Boost pump for low water pressure

[Alaska]

The municipal water system only provides 20 Psi at my home (I'm on a hill). I have a holding tank down the hill, 40' lower than the house, and I pump from that tank on up to the house with a separate pump. I run my system at the holding tank at 85/65 Psi and it is OK. The municipal supply is from a 2" line and has good volume.

Can I put a booster pump in parallel with the municipal line and get good pressure at the house? The pumps I see only go to 60 Psi or so and with the 40' lift this would be very marginal. Does the booster pump add to the pressure of the municipal line or does it just increase the volume?

Thanks for the help.

 

[TD2K]

You have another problem than just the lift to your house I think. If the pressure is your holding tank is 65 to 85 psi, a 40 foot lift would drop this pressure by about 17 psi so you should have at least another 25 psi at your house at the low end of your existing surge tank pressure. Is there any sort of pressure regulator at your house where the water line enters that is stepping down the pressure?

You could install a booster pump at your existing surge tank and feed a new surge tank at the house. You would need the surge tank so that the pump could cycle on and off as needed, you wouldn't want it running constantly as for much of the time, there would be no flow through it (sorry if this is all obvious to you).

A 60 psi booster pump would not be marginal in my opinion. With a 17 psi loss due to the lift up to your house, you would add 43 psi to your house water pressure. I do not know what pressure domestic water piping is good for, this doesn't sound like it should be too much but oh mother, what a mess if I'm wrong.

 

[KernOily]

Better be careful. Most domestic water systems (faucets, dishwaher valves, washer valves, etc.) are not designed for pressures much in excess of 60 psig. Any higher than that and you'll start seeing pieces of O-ring in your kool-aid. In fact I think the UPC limits the pressure at the service entrance to 45-70 psig, if memory serves. Thanks!
Pete

 

[KernOily]

Also, without knowing much more about the system than what you've written, a pump in parallel will not add any more pressure to your system because, as you remember, fluid systems in parallel must all have the same pressure across them. So any pressure you add in the parallel branch will end up pressurizing the entire system by a little bit and will not have the effect you are after. Again, this is a 5-minute analysis based on no more than what you posted. I know nothing about how the system is actually piped up, so I can't say for sure what will happen.

Now, if you disconnect the parallel line and add the pump, you will get the boost you are after. As TD2K said you don't want the pump running all the time. How about adding a volume tank with a pressure bladder in it? Thanks!
Pete

 

[Alaska]

I have posted a better description and a drawing of the existing system and the proposed booster pump.

I didn't do it here because I don't know the rules about posts. A link to the picture is here and again thanks for the help.

http://www.rblantz.com/~pump

 

[kbander]

I understand what you are trying to do...but I agree with TD2K that you are having a big pressure drop problem somewhere (possibly a regulator). From what you provided, you should have 48 to 68 psi at your house right now, assuming line losses are negligible.

Also, on your drawing you show a check valve in parallel with the booster pump. The way it is drawn it would just cause most (if not all) of the water to recirculate. You have to get rid of this bypass to get any boost.

Without the bypass, at 60 psi max dp for the pump (is this the correct shutoff pressure?) and 85 psig suction, the maximum shutoff pressure that your piping will see is 145 psig (128 psig at your house). I don't know what the limits are on your piping, but 128 psig is way too high for your fixtures....