is like 50# flowing and won't go higher. Check and find out what the well is flowing when new. Take the cap off and see if you hear the pump sucking because the well yield is overcome. Its hard to measure a 4" casing with a plumb bob to check the range without getting caught on the wires and pull rope. Remember, if it is a 1/2 HP 12 GPM pump, it doesn't develop 12 GPM''s if you go too far past the pumping range. And the delivery drops off. A 3/4 HP 12 GPM will give you more pressure.and the same 12 GPM volume at the same depth if you have gone over the head limit. Then there's the issues of smaller GOP pumps. They produce more pressure from greater depths. A whole other issue. If you don't understand the issue, ask. I'll explain it.

    It would be cheaper to install a shower door before going to all the problems with the shower valves. Because the Moen cut out in the wall is so large, cleaver and patient installers can often get a different valve in. Especially if you can get into the back of it without ripping out irreplaceable tile. I had to do that on a German thermostatic valve that (Dornbracht?) that the plant burned down in Germany and they lost all their casting molds for old parts and could no longer provide replacement parts for their old valves. I used a Summons high flow valve that uses the S-1 cartridge. The old one, not the S-96 type. It is designed to pass far more water than a Moen Chateau will ever think of passing. It might improve it.

    A quality shower door will really improve things. If you get a big pressure drop in the bathroom, the piping is too small and just a rise in pressure alone won't solve it.

    You'd be surprised about how quickly some problems go away when the women using the shower are warm and comfortable in the shower. If the door had been installed in the first place, you probably wouldn't be hearing about it.

    My gut feeling still says that there are "issues" that haven't been discussed with you about the history. Like low bid incompetence. The shower door is the last thing to go in. Sounds like there might have been a ca$h issue.

    Who ever heard of a high end bathroom without a quality shower door. I've installed loads of them. It makes or breaks some jobs. But they aren't cheap. How many sides?
  • icesailoricesailor Member Posts: 7,265
    MQ & 62#

    And if you had 62# flowing at the valve, it would be shredding skin off your body.

    Something else I forgot to mention. Be sure to check the HOT water pressure, flowing. Do both at a lavatory in the bathroom. Hopefully, they didn't install those worthless POS Pedestal sinks and used cabinets. Then you can install  flex supplies temporarily to check the pressure. .

    Chateau's have those nasty check stops that are always broken and a Pee Poor balancing spool. Smaller than a pencil. When you go into the bathroom, turn on a sink faucet and turn it off. Do you hear a "Click" behind the shower? That's the balancing spool going back and forth. It means that the check stops are bad. When that happens, you  get a cross connection between the hot and cold and you lose available pressure. Remember, that Moentrol spool is OUTSIDE the 1200B Cartridge spool. It is in contact with the active water when the valve is off.

    And cut a notch in the bottom of the escutcheon cover so that the water doesn't collect there and run in behind the wall. Every Moen valve does it. Just look at the high tide mark on the wall that lines up with where the water runs out the back.

    Ask me how I know.
  • TomTom Member Posts: 455
    Thanks Guys

    Ice and Zman,

    Thanks for the helpful info, I will try the recommendations. These customers are "eccentric" both are very nice, wealthy, and have almost no common sense. Like I said I came to this project very late and was only suppose to trim the new shower with the new brush copper trim. I did that, while I was there he showed me his new Grundfos MQ 3-45 and asked I would put that on the 3/4" hot line that feeds the shower? I said no not possible for many reasons, I showed him the max incoming temp explained the balancing aspect of shower valves, etc and he agreed. Then he asked me to put it on directly after the expansion tank, I said why dont I bump up the pressure switch and add pressure to the tank to compensate then you use the shower a few weeks and tell me if it's better. He agreed, it's currently at 50-70 and he said it's not enough.

    I can easily walk away from this, but was curious if that style pump could be installed after the expansion tank. Sounds like no, so I will let them know that the answer is no. I am curious if this might be a different problem as Ice suggested, I will test pressures all over the house and check. BTW this is a first floor shower, it's being fed with 3/4" copper and was probably very nice back in the day. I did let the homeowner know that if he ever thinks he's going to renovate anything water related again he should bring in the plumber much earlier if for nothing else to avoid this type of problem.
    Montpelier Vt
  • icesailoricesailor Member Posts: 7,265
    Not Enough:

    The "Not Enough" is because the hot water inlet temperature isn't hot enough and it won't mix down enough. If the hot water is too cool, the hot water can't overcome the cold. Or, the Chateau's have bad checks. If you can't shut them off completely to service the valve, they are bad. And when they go bad, it's often because one of the washers is broken and jammed into the port, obstructing it. Usually, if both valves behave the same way, the hot water isn't hot enough.

    If you're running 50#/70# pressure and the shower is on the first floor, it HAS to hurt. Seriously.

    Do you hear the "Click" behind the wall when you operate the sink faucets in the bathroom? The balancing spools might be sticking. If they stick all the way in one direction, they won't pass water. If they stick part way, they will pass water but restricted flows on one side.

    Have you changed the cartridges? The 1200B brass cartridges are actually the wrong cartridges for the later valves. You need the 1205 plastic ones. Sometimes, if you replace a plastic cartridge with a brass one, they won't shut completely off.

    How's the well water quality?

    If you get "Legs" on the side of the toilet bowl which tells you that the flush ball is leaking, is it a light brown/green color? Does the toilet tank stay sort of clean (not thick with rust) but has this light brown/green color on the sides and it is a slime on the flush valves? That stuff will cause spindles to stick.

    That Moen valve body was a very good valve body. They used it for all their valves. Does it have the Moentrol feature with the big nut to the right of the spindle and the escutcheon screws on an angle rather than horizontal? Good luck getting the nut out. Even more luck in getting the Moentrol spool out.

    Keep us posted.
  • icesailoricesailor Member Posts: 7,265
    Equal Pressures:

    I forgot to add:

    Pressure Balance shower valves depend on EQUAL PRESSURE ON BOTH SIDES OF THE VALVE!!! If you put a pump on the hot only and increase the hot side pressure, the valve may stop working completely.

    "Pressure Balance" is the operative word.

    Another reason why Countermen and Sales Persons that aren't plumbers, and don't understand how pumps work and shower valves work should STFU and leave it to the Professionals who at least have a clue.
  • hot rodhot rod Member Posts: 7,012
    check for a partially closed valve

    it could be a flow restriction somewhere.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • HillyHilly Member Posts: 367
    edited May 2014
    check hot pressure near by.

    Definitely check the pressure on the hot side somewhere near by too. Like was mentioned, the pressure will drop on the cold side to match the hot… pressure-balancing control valve. Anything over 40# and that fixture should be just fine from my experience. There was a reno as you mentioned, so who knows how many times those lines were cut and joined elsewhere in the system upstream. I cut out a troublesome shower valve one time on a service call and found a electrical wire connector slammed up against the inlet of the valve. Wasn't my mishap, was only lucky enough be on the service call and even luckier to find the problem. Pull the cartridge and carefully blow the water through to make sure nothing got caught in there. Found wood chips, burrs, etc all over cartridge's before. Anyway I can't wait to find out how you overcome this. Please be sure to share you're triumph with us in the end.
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