Need Water Pump Switch That Comes On When Float Rises

[chiangmaibruce]

Hi. Our house block is small and surrounded by a tall fence. The stormwater drainage situation was marginal in heavy rain due to level of the road, and now the neighbour has rebuilt and raised their level.

Things not looking good when we get the next heavy session of rain - may need to raise the aircon unit - maybe sandbags!!

So I was thinking that perhaps our only saviour might be a system to pump water over the fence to the side road using a small concrete sump and an automatic switch connected to an electric pump.

In other words just like in a boat bilge pump, but with a 240v system. Have any TV users rigged up a similar system? Can you get this type of switch in Thailand (the reverse of the normal water tank switch which comes on when the float drops) - and in 240v? Any alternative ideas?

Thanks

[lopburi3]

Sump pumps are available everywhere, including places like Lotus, and would assume that have the built in switch to start them.

[IsaanAussie]

I have used such a sump pump to recirculate fish pond water. The pump and switch unit was around 1500 baht and was suspended by its power cable. You set the depth of water to activate it, both on and off, by adjusting by the length of the float arm (cable). Simple to install, Macro, Tesco, Big C etc all stock them.

What you need to check is the amount of water per minute you need to pump. Get a pump that will move that much and can lift the water over the wall, if that is your exit path. Make sure that the sump pit is large enough to hold that amount of water but not too big to limit the floats vertical movement.

I would suggest you build a filtering pit full of stones next to the pump pit and build two of three baffles so the water draining into the filter has to move under the first baffle, over the second and under the third before going into the pump pit. This will limit the crap carried with the rain water blocking up the pump.

If you dont fancy masonry work, buy a large round stock drinking concrete bowl (A segment of pipe with a base cast into in) at the local building suppliers. Use whatever you can get your hands on the segment the circular shape.

Lastly it is a good idea to put a cover over the pit. Stops rubbish, broken ankles and also most of the algae buildup.

PS. If there is foot traffic on the other side of the wall, then put a shower rose on the end of the exit pipe. Will not achieve much more than keep them guessing.

[chiangmaibruce]

OK, thanks for the feedback. I have now done the rounds of some of the shops and have some info to share with others.

There are two types of pumps you can use for this - a submersible pump and a pump that is mounted out of the water.

Submersible pumps: range from about 100w up to 400w for the basic domestic units (but can get bigger)

The outlet pipes for the basic units range from small (about 1/2 inch) up to 1 inch (have seen one 2" mitsubishi unit). The better ones are stainless steel, the cheaper ones plastic and whatever.

Some have automatic water-level switches (on a a lead) attached but most don't. Of those that don't, some have auto cut-out (in case the water level is too low) and others don't. Some can only really run with clean water, others can handle a bit of sand, mud - some are even ok for sewage. Prices range from around 1,500 baht up to 4,000 baht and beyond for the bigger/stronger units.

The best value one of these I have seen is an Italian unit at HomePro, 400w and fairly robust looking. Has attached water level switch. 1 year warranty and 1" outlet. About 1,700 baht.

Pumps mounted above water level: Here you have the whole range of house units of many capacities and much difference in construction quality and capacity. Again, not all of these can handle dirty water with bits of leaves, etc. With these (for my intended use) you have a couple of issues. First the need to have a water level switch wired in (operating as per my original post). I have seen a couple of types of switches but they are pretty simple, float on string things, that can be wired to switch on either when pressure is applied to the sensor arm - or when pressure comes off. The problem here is that - unless the set up is in an enclosed space then kids/dogs etc can get at the string/float and wreck it. So for me I would need to have the string inside a PVC tube and the float in a semi-sealed sump.

The other issue is that not all pumps are self-priming and the pump would need to suck air for a while to get any water (depending how high about the water level it was mounted). In other words you don;t want to be out in the rainstorm trying to get the pump primed every time you need it. Not sure how many pumps will self-prime like this and of course the shop assistants are generally useless. At Homepro for example we ended up having a small crowd of staff gathered around until we could find one who would even venture to answer our complex questions like "which pumps have automatic switches?". This done in Thai mind you, so it wasn't a language issue. Again, I am not sure whether the submersible pumps will self prime or not, but at least they are sitting down in the water already.

OK that's it for now. Happy pumping folks. CB