Bypass Heater with Automation System

stever · Mar 22, 2008

I agree a flowmeter is a good idea... I figure a plumbed-in meter is probably best. Is there a location in the piping that this should be placed? I'd guess right after the filter, but that's just a guess. Also, what brand is best (works best, fewest breakdowns, less cleaning needed, etc)? I've seen some that are post-installed (after everything is in place). In this case I have the chance to pipe it in with all of the plumbing.

Thanks

JasonLion · Mar 22, 2008

You need a couple of feet (actually pipe diameter times 14 or 15) of straight pipe to install a flow meter. The two brands of flow meters I have heard of are Blue-White F300 series and Rola-Chem. Rola-Chem is less expensive but also is made of less sturdy materials. Both of them must be purchased to match the pipe diameter and orientation and install into a hole drilled in the pipe.

stever · Mar 23, 2008

Thank you -- am I correct in thinking it would be best to put it right after the filter?

JasonLion · Mar 23, 2008

You can put the meter on any suitable section of pipe that all of your water flows through. It doesn't really matter if that is before or after the filter.

stever · Mar 28, 2008

OK -- now that I have decided to bypass the heater with an automated valve -- two ways have been suggested to me:

1) automatic (3-way) and manual valve -- allowing metering of the flow to the heater and more throughput when heater isnot in use due to both bypass and heater (at least a little) circuits open.

2) strait-shot bypass that will shut off for heater use. No adjustability. Simpler. 2-way valve. Figuring that some water will choose to go the 'harder path' and most will choose the easier path.

If you think option 2 will not get enough water through the heater, then the same problem exists in option 1, as the manual valve will not force water through the heater. The only difference is option 2 being simpler, but no having the ability to LIMIT the water though the heater when the heater is off. I am not a hydraulics expert, but I think that given the two paths, I cannot force more efficiency by forcing more water around the heater. It will naturally find the most efficient flow between the two.

I'd love your thoughts on this!

Thanks
Steve

mas985 · Mar 28, 2008

I would choose the second method although you really don't need the manual valve in the first setup either (use cam stops in the autovalve to make it partially open in the bypass position). Most of the water will flow around the heater when open and you don't need to close the valve all the way when running the heater (use cam stops in the autovalve) so you do have a bit of control on how much water goes through the heater in the off and on positions. In either setup, you can use the cam stops in the autovalve to make each valve position anywhere you want it. Also, if your main goal is to reduce head loss, the lowest head loss is with flow completely open to both the heater and bypass. Although I still don't think doing this is worth the trouble.

One thing to be aware of and I am not sure it applies to your heater but my heater will turn on the fan automatically when it doesn't get enough flow. So I would check your heater to make sure it doesn't have this "feature" otherwise the fan may be running in bypass mode unless you cut power to the heater as well.

stever · Mar 28, 2008

I understand your skepticism.... I might very well be wrong, but no real harm done (except for $200 or so to the pocketbook). I'll have a flow valve -- and the pressure valve on the filter (will that read the pressure for the whole sytem?).

I am leaning toward option 2 for the reaons -- simpler -- better flow, etc.

I'll be the test case -- can sombody tell me how to best read the pressures in heat mode and in non-heat mode.

Might be a few months, but soon either we'll all have a good new way to reduce pressure or I'll admit defeat!

Steve

mas985 · Mar 28, 2008

stever said:
I understand your skepticism.... I might very well be wrong, but no real harm done (except for $200 or so to the pocketbook). I'll have a flow valve -- and the pressure valve on the filter (will that read the pressure for the whole sytem?).

I am leaning toward option 2 for the reaons -- simpler -- better flow, etc.

I'll be the test case -- can sombody tell me how to best read the pressures in heat mode and in non-heat mode.

Might be a few months, but soon either we'll all have a good new way to reduce pressure or I'll admit defeat!

Steve

Don't get me wrong you will see a measurable difference. If you are able to shave off 10-20% of head, the difference in flow rates will be only 5%-10%. In fact, if you give me some details on the current plumbing and pump, I can give you a good estimate of the savings.

The change in filter pressure will only show the change in return head. Because you are reducing return head, flow rates will go up but the suction head will go up too. To know how the total head changed, you need a before and after suction measurement on the pump as well. Using the filter pressure alone will give you an overly optimistic change in head.

One more thing, Pentair heaters have internal flow bypass so when the flow rates get real high, they bypass most of the water to keep head loss low and to maintain a constant flow rate through the heater. So in effect, they all ready have a bypass mechanism within the heater itself.