Does anyone know where to get a water flow meter that will close or open a switch when water is flowing? I have an AC unit that uses water to cool itself and it produces 110 deg water if you reduce the flow enough. I'm trying to build a setup that will switch between the on demand hot water heater and the AC unit for the house. The major difficulty is determining if there is water flow to the hot water lines in the hosue..
At work we had a problem in finding a reliable way to detect water flow. The mechanical types just get eaten up or jammed over time. The electronic ones could not stand the environment it was subjected to (High irradiation). So we set forth and designed a basic 2 probe sensor in a gutted ball value to be used as the body.. shielded the probes back to a safe environment where we use a osc circuit through the probes in to a balanced system. when the waters moves a shift is created in the signal.. etc..
My (very typical) automatic shower pump has a flow operated switch in both the hot and cold sides, to start it up as soon as water flows as a result of opening the water valve. It's based on a small magnet that moves up against gravity in the water flow, and closes a reed switch. When the valve is shut and water flow ceases, it sinks back down, and the reed switch opens. If you know any plumbers, they're sure to have an old pump that they have changed lying around, that you could cull the switch assembly from.
Hmm.. Automatic Shower pump? What exactly is that? I'm not sure we have that here in the USA. Could you describe a little more? Even if we don't have them I could build one eaisly enough with a hdd magnet and a checkvalve and a gutted relay. Just don't know how reliable it would be. Thanks Arfa!
OK. Stored hot water system in house (common). Header tank located on low platform in roof space. Low pressure cold supply for basin / bath feeds derived from same header tank. Shower room upstairs. Shower head only 3 feet below header tank. Result ? Not a lot of pressure at the shower head - certainly not enough to run a fancy 'power' or 'massager' head. Solution ? An automatic shower pump. Take a look here for a picture
It is a twin impeller pump that is 'broken into' the hot and cold feed pipes to the shower. As long as the shower is off, it just sits there dormant. However, as soon as you turn on the shower valve, water starts to flow through the impeller housings, and up through the reed switch assemblies on both sides. This switches the power to the pump motor via the (presettable) speed control circuit. The pump raises the low feed pressure to over 20 psi. Result ? A nice powerful hot and cold feed to your shower valve, allowing you to have just about any type of shower head fitted, that you like.
I have a dead one here. Not sure how easy it would be to canibalise, but might be able to fix you up with the switch unit from one side. It is very sensitive, and in all the years I've used these pumps, the system has been very reliable.
I couldn't put you a figure on it, but turning the shower valve just a quarter of a turn out of perhaps 3 turns available, equating to just about a dribble of water from the shower head, is enough to activate it - I just went and checked for you, how dedicated is that ??!! :-)
Very reliable system. Never fails to activate the pump. This shower is used every day of the year by at least 2 people, and often as many as 5 people. I am on my third pump in about 20 years. First (cheapo) one developed a motor fault after doing stirling service as the kids grew up. Second one just wore out its bearings, and became very noisy. Current one is heavy duty version, rated for 'continuous' use, and has been in service probably about 5 years. If you know any plumbers, I'm sure that they would have an old one lying around the yard somewhere. All the ones I have owned / seen, employ the reed switch method to control them.
: :Hmm.. Automatic Shower pump? What exactly is that? I'm not sure we have that :here in the USA. Could you describe a little more? Even if we don't have :them I could build one eaisly enough with a hdd magnet and a checkvalve and :a gutted relay. Just don't know how reliable it would be. :Thanks Arfa! : :Mike :
There are a number of flow switches available but only those made of plastics (Noryl) would be considered inexpensive. Gentech International make several inexpensive (approx $50 per one) including the FS-01 and FS-02.
Farnell, a UK parts distributor, is represented by Newark in the USA
If you type "gentech international" (without quotes) into the search box you will get a complete listing including the FS-01 nad FS-02.