Taco 007 or B&G 100?

Mr Takagi

I am looking for the correct size system circulator for my converted gravity system w/ cast iron radiators. According to Dan's book -http://www.heatinghelp.com/heating_howcome1.cfm - I need a lot of flow and the B&G 100 would be the best choice. But I've also heard that I need a slower flow, like the 007 would supply, to get a higher delta T and give the radiators a chance to absorb the heat. Any ideas?

Mike

DanHolohan

Please read this

By Steamhead:

Gravity Conversions

Kal Row

you can put in all the rust inhibiter on the planet

nevertheless your system will still get rusty and sludgy - do yourself a favor - buy the BG 100 BRONZE - if you oil it as recommended - it will outlive you, sludge and all

having said that - slowing the flow wont make the radiators hotter - rather your return water colder - slower is only more efficient if:

1)you don't have well insulated return pipes which would cause the hi-temp return heat to get lost,

2)you have a bypass/mixer on your cast iron boiler to keep it above the 140 condensing temp

also with slow-flow, if you don’t have well insulated supply pipes, the water could be significantly cooled by the time it even gets to the radiators

fuel was cheap in the gravity days - not so anymore - make sure you get this right - cast iron radiators need hi temps to be effective - unless they are large and visually out in the open where they can heat people with infrared light a-la-radiant energy, then they are effective as low as 100f, depending on the day, and you can use an outdoor reset to drop the system temps – will save you a bundle - provided you have a boiler bypass and mixing system – I helped a guy on the wall (whose contractor had no idea what he was doing) put in a weil-mclain ULTRA fully condensing boiler into a gravity system and is saving a bundle – attached is a system diag, even has domestic hot water coming off it – ps he is using a BG 100 bronze on the system loop – the boiler loop is using the taco 011 that came with the boiler and shouldn’t be a problem since the boiler will run the pump for at least a minute day even in the summer to keep it from sticking on the iron oxide in the system - cant tell what the long term effects of the iron will have on the ULTRA’S aluminum heat exchanger – I know that weil-mclain has one running for 15 years but don’t know that kind of load it’s attached to

RC

Pump to use

If flow is a concern but you don't want to use a three piece pump Taco's 0010 has a very similiar pump curve to that of the B&G 100. without the maintenance

Weezbo

Pumps arent the only consideration.....

distributing the heat ,so it does what you want it to (for example)initally you may want high heat delivered...then you may want slow flow for economy...mixing back at the boiler (oil fired) .........to answer it any different might send you off in the wrong direction. some gravity systems have pipe that acts as distribuion "Points"in the system...as long as you are distributing the heat properly for the emmiters and stradgey you may find variable speed to be a handy item...some of these conversions i liked the grunfoss three speed...and...modifing some zones with losing the pipe and installing somezoned convectors as well or instead of radiators.

R. Kalia

I posted a question about this in a separate thread---I should probably have put it here instead, sorry. The new thread is called "gravity conversion and flow rates".

R. Kalia

how?

> initally you may want high

> heat delivered...then you may want slow flow for

> economy...

How do you achieve that? I know about variable speed motors, but how does it decide when/how to vary the speed?

Joe Mattiello

Pump selection

Is based on load, and system resistance. You can calculate load, by adding the btu output of the radiators on each zone. GPM required, is 1 gpm, per 10,000 btu output. The system resistance is calculated by adding the lineal footage of pipe, elbows, and valves. Once we have accumulated this information, we can refer to a frictional loss chart, for the pressure drop of the system, when pumping X amount of flow through the system, to satisfy the load. Because you have an old gravity system your system pressure drop will be minimal, which means just about any small cartridge type circulator will work. I always recommend the Taco, 007-F5, because of reliability, availability, and cost. It has The Three major attributes needed for classifying it as a great product. However, we need to consider iron oxide, and residual debris, in that old system, which can be a detriment to a small cartridge type circulator. You may want to consider a three piece type pump, like the Taco 110 circulator, which would probably be oversized, but is more suitable for hostile duty. Please feel free to contact me at taco, if you have any additional questions, or concerns

Joe Mattiello
Technical Support Services
Tel. 401-942-8000 X 484
Fax. 401-942-2360
joemat@taco-hvac.com

hr

Look into the Grundfos

Super Brute 15-58. On speed one it may be exactly what you need.

I've never done a gravity conversion myself. The idea about slowing flow to increase output goes against all the engineering and formulas found in Dans, Siggys and many other writings, and the laws of thermodynamics! Generally the faster the flow the higher the average temperature the higher the heat output.

Q (rate of heat transfer into or out of a stream of water) Q= f X 490 X deltaT. The more GPM (f= flow)the more heat delivery. Look at baseboard and fan coil spec sheets. More flow, more heat output.

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,3760,00.html

BUT I'll go with Steamheads personal experience on this, as he has proven and documanted the concept. Hard to argue with sucess! I suspect the flow patern through the old style radiators has a lot to do with "slower is better" in these old systems?

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Weezbo

Hmmm...

maybe i not clear. so let me state this with out miss statement.".FullHeating is achieved with maximum flow,as the Outdoortemp rises,Less Heating is required hence less flow is required" that isnt something new and innovative i dreamed up .

Weezbo

Perhaps you could send me a picture of your system....

what kind of controls you have and some of the paticulars requirements of BTU's ,For the area where its located,your existing Iron Radiators what thoughts you have on zoning, what you would like to remove or replace in the system....I hear you saying you think it is all amatter of pump i dont buy that...there is more toit than that in my experience with remodeling gravity systems.and old coal fired steam systems. It is cold as a whiches coalminers ;)around here.I cannot fornicate up its too damm cold to be going back doing things to make it work right.ok? putting a oversized recirc pump is just going to waste money and your time. controling the flow through old radiators that work right isnt a problem ,controling the flow through new convectors isnt either,adding myson pannels or Buderas isnt some kinda difficult trick to preform,doing it right and getting it all balanced the first go round can be a bit of a chore..if my e-mail address is available to you send along some sorta picture or outline or something scratched on a paper bag...i am damm near clayrvoyiant:))i usually zone heat,call me frivilous whatever no problem...if what you want is one gert zone no indirect fine...give me an idea of the parameters...in our summer it gets over 100¡ãF some years in the winter in places it gets so cold the outside termostats indicator liquids fall out the bottom of the glass:)seen it! the last system of some rememberance was a Huge boiler that was placed then the building was built around it. i chopped out twenty bell an gossets,200 lineal ft of 2"black iron, put a pinner weil mclaine and a oversized pump pumping away just to get heat and remodel.installed some (convectors what we call baseboard)zoned it,modified some of the piping and paths jazzed up the radiators in the new church,added some bathrooms and a waterheater and a shop sink... lashed up another boiler later to run lag and lead smaller yet....and changed out the heavy grunfoss which was no longer butting heads with all the extra piping andfricked up iron radiators....and the guy and his wife are happy with the conversion..it has three zones now,a much smaller grundfos and i think that i talked him into outdoor reset though i didnt lash up the control if it now has one. i did however lash up some outdoor reset from honewell many decades ago on the original boiler...on the roof. how the system got all kinds of recircs on it over the years is anyones guess...there were hundreds of feet of copper runn all over the place too. there is no picture that i can send you to see how the original system looked...all i know for sure is the place ran outa fuel froze kinda hard a few times and it only vaugely resembeled the original installers work after twenty five or thirty years of well meaning Pump installers and leak fixers.Gone is the twenty inch stove pipe..and the Big bell an gossets now it has A singular 15 series ....the radiators all work the base board works and none of the plumbing freezes,and the church can be dialed up and down by going in and turning up the t stat.for an hour or so...then turned down when the people show up ...theres also a vent fan that dumps heat off the room if its t stat tells it its getting too warm.down stairs ,we put some baseboard in and jazzed up some bathrooms and it is conditioned and has a few radiators...and some base board.and it is zoned,with a seperate t stat. it isnt all about Pumping.especially if someone has alredy made the conversion and what was working at one time dosent. the coal fired boiler was like a megger the boiler i replaced it with is like170k true i had him insulateceilings, furrout and sheetrock block walls etc.still i stand by saying you may want to deliver high heat to an area and temper it down for economy by reducing the flows. i willtry to find some other way to say this ...something that dosent make anyone think that i suggest not recirulating BTU's....or that what i say is in defiance of the general laws of physics we all live under on the planet.

Mark J Strawcutter

criteria

reliability, availability and cost can be among the valid criteria for pump selection - but _after_ selecting pumps whose curves matche the application.

One of my pet-peeves is that around here the 007 is the "universal" pump. It's a great product, but not for every application.

Mark

Steamhead

Joe, I'm running your 005

on my gravity conversion having 545 square feet of American Peerless column radiation. That turned out to be the "perfect pump" for my system. The only thing a circ really needs to do on a gravity conversion is to move the water thru the boiler- there's usually enough motive head in the pipes to do the rest.

We bid a boiler in a rowhouse with about 300 square feet of radiation- one of the smallest old gravity jobs I've seen. Assuming we get the job, I'll probably use an even smaller circ on that one- maybe a 006.

I've never had a problem with a smaller circ getting sludged up on an old gravity system. Maybe it doesn't generate the excess flow that would stir up the sludge?

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"