Circuit Setter Adjustments

[SteveJ]

So, I figured out my heating issues are due to flow issues and I would like to set the flow to a known value.

To this end, I got some Taco Accu-flo circuit setters off of eBay and was wondering if there is anyway to measure the differential pressure without purchasing the $3000 Taco 779 gauge?
http://www.hvacplus.com/product/779/260333

If not, I have some kind of expensive ball valves

 

[jebatty]

At least you can feel good about your fancy valves. Someone else will need to supplement my comment because I may be off base. It looks like each valve has a fitting for valve upstream and downstream. You should be able to find a couple of pressure gauges, maybe 0-5 psi is right (maybe something less?), connect a short hose to each, and then connect one to each fitting. You might have to get the air out of the hoses. The difference in pressure is what you will want to note. Do the same for each valve, and then also adjust each so that the difference is equal for each line. You might have to repeat this a couple of times. At that adjustment each line should have equal flow.

Here is another place where some additional input might be helpful. These numbers probably can be fine tuned. Assume you have 1/2" pex lines, and each line is 300 feet. A normal flow for 1/2" pipe is 0.5 gpm. This means that each line has about 3.53 feet of head or 1.528 psi pressure drop.

The 1.528 psi pressure drop seems to me to be your target, if the only thing you were measuring is the flow through the 300 feet of pipe, but you have other flow to get the water to and from the run of pex, so you will need to calculate your pump head or pressure drop between the boiler and the manifold based on total system flow. If you have 6 runs of 1/2" pex, 300 feet each, your total flow would be 3 gpm, and that's what you would use for calculating pump head/pressure drop upstream of the manfold. Divide that by the 6 runs, add it to the 1.528 psi pressure drop for the run, and this would be your new target of differential pressure.

For calculating pump head/pressure drop:

Fiction Loss

Good luck.

 

[bigburner]

I have a bunch of circuit setters-- It's far from an expensive ball valve. If you don't have the tool [mine is a B&G]. U can make one using a gauge and a couple valves. All it does is tell you the pressure drop across a calibrated orifice. Then you need to get the manufactures numbers and it will tell GPM. I also bought some taco 1.5 inch circuit setters off ebay for 11.00 each - cheaper then ball valves.

 

[SteveJ]

jebatty, bigburner,

Thanks for the replies and info...

I got four of the 1" Taco Accu-Flo of eBay for $20 each - I thought I was getting a good deal until I saw what bigburner paid :ahhh:

As far as measuring the differential pressure, can I measure each shrader independently and then subtract to find the difference and then use the chart at (broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/400-2.4.pdf) to find the actual gpm?

I am trying to find 60" wc differential pressure - is that the same as 5' which is about 5'/2.31ft/psi = 2.16psi?

I have a digital gauge that does tenths of a psi but not hundredths :long:

What about a draft manometer?

 

[jebatty]

Your math is right, but that's as far as I can get you. If you have the Taco valve and can get a good reading on the differential pressure, I also would think you could use the chart.