Flow rates and pump curves

Steve Ebels

What's 11 feet? The whole system? Munchkin and near boiler piping? Just the Munchkin?

Cliff Brady

Flow rates and pump curves

Looking at the Munchkin installation docs I see that the recommended circulator to maintain 14 GPM at 11 feet of head for a Munchkin 140 is a Taco 0010 or Grundfos 26-64. But looking at the pump curve for the 0010 at 11 head feet flow rate is < 10 GPM. Is there something else being taken into account here?

Taco pump curves:
http://taco-hvac.com/uploads/Product_Chart/1.jpg

Gary Fereday

munchin pumpkin

Seems to be a problem there huh ? I'd get the Munchkin Rep on the line and ask ! Looks like a 0012 is needed!
bigugh

Cliff Brady

Can we get

Jeff the Munchkin Man on the line here?

Cliff Brady

The boiler heat exchanger

pressure drop per the manual:

80 = 8 ft at 8 gpm flow
140 = 11 ft at 14 gpm flow
199 = 18 ft at 19.9 gpm

The recommended flow rates based on 1 gpm per 10,000 BTU/HR W/20 degree delta T.

munchkin-man

Pumps curves we show are specific to the Munchkin

The curves shown in Taco literature are what that particular pump can do aside from being used on the Munchkin. The suggested model pumps in our manual are to over come the pressure drop through the boiler exchanger only. The primary loop must be considered in the sizing of the pump. In most cases the resistance through a primary loop will be overcome by the pump specified for the boiler being used. Sorry for the delay guy's I was traveling and my e mail crashed out.

Cliff Brady

> The curves shown in Taco literature are what that

> particular pump can do aside from being used on

> the Munchkin. The suggested model pumps in our

> manual are to over come the pressure drop through

> the boiler exchanger only. The primary loop must

> be considered in the sizing of the pump. In most

> cases the resistance through a primary loop will

> be overcome by the pump specified for the boiler

> being used. Sorry for the delay guy's I was

> traveling and my e mail crashed out.

Cliff Brady

Pumps curves we show are specific to the Munchkin

>Pumps curves we show are specific to the Munchkin

Aren't these curves in the Munchkin/Pinnacle pump independant friction per gpm flow curves?

>The curves shown in Taco literature are what that particular pump can do aside from being used on the Munchkin.

I understand that. But still I see a disconnect between the recommended GPM flow the pumps recommended for the M-140 and M-199. However, the M-80 recomendation of a Taco 007 for 8 GPM at 8 feet of exchanger head seems correct per the 007 pump curve.

I read the Taco pump curves as follows:

M-80 Taco 0007 at 8 feet of head = 8 GPM ok!!

M-140 Taco 0010 at 11 feet of head = 8 GPM not 14 GPM

M-199 Taco 0011 at 18 feet of head = 15 GPM not 19.9 GPM

Am I still missing something here?

flange

yes, you are missing the fact that if you size the pump correctly from the manuf's specs, you needn't worry about servicing that pump for a long long time. if you had a problem based upon selection og the pump based on the boiler alone, you would be told later that you needed to take into consideration the friction losses of the piping as well and you didnt.

[Deleted User]

Water temperature, water density, friction

theres a lot more to sizing a pump than meets the eye.

I assure you that the chief engineer at HTP has tried that pump on a boiler before he recommended it.

The interesting thing about these modulating boilers is that they really don't care (within reason) what the flow rate is. They will "see" the load as it actually is and compensate their burn ratio to match demand.

Don't worry, be HAPPY. Just use that they say to use and if it becomes an issue, you have written proof about their recommendations.

Just make sure you pipe it the way they recommend or your warranty may be in jeopordy.

ME

Cliff Brady

Look at the numbers

According to the Taco pump curves you won't get 14 GPM through 11 feet of boiler head (especially with the additonal head of near-boiler/system piping) with a Taco 0010.

Per the manual this is the the recommended circulator for M-140 based on 1 GPM per 10,000 BTU/HR which comes to 14 GPM. Agin, the M-80 fits the pump curve but the m-140 and m-199 don't.

I appreciate the responses here but, no one has addressed this in a concrete manner.

hot_rod

It's all calculatable

as far as the additional piping loss. A B&G System Sizer or Siggys piping design program will give you exact numbers, if you need it. You may not find the EXACT pump, however. You could upsize and use a flowsetter if you want it exact.

The Munchkin, as I understand it, modulates output by watching supply and return temperatures. Changing the flow changes the delta T across the HX, as ME mentioned, and the burner, and output, regulates accordingly.

Same thing if you over flue them. The blower moves less air which draws less fuel through the negative pressure gas valve and the output is diminished accordingly. Again, a pretty forgiving little heater.

With the latest batch of 3 speed pumps out there you should be able to find a pump real, real close to your designs needs. Should see a 3 speed 26 series from Grundfos soon, between this and the 3 speed 15-58 Super Brute, two pumps will cover a very wide range.

hot rod

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munchkin-man

Thank gentalmen for your help in the explanation of circ sizing

The statments made a true and correct and will work if sized correctly. Thanks again guys