Ways to increase water pressure before entering water heater?

[Home Improvement]

Hi all,

I'll put a diagram of my house to make things clearer

my water heater (WH) is of type paloma PH-5RX. Ideally, it needs pressure of 1 bar, but minimum working pressure is 0.2 bar.
the water from local water mains can reach about 1 m above second floor, so that's about 0.2 bar when it hits water heater (if city water main is directly connected to water heater), cutting it close. So, I've thought of 2 solutions:
1. the GREEN route --> from tank A, I use Pump 1 to supply pressurized water to water heater. what I dont like from this setting : the pump will turn on/off very frequently. I count for each bath, the shower will turn on/off 5 times. so for 3 persons, and 2 baths a day per person that's 2 x 3 x 5 = 30 times the pump goes on/off per day. pretty sure this will shorten the lifespan of the pump considerably. as for electricity, I dont think that's gonna be a problem since pump like this shouldnt take too much electricity. second con of this approach is it gets noisy more frequently.
2. the RED route --> also from tank A, I use Pump 2 to suck and move the water to tank B first before letting gravity taking care of the pressure for me. it's just around 0.5 bar, but at least it's above the minimum requirement for the water heater to operate. the upside of this approach is that the pump wont run very often. and since pump is on third floor (everybody's living on first floor, nobody's on second and third floor), nobody cares about the noise, which is already a lot less frequent than the GREEN route.

which of the two is better? did I miss anything?
is there another way that's even better than the 2 solutions I proposed? I heard about pressure tank, what are those? is it suitable for my needs?
for RED route, is it better for pump 2 to be closer to tank A or tank B? what kind of pump is recommended?
for GREEN route, what kind of pump is recommended?

thanks

 

[LLigetfa]

You should not put a tank before the pump as shown in your layout. If the pump draws faster than the municipal source can supply, the vacuum can collapse the tank.

Why do you need two pumps? I would use only one at the service entrance to serve the whole house, both hot and cold sides.

 

[Sponsor]

 

[Valveman]

All you need is a booster pump attached to the city water line and boosting to a pressure tank and on to the hot and cold water supply. You are right about the pump cycling. Not only is cycling bad for the pump, but causes the pressure to go up and down over and over. Your choices are to use a large pressure tank, which will cause low pressure for much of the time, or to use a Cycle Stop Valve. A Cycle Stop Valve like the CSV1A will stop the pump from cycling, allow the use a of little 4.5 gallon size pressure tank, and deliver strong constant pressure to the house. Here is a link to a graphic you can play with. http://www.cyclestopvalves.com/simple/home.php?anim=1above
And here is a video of how the CSV works.

 

[Reach4]

Why do you need two pumps?

I think he is proposing to use one or the other. I think the proposed tanks may be atmospheric tanks.

 

[LLigetfa]

I think the proposed tanks may be atmospheric tanks.

Could be. Tank B would then only gravity feed at .43 PSI per foot so not a lot of pressure. I don't know how high the ceilings are to calculate the height of the third floor but at 10 feet per floor, that is just 4.3 PSI per floor. Then to limit cycling, it would have to be a large and heavy tank when full.

A large in or on ground cistern would work well with what Cary proposes.

 

[Home Improvement]

what kind of pump is recommended for the pressure tank configuration? any normal booster pump? the WH recommends water pressure of 1 bar for optimum performance.
is it possible if I use a 200 liter pressure tank and I want the water pressure out of the pressure tank to remain constant between 0.9 - 1.1 bar (14 - 16 psi)?

thanks

 

[Valveman]

A jet pump would be best. Something like a J5S Goulds. A 200 liter pressure tank only holds about 50 liters of water. And to get this 50 liters from the tank you will need a 20 PSI bandwidth on the pressure switch like 20/40 or 30/50. A pressure tank does not supply water, the pump does that. If you want constant pressure you need a very small tank and a constant pressure valve. But I would still use at least a 20/40 switch with the CSV set to maintain 30 PSI constant. A J5S pump with a PK1A constant pressure control kit would be my first choice. It will look something like this.

 

[Home Improvement]

the scenario that I face:
1. 3 people living in my house, each people showers twice a day, morning and evening
2. I've calculated that for each shower, the average water needed is 20 liters
3. during shower, I observed the standard behavior is : rinse, apply soap to body, rinse, apply soap to face, rinse, apply shampoo, rinse, done. for this, I count 4 times the water heater will be turned on.

my concern:
1. I dont want pump cycling (turned on/off too often)
2. noise when pump is turned on

can this J5S Goulds jet pump achieve this? my reasoning for 200 liter pressure tank is to make sure that the pump doesnt start everytime we take a shower. preferably only once every 3-4 days. with CSV, seems that we can make the water pressure constant, but can it be set to 14 or 16 psi? secondly, with this pump, and assumption that each shower takes 20 liters of water, how many times the pump turns on per day (one day equals 6 showers, so that'll be 20 x 6 = 120 liters of water)?
thanks

 

[Valveman]

I commend you on being able to use only 20 liters per shower. Most people use more than 20 gallons. Like I said a 200 liter pressure tank only holds 50 liters of water. And that is when using 20 PSI between on and off like 20/40 pressure switch. To have more than 14 PSI and get any water out of a pressure tank, you would need a pressure switch setting of say 14/34. On at 14 and off at 16 would mean you only get about 3 gallons out of that pressure tank.

But even if the pump turns on and off 4 times per shower X 6 showers per day, that is only 24 cycles per day. That is nothing to a pump that can handle a maximum of 300 cycles per day. Yes the CSV1A can be set as low as 15 PSI, and when used with a small 20 liter pressure tank, a 15/35 pressure switch setting would mean it would tank over 1 minute to fill the tank and shut off the pump. So if during showers you turn the water back on for another rinse within 60-70 seconds, the pump would still be running and the pump would only cycle once per shower. But just using water in short spurts like that, the constant pressure from a CSV would not be of much benefit to you.

A J5S with a 200 liter tank and a 20/40 pressure switch and no Cycle Stop Valve would mean this pump would only cycle about 3 times per day to give you the 120 liters (27 gallons) you normally use.

 

[Home Improvement]

20 gallons? that's like 75 liters...yikes...unless you keep the shower running while you apply soap, shampoo, etc...
assume the duration between each rinse is 4 mins, for 20 liter tank pressure and 15/35 pressure switch and CSV set to 15 psi, how many times the pump will cycle per shower?
thanks

 

[Valveman]

People here rarely turn the water off during a shower. We would call that a Navy bath or a "spit bath". I enjoy the hot water on my back during a good ten minute shower. With a 2.5 GPM shower head that would be 25 gallons per shower. And that is no where near as extravagant as some who have 18-23 gallon per minute multiple shower heads and features.

If you turn the water off 4 times during a shower, and there is 4 minutes between those times, that would be a 16-20 minute shower? With a CSV and a 20 liter tank, the pump will cycle once for each use, because they are 4 minutes apart. So that would be 4 cycles per shower. If you only have 1 minute between uses, the pump would not have time to fill the tank and shut off, so there would only be one cycle per shower. Four minutes between water uses would give the pump time to shut off, but then you would have 5 liters in the 20 liter tank to use before the pump comes back on. So if the next rinse uses less than 5 liters, there would only be 2 cycles per shower.

 

[Home Improvement]

so, I was looking at pressure tanks in my country, and I stumbled onto this
http://www.globalwatersolutions.com/index.php?page=pressurewave-series

according to the seller, the water coming out from these tanks is guaranteed to have constant pressure. so, if I pump 130 liters at 1 bar to this tank, doesnt matter if the tank is full or only have 1 liter left in it, the water will always come out at 1 bar out from the tank, even without CSV. is this possible?
I'm interested in their model PWB-130LV that can hold 130 liters of water and have total tank volume of 210 liters (so effective volume a little bit over than half). same with PWB-150LV that can hold 150 liters with total tank volume of 280 liters.
thanks

 

[Reach4]

according to the seller, the water coming out from these tanks is guaranteed to have constant pressure. so, if I pump 130 liters at 1 bar to this tank, doesnt matter if the tank is full or only have 1 liter left in it, the water will always come out at 1 bar out from the tank, even without CSV. is this possible?

No.

But you still want a precharged pressure tank with a pump that cuts on and off. Precharge pressure tanks will hold the pressure more even, but it will not be constant. People with wells commonly have a pressure tank with captive air. The amount of practical drawdown is about 25% of the nominal tank size. This is because considerable space is needed to hold the captive air.

 

[LLigetfa]

according to the seller, the water coming out from these tanks is guaranteed to have constant pressure.

It is just a sales tactic. It goes against the laws of physics. There is no way you can have as much drawdown as is purported either.

 

[Home Improvement]

yeah, I guess that's too good to be true...
for these CSVs, is this only available in USA?
I'm in Jakarta, Indonesia, is there any distributor in my area?

 

[Valveman]

I just sent some CSV's to Indonesia. I don't have a distributor there, but can send them to you if you like.