Is is possible to use a speed controller (like a light dimmer) with a small pond pump?
I have a Bermuda 3000 (3000l/hr) submersible pump that's really a bit more powerful than I need. The motor has a solid rotor that appears to be made of a ferrite like material.
I know that speed controllers can cause overheating problems with some motors but given that it's underwater with water bathing the rotor, I don't imagine this would be a problem in this case.
Tim
Unless you want to boil the water. It is simpler to install a restriction washer to the outlet spout I would think. If the diameter of the spout is, say, 10 mm full bore. Then placing a washer with a hole size of 5 mm should greatly reduce the output from the spout.
Is the fancy head removable ? If it is, then put a small rubber washer with a smaller hole on top before you put the head back on.
Get a smaller pump it may pay for itself in electricity.
Quick calculation - 3000 l/hr pump takes 30 Watts - 1500l/hr pump takes 20 watts, so you save 10 watts switching to a smaller pump. 10 watts costs about £5 assuming you run the pump 24*7, pumps cost £50, so you only save money by changing the pump after 10 years!
Of course these numbers are almost certainly wrong!
I thought the best way to control the flow would be to bleed some water off before the fountain/filter or whatever is taking too much water.
Andy
I'd suggest the following...
BV.
Pumps may use less than sticker ratings. I have several 600W submersible pumps, that are (IIRC) 3000l/sec, from lidl. I stuck a meter on them, and they come out at around 360W.
Rather than waste the pump's output by restricting it, run a "T" off the output side and divert some of the flow to a home-made venturi (another "T" with a restrictor on the long side and and an air intake tube into the short side - you have to experiment a bit to get it right). This will add valuable oxygenation to your pond and add a little more movement to the water. Balance the flow between the two outputs with ball valves on the hoses.
In this case, simple speed controllers won't actually work, it'll stay at a constant speed (3000RPM) until it stops working, and hums loudly. Suitable speed controllers are going for around 40-50 quid on ebay. Search on inverter phase motor induction on ebay, searching titles and descriptions.
I've already got a restrictor and T-piece on the pump outlet so I can control the output at present. Somehow it doesn't feel "right" to reduce the flow this way. I can't help feeling that it's putting extra load on the pump. As I have a reasonably hefty lamp dimmer kicking around, I was just wondering if using a device like this would be more mechanically "sympathetic" IYKWIM. (Probably complete nonsense I know).
Tim
Pace "Home Improvement", there is no such concept to a man as "too much power". What you need is more pond...
Well put.
Since these are just turbine pumps, there is no difference as far as the pump is concerned as to the location of the restriction on either the input or output. I would not use a lamp dimmer since these are typically just triacs and have a spiky output waveform which will cause motor heating, however a variable speed control for a ceiling fan should work fine. One other aspect to be aware of is that many pumps use either a fan or in the case of submersibles, water to cool the motor. In this case any restriction of flow, either by speed control, or by restriction may result in some heating and should be watched.
Jeff Lowe
On Fri, 21 May 2004 17:05:22 +0100, in uk.d-i-y "Tim Downie" strung together this:
If you read the instructions on most pumps that's how it's supposed to be done. And under high pressure it probably would put additional strain on the pump, but not really a concern at low pressures.
I have often wondered about that and assumed that by restricting the input the pump would be able to empty the chamber faster then it could fill it causes the chamber to be a mix of air and water, whereas if you restrict the output, the chamber will retain more water and less air. Surely both ways make the pump work a bit harder, but it seems to be restricting the output is better for it then restricting the input.
BV.
It is generally best never to restrict the input of a pump. I did not get to see the original pump type, but many explicitly spell that out in their directions as it does for my Sequence pump. Try to "reuse" the pump pressure in other ways - redirect part to a filter/waterfall. Restricting the pump on the output side is the same as adding head pressure due to vertical pump height, fitting losses, change in pipe diameter etc... All reduce flow rates. Tim
Cavitation is a real concern if you put it on the input. This does cause RAPID wear on the impeller.
Since we were talking about lamp dimmers I guess I assumed we were talking fractional horsepower. I didn't think these capable of enough suction get below water's vapor pressure at pond temperature. I mean that's 29" Hg. Of course some ponds and pumps are bigger than others ;-)
Jeff
That's not quite how it works. The large amount of turbulence in the pump means that the pressure varies quite a lot. It's quite easy to get pressure locally to fall down below the vapour pressure. Then the bubbles collapse, and the rebound is VERY powerful. This happens even to speedboat propellers ofr example.
Using real numbers from Via Aqua pumps
3000 lph = 45 watts 1500 lph = 15 watts 30 watts x 24 hours = 720 watts perday 365 days x 720watts = 262800 262.8 kwatts x .5L (your pricing) = 131.4L Pump pays for itself in 4.5 months @49LHow did you do your caculations?
10 watts per hour x 24 hours = 240 watts per day. 365 days x 240 = 87,600 watts 87.6 kwatts x .5L (your pricing) = 43.8l Pump pays for itself in 13.2 months.HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.