How many pumps does my system need?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by mtbguy, Apr 28, 2005.

  1. mtbguy

    mtbguy New Member

    I am planning a unique plumping system for a house, but know very little about plumbing. I want to know in general how many pumps do I need for this system.

    The cold water I get from the city comes in my house at a pressure. I need a pump to get that pressurized water into my tank and around my house for the different appliances.

    1. Is city pressure not high enough to run my home pluming alone? and is that why I need a pump from the main to my tank?

    2. Do I need another pump for each loop(or appliance) going to and from my water storage tank? For instance, if I have a radiant floor system, I guess I need a second pump in my house just to run that, right?

    Simple questions right?, but I need an answer.

  2. Terry

    Terry Administrator Staff Member

    Bothell, Washington

    Most of the time, heating and water supply are two different animals.

    There is also a combined system that you can get.

    The first thing you need to know is the city pressure, which you can find out by gauging it. They sell the gauges that fit on a hose fitting in the irrigation departments.

    If you are between 30 and 80 psi, then you are fine.
    Under that and you may want a booster pump, over that and you should have a pressure reducer.

    In floor heating systems don't use very much pressure and may need to be reduced.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    You need "on site" help.
    1. We do not know what the pressure is, what you are going to use it for, why you need a tank, or what final pressure you need.

    2. Heating systems are a self contained closed system so it needs its own pump, along with a pressure reducing device. As in #1, we don't know what you are ultimately going to do, so cannot tell you if you need one pump or twenty.
  4. mtbguy

    mtbguy New Member

    Struggling to chew what I bit off

    The radiant flooring will be some 700 sqft for the house. The hot water will be provided by solar collectors mounted on the roof. Both systems will excahnge heat with the hot water tank.


    The hot water tank has two internal heat exchange coils, one on top and one on bottom. The bottom coil will be supplying the heat via the solar collector loop. The top coil in the tank will be in a loop with the radiant floor system. The hot water for all the other appliances (washer, sink, etc) will be supplied by the water within the tank (which is heated by the bottom set of coils).

    I have an idea of how it needs to be layed out, but I am still learning the basics when it comes to supplying pressure to the system.

    My guess is that I will need three pumps. One main pump to pressurize the tank and water supply for all other appliances. The second pump will be in a closed loop with the solar hot water collectors and bottom coil of the tank. The third pump will be in another closed loop with the radiant flooring system.

    So I essentially have one hot water tank and three closed loop systems; Radiant floor, solar hot water collectors, and general appliance/potable hot water supply.

    Do you guys see any horrible assumptions in my plan so far?

  5. quiet pumps would be nice

    I used to install NOVAN soalr panels and other brands in Colorado and I wouldent wish
    what you are doing on a dog....Novan was a great system, but they are now bankrupt and gone , probably like the company you are presently looking at will be some day too.

    If you are completely unaware of the amount of water pressure you have and
    wether to gear it down for the boiler and solar system, and what needs pumps and what does not, that is not a good sign of things to come...
    I have looked at the design , hope-fully you are not installing "drain down" water type type solar panels... they are nothing but problems
    depending on where you live.... they lime up over time...and
    maybe in arizona they might work fine
    IN arizona things dont FREEZE UP as much...

    I did not look in depth, but it appears that the solar panels use water ..??
    It looks like the heat excahnger is mixing with potable water, so I doubt they are useing Glycol or anything else that might poison you....

    you might want to check into this before getting in too deep...

    keeping things simple is the best path to take my opinion

    water type solar panels are nothing but trouble.....they freeze up with any type of malfunction, (thats real bad) they waste water cause they have to drain down at night, ect, ect...

    Also keep in mind that your heat excahanger tank is good for maybe 10 years if you are real lucky.

    I have torn out dozens of these old solar tanks over the years....Never re-installing the same thing again. They just leave the panels dead on the roof and install a hot water heater cause they usually never worked right in the first place andthey dont want to spend any more money on it anymore.....

    Honestly, installing a solar system enough greif for anyone that knows basically what they are doing...

    I have seen solar system disasters that were designed by people that actually knew what they were doing...all the big plans and designs come crashing down after only a year or two.......that aint good.
    I respectufully advise that if this is your home, it might be prudent to think this over pretty long and hard...

    and at the very least get some estimates and get advice from people who do this every day...

    Because once you have got this radiant system buried in concrete, and everything bought and installed, panels on the roof,ect.....
    you really cant go back... its a done deal....

    A passive solar system is far less trouble....and works pretty good if you got a south faceing area where you could just install a fan and pump air through the panesl to force warm air down into the house...

    I would rather install a wood burning boiler and use it as the back up to a hydronic system than get involved in what you are about to do...

    please check into wether the panels use water or glycol....thats very important...

    keep it simple

    thats just my opinion...
    Last edited: Apr 29, 2005
  6. mtbguy

    mtbguy New Member

    Normally, yes I would 'keep it simple' for my own home, let alone my first DIY, but this is not the case. This is a research project to explore solar technology at my college. Normally I am a keep it simple kind of guy, but this is a learning experience with minimal consequence for exploring better altrernatives. Besides, the system we're planning is really not any more complicated than a traditional system. It just that we're rookies and this seems techie bc it's new to everyone, especially most professional plumbers.

    You're right about solar panels not using water, but these are not solar panels, they are solar heat collectors for a hot water system. An example of of can be found at Very cool technology and not complicated or riskey as you may think.

    As for the glycol issue... I could use a substance like this in a closed loop without contaminating my potable water. It really would not matter since it's in a closed loop. Nevertheless, I will not be using any non-potable substances in any part of the setup.

    My questions pertain more to the basic concepts of plumbing and I'm trying to find a basic explanation of pressures, pumps, primary/secondary loops, tempering valves, etc. I need something like plumbing for dummies to explain what a system is composed of and what is needed in the typical case and what the function of each part is.

    So in most cases do people just run there dishwasher and other things off of city pressure? and do you need a special valve or pump for each different appliance to adjust pressure and max temperature?

    Any help anyone could lend would be much appreciated.

    Thank You!
  7. SteveW

    SteveW DIY Senior Member

    Omaha, NE
    I'll chime in here. I'm not a plumber, just a DIY'er interested in your project (many of my friends are engineers --).

    I can't help with tempering valves and the like. Regarding your other question, though, I do know that in normal residential situations using "city water," there are no pumps in the plumbing system per se as long as the supplied water pressure is within a certain range (something like 30-60 psi give or take). The typical residential problem is too high of pressure, treated with a pressure-reducing valve (PRV); I think it is very rare that city water supplies would be below the proper range and need a pump to maintain pressure. On the other hand, some newer systems use a recirculating pump to keep the hot water side hot all the time.

    Residential appliances like washing machines and dishwashers are designed to run off of the sort of pressures I mentioned. There are no PRVs in the plumbing system at those appliances (although some appliances may have some sort of flow restrictor within the appliance; for example, an ice maker in a refrigerator).
  8. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    A solar collector can overheat the stored water, and sometimes that is a good thing in areas with minimal sunshine, since it allows the amount of stored water to be effectively increased. But a temperture mixing valve is then used to reduce the temperature to a usable, safe, level. Normally you will not need a domestic water supply pump. The heating system has its own pump since it is a closed system, and the solar heating section would also have a pump since it is a second closed system. If you are in a cold climate the solar system has to have a freezing temperature override to turn the pump on to prevent the panel from freezing and rupturing.
  9. you get what you get.

    you are useing solar panels that use water,
    they are simply a pain in the ass..

    water freezes in the winter..always has and always will
    . thats all I am saying ....

    whatever the new "high tech term" for your panels are , its still water

    and it depends on where in the country you are putting them.

    they usually drain down every night under 40 degrees in the winter and pour the water down the drain..... whatever the water is worth... be sure to calculate that into the energy saveings too....

    Lime deposits in the heat exchanger are the same too they degrade the cost saveings too..

    Limie deposits in the water heater are a problem too.....


    I have been down this road before, someone is getting something put on their house as a college experiment basically for free or at cost...
    so they think.

    all your buddies are working for a school credit ect....

    the guy thats house is going to be the "GUINEE PIG"
    just cant pass up the deal .. thats my guess....

    you want free advice and your mind is

    already completely made up.... so good luck with it.

    as you stated in your first post.....

    you are certanly going to have a very "unique" plumbing system
    when you are through. It will be one in a million, no doubt about it.

    Getting someone to service it down the road when the experiment is over,
    the engenering students are all gone and moved on,
    and that homeowner is left holding the bag,
    thats going to be the fun part.

    I have literally been there and done that over 25 years ago.

    good luck to you and all your freinds.

    Last edited: Apr 30, 2005
  10. mtbguy

    mtbguy New Member

    Tempering valve

    HJ, thanks for the info that was helpful.
    Mark, I think you are confused about the situation, sorry if that's my fault.

    Two questions regarding hot water for anyone out there.

    1. Pipe material: We were thinking of going out on a limb and using a new product for the piping (pretty new stuff, but that's the point of this experiement). It's called Aquatherm. I believe it's a poly butylene, but the max temp seems to be around 120F(anti-scold). Our dishwasher requests 140F and our heating system can and will heat up to ~190F. Obviously we can't use the Aquatherm here, but is copper going to be our best alternative for the hot water pipes?

    2. Tempering valves: What's the jist of these things. Are they simple mechanical valves set for one temp or is it something the user sets once for a certain temperature. And I've also heard of three-way and four way valves. Are these tempering valves or a different beast?

  11. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    They are user adjustable. The degree of precision is directly related to the cost of the unit. Three and four way valves are used with circulating pumps to mix cooled water, possibly from a hot water circulation system with the hot water to give a reduced temperature, and/or cold water whichever is needed to give the proper final temperature..
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