Water Pressure

[supaprik]

I live in a double storey house, the water pressure down stairs is exceptable but isnt upstairs..

The pump we have is a Mitsubishi model WP155N which kind of looks small but I really don't know much about this. and the water heater upstairs is a 5500 series which can make blistering hot water at the current flows,all I basicaly need is a decent shower up stairs, I guess my question is, If i buy a bigger pump would this give me HIGH pressure for showers?

Thanks

Edited January 11, 2011 by supaprik

[Beardog]

The pump is most likely to small for the application a Mitsubishi 305-405 or Hitachi same sizes & last but not least a Grundafos series pump is king for upstairs setups.

First I would remove the tap in the sink or toilet outlet (& make sure to cover the flow so it doesn't go everywhere) & check that you do not have obstructions in the pipes. On heavy rain years we get tiny pebbles that can restrict the flow. Or it can be scale sand or many other organic things clogging the lines.Also if you have a filter before or after the inlet check to see it is not clogged. You didn't mention is it a well borehole or city main you are off of----if it is a well you may want to pull up the pipe inside the well & see if the filter basket on your foot valve is not clogged. Sometimes it will deliver good to down stairs but no pressure when taxed to push upward. Check first so you don't spend unnecessary funds. I still think your dealing a little short for a 2 story build. Mitsubishi pumps will run 6800- 7500 for a 3 or 4 series & a Grundafos around 9000+ baht(ball park figures)

Edited January 11, 2011 by Beardog

[Pib]

Not familiar with N model WP155 but if it's like the Q models such as the WP-155Q, then the WP-155Q pressure switch settings are pump-on at 18.9 PSI / 1.3 Bar and pump-off at 27.5 PSI / 1.9 Bar, which will end up feeling like an average water pressure of 23.2 PSI / 1.6 Bar. And the effective water lift height of the pump is 12 meters. Assuming your shower hose/head ain't clogged/still has a restricter in it (but sure to check for that), a 23 PSI pump output (less by the time it gets to the second story of your house) ain't going to provide a strong shower.

I have a WP-255Q pump which uses a pump-on pressure of 30.5 PSI / 2.1 Bar and a pump off pressure of 40.6 PSI / 2.8 PSI, which provides an average water pressure of 35.5 PSI / 2.45 Bar. And it has an effective water lift height capability of 19M. My upstairs shower pressure is strong. Pressure throughout my two story, 4 bedroom, 3 bath house is strong even when the wife has the washing machine going, a sink tap running, and me taking a shower.

I would recommend a WP-255Q or WP-305Q, both of which use the 2.1 - 2.8 Bar water pressure settings and have a water height lift capability of 19M. A WP-255Q should be more than enough and be about 10% cheaper than a WP-305Q. Any larger Mitsubishi pump than the two I mention in this paragraph ain't going to give you any higher pressure and just a little more water volume capability and water height lift capability.

What ever pump you end up buying be sure you get one where the pump-on pressure is at least 2.1 Bar....and you'll probably find out the corresponding pump off pressure will be around 2.8 PSI...this a pretty normal pressure switch setting/design for the medium to large size Mitsubishi, Hitachi, etc., type pumps sold widely. You can get higher pressure range by going with a centrifugal type pump but these types of pumps are in the minority when it comes to pumps commonly used for a household. See below for specs on the WP series of pumps.

[supaprik]

thank you guys, I have checked all the other outlets and all seems fine. the house is only 4 years old and is on bangkok mains water, there is a filter between the pump and storage tank which also is clear, so by the sounds of things I should just buy a larger pump and all should be ok, again thank you for your responses, I greatly appreciate the time you spent to write

[transam]

I have a 250w pump that doesn't have a pressure vessel attatched. Sorts stuff out internally. Two story house, great.

[Pib]

I have a 250w pump that doesn't have a pressure vessel attached. Sorts stuff out internally. Two story house, great.

250W pumps seem to be a sweet spot for home water pumps...my WP-255 is a 250W pump also.

But the thing about pumps that don't have any pressure vessel (a.k.a., expansion tank, pressure tank, booster tank) is they run continuously during any water usage...or kick-on frequently if you have a small leak somewhere like on a commode valve, sink faucet, water hose faucet, water pipe, etc. But most do have a small pressure vessel of around one liter that does keep the pump from kicking on if only turning a faucet on for a second or two, to help prevent very frequent pump turn-on due to very small leaks, etc.

With a pump design that sets on top of a 15-20 liter pressure vessel like the WP series, the pump only runs approx 50% of the time during constant water usage. And for small leaks or a faucet being turned on full blast for 3 to 5 seconds won't cause the pump to kick on due to the water stored in the pressure vessel. Now, you won't get 15-20 liters to come out before the pump kicks on, you'll only get about 1 to 1.25 liters out before the pump kicks on due to the amount of water & air in the pressure vessel and the physicals of such a non-bladder/non diaphragm pressure vessel. But you definitely get a lot more water drawdown capacity with pump using a 15-20 liter pressure vessel than one without or a very small vessel.. And the pump designs using a pressure vessel also use less total electricity since they need to run less often even considering the current surge each time the pump turns on.

The constant pressure design with no-to-very small pressure vessel does provide a more constant pressure specifications-wise, but with a properly operating WP design a person can't feel the pressure change from 2.1 to 2.8 Bar for household use since it a slow change over approx 10 seconds as the pumps kicks in & out, and due to the water buffering throughout the home water pipes/system if feels like a constant pressure....or at least my house/WP-255 does.

One of the few ways to "visually" notice the small pressure change without a pressure gauge is to turn on a kitchen sink faucet (faucet output and sink bottom separation about 16 inches) full blast and watch the water stream impact point go back and forth on the bottom of the sink by about one inch as the pump cycles on and off...but as it is oscillating that one inch the stream of water flowing from the faucet should look constant and should feel constant to the touch. A person could also use a water hose to shoot out a jet stream and watch the small distance change as the pump kicks on and off. I sure know my shower feels strong with constant pressure visually and to the touch with my WP-255.

Yeap, a 250 watt pump seems to be a sweet spot for most households.

Edited January 11, 2011 by Pib

[Artisi]

Before running off buying a new pump,

1. is the pressure in your second level low without any other taps open?

2. have you checked the shower head for blockage.

3. some water heaters have an internal flow regulator - check it is not on low flow.

4. check if there is sufficient pressure at the heater inlet.

[najman]

Strange the 150w pump isnt enough for the shower upstairs.Per the Mitsubishi brochure it should be sufficient. We use a 105w for a 1 level house and the shower is strong. 150w should be enough. Unless your shower head is restricting flow such as some stainless steal taps and heads are designed for high pressure western systems. Can you unplug the shower water heater from the tap and see how strong it is?

Its worth checking these points first if you dont want to fork out the money for a new 250w pump.

[lopburi3]

The heater showers are self restricting in order to have time to heat the water so require strong water pressure if you want what most people would consider normal flow. I (and wife) find the 60+ pound pressure we now have to be good but did not find the pressure from even 405 Mitsubishi series well pump to be to our liking as pressure was limited to about half of what we have now. I suspect it has a lot to do with what you are used to having. But most people have two streams of water in home country (hot and cold mixed) but with point of use heater it is the one system coming through very small tubes inside the unit and to push enough water through requires more pressure.

[harrry]

Does increasing the pressure by using a 250w pump risk leakage in the pvc pipes?

[Pib]

Does increasing the pressure by using a 250w pump risk leakage in the pvc pipes?

If it a 250W pump like the Mitsubishi, Hitachi, etc., series sold in most stores then its pump cut-off pressure (i.e., max pressure output setting) is around 2.8bar (41psi). The blue PVC pipe sold in Thailand comes in different max bar rating, usually of 5 bar (72psi), 8.5 bar (123 psi), and 13.5 (196 psi). This pressure bar rating will be shown along the pipe every few feet unless the marking has has faded away. So even if the house builder used the lowest rated pressure PVC pipe,the pipe's max working pressure is still almost double the output pressure of the normal pump used by most people in Thailand. My house was built about 3 years ago and uses 13.5 bar pipe; my Thai mother-in-law's house out in the village was built about 20 years and also comes with the 13.5 bar pipe. There ain't much of a price difference between the different bar ratings. So, unless the PVC pipe was poorly glued together, faucet seals are old, etc., it should not cause any leaks even if you using a pump that provides around a 60 psi / 4 bar output. Any leaks anyone gets would probably be due to some loose faucet connections and old seals that were already borderline to begin leaking and could easily be tightened up or rubber seals replaced.

[Pib]

The heater showers are self restricting in order to have time to heat the water so require strong water pressure if you want what most people would consider normal flow. I (and wife) find the 60+ pound pressure we now have to be good but did not find the pressure from even 405 Mitsubishi series well pump to be to our liking as pressure was limited to about half of what we have now. I suspect it has a lot to do with what you are used to having. But most people have two streams of water in home country (hot and cold mixed) but with point of use heater it is the one system coming through very small tubes inside the unit and to push enough water through requires more pressure.

Yeap, even through the Mitsubishi WP405 (400 watts) pumps out more water volume suited for households with large water volume needs (i.e., it can pump out 60 liters/minute compared to a Mitsubishi WP 255 (250 watts) pumping out a max of 45 liters/min), the WP405 pump cut off/max pressure setting is still 2.8 bar (41psi) just like many of the lower output volume pumps in the 200 to 300 watt range. When buying water pumps a person needs to consider both their water volume needs and desired water pressure.