Is This The Right Pump For Me? Grundfos Cmb3-5

[Superskunk]

Just came back from Homepro with a new water pump. Actually not the model I want to buy at first but the staff suggested me this one. After unpacking it I read the manual and learned that this Grundfos CMB3-5 pump is suitable for water tanks above ground. Our water tank is underground....

Anyway the manual tells that the distance between the pump and the surface of the water should not be more than 1 meter (even if it`s a underground tank (?)).

Usually our water tank is almost full and this distance will not be more than 0.5-1 meter. But what is in the dry season? In our area, south of Hua Hin, we had one or two weeks this year without water from the village supply. The tank will me almost empty and the distance between pump and the surface of the water in the tank is more 1.5-2 meter.

Will I destroy my pump or is this nothing to worry about? If this is the wrong pump for the house I hope Homepro will accept a change to another model (Grundfos CH2-50PT), which was my first choice and it is also recommended by many others.

[Crossy]

Go straight back to HomePro, you should have no issues whatever swapping it for the correct unit.

Chances are it would actually be OK with a foot valve, but why risk it?

[linno2]

I have 5 pumps at my farm in Oz. Grundfos and Davey. Grundfos is a good brand and the model you purchased is about $900 in Australia. It has the very useful feature of 'run dry or loss of prime and overheat cut out' and it is quiet and energy efficient BUT it is only for above ground tanks or to boost low mains pressure. Completely agree with Crossy, take it back as soon as possible and I hope you still have the receipt. It may be they were not up to scratch with product knowledge or there was a supplier inducement to buy Grundfos at this time. If sucking from an inground tank or bore you will need a non return valve for sure to help maintain prime. Make sure the suction pipe is off the bottom of the tank so that it is above any sludge build up. So in addition to the 'maximum suction lift' distance you also need to consider how high you may wish to pump the water - if you have an upstairs toilet or shower for example. There are lots of pumps on the market that suck from a depth of 8-9 meters and delivery from 40-70 litres a minute at the outlets. Go for higher litres/minute if a 2 story house.

[kamalabob2]

I am of the opinion that every province in Thailand has a "pump shop" where the staff "know pumps" as they sell and install hundreds of pumps each year. Typically an independent shop with lower over head, lower prices, non commissioned sales staff and REAL service, before and after the sale. This sort of shop will send a trained person to your home PRIOR to you buying a pump, so they can recommend what pump to buy for YOUR situation. Real name brand pumps such as Grundfos, Mitsubishi, Hitachi that can be installed at your home by a solid crew. The same place where Thai business owners go to buy water pumps, that schools and villages have water pumps installed could be your supplier and they are in every Thai province. A store that would at no extra charge swap out your broken pump, hook up a "loaner pump" if they had to take your pump back to the shop. Buriram has such a shop, I know Korat has such a shop, as these are the high volume Mitsubishi pump dealers. The kind of store that will design and sell a booster tank system for a multiple story building as a matter of course. Not a shop that sells window curtains. It would be worth it for the OP to get his money back from a store that sold him the wrong sort of pump, and go to a "real pump shop". He will save money, get way better service, and deal with adults who "know pumps". The successful Thai people in every community know these shops in their area.

This is just one example, but this sort of shop is in all the provinces.

http://www.facebook.com/pages/Buriram-Ruangsangthai-Ltd/503589409660852

[Artisi]

The pump you have is in fact Ok with a footvalve, but a Grundfos JP of approriate size is probably a better selection and should be a similar price.