House and Garden Pump Review

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I have seen a few reviews about house pumps and i think there are some misconceptions out there. I have worked in the industry and i would like to straighten out a few things.

Work out use.

For a pump for the house. (Whole house, like a farm house where no mains is available)

1.Work out how many people you want to cater for at once. (forget parties or christmas when everyone comes round cos you will be fine).

Simple way is to allow 15-20 litres per min per person.

Hard way is to work out all the appliances in the house, rate them (i.e. 6 L/min per toilet, 10 L/min per shower, 15 L/min per tap, etc). Then to work out based on number of people, worst case scenario. i.e. I could have two people in the shower, washing machine going, and someone has just flushed the toilet and is washing there hands. so 10 x 2 + 10 (for washing machine) + 6 +15 =51 L/min.

2. Work out pressure required.

Starting pressure i used to recommend was 300 kpa or 42 psi WORKING PRESSURE. This means pressure at the required flow. (not max pressure). If you tank is at the bottom of the hill and your house is at the top you will need an extra 10 kpa (1.42psi) for every vertical metre (plus a little extra for pipe friction). Alot of people at this point go for 500 kpa. WRONG. (Well mostly misguided). Most people get this figure from the pressure reducers that are on the street. 500kpa pressure reducers. This does not mean you have 500 kpa at your house, it means you are limited to 500 kpa. With pumps, you are paying electricity for all the pressure and double the pressure is four times the power required. So go easy on the pressure. Sure if you like a nice firm massage in the shower or your washing machine to finish quickly, get more pressure. But for 75% of people 300 kpa is fine.

Allow for pipe friction, a rule of thumb is to add 10% to your pressure required, but if you have a lot of small pipes or your pipes are long (tank is a long way from the house), you will need more. If in doubt, i recommend consulting a local pump dealer, not a plumbing store. Plumbing stores are generally just interested in selling you bits and pieces with no advice and no after sales service. Pump dealers help you all the way. (Usually). Even online pump dealers can be helpful if accurate information is required for pipe friction.

3.Get your Duty and review.

So now we have our flow rate (51l/min) and our pressure 300 kpa we now have our pump duty. Pump duty or duty point is the designed flow rate. For domestic pumps this often means worst case duty. Our duty for this case is 51 L/min at 300kpa. Once you have this, you need to look at you house plumbing. The pipe sizes installed might dictate that we can't get the desired flow.  A max guide is 1/2" pipe 13 l/min, 3/4" pipe 37 L/min and 1" pipe is 60 L/min (based on max speed of 2m/s).

In my case if i was 51 L/min and i've got 3/4" plumbing (referring to copper, poly can be worse), i'm unlikely to get it. I'm more likely to be stuck to a max of around 37 L/min. Let just assume that's not a issue and we  can use 51 L/min at 300 kpa. You can know use this information to accurately compare pumps. All good manufactures will have published performance of there pumps. You may need to convert units.

i.e. 51 L/min at 300 kpa = 3.06 m3/h at 30 metres. (same but this just different units.)

Looking at the performance from Grundfos fir a CMB3-6 as an example you can see that the pump will do the job fine. (anything below the curve will do the job).

Picture to come later

4. Type and brand selection.

Above Ground pump

Multistage is typically best (most efficient), however if sucking out of dam, river or well sometimes it better to consider a jet pump. Jet pumps are less effiecent but can handle air better and generally suck better. If using of typical tank installation i would always, always recomend multisage. You will not waste electricity and it will be nice and quiet.

Below ground pumps

Good quality submersible pump. Make sure it is a multistage as well. Perfably double cased or shrouded for cooling. Another misconception is if pumps are in water, people automatically assume it will cool. Submersbile pumps accutally need water to move over there motors to cool. This needs to be considered when installing the pump for a good install. Double cased pumps will pump the water over the motor during operation. Shrouded pumps do the same thing but the shroud has been custom made by the installer and does not form part of the original pump.

Brands, without a doubt there are many.

Major quality brands for domestic pumps in Australia are Grundfos Pumps, DAB Pumps, Lowara, Davey, Onga, Southern Cross and Ebara. There are also alot of brands that claim to be a major top quality brand but i would argue these pumps have a long way to go before meeting this catergory. There are also alot of cheaply made pump brands.

If you are looking for a house pump, my personal preferance is GRUNDFOS. There are multiple reasons for this. 1. Long history of high quality product. 2. The modern Grundfos philosphy is to look at the Life Cylce cost. They look at making a pump that will last a long time, be cheaper to operate and be made with materails of less embodied energy (more enviromentally friendly materials). The result is simply a cheaper Life cycle cost. They would argue that although you pay a bit more to begin with, there pumps will generally be cheaper over time compared to even the cheaply made pumps or low end pumps.

5. Price guide.

Quality Pump. (Above ground).

0-25 L/min $500-$700

25-50L/min $700-$900

50-80L/min $800-$1300

(Below Ground)

Generally alot more ($1200-$2000 for the pump)

Premium House pumps (varible speed) $1200-$3000 for a small to medium

Large house light commerical can go up to $10,000 depending on depend (i.e. Top end would be large flow, standby pump and some fancy electronics)

Budget Pumps

0-25 L/min $100-400

25-50L/min $250-$500

50-80L/min $400-$600

(Below Ground)

$300-$800

6. Cheat sheet.

If you want a really simple recomendation. Here are some really simplfied suggestions

From a Tank.

Grundfos CMB 1-4 for one tap. Single person home.

Grundfos CMB 3-5 for two taps. Two person home

Grundfos CMB 3-6 for three taps. Three person home (medium home)

Grundfos CMB 5-4 for a medium to large home.

If you have a larger home than this i would consider a Grundfos Hydro Solo E Variable Speed drive Pump Set. You will have to sit down when you here the price but it will really save you money for a large house becuase the pump will speed up and down to suit your needs, saving electricity and giving you more constant supply. This product is the same product used on commerical situations, so you would be getting heavy duty gear.

If still in doubt have a chat to your local pump dealer, try to avoid phrases like "this is a 1 horse pump" or "this pump does 80 litres a minute" (but not stated at what pressure) or worst of all "this is a 8 tap pump". I know i have stated exactly this above but in context, i feel i have justified this. However, i still prefer to look at the duty point. The worst thing about tap ratings on pumps is there is no standard. Pump manufacturers can make up what ever they like and it will be correct. They can't make up the performance charts (flow versus pressure).

Hope this helps.

If it does please rate and i will write more reviews on other pump applications.

Best of luck buying a pump.

 

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