Another Water Pump Question

[MeetJohnDoe]

Situation: I have a small bungalow house with a SS water tank connected to a water pump that sends water to the house.

Problem: The first water outlet past the pump, and spout used for a garden hose hook-up works fine and has very high water pressure. However, all the subsequent water access points, which are all inside the house (i.e., kitchen sink, bathroom sinks, showers, etc.) have adequate but not as high a pressure. In addition, whenever one of these inside points are used, the water-pump seems to cycle on and off...you can hear a pumping action like a heartbeat that is not present when using the garden hose (outside/first) water access point.

Also, the hot water heater unit under the kitchen sink (small Fagor unit) does not work. My electrician says it's because of inadequate water pressure which is not strong enough to cause some sorta internal contact to connect in order for the unit to produce hot water. The red "on" indicator on the unit goes on when I turn on the tap but water mai lon

Question: Why is this and what would be the solution to have higher pressure in the house? Do I need a more powerful pump...it's a fairly large unit already.

[Rimmer]

Have you checked the filters at each faucet? Maybe you have sand in them.

[Rimmer]

Have you checked the filters at each faucet? Maybe you have sand in them.

[Crossy]

Are the inside taps significantly higher than the outdoor one?

Trace your pipes from the pump, the plumber may have installed a convenient pressure reducing valve which you can open up.

Is the pump actually switching on and off rapidly when running the tap, if so the pressure reserve tank has probably lost its air. How to get the air back in depends upon the pump type but the easy ones have a valve on top of the tank which you open to let air in having turned off the water and power and drained down the pump.

If the heater 'on' light is coming on then it's seeing the water pressure. Check the dial is not turned to 'cool' or something. Of course the heater could be dead

[dotcom]

I think you are confusing pressure with volume.

Theoretically (I am a hydraulics engineer) the pressure is the same across the system (excluding multi level house as Crossy has said. Water exerts a force of .4328 psi/foot so for your second story - assume 12 feet - would be a pressure drop of 5 psi. (You would hardly notice that).

Where you will get problems however is due to friction & restrictions in your piping system.

Rimmer is 100% correct remove what he is calling "filters". Those are actually "bubblers" which breaks up the stream of water at the faucet (mixer).

Most homes use 1/2 inch pipe downstream of the pump & for most installations & that is fine.

What can happen though is that glue can partially block some joints etc. This will restrict "volume" despite having perfectly acceptable pressure.

The way to check is this. Disconnect your toilet fill up hose. (there should be a stop valve fitted at the toilet).

Fit up a garden hose to that & run it into the toilet bowl. Compare what you get at the toilet versus what you are getting in the garden.

99% of the time you need a bigger pump. Failing that rip out the piping & upgrade to 3/4 inch.

You haven't told us the wattage but 250 watt gross is probably not enough.

[trogers]

My guess is that your garden hose is a direct tee-off of the same diameter to the main distribution pipe.

Your problem is probably a distribution pipe of too small a diameter. I would recommend at least a 1-inch diameter distribution pipe to run from the pump to the top most bathroom. All tee-offs should be 1/2-inch dia. This should allow a 1.5 bar pressure to the top most bathroom.

Tank size will depend on rate of water consumption - litres per minute. If you use the bathtub often, you will need at least a 1 cu metre tank.

Edited February 26, 2009 by trogers

[dotcom]

At my house (2 storey) I use 3.5 bar at the pump.

One inch is too big. 3/4 inch is perfect.

My house is all 1/2 inch (3/4 suction) & it's fine. Big ass pump.

[dotcom]

At my house (2 storey) I use 3.5 bar at the pump.

One inch is too big. 3/4 inch is perfect.

My house is all 1/2 inch (3/4 suction) & it's fine. Big ass pump. 400 watt gross.

[trogers]

At my house (2 storey) I use 3.5 bar at the pump.

One inch is too big. 3/4 inch is perfect.

My house is all 1/2 inch (3/4 suction) & it's fine. Big ass pump. 400 watt gross.

Sorry to disappoint you. X-sectional area of 1/2-inch x 2.25 = X-sectional area of 3/4-inch. Thus, with 2 tee-offs tapping from the 3/4-inch distribution pipe at the same time, not much water will flow further down the line.

A 1-inch pipe can accommodate 4 1/2-in tee-offs.

Edited February 26, 2009 by trogers

[dotcom]

You aren't disappointing me. I do this for al living.

Not in an armchair or a classroom.

I can assure you I can shove 100 liters per minute through a 3/4 inch line. Distance no object.

Thanks for your 11 posts though.

Keep trying.

I no bite on trolls.

Maybe you are well intentioned. If yes read learn & fit in.

[Artisi]

You aren't disappointing me. I do this for al living.

Not in an armchair or a classroom.

I can assure you I can shove 100 liters per minute through a 3/4 inch line. Distance no object.

Thanks for your 11 posts though.

Keep trying.

I no bite on trolls.

Maybe you are well intentioned. If yes read learn & fit in.

Well dotcom, you statement " I can shove 100l/m through a 3/4 " line. Distance no object." is certainly wrong wrong wrong, when it comes to flow you are confusing pressure with volume.

Using the following data (link below) for ¾" PVC and a flow of 100 l/m (26 USGPM) the pressure drop thru 100 ft (30 m) of 3/4" PVC pipe is going to be in the order of 6.5 bar.

This is based on the tables (link) this only lists for a max flow of 15 USGPM thru ¾ PVC - and gives 31 PSI friction loss , however, friction varies as the square of the flow – therefore

head loss for a flow of 26 USGPM =

26/15^2 x 31 = 93 PSI = 6.5 bar = 65 m

Therefore your statement stating that " I can shove 100l/m through a 3/4 " line. Distance no object", is absurd in the extreme.

I am happy to run hydraulic lessons for those interested in learning and maybe a few others might also read and learn something.

http://www.engineeringtoolbox.com/pvc-pipe...loss-d_803.html

Edited February 26, 2009 by Artisi

[trogers]

You aren't disappointing me. I do this for al living.

Not in an armchair or a classroom.

I can assure you I can shove 100 liters per minute through a 3/4 inch line. Distance no object.

Thanks for your 11 posts though.

Keep trying.

I no bite on trolls.

Maybe you are well intentioned. If yes read learn & fit in.

The use of 3/4 inch distribution pipe can be correct if the water outlet points are separately located (right and left sides of the house). A main 1-inch dia. pipe can be branched into two 3/4-inch dia. pipes and then fed to two water outlet points each - kitchen or bathroom. But the main pipe coming out of the pump will still have to be 1-inch dia. to feed four water outet points.

Edited February 26, 2009 by trogers

[Artisi]

trogers- no argument in general with your statement - I was commenting on dotcom's statement re any distance.

[Gary A]

It's a simple thing. The pump's storage tank has lost the air head. Turn off the pump and drain the tank. When you turn the pump back on the problem is gone. The reason the pump doesn't telegraph when the outside faucet is turned on is because it uses all the water the pump can deliver. When the storage tank has lost the air, there is no room to store the water and the pump will cycle on and off rapidly. The common term is telegraphing.

[dotcom]

Ok well then pal. I can shove 100 liters per minute through a 3/4 inch line at 60 psi - distance 1 meter - with virtually ZERO pressure loss.

Absurd in the extreme is suggesting you need a one inch supply line for a single family dwelling.

Yes if I were designing a 20 room apartment I might consider a 1 inch supply line but probably just go with 3/4 inch. No problems with volume.

Some of you need to learn how to do quotes.

[Artisi]

Ok well then pal. I can shove 100 liters per minute through a 3/4 inch line at 60 psi - distance 1 meter - with virtually ZERO pressure loss.

Absurd in the extreme is suggesting you need a one inch supply line for a single family dwelling.

Yes if I were designing a 20 room apartment I might consider a 1 inch supply line but probably just go with 3/4 inch. No problems with volume.

Some of you need to learn how to do quotes.

Your comment was any distance, not 1 metre hence my reply.

And why wouldn't you use 1" on a 20 room apartment, PVC is cheap and any reduction in head loss is a big money saver when it come to saving on power costs, but then what would anyone other than yourself know about pumps/ pipes and quotes.

[dotcom]

For the test I'll use a Halliburton triplex pump rated at 12,000 psi and 1900 liters per minute at < 100 psi. 4 inch suction 2 inch discharge.

Lighten the flock up.

What I said was that 1 inch pipe for a single family dwelling was massive overkill.

Get the Grundfos pump & you can shower like Paris Hilton.

[trogers]

For the test I'll use a Halliburton triplex pump rated at 12,000 psi and 1900 liters per minute at < 100 psi. 4 inch suction 2 inch discharge.

Lighten the flock up.

What I said was that 1 inch pipe for a single family dwelling was massive overkill.

Get the Grundfos pump & you can shower like Paris Hilton.

One wonders whether you are designing for a linear accelerator or for a domestic water supply.

Note from earlier engineering guide: http://www.engineeringtoolbox.com/pvc-pipe...loss-d_803.html

"Note! Velocity should in general not exceed 5 feet per second to avoid damaging noise and wear and tear of pipes and fittings"

If you need a visual aid, see figures 7.1 and 7.2 of page 37 of this guide:

http://www.toolbase.org/PDF/DesignGuides/pex_designguide.pdf

[Artisi]

For the test I'll use a Halliburton triplex pump rated at 12,000 psi and 1900 liters per minute at < 100 psi. 4 inch suction 2 inch discharge.

Lighten the flock up.

What I said was that 1 inch pipe for a single family dwelling was massive overkill.

Get the Grundfos pump & you can shower like Paris Hilton.

Use what you like - it doesn't change the fact that 100 l/m thru 3/4" PVC will always be 6.5 bar pressure loss.

[Artisi]

For the test I'll use a Halliburton triplex pump rated at 12,000 psi and 1900 liters per minute at < 100 psi. 4 inch suction 2 inch discharge.

Lighten the flock up.

What I said was that 1 inch pipe for a single family dwelling was massive overkill.

Get the Grundfos pump & you can shower like Paris Hilton.

One wonders whether you are designing for a linear accelerator or for a domestic water supply.

Note from earlier engineering guide: http://www.engineeringtoolbox.com/pvc-pipe...loss-d_803.html

"Note! Velocity should in general not exceed 5 feet per second to avoid damaging noise and wear and tear of pipes and fittings"

If you need a visual aid, see figures 7.1 and 7.2 of page 37 of this guide:

http://www.toolbase.org/PDF/DesignGuides/pex_designguide.pdf

Thnxs for the link - some of us will understand it.

[dotcom]

Use what you like - it doesn't change the fact that 100 l/m thru 3/4" PVC will always be 6.5 bar pressure loss.

Over what distance?

You like mixing metric units & US units. No probs.

[dotcom]

Here's the reality.

Not all of us are backpackers or Emglish teachers. Those folks rent accomodation & are usually not willing to spend the money to do stuff right.

Ask the Vietnamese or the Saudi's. The first thing American's will DEMAND is a hot shower at 40 liters per minute.

Second & third are ice & coca cola.

I never said you couldn't design a residential water system - but that website is junk.

I will state once again for the record. My system at my house is rated at 40 liters per minute at 3.8 bar.

And I have no problems delivering that - even to the second story - via 1/2 PVC pipe. The 13 mm wall stull. The heaviest type they sell.

Chill Phil.

My set up.

I already bolted the header tank down.

I got 4 bathrooms & no shortage of water. 750 liter holding tank.

[Artisi]

Use what you like - it doesn't change the fact that 100 l/m thru 3/4" PVC will always be 6.5 bar pressure loss.

Over what distance?

You like mixing metric units & US units. No probs.

Over 100ft (30 metres) as was discussed earlier, copied here for your attention.

" Using the following data (link below) for ¾" PVC and a flow of 100 l/m (26 USGPM) the pressure drop thru 100 ft (30 m) of 3/4" PVC pipe is going to be in the order of 6.5 bar."

As for mixing metric and US units, other than 3/4 PVC (20mm) I would think l/m and bar are reasonable metric terms.

By the way, like your Grundfos pump certainly streets ahead of the Hitachi / Mitsubshi units.

[trogers]

My set up.

I already bolted the header tank down.

I got 4 bathrooms & no shortage of water. 750 liter holding tank.

Seems to be a 2-inch pipe coming out of your pump. Where in the distribution do you reduce it to be a single 3/4-inch pipe to service your 4 bathrooms?

[longball53098]

That's a 1 inch in and out on that pump.

[Boksida]

- via 1/2 PVC pipe. The 13 mm wall stull. The heaviest type they sell.

I can't figure this part out - can anybody explain?

[Artisi]

That's a 1 inch in and out on that pump.

Well it sure isn't 3/4" (20mm) - so this raises a problem, we have been told in no uncertain terms that 1" (25mm) is not necessary - so either we are mistaken, back-packers or English teachers.

Also interested to know why 2 x 90 bends prior to the pump inlet - certainly poor pipe design.

I all fairness to dotcom, 13mm wall thickness must be a typo as you cannot have a wall thickness equal to the pipe diameter of 1/2" (12 mm) pipe, more likely 3mm wall thickness.

[longball53098]

I'm gonna take a wild guess he means Class 13.5 blue pvc and not 13 mm thick.

[Artisi]

I'm gonna take a wild guess he means Class 13.5 blue pvc and not 13 mm thick.

After checking Thai PVC pipe specifications I would agree - 22mm OD, class 13.5, 2.5 mm wall thickness.

I have calculated approx. head / pressure loss for a flow of 20 l/m, this is approx 6m / 100 metres of pipe length.

Edited March 1, 2009 by Artisi