Too much pump?????

Brad White_9

New Definition of \"Heat Pump\" (NM)

Ron Schroeder

Hi Steamhead,

Most likely something else changed too. Examples could be the small circ was flowing properly but the larger one was defective. Not measuring from the exact same point for both before and after. Different supply temperature. Different air flow in room causing either improvement or degradation in convective flow. Partial blockage etc. etc.

If heat output decreased with increased flow, TRVs wouldn't work, but we all know that they do.

I have variable flow circs that can be varied over at least a 20:1 change in flow rate on my system and about 30 precision temperature sensors thru out the system. So far, I haven't seen it violate any laws of physics. ;-)

Steamhead (in transit)

Hmmmmmm

I haven't had the benefit of flow meters on the systems I've been working on- I wonder if the flows thru those baseboards were well in excess of 4 GPM before I worked on them?

I doubt the circs I took off were bad. I could hear them running, and as the zone valves started to close I could hear a bit of velocity noise.

And I measured the temperatures to get my delta-T in the same places each time. Of course the temps were a bit different after changing circs- that's why I had more delta-T.

ME- have you boosted the flow in your system way up over 4 GPM? If so, what was the result?

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Steamhead (in transit)

It's true some wet-rotor units

don't have a good wire-to-water efficiency. But for example, on a converted gravity system with 300 square feet EDR, I'd still use a B&G NRF-9F/LW simply because the pump is the right size for that system. No sense in using a 3-piece circ on such a system even if its W-W efficiency is much better- it's just too much pump in that application.

And besides- how many people other than heating pros actually oil their 3-piece circs each year?

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[Deleted User]

An explanation for Frank's findings...

One hypothesis' is as good as another, right?

In my readings and followings of your situations (the one published here at The Wall anyway) you are usually dealing with older equipment in the way of heat sources and heat emmitters. Both of these devices were intended for use as gravity curculation systems, whereby the resistance to flow through the units, and the conductivity of the units are EXTREMELY different than todays equipment.

In the case of the boiler, slowing down the flow probably would allow the water more contact time with the extremely thick castings of the heat exchanger, thereby increasing the delta T. Same holds true for the upright radiators, except that their design was such that they depended upon the suttle upward flow of water through their internal passage ways, thereby delivering more heat. When you throw a pumped fluid at them, the water SCREAMS past the vertical portals, causing a short circuiting of the heat and potential output and delta T.

So, in the case of converted gravity equipment, it IS possible to move the water through the equipment at a velocity that is not conducive to good thermal transfer, and slowing the water down in your case did increase the output and delta T.

In the case of newer high efficiency generating and delivery systems, I don't think it makes that big of a difference. As a matter of fact, if you have Siggys software, you can model a load, and model a baseboard system around that load, and by switching the circulator, the load remains the same, but by increasing the flow, the delta T is lessened.

Decreasing the flow increases the delta T, but the amount of energy delivered remains the same.

One means of being able to verify my theory on the boiler would be to watch the flue gas temperature. An increase in flow, and a decrease in delta T should equate to a higher stack temperature, and vice a versa.

That's my story and I'm stickin' to it!

Anyone else care to chime in???

ME

[Deleted User]

No can do 4 GPM...

At least not without a major change in near boiler piping and plumbing, and if it didn't do anything between 1 and 4 GPM, other than creating heat from friction, I don't think it would do anything on the top end either.

ME

Steamhead (in transit)

OK, ME

next time I run into one of these I'll run before-and-after combustion tests too. But I'm not sure if a lower stack temp would indicate greater heat transfer in the boiler, or in the radiation. Or maybe both.

I do remember on my own system, when it was still running the B&G 100 circ, as soon as the burner and circ stopped the water temp in the boiler (Burnham V-14) would rise sharply, maybe 40 degrees or so. I think this was because the water was moving faster thru the boiler than it should have been, not picking up enough heat, and when the flow stopped there was all this heat waiting to be picked up. Since I switched first to the Taco 005 and then the Grundfos 15-42, it no longer does this.


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Steamhead (in transit)

Welllll

until someone tries this, we'll never know for sure.

If ya don't test.......

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Mark Hunt

Frank


Darin got those stats from Siggy.

It's got nothing to do with oiling. It's all about design.

Mark H

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Steamhead (in transit)

Lack of oiling

has nothing to do with the stats, but has a lot to do with bearing failures. That's another reason I like wet-rotor circs.

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Mark Hunt

Agreed


But Darin came back from Siggy's class with some WILD info.

Frustrating as all get out when you want to rock but the accordian is the only instrument you get to use.

Mark H

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Steamhead (in transit)

Tell that

to Danny "The Phantom" Federici- he plays organ, accordian and a few other things in the E Street Band.

"Sandy, the aurora is rising behind us...."

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[Deleted User]

My eldest daughter played piano...

in the high school marching band:-) Had legs that looked like telephone poles ;-) NONE of the other band geeks ever gave her any crap though...

ME

Mark Hunt

Piano


in a marching band eh? Piece of cake!

My cousin's best friend's father's dad(Clem) carried the church pipe organ over Niagara falls while juggling dynamite with a rabid skunk stuffed down his Viessmann speedos in 1877!!!!

Had there been a world book of records then, he surely would have had an entire chapter dedicated to him.

He played the national anthem on his way down. Folks that had gathered to witness the suicid.....err.........spectacle said that it sounded like he was pressing all of the keys at once. Clem responded by saying that he had to play the song REALLY fast so it may have sounded like "one long note" or "screaming" but he assured me that he did, in fact, hit every note in the national anthem.

I think he's full of it.................no way he played the national anthem!

But I am not about to argue with a guy that can carry the church pipe-organ!

Mark H





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bob_50

Three piece versus wet rotor

Water molecules move in three ways simultaneously,translational,rotational and vibrational. I believe it is well known in some circles that wet rotor pumps transfer more heat. It is because of the intimate contact of the water with the rotating magnetic field in the rotor of the motor. This increases the the speed of rotation of the molecules reducing the stagnant boundry layer on the heat exchange surface.
(edit)This post is pure B.S. I was laughing so hard at Mark H's story about the pipe organ in his speedo's that I lost my mind.
Seriously, since we are now going to design for a SWEET-SPOT I need to know where to put the marks on my System Syzer.

Unknown

Wet Rotor Efficiency

The "line to water" efficiency doesn't tell the whole picture when referring to wet rotor pumps - let's not overlook there is a thermal heat gain with wet runners not included in the "line to water" efficiency calculation. Up to 70% of the heat a wet rotor pump's motor generates is "scrubbed" away from the motor at the inboard bearing plate and is transferred into the heating system.

Unknown

Wet Rotor Efficiency

Hey Hot Rod - good point. That's why I like "The Wall".

Yep, I guess there would be a small amount of hydraulic drag but these sleeve bearing wet rotors are very smooth.

Would this drag be the same amount as oiled or greased bearings in a dry rotor motor (and/or bearing assemblies in pumps that have bearings in their wet ends)? And how much effeciency is lost with this drag as compared to the thermal gain? Both difficult to answer (the "line to water" effeciency should take into account the hydraulic drag and ball bearing drag anyway).

Point being wet rotor pumps do add heat to heating systems - a thought that is mostly overlooked.

Different views from different perspectives...

hr

Ball, roller, or needle bearings

offer less drag than a bronze bushing, I believe. I think the PL series uses a sealed, lubed ball bearing.

Spin a shaft in a ball bearing, then spin a shaft in a bushing, the difference is usually noticeable.

hot rod

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Unknown

Hey Hot Rod - Bronze sleeve bearings? Don't know any wet runners that use bronze bearings...

hr

Ceramic?

My point being an open fram motor used on the PL series has a ball bering while the wet rotor circs use a sleeve type, regardless of the material

Actually bearing design is the critical component in that "state of the art" Dyson vacumn cleaner you see advertized everywhere.

It's not so much the blower wheel or design that is key to that performance, it's the fact he designed a bearing that can handle 100,000 RPM and last in an environment like that. Maybe

hot rod

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hr

The dilemma becomes..

how do you stand in front of a class room explaining the "most important" of all hydronic formulas used to design and spec equipment then give them "But not if"

Then you get blank stares and questions like how much of a difference, or how exactly do we tweak the calculations for certain exceptions to the rule.

And how do we know when we have exceptions to the rule?

It would be nice if we could frame a response around some solid, agreed upon numbers instead of "it depends"

It should not have to involve trial and error pump selection 101

hot rod

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bob_50

On the bearing issue

I think "it depends". Formula One cost no object racing engines use bushings. Lance Armstrong's bicycle uses ball-bearings.

Steamhead (in transit)

It's time

to set up a test-bed system.

And I think I know just where to do it.

Stay tuned.......

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Steamhead (in transit)

And

the mechanical seals used in dry-rotor circs generate some drag on their own. Case in point: the dear old Taco 110 requires a 1/12 HP motor that uses 2.2 amps. But the Taco 0010, with a nearly identical performance curve, has a 1/15 HP motor that only uses 1.1 amps.

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