Flow switch?

[NCFord]

I'm looking for a flow switch that will turn on a pump for my DHW. In searching for a switch, it seems that it's not as simple as I thought. First, they are a little pricy and not exactly what I need. Look at the specs for this one: http://s3.supplyhouse.com/manuals/1349181931851/81625_PROD_FILE.pdf

It's something like 4.5 gpm to activate the switch? I'm looking for one for DHW so I need something that will activate below 1.0 gpm. I think I'm missing something!! Thanks

 

[Beagle Dad]

I used the McDonnell & Miller FS6-1 which is a low flow sensing switch for 1" pipe and is available for 3/4" as well. This switch works reliably down to .15 GPM which makes the pump and plate HX operate as if you have an instantaneous DHW heater. The only problem is the price which was over $200.00

 

[NCFord]

Why does it say Not for Potable Water? Dose not sound good for DHW

 

[maple1]

You want to turn on a DHW pump, I think - but what flow will be flipping the switch? Boiler water flow? Or something else?

 

[leon]

I'm looking for a flow switch that will turn on a pump for my DHW. In searching for a switch, it seems that it's not as simple as I thought. First, they are a little pricy and not exactly what I need. Look at the specs for this one: http://s3.supplyhouse.com/manuals/1349181931851/81625_PROD_FILE.pdf

It's something like 4.5 gpm to activate the switch? I'm looking for one for DHW so I need something that will activate below 1.0 gpm. I think I'm missing something!! Thanks

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Why do you want one is the more important question?


If you are worried about heat loss through convection is there a reason
you cannot install a check valve to accomplish the same thing???

Is a remote hot water generator under the sink/basin not possible??

Why not install a very small bladder tank with a 20-40 pressure switch T wired
to your hot water pump?????????????? This would be less work using a
simple check valve to break the hot waters convection through the piping.

 

[NCFord]

When DHW has flow, I would like to turn on a pump. Basically I have a plate heat exchanger that will be pre-heating the water before it hits my Rinnai tankless. I only want hot boiler water "on demand" I realize there will be a bit of delay, but it will work.

 

[maple1]

Ah I see - you want the DHW flow to start a pump elsewhere. I was think from the first post that you wanted a flow to start the DHW pump.

I think some get around this by just pumping the hot supply water 24/7 and not swithing it - like in an OWB setup that heats DHW all summer. Which IMO is kind of a waste.

But seems to me there have been others posting about doing what you want to do - hopefully more feedback will come.

I haven't had to source a flow switch so not really sure what's out there. Would putting in a buffer tank or using a hot water tank as a buffer be an option, and controlling the temp of that (and thereby flow) by an aquastat or thermostat?

 

[NCFord]

Definitely don't want to run 24/7. What I would like to do is run the same pump that is turned on by my furnance fan, so it would come from a signal from the fan and or from the flow switch, but I have not figured out the wiring for that yet.