Which circ?

Uni R_2

Do you use a spreadsheet to calculate head losses for cast iron monoflo clircuits? I have Modern Hydronics, but it's about copper and PEX only and just a rough mention of diverter tees with no support from the tool trial kit or the full blown version. When I think about section of section of main might have 3 branches open at the same time with one doubled up for heating below. It makes me realize the limitations of my math.

adambuild

Which circ?

Did a heat-loss for a home in Northern NJ and are installing an Ultra 105 to replace a 270,000btu beast that currently resides in the basement! Actual heat-loss came in at 80,000! The owner's bills are off the charts! The home has a Monoflo system with an 1.5" loop around the basement and .75" off each Tee to the rads. Round trip for the longest run is about 140'. QUESTION: Which Taco circ is best used? And why? How can I figure it out myself?

Thanks in advance, Adam

Uni R_2

Questions

Why wouldn't you install the Ultra 80? The load for the monoflo is hard to determine without knowing how many diverter tees are in place, if any of the branches are closed etc., but in a way this should basically be known. Can we assume that the existing system circ is properly sized? If it's too small, the heat in the home is going to be very sketchy because it needs a minimum flow to work. If it's too fast, then you'll hear the velocity. The Ultra will ship with a correctly sized circulator for the boiler loop. For the heating loop, could you just use what you have?

Alan R. Mercurio_3

This may help some?



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adambuild

Still confused.....

Which Taco circ would you use on this Monoflo system and why?

Thanks again, Adam

Brad White_9

One needs to know

the number of monoflow tees in series and the worst branch run and if any are closed off as UniR pointed out. Total round trip including elbows, fittings in the main and worst branch circuit. From there the head loss can be calculated.

I think you have established your flow (8.0 GPM assuming a 20 degree temperature drop).

Use the curve by drawing a vertical line at the 8 GPM line. When that intersects your nearest available head, the next pump size up if not exactly on, will be the first pump to check out. May not be the actual one but it is a good start.

adambuild

Brad

Thanks Brad,

32 Monoflo Tees, 140' longest run with 6 90's. What would the head loss be?

Thanks in advance, Adam

Rich Corcoran_41

Circ selection

You need to determine the resistance of your piping circuit at the desired flow rate. To make math easy, your looking at 8 gpm for 80K input, assuming a 20 deg delta T is the desired temperature drop in your system.

I don't have my tech. data accessable to provide friction loss for your system, but check out the attached flyer for our SuperBrute line of pumps - the three speeds will allow you to fine tune the selected circ after it's installed.

Brad White_151

Is that actually

32 monoflow tees or 16 monoflow tees on the returns each paired with a regular tee on the supply for example. Big difference!

Brad

adambuild

DUHHHHHHHH!

My apologies Brad! 16 Monoflo Tees with mating regular Tees.

Thanks, Adam

Brad White_151

No worries....

I calculated the main loop and branch losses including the fittings at 3.8 call it 4.0 feet of head. This does NOT include the boiler if that is on this circulator. You have to add that in plus any air separator, valves, near-boiler fittings.

If we assume another 2 to 3 feet of head for these and a total head of 7.0 feet, the Taco 005 or 007 seem right. The Grundfos 15-58 should offer similar performance plus speed control for optimum performance to actual load.

Here is the "show your work" part: (Glaze-Over Alert!)

It is less than I would have thought because I forgot
that you have 1-1/2" pipe mains and 3/4" branches. The Cv ratings are huge (a lot of flow at 1.0 PSI differential).

How much? 39.0 GPM per tee. You are running 8 GPM which makes me wonder why the fluid would leave with any enthusiasm. It will in proportion but we are dealing with very small overall pressure drops. At 8.0 GPM through each (7.5 through the neck because 0.50 GPM is in the branch), the pressure drop of each is only 0.144 call it 0.15 feet of head. All 16 are worth 2.4 feet of head.

I will assume equal flow to each, 16 branches at 0.5 GPM each = 8.0 total GPM and the mains would be iron if you care.

Anyway, the main loss including monoflow and regular tees comes to 3.28 feet of head. Technically that should include the branch losses because the main loss at the tee is supposed to be greater than the branch. I always add half a foot of head for the branch, sort of like adding a scoop of coffee for the pot. Call me conservative.

Now you have to add in your boiler loss. I do not have a chart for the Ultra 105 but if you are running Primary/Secondary to guarantee the Ultra it's own flow, your distribution pipe head loss I calculate conservatively at 3.8 call it 4.0 feet of head.

Brad White_151

Spreadsheet

Uni- I do have a spreadsheet I developed in which each segment/size is assigned a flow rate and this is converted against the Cv of 100 feet of pipe (the flow that will pass at a pressure drop of 1.0 PSIG or 2.31 feet equivalent. Thus each segment pressure drop is based on the actual flow, not an assumed maximum.

Fittings and such are converted into "Equivalent Linear Feet" which in sum is multiplied by the friction rate per 100 feet.

Generally this method is about 2-3% higher than the dynamic fitting loss method.

For special fittings like Monoflow, I enter that manually.

If it is any consolation, I hated math as a kid and am still not very good at it believe it or not. Perseverence over aptitude!

Uni R_2

Source

Do you actually have Cv numbers for cast iron monoflo's? The only ones I have ever seen were for when it is closed.

No consolation is necessary. The limitation of my math to me is the fact I couldn't figure this out. I can't really get all of the formulas and the constants seems to be missing too. My diverter tees are Armstrong and Armstrong hasn't made them in decades (that was there answer when I asked). I'm gonna try the DeltaP method and plot the lines for all 3 speeds on the 'lil Brute. Just how close to the pump do the readings need to be in order to be accurate? Would 2; up and 2' back be bad - there are tees there. Must they me absolutely equidistant?

Uni R_2

Adam

What circulator do you have right now?

Brad White_151

Give me a \"C\" Give me a \"v\"

Here is the Cv data but now that you mention it, I do wonder if it is with the branch closed. I just checked, you are correct. So whatever I posted pretty well cancels out the need to figure the worst branch run. Given the subject main is so large compared to flow, I think any of the circulators should be fine.

adambuild

Brad

Thank you so much for your effort and explanation. I came up with a similar solution based on the previous posts but was surprised and doubted myself. I appreciate your validating my solution. At first glance, a 007 seemed small, but now makes sense.

Thanks again, Adam

Unknown

Uni R,

Did you want the Cv ratings for CI Mono-Flo`s? I have them here, but it`s also with the branch closed. I also have the "pressure drop curves" chart too, for 1 or 2 tees, if that helps.

adambuild

Uni R

There is currently a B&G Series 100 on there. The initial reason fro my thread was because I plan to replace that circ when we install the Ultra 105. By the way, I just reread your 1st post. Why would you use an Ultra 80 which nets out 71mbh if the heat-loss is indicating a need for 80mbh?

Thanks again, Adam

Uni R_2

Adam

Adam, a 007 would be fine for the system. That series 100 would last you forever but if it's on constant circ for 200 days a year, a new 007 would pay for itself in electrical savings in only 2 seasons.

If you are presuming that by the time you get down to design temps you aren't condensing then yes you'd be short on BTUs according to the inflated Manual J calcs, but I wouldn't be surprised that you could go 10 degrees below design temp with an Ultra 80 and maintain temp. That's purely my opinion...

Uni R_2

Dave..

Thanks, I found the Cv ratings for B&G Monoflos (probably here thanks to Dan) but they were never of much use other than making me want to get the renos done quicker in my basement so that I could get the heat flowing past a double set of closed tees. Actually, once that rad was replaced and the circuits were open it made no difference to my 15-58. It can heat the house at speed 2 either way but it still failed to provide minimum flow at speed 1 with all the diverter tees back to normal fully open position.

Unknown

Uni, that`s OK,

just thought you were "looking", I have all that stuff, but the math involved, makes my head spin, aren`t vari-speed circs. the greatest!